Diy pellet boiler: DIY Pellet Fed Boiler Is Hot Stuff
drawings, device and principle of operation
The heating issue in the house has always been quite acute. The search for the best options continues to this day. Some choose solid fuel heating, while others stop on gas. One good option is a pellet burner.
In this article we will look at what this design is, what is the principle of its operation, features, advantages and disadvantages. Although the furnace mechanism is rather complex, we will consider the technology for its manufacture, since the furnace is expensive.
Why use a pellet burner
Pellets are the material for the firebox. We are not talking about ordinary pallets for transportation. Burner pellets are pressed wood in the form of small cylinders. Their diameter reaches 25 mm. They have successfully broken into the market and never cease to conquer it. People who have used such fuel note its high quality and use only it.
However, if the pellets are the same wood that is loaded into the firebox, why spend money and effort on creating an additional mechanism? Although this is logical, but in this case, the solid fuel material will burn by 80 or even 40%. The leftovers are simply disposed of. As a result, the efficiency of such a furnace is significantly reduced. If a burner is used, the combustion of the material will be 98%. The difference is significant.
Note! Pellets are not suitable for pyrolysis boilers. During operation, they harm him, and the equipment has to be serviced more often.
It is also important that the temperature inside the burner reaches 1000 degrees Celsius as the pellets are burned! That is why it is worth considering whether it is possible to put a pellet burner for your boiler. This is quite rational if you understand the principle of operation of a pellet burner during assembly, as well as follow the instructions. Then the burner will be an excellent addition to the boiler, improving its efficiency. The video shows a pellet burner and how it works.
The main task of the burner is to organize a powerful torch that will heat the boiler. A pellet burner is used for the same and consists of a small combustion chamber in the form of a wind tunnel. Pellets are fed into it from the bunker. A directed flame is generated by the air flow. The combustion chamber is made rectangular or round. The outer part consists of a screw conveyor. Fuel from the bunker is supplied through the inlet pipe. The next irreplaceable element is the fan. It will supply air to the bottom of the chamber.
The principle of operation is as follows: the pellets enter the chamber, where they are ignited. The fan turns on, supplying a minimum amount of air. When the flame ignites, the fan spins faster, blowing in more air. The result is an even and powerful torch. Factory burners are fully automated. The pellet burner controller allows you to regulate the supply of pellets, air, etc.
Features of the work
The device of a pellet burner assumes the presence of an even powerful torch, which is necessary to heat the water jacket. The intensity of the flame can be adjusted. To ensure the supply of husks and granules, a screw conveyor should be used, while fuel will flow into it from the loading hopper. The volume of the latter should be determined by how long the operation of the device will be.It is important to equip the structure with a fan that will blow air into the combustion area. Pellet burner drawings can be made by you yourself. It is important to take into account the estimated dimensions. For example, a combustion chamber can have both circular and rectangular cross-sections. The first option is somewhat more common, since manufacturing in this case is simpler. A flat fuel pan is installed in the round chamber, while the chamber itself is fixed to the flange plate. The latter must adhere to the outside of the device.
The pellet burner is one of the most economical devices combining:
- security;
- cheap fuel, moderate consumption and high level of efficiency;
- one of the advantages of this type of burner is the ability to automate the boiler room operation.
A solid-fuel type device in various modifications is produced mainly by foreign manufacturers. Their cost is not always available. However, if you have certain technical skills, making burners is permissible with your own hands at home.
Why pellets
For those regions where gas is not available, such biofuels are salvation. It is extremely efficient and cost effective. For comparison: burned 1 kg of pellets emit heat energy equal to 0.5 liters of diesel fuel. They are capable of delivering 5 kWh. To heat a one-story house in an area with mild winters, you need 50 kg of pellets per day. The advantage of fuel is that it can be filled up once for several days. It all depends on the boiler model. Pellets are loaded into the hopper, and then they are fed into the burner itself. A DIY pellet burner needs to be serviced twice every 7 days.
If we talk about the disadvantages of this solid fuel and burners, then this is the likelihood of reverse thrust. In this case, the fire will burst into the bunker. The result is a fire in the house. The second point concerns the amount and intensity of air supply. Pellets are lightweight, which means that the air flow sometimes blows them off the device. Then they will not burn. And when the air supply is small, the fuel is not completely burned. In order for the burner and stove to function correctly, it is important to adhere to the sequence.
You need to ignite the fuel with a ceramic rod lighter. It not only gives direct fire to raw materials, but heats up over 1,000 degrees. This is done so that during firing up the flame does not go into the hopper with other pallets. Further, air is fed in so that the combustion torch remains stable and even. After this, an exit to the operating mode occurs, since a large amount of air is supplied inside. The process can be stopped by stopping the air supply to the burner.
Malfunctions and their elimination
A do-it-yourself or purchased industrial pellet burner may have malfunctions caused by:
- the content of foreign inclusions in the pellets. It is diagnosed by the presence of dirty greenish slag in a stopped burner. Eliminated by cleaning the bunker or increasing the power and air consumption;
- using pellets of different diameters or sizes exceeding the required design. Leads to failure of the mechanical fuel supply elements, which can be restored only by complete replacement of parts;
- transition to a new pellet size. Possible stopping of the boiler in this case can be prevented by increasing the feed rate of wood pellets;
- using peat pellets, which causes contamination of the optical sensor and leads to an error indication. The solution to the problem is to replace it with wood fuel, or constant visual control;
Equipping boiler rooms with economical and automated solid fuel burners greatly simplifies the life of the inhabitants of the house.However, any technical device requires timely diagnostics and preventive maintenance. Clean up waste waste and take time to periodically inspect the technical condition of all elements of the boiler room. Such simple steps will allow you to get maximum safety and comfort.
What are pellet burners
Products are divided into several varieties. After reviewing them, we can choose the option that best suits different conditions. For example, in order for a pellet burner to function, electricity is needed to drive the mechanism. But what if the electricity in the area is often lost? This we will find out by considering the following types of burners:
- pellet burner with forced intake;
- gravity pellet burner.
Pellet burner with forced intake
This device is one of the best when it comes to fire safety in the house. The representative is the Teplodar pellet burner. The downside is the high cost of burners, reaching $ 3000. The burner has several mechanisms for supplying pellets inside. One mechanism operates the auger and the other operates the pneumatic system. The safety of the product lies in the fact that the channel runs from bottom to top (pellets move along it). The flame will move in the opposite direction, so it will not get into the bunker.
Note! Fuel is supplied in portions and does not remain in the channel through which it moves.
Another advantage is that pneumatic designs are equipped with large bins. They can be downloaded once a month.
As for the auger feeders, they have two main units. The first is the auger. He takes the pellets from the hopper, pouring them into another mechanism. Another auger lifts them directly into the burner. Even so, a fire is possible, as fuel remains along the entire length of the auger. For protection, engineers create another assembly that matches the material to the burner. It melts and self-extinguishes. This is a kind of fire cutoff.
The disadvantage of these mechanisms is that they are dependent on electricity. Without it, the supply of pellets stops, and even worse, the heating system may suffer. You need to supply power to two electric motors. In the case when the electricity is stable and does not disappear, then you can buy air blowing. With it, the combustion of pellets will be better, as well as the efficiency.
Gravity pellet burners
Such constructions are easier to use. Their great advantage is their performance even without power supply. The principle of operation of the device is to pour pallets into the firebox under its own weight. Pellet burner behemoth and pellet burner pelletron are the brightest representatives of gravitational products. They can be brought into operation by adjusting the flow damper and the draft regulator on the chimney. Minus designs – pellets in the hopper can ignite.
To solve the issue of fire hazard, manufacturers install thermal dampers on burners of this type. When the flame is pulled out of the hearth and moves to the bunker, a special sluice comes into play. It is heat activated. The airlock serves as a fire barrier. Another protection option is a double grate. It is a simple two-part mechanism. The upper one goes to the pellets and takes a certain amount of them. Further part is shifted to the flame. The second part begins to dump ash into the receiver.
Advice! For a double grate, it is also recommended to install a fire lock. The mechanism can jam, and the fire will penetrate to the pellets loaded into the bunker.
Do-it-yourself burner
How to make a pellet burner? The combustion chamber is made from a steel pipe. Wall thickness – 4 mm, not less. The steel is heat-resistant and will withstand high temperatures.Attachment to the boiler plant body is carried out by means of a flange plate. For manufacturing, steel 3 mm is required. It is better to buy a conveyor for feeding pellets or use an auger.
To rotate the mechanism, you need bearings, a low-speed motor (electric) and a gearbox. The air blower can be purchased at the store. It is fixed on the plastic, in which the place has already been prepared. The plate is made based on the drawing. The configuration depends on the boiler door itself. A drawing of the burner can be seen in this photo.
An obligatory step is to adjust the amount of incoming pellets and air. Without this, the device will be unstable or constantly at full power. To change the intensity of the fan and auger, you can set a manual regulator. In this case, you will have to constantly watch and adjust the burner, taking into account the temperature of the coolant and air.
It is important that for various work processes, fuel and air are correctly selected. Only then will the torch be even and stable. This requires an automated device. You will need a control unit. The controller for the burner has free control contacts, to which the electric motor from the auger and the fan is connected.
To automate the ignition of pellets and control the flame, you cannot do without a photosensor and an electric filament element. The photosensor monitors the appearance of a stable flame and notifies the controller. It will shut off the filament element. But the incandescent element is needed to ignite the pellets. The delivery pipe is equipped with a filling sensor. It stops feeding the pellets when the auger and the top nozzle are full.
Preparatory work
A do-it-yourself pellet burner cannot be made without the main component of the same name, which is recommended to be purchased in the store. This is due to the fact that the burner itself has a rather complex design, and although it is possible to make it yourself, such manipulations are difficult to implement. The burner is an element where the fuel is ignited, however, it also regulates the intensity of the flame. Among other things, the design will include sensors and programmers that allow for more economical fuel consumption. With the help of these elements, it will be possible to achieve a comfortable indoor temperature. The pellet burner must have a housing that is recommended to be placed horizontally. This will allow the most efficient use of the heat recovered from the combustion of the fuel. Sheet steel can act as a material for forming the body, but experts sometimes advise using cast iron or brick. You can choose the material that, in your opinion, is able to keep warm longer. The housing must ensure high-quality heat transfer to the next element of the device, that is, the heat exchanger.
The pellet burner must have a heat exchanger that is located inside the body. It looks like several pipes, which are sometimes replaced by a coil. They are connected to the building’s heating system. Among other things, an inlet for pouring cold water should be provided. When making a combustion chamber, a hole should be provided in it, the diameter of which should be equivalent to the parameters of the purchased burner. The 100mm auger and electric motor will work in tandem. The latter is to be connected to the device control unit.
Anyone else doing a DIY oil to pellet burner conversion?
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#1
Wondering if anyone else is doing this and might like to share ideas, results, etc.
I have a Biasi 4 section cast iron boiler that was fired on #2 fuel oil. I wanted to convert it to burn wood pellets, but after looking into what’s available, I think the imported pellet burner guns are just too pricey and they don’t address the issue of ash removal. Ash removal is really more about the boiler than it is about the burner. In the case of my Biasi boiler, it’ll hold about a weeks worth of ashes.
I burn more fuel (oil or pellets) than most people because my house needs some work. Yeah… I know… but I’m working on that… I chose to get away from buying oil so that I could invest the money into tightening up the house and replacing some ductwork on my air handler for the large room over the garage.
Last year I burned waste motor oil in a custom burner that I built. I started with a Beckett AFG burner and added a custom drawer assembly with a 400W preheater and a digital temperature controller connected to a solid state relay to controll the preheater behind the nozzle. It worked great, but it’s such a hassle collecting waste oil and I found that towards the end of the winter I couldn’t get enough to heat the house with, so I decided to move that into my shop and build a pellet burner for my boiler.
The Biasi has a cast iron cover on the firebox that the burner bolts up to. I removed that cover and fitted a 1/4″ steel plate to replace it. I built the burn pot from a short piece of 4″ angle iron welded to the plate and lined it with firebrick. firebrick cuts easily enough with a masonry blade on a table saw. I slotted it on the bottom where it meets in the center of the angle iron so that I can blow some primary combustion air under the firebrick and use the angle iron as a duct to get the air under the fire.
The feeder tube is a piece of 1 1/2″ black iron pipe. It’s cut off flush with the 1/4″ plate and positioned at a 45 degree angle so that it allows the pellets to drop into the burn pot. My phase 2 burner will use 2″ pipe insteas of 1 1/2″ pipe because I’ve found that a couple of times that the pellets have jammed in the feeder tube and it was only necessary to give the tube a tap with a wrench to get them moving again. So I learned that 1 1/2″ pipe will work most of the time, so I think that 2″ pipe should work all of the time.
I put two 3/4″ holes in the plate for primary combustion air. One hole is between the fire brick and the angle iron, the other is right on top of the firebrick so the pellets cover it as they drop into the burn pot. I built a primary combustion air plenum, a small steel box on the outside of the plate with a damper in it so that I can adjust the airflow between the two holes. I’m using a small centrifugal blower from a dishwasher as the primary combustion air blower. Even this little blower is overkill and I have the blower inlet restricted to leave an opening about the size of a quarter.
My chimney is about 10′ of 6″ type L wood stove pipe that goes through the ceiling and roof of the boiler room. It’s not much of a chimney and I didn’t trust it to make enough draft to safely operate a pellet burner. I had an old power vent blower in my shed, so I brought it in, cleaned and lubed it, and installed it on the back of the boiler to force the gases up the chimney. I’m sure this is why I need so little combustion air from the primary combustion air blower. Someone else with a better chimney may not even need a power vent, but it’s absolutely imperative that gases never, ever be allowed to go back up the feeder tube. Pelix uses .03″ as a minimum draft requirement for a chimney and I think that’s probably a good universal standard. For pellets, I’d measure that over the fire rather than at the breach to account for restriction in the boiler itself.
Ignition was an interesting part that required a little tinkering to get it to work right. I wanted hot air ignition, not hot surface ignition. I didn’t want anything laying in the burn pot getting eaten up by the fire over time. I welded a piece of 1/2″ black iron pipe in and through the primary combustion air plenum, stopping just short of the upper inlet port through the 1/4″ plate so that hot air blown through the pipe would blow directly onto the pellets.
I looked at the Leister wood chip and pellet ignitors and they looked perfect for this, but they’re just too pricey at $275. 00. I went to the local discount warehouse and bought a cheap chinese heat gun and took it home and dissassembled it. It looked perfect for the job. It had a centrifugal inline blower and a ceramic heating element. It’s weakness is the little 17V DC motor that spins the blower. I went through 2 of these in 3 weeks. The brush holders are made of something not much stronger than an aluminum beer can and both of these tore up the brushes after about a week and a half of service. I had another heat gun around. This one has a squirrel cage type blower and nichrome heating elements. That one works much better and it’s still working just fine after a month, but it looks a little strange hanging off the front of the boiler. It’s the one that Harbor Freight sells and it’s sold in a lot of different stores as well.
The hopper and the auger were my next build. I decided to use a 55 gallon barrel as a hopper. It’ll hold about 7 bags of pellets, and about 6 and a half bags are usable fuel. I could have gotten fancy and tapered the bottom, but it was easier to dump an extra half a bag of pellets into the hopper than it was to spend a day with a cutoff wheel and a mig welder. Small augers aren’t easy to come by either. I put the barrel up on a stand and I needed about 42″ of auger. I chose to keep the auger as short as possible to make the motor lead an easier life. I bought a commercially made auger motor, 2 RPM, CCW rotation, off ebay for $65.00. The auger tube is a piece of 2″ ID black iron pipe. I bought 5 Rotodigger RD-2 bits. These are for digging in gardens, putting pipe or wires under sidewalks, etc. they chuck into a drill for normal use. I cut 4 of them off in the bandsaw and laid them all out on a piece of angle iron to keep them true. I welded the shafts with 7018 rod and my stick welder and mig welded the flighting together. I connected the auger to the motor with a home made drive coupling made from a piece of 7/8 rod.
end part 1
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#2
Hi Treetopflyer
Great thread,needs pic’s. says the guy who can’t post pic’s.
Sounds like you love to tinker and build things.
I have never used pellets for heat,but heat my garage with waste oil,i have no trouble getting oil,i have about three winters worth now.Used cooking oil works great too,unless you can use it in your truck.
On a different forum,different content and all,there is a lady that burns nut shells in her pellet stoves.They are a by product from a processing plant.She buys them by the dumptruck load,she has her own dump truck.Costs her peanut’s to heat her house for the winter:}
Thomas
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1080sg ft log house,full basement,2/3 loft,26ft ceiling to ridge pole.R 80 insulation
Econoburn 200 the outdoor one, 1000 Imp gal storage 110ft to house 20×26 boiler room.
Stihl saws,Many Big toys
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#3
Begin part 2
When I tested the hopper / auger assembly, I ran it for 15 minutes and weighed the pellets that came out. Multiply that times 4 and I had an hourly feed rate of 12.38 lb per hour. Roughly equal to a .75gph nozzle on an oil burner at 100 psi.
Now the challenge was to control it and to build in some failsafes. I settled on using a Basic Stamp 2 microprocessor from Parallax. I used thier development board, then thier prototype board to make the actual controller that’s in my boiler now. I used a cad cell from an oil burner to allow the controller to see if fire was present, or should I say not present. The first test run showed me that glowing embers in the burn pot will fool the cad cell into thinking there’s fire when there’s not. The solution was simple, test for the absence of fire, not for the presence of fire. If the fire is out or fails to light, the pellets will come in and cover up the burning embers. If they light, that’s great, if not they will cover the light from the embers and the controller will retry once and then lock out on safety if there’s still no fire. I also designated an input for a thermal disk to be installed on the feeder tube. This will sent it into immediate lockout if the feeder tube temp reaches setpoint. I haven’t installed the disk yet, but I’ve measured the feeder tube temp at various times. It’s hottest when everything is off after a burner cycle is complete. I think a 250 degree F disk will do the trick nicely.
In phase 2, I’m going to reverse the function of the switch so that the switch will open on temperature rise rather than close. This will protect the wiring for the switch as well. A wiring fault will send the controller into lockout as opposed to causing the safety limit not to work at all. That makes better sense than the way I have it now.
It took about 10 rewrites of the software to get it working perfectly. Tweaking the ignitor cycle was the biggest one. You don’t want to run the ignitor for too long because it moves a lot of air and it will empty the burn pot rather quickly by burning up all the pellets too quickly. Too short of an ignition cycle will cause it not to light at all (sometimes) and go into safety lockout. So the solution was to stretch the ignitor cycle out longer than it needs to be and pulse the auger in 2.5 second intervals to keep something being added to the burn pot during the ignitor cycle so the ignitor can’t completely empty out the burn pot.
So the thing is heating my house and it’s cut my fuel cost in about half as compared to heating with fuel oil. I’m burning the cheap premium hardwood pellets from Maine Wood Products that Walmart sells for $3.88 a bag in Biddeford, ME. I have to empty the ashes weekly during the heating season because of the tiny firebox in the Biasi boiler, but it only takes 15 minutes so it’s not a big deal. I know there are cleaner burning pellets out there, but I want to keep my design so it’ll deal with the cheap pellets well because I like the price. $3.88 per bag wether I buy 1 bag or a ton is hard to beat.
I cleaned the boiler after about 5 weeks use. It was unnecessary to do a full cleaning, but I wanted to see what’s in there. I did not clean the boiler when I installed this. Turns out it burns itself clean. Only a tiny bit of fly ash was in the upper heat exchanger, it looked like a new boiler inside. It even burned off the crap left behind from burning waste oil. I’ve set out from the beginning to try to let the gases burn through the boiler rather than completing the whole cycle of combustion right in the firebox. I use as little primary combustion air as is possible and let the secondary combustion air that comes down the feeder tube mix with the gases and burn on it’s way through the heat exchanger. I nearly lost my moustache and eyebrows a few times while I was experimenting with the airflow adjustments. Wood gas is a very powerful thing and we don’t ever want it to load up and ignite suddenly. Turning on the power vent during the ignition cycle prevents that and since I wrote that into the software, it hasn’t happened again.
So phase 2 is coming up really soon. I’m going to start with another 1/4″ steel plate. I’m going to reduce the size of the burn pot by using 304 or 316 stainless and eliminating the firebrick. I’ll see how stainless holds up without firebrick. The space under the burn pot where the ash collects is big enough that I could put another small auger in there to auger the ashes out into an airtight steel box so that I can put an ash pan in there and dump it from there as opposed to removing the burner weekly.
In my case with the small firebox on the Biasi boiler, I think the gun type solution is not the best way to go because it’s too much work to clean it. This is why I went this route instead of building a gun type burner. If I can get phase 2 completed succesfully, the thing will auger out the ashes into a pan by itself so All I need to do is empty the pan and check the heat exchanger a couple times a year for fly ash buildup. I’ve got less than $500.00 into this so far and it’s been heating my home for about 6 weeks now with no major issues so I think I’m onto something here with this burner design, but it’s not quite ready for prime time yet…
After I see how well the stainless steel holds up in my phase 2 burner, I’m considering building a gun type burner for my son. He has a 5 section Vaillant boiler with a huge firebox and a swinging door that the burner is mounted on. This looks like a perfect scenario for a gun type burner. I’m thinking that if the stainless steel holds up in mine, some 4″ heavy wall stainless steel pipe might make a nice blast tube on a Beckett AFG chassis to lead into the firebox and attach a slightly larger piece of stainless for the burn pot.
Has anyone else built thier own burners? I’d be very interested to hear about different burner designs and how they work. Clinker formation, maintenence, etc. Sharing info, pictures, etc. might be beneficial to all of us and it might help the commercial guys wake up and see that these things can be built in the US and they don’t need to be imported from Europe to work properly. Maybe someone with enough money to certify the thing will see it and build them so we can all afford to buy one.
Next week when I clean it, I’ll try to clean up my boiler room a bit and get some pictures to post here if there’s any interest
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#4
Hi Thomas,
I will post some pics next week when I have it apart to empty the ashes. I realize that it’s probably pretty hard to visualize the stuff in this burner without pictures. I also need to clean up my boiler room a bit before I shoot pictures so people don’t dismiss me as a lunatic too quickly (that should take a little time). You know how when you get done with a project it looks a bit like a bomb went off… Spilled pellets on the floor, tools on top of the boiler, etc…
Mark
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#5
treetopflyer said:
Hi Thomas,
I will post some pics next week when I have it apart to empty the ashes. I realize that it’s probably pretty hard to visualize the stuff in this burner without pictures. I also need to clean up my boiler room a bit before I shoot pictures so people don’t dismiss me as a lunatic too quickly (that should take a little time). You know how when you get done with a project it looks a bit like a bomb went off… Spilled pellets on the floor, tools on top of the boiler, etc…
Mark
Click to expand…
Wow…….. Very nice write up. Looking forward to pics. This is my formal welcome and my subscription to this thread. Cant wait for Pics…..
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#6
Sounds pretty cool, except I’m more interested in the details of the waste oil burner. Anyway, in the interest of safety, you might consider what happens if you get a spark or flash fire up the auger and into the pellet bin. This happens in LOTS of residential pellet burners. The big pellet boiler at my workplace has an auger feeding from an outside hopper, into a metering bin that has a slide-gate. The gate opens when pellets are needed and closes when they are not. There is also a simple deluge tank of water attached to a water valve that looses the water if the sensor, strapped to the last feed auger, senses temperatures that indicate the fire has expanded into the auger. Fairly simple, all safety devices and commercially available or fabricated. Good luck. Please PM me if you are interested in sharing info about the oil burner. I am thinking on this as backup for next year.
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#7
The slide gate is a neat idea, but won’t work for me since I spin up the auger continuously whenever the thing is running. It would be open whenever the burner is running, but the deluge system sounds like a simple and effective safeguard. I’d hate for that to go off by mistake though. The pellets would expand into wet sawdust and fill the auger and feeder tube with snot. Still better than a hopper fire though. What are you using for a temp sensor? A bimetal disc?
I sent you a PM about the waste oil burner. I’ll get you some pics.
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#8
treetopflyer said:
The slide gate is a neat idea, but won’t work for me since I spin up the auger continuously whenever the thing is running. It would be open whenever the burner is running, but the deluge system sounds like a simple and effective safeguard. I’d hate for that to go off by mistake though. The pellets would expand into wet sawdust and fill the auger and feeder tube with snot. Still better than a hopper fire though. What are you using for a temp sensor? A bimetal disc? I sent you a PM about the waste oil burner. I’ll get you some pics.
Click to expand…
A bimetal disc might work, however a high-limit controller with remote bulb like a Honeywell L4008 might also work. The devil is deciding if you use a normally open, powered close bulb that will open in a fire OR the power failed(!) Or you use a normally closed, powered open valve and hope it works when the time comes. I don’t recall the models of the deluge valves we have at work, and I am not back until Wednesday for day shift. However, to implement one of them, you just weld a pocket that the bulb fits into on the side of the auger tube. It will sense the heat of the tube. In a fire the pressure in the bulb pushes open the water valve and the water flows. No need for electricity, works all the time. For sure, isolate it with hand valves for maintenance. Yes, it makes a mess, but better than several hundred pounds of pellets in the fuel hopper going up and filling the building with nasty acrid smoke. (or burning it down)!
Got the PM. Thanks! I will follow it up.
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#9
Here are the pics as promised. I let it run a little over a week without emptying the ashes since the weather has been fairly mild here this past week. I cleaned it yesterday and took the pictures.
Keep in mind that this burner is just the phase 1 test. Phase 2 will include such luxuries as air shutters on the combustion air blower and on the top of the feeder head at the end of the auger tube and a few other things that will completely eliminate the use (or abuse) of aluminum tape.
Here’s the boiler as I run it now. I took this one just before cleaning it.
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#10
Here’s the hopper / auger assembly.
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#11
Front of the burner showing the feeder tube at the top, the heat gun that I’m using for an ignitor, the combustion air plenum, and the two yellow wires are for a cad cell to let the controller see if there’s fire in the firebox.
It’s hard to see from here, but the heat gun blows into a 1/2″ black iron pipe that goes through the combustion air plenum and stops just short of the opening for the upper combustion air inlet so that the heat blows directly onto the pellets, but when the ignitor is off, the combustion air blower can blow through the same hole into the burn pot. I cycle the ignitor for 15 seconds at the start of every burn cycle before I preload the burn pot. The heat gun blows a good strong stream of air. This keeps the ash and small clinker pushed back so I’m not constantly scraping out the burn pot..
The second pic is the inside of the combustion air plenum looking in with the combustion air blower removed. You can see the damper that allows me to divide the airflow between the upper and lower (under the fire) inlet ports.
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#12
Here’s the burn pot and the firebox with a weeks worth of crap in it. Keep in mind that a weeks worth of buildup at my house is probably two to three weeks at a “normal” house. I do have to tighten this place up…
Looks like the burn pot is largely wasted space and I could build it about half as long as it is. You can see where the ignitor is doing a good job of keeping the pile of crap pushed back by using it to blow out the burn pot it at the beginning of every burn cycle. Unfortunately, I forgot to take pics of the burn pot after cleaning it. It’s just a piece of angle iron welded to the front plate with some shims welded inside the angle iron to support the firebrick so that I can blow air between the firebrick and the angle iron through the lower port in the combustion air plenum. Doesn’t really look like the bottom port is doing anything because it’s filled with ash and clinker. I think I can safely eliminate it from the design in phase 2.
Looking at this, I see some room for improvement in phase 2. By going to a smaller burn pot made of stainless and putting an ash auger under the burn pot, I cab all but eliminate this buildup. Even still, this may look like an awful mess, but it takes 15 minutes once a week or so to scoop out the firebox and burn pot and run a soot vac through it. Here’s a weeks worth of crap in a small metal bucket. This is all that was in there except for the little bit that the scoop wouldn’t get and I cleaned with the soot vac. The bucket is 9″ tall and 10″ arount at the top. It’s a very tiny firebox on the Biasi boiler.
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#13
Here’s the heat exchanger. There’s more than a weeks worth of buildup in here. I normally limit my weekly maintenence to scooping out the firebox. The photo doesn’t do it any justice. The pile of fly ash is what settled against the cover plate and does not go all the was back through the heat exchanger. The pic on the left shows the heat exchanger after I took the soot vac and removed only what settled against the cover plate. I haven’t cleaned it at this point, just cleared away this little pile of ash about an inch deep so you can see what’s really inside the heat exchanger.
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#14
These pics show the heat exchanger after blowing it out with an air hose. No brush needed. I just turn on the power vent and it carries most of the fly ash up the flue as I blow it out instead of filling the boiler room with dust. I have to start slowly at first, but the further back in the heat exchanger I blow, the more air I can put to it without letting very much dust out into the boiler room.
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#15
The controls for the pellet burner. It’s a parallax prototype board complete with a wall wart transformer to power it. In one pic, you can see the 4 transistors and thier base resistors that I use to switch the solid state relays. Phase 2 will use a darlington array instead of the individual transistors and the controller will be seperate from the relay box.
The mechanical relays have 120V coils and I use two of them to sense zone call and burner call for the controller board from the zone control panel. The third is not connected and it’s just to keep a spare relay handy in case one fails.
Burning pellets is a lot different than burning oil, even waste oil. You can’t just switch off a pellet fire, you have to let it burn out by stopping the auger and keeping combustion air going. In this case, I also have to keep the power vent going too to make sure there’s good draft while all this is happening.
If there’s no zone call when you do this, you’ll make steam in a boiler this tiny, so if we’re ending a burn cycle with no zone call we’re going to have to do something with the heat from that fire. If there’s already a zone call, then the post burn heat will take care of itself, but if there isn’t a zone call, in other words, if the last thermostat is satisfied, we have to divert that heat somewhere so we don’t overheat the boiler, so I used my superstore tank as a dump zone for the duration of the 4 minute post burn cycle under these conditions. The controller senses no burner call and no zone call and powers up the circulator for the superstore with one of the solid state relays. I have a tempering valve on the superstore tank anyway, so handling the extra heat in the tank isn’t a problem, no one gets scalded and the tank is no where near relief temperature, ever.
The controller has a couple of failsafes built in. I have provisions for a thermal disk to be mounted on the feeder tube (no I haven’t installed it yet and I probably won’t until the phase 2 burner is in place). I wrote a subroutine that sends the controller into an immediate lockout if the temp sensor on the feeder tube is tripped and flashes the red LED. a 250F thermal disk should do the trick.
If the controller sees no fire at all, it will retry once. If it still sees no fire, it will lock out and flash the yellow and red LEDs alternately like the lights on a school bus.
The switch to the left of the outlets where the auger and ignitor plug in is labeled “pellets” in one position and “oil” in the other. That simply switches control of the power vent between the boiler’s original control to the pellet burner control. This way, I can simply plug in my oil burner gun, flip the switch, and use it for a backup. There’s a pigtail that hangs under the same switch box that the combustion air blower plugs into that isn’t shown in this picture that’s also controlled by the switch. I can plug my waste oil gun into that, or I can plug my #2 oil burner gun (the riello) into the twist lock plug shown in the picture. Between the oil guns and the Hunter wood furnace that’s also in the boiler room, I have plenty of backup alternatives.
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#16
So I’ve learned quite a bit from the phase 1 tests. The thing has been absolutely reliable, no complaints there, but I see a better way to do a number of things. The burn pot design and the addition of the ash auger will be the first thing to get updated. I think the stainless burn pot will be a better way to go. Less ash and clinker will stick to it and an ash auger that fits under the burn pot to carry most of the ash out into an enclosed collection container will be really convienient with such a tiny firebox.
I’ve got a lot of things that I’d like to do differently, like building an auger that will drop into the top of a 55 gallon barrel and clamp to the side of the barrel. This will allow me to set the barrel on the floor and make it easier to add pellets. The way it is now, my wife is too short to add pellets to the hopper and I don’t want her standing on a milk crate lifting bags of pellets…
Speaking of bags of pellets, the pic below is what I’m burning. These are the absolute chepest pellets that one can buy in southern Maine. Maine Wood Products pellets for $3.88 a bag. Doesn’t matter if you buy a ton or a single bag, same price. Walmart in Biddeford, Maine has them. I go right by there every day on my way home from work so it’s really convienient for me. I’m not convinced that the higher quality pellets will be a better bottom line. I’d rather make provisions to handle the ash and clinker from these cheap pellets and beat the bottom dollar out of the heating cost, so for me, its all about the numbers.
So assuming that the btu value of my cheap pellets for $194.00 / ton is 8000 btu per lb, and assuming that the $250.00 / ton high end pellets carry 9000 btu per lb, that’s 2,000,000 btu difference per ton and a cost difference of $56.00 per ton. Cost per 100,000 btu of the cheap pellets is $1.21. Cost per 100,000 btu of the higher end pellets is $1.39. I do plan to buy a ton of high end pellets anyway and try them just to see if I’m missing something, but unless I am, the numbers speak for themselves…
I can see the advantage of high end pellets on a pellet stove that requires frequent cleaning of the burn pot or another piece of equipment that the reduced maintenence is worth something to the homeowner, but my goal is simply to heat my house the cheapest way possible without starting my chainsaws. That’s the thought I have in mind as I design and test this project, so handling the cheap pellets gracefully is priority #1 (next to not burning the place down, of course).
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#17
Treetop awesome job! Please keep us updated on how things are going and more pics when phase 2 unfolds. Where in Maine are you? Brian
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#18
Hi Brian,
Thanks. It’s got a long way to go yet, but at this point, it’s been very reliable and it loves the cheap pellets too. I’m in Lyman, that’s between Sanford and Biddeford.
Mark
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#19
Hi, Awesome work. I’ve done something somewhat similar. in 2008, I built a biomass outdoor boiler using many of the same principles you are. Every year since, I’ve learned a few things, and by now, mid 4th season, I’m down to 0 equipment failures so far this year (down from weekly or more often during the first season. My control system is built around a cheap ($130) self contained plc, programmed with ladder logic. I also use a cad cell for a flame sensor. My fuel is hazelnut shells (As mentioned by someone earlier in the thread, there is another shell burner on this forum burning shells directly in a Whitfield pellet stove. I live in the same valley as she does. In fact, I’ve patronized her business without even knowing who she is at the time) Rather than igniting the fuel each burn, I use a mass refractory burn pot, so the fuel self ignites upon delivery. The fuel is delivered from the hopper via 2 sequential augers. For fire protection (added after a couple of almost hopper fires) I use a snap switch (open on rise) on the second auger that shuts down everything but that auger. This way, that auger sweeps any burning material away from the primary auger and dumps it in the fire pot, where it sits and smolders until the snap switch cools and everything reactivates. So far, this has worked perfectly. My plan is to add secondary fire protection in the form of a deluge system, as described above, but rather than using electrical components to control that, I plan to use fire sprinkler heads mounted in bungs welded to the primary auger tube. This way, if a fire ever got through the secondary auger and to the primary auger, before it could travel to the hopper, it would heat up, and break open the sprinkler heads, dousing the fire in the primary auger tube. This will work even in the event of power failure, but won’t false trip in a power failure of other control system fault.) Hope this provides some food for thought. Good luck in your continued venture.
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#20
jbrown9709 said:
My plan is to add secondary fire protection in the form of a deluge system, as described above, but rather than using electrical components to control that, I plan to use fire sprinkler heads mounted in bungs welded to the primary auger tube. This way, if a fire ever got through the secondary auger and to the primary auger, before it could travel to the hopper, it would heat up, and break open the sprinkler heads, dousing the fire in the primary auger tube. This will work even in the event of power failure, but won’t false trip in a power failure of other control system fault.) Hope this provides some food for thought. Good luck in your continued venture.
Click to expand…
Interesting, out of the box thinking. I know there are MANY types of sprinkler heads, but I would recommend the types that have a flat circular disc on the sensing end that (usually) sits flush to the ceiling trim or finish material. This would reduce or prevent any dust or bits getting rammed into the bung or sprinkler head. They are called a “concealed pendent style”. Could you speak more as to what the type of head you are planning to use is? Interested, I am. Cheers.
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#21
Wow, great thread, lots of great ideas. I’m thinking about doing something similar with my old HB Smith boiler.
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#22
I found a pellet boiler conversion burner made right here in the states: http://heutzpellets.com/burners.htm
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#23
Been a while since I posted on this project. The DIY conversion is still heating my home. I’ve rewritten the software for it a couple of times to better deal with short load calls from small zones and/or warmer days. I found that with the firebrick burn pot I had to change the stones a couple times during the last heating season, so I made a new burn pot out of a slice of a cast iron cylinder liner from a truck engine. That solved the problem of the burnpot destroying itself over time and dropped my stack temp by about 50 degrees. It lights cleaner, the fire is better color and quieter and the boiler comes up to temp a little faster.
I also added two stage firing. I’m adjusting the air on high fire and letting it run a little lean on low fire. It doesn’t seen to bother it. Prototype #2 will have an air damper operated by a solenoid coil to allow ait setting adjustment on both firing rates. I’m feeding about 13.5 lb/hr on high fire and about 8 lb/hr on low fire. It helps a great deal with light loads. Reduces short cycles a lot. I hung an aquastat on the supply manifold on the boiler and as the temp approaches high limit it kicks down to low fire.
The pellet shortage up here in Maine has been a problem recently. My house isn’t the tightest construction and it normally went through 1200 – 1400 gallons of fuel oil. I find that a ton of pellets equals about 120 gallons of #2 fuel oil, so I still need a lot of pellets. Pretty hard to deal with when the stores that do have them impose a 10 bag a day limit. If I can find pellets, I have to go as many days in a row as I can until they run out.
The bulk delivery guys have not been affected by the shortage. They have bulk contracts with the mills and it appears that they have first dibs on the supply. We’re building a 4 ton stick built hopper in the garage this weekend. The truck is coming Tuesday to start us off with 2 tons and see how it works. It’s a little more expensive buying bulk, but in my opinion, worth every cent of it just because I don’t have to deal with unloading and stacking bags. The going rate here is $249 a ton delivered. I used to get pellets at Walmart and Home Depot for $209.00 a ton.
They use 4″ camlock fittings to connect the truck. These are ordinary trash pump fittings available everywhere. The truck is scheduled for Tue morning delivery. For now, I’m still going to lug pellets from the storage hopper to the day hopper in 5 gallon buckets, but I’m exploring pneumatic transfers now to see if it’s practical to set this up to fill my day hopper.
Reactions:
chken and Hoot23
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#24
Very cool setup. My father-in-law would be really interested in this. He has a Biasi wood/coal burner that he would like to convert to a pellet burner.
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Pellet Burner Controller Circuit – Homemade Circuit Projects
The following post explains a programmable sequential timer with controller circuit which may be used for automatically controlling a homemade pellet burner/boiler system. The circuit was requested by Mr. Vasilis.
Contents
Technical Specifications
I have used your circuit on my homemade pellet burner that uses a 12V Ac motor for the feeder screw running 8 sec on, 30 sec off , and it works great, my idea for my project was similar to your circuit,
I also have a monostable circuit istalled using the famous 555 ic for the igniter which is a 12V glow plug that stays on for 2-3 min which is enough to ignite the pellets, here is the fun part now,
I run in to some problems during ignition, my idea for this project was for me to use a plc controller for all the action, money is short and i find building the circuit more interesting.
My question is if i can produce a sequence of actions for the ignition process, when power on the circuit 8-10sec on time 30 0ff time for the feeder, at this point glow plug to stay on around 2-3 min, and the fan blower which is a 220Vac to pulsate for the shortest 2-3 sec on 10- 15 off to it’s lowest speed if possible,
when fire is detected using a LDR to activate the second circuit ( 8 sec On 30 sec off)and the fan blower to its regular speed via a relay..
I hope i explained everything correct!
Analyzing the Circuit Request
Can you provide your requirement in a step-wise manner because I am finding it difficult to understand the sequence in the above explanation.
If you can provide the circuit operating sequence serially with the relevant timing functions, then I can try working on it.
Pellet Burner Circuit Specifications
There is a room thermostat that I turn on, which gives power to
the circuit.
1) Timer for the pellets- 15 seconds then off
2) Timer for the glow plug – 2-3 minutes then off
3) Timer for the fan – pulsing 2-3 seconds on then 30 seconds off
(this needs to cycle until the photo cell is activated,).
4) Photo cell – when it sees fire, it is to stop the entire cycle.
Then the next cycle begins:
5) Timer for the pellets – 8 seconds on, 30 seconds off until the water
temp reaches 75 degrees C (the boiler will cut the power at this temp).
So every time power in on it should do the steps above, I hope it’s clear!
Let me know if you need more info..
The Design
The presented design of a programmable timer controller circuit for homemade pellet burner system looks quite complex, but actually it’s not, the design is simply a chain of a few monostable, and astable multivibrator stages configured sequentially.
The entire circuit can be understood with the following points:
The circuit is initialized by applying power via a thermostat, as soon as its powered, current passes through C1 and triggers the stage#1 monosatble.
T1 activates the connected relay and the relevant load, and also ensures that the reset pin of stage#2 and supply pin#8 of stage#3 gets grounded so that they stay deactivated.
After the set time elapses, T1 releases itself and the connected load, triggering stage#2 into action.
Now T2 activates switching ON the relay and the relevant load, T2 also makes sure that the reset pin of stage#3 is held grounded so that it doesn’t activate.
Once the set time of stage 2 gets over, the connected load is switched OFF and stage 3 which is an astable now gets activated.
Stage three toggles the connected load ON/OFF at some specified rate as per the duty cycle set by appropriately selecting the value R16.
The above astable remains ON until the pellets ignite, and the light from its glow activates the comparator associated with stage 4.
With the detection of fire the opamp output goes low grounding the reset pin of stage 3 astable, thus deactivating its function.
The opamp triggering in the process also activates another astable at stage 5 which just like stage 3 toggles a connected load at some specified rate determined by the evaluation of R24.
The last stage is responsible for heating up the boiler water whose temperature is monitored by the thermostat. Once the water temperature reaches the set degree, the thermostat switches OFF power to the entire circuit so that everything is reset back to the original state, ready for commencing a
fresh cycle.
Feedback from Mr. Vasilis K:
Hello swagatam vasilis k here.
I have started putting the circuit together on a breadboard then i realized my mistake at (stage #3) which toggles the fan blower on/off will go off, which is no good as the pellets will go out if there is no air, please is it possible to make an add on to the circuit when (Stage #5) is activated the fan blower should be on steady!Also please can you specify the connections made between P1 , R18, R19, R20 really stuck at this point.
Thanks in advance
Vasilis K
My Reply:
Solving the Feedaback Question
Hi Vasilis,Please do the following modification:
Disconnect D2 connection entirely, it’s not required. That’a all, this will rectify the issue.
The circuit additionally requires a few corrections as suggested below:
1) Put a 10K resistor across pin#4 and ground of strage#5 IC, which is missing in the diagram.2) The LDRs must be connected in parallel for better response and not in series as wrongly indicated in the diagram.
As regards the P1 setting, do it in the following manner:
initially keep the D1, R17 feedback disconnected.
Introduce the LDRs with the required amount of light from the burning pellets, and through some trial and error adjust P1 such that the output pin#6 of IC741 just becomes low or zero volts.
Now removing the light from the LDRs should make the output high or equal to the supply voltage, check this a few times to confirm the results.
That’s all, the IC is all set…..now reconnect D1.R17 back in position.
Remember the LDR should not receive light from any external source, otherwise the whole circuit will malfunction.
I hope you got the points,
Prototype of Homemade Pellet Burner Design
The above circuit was designed by me as per the requirements requested by Mr. Vasilis.
Once it was completed, the unit needed some more refinements/enhancements and customizations for achieving improved optimization.
With the suggestions provided by Mr. Vasilis, we could together successfully implement the features.
The following discussion between Vasilis and me, and the video explains how things were put into place using a few add-on circuits with the original pellet burner design.
Customizing a Homemade Pellet Burner
Query: I have started putting the circuit together on a breadboard then i realized my mistake at (stage #3) which toggles the fan blower on/off will go off, which is no good as the pellets will go out if there is no air, please is it possible to make an add on to the circuit when (Stage #5) is activated the fan blower should be on steady!Also please can you specify the connections made between P1 , R18, R19, R20 really stuck at this point.
Answer: Please do the following modifications:
Disconnect the reset pin#4 of stage#3 IC from D2 and R13. Connect it to the anodes of two 1N1448 diodes joined together. Cathode of one diode now goes to collector of the stage#2 transistor and the other to the collector of stage#5 transistor. Also put a 10K resistor across pin#4 and positive. D2 and R13 are not required any more.
Put a 10K resistor across pin#4 and ground of strage#5 IC, which is missing in the diagram.
Another point, the LDRs must be connected in parallel for better response and not in series as wrongly indicated in the diagram.
I hope you got the points,
The first modification explained above needs correction.
Only D2 connection needs to be disconnected, rest of the things can be ignored. R13 is necessary do not remove it
As regards the P1 setting, do it in the following manner:
initially keep the D1, R17 feedback disconnected.
Introduce the LDRs with the required amount of light from the burning pellets, and through some trial and error adjust P1 such that the output pin#6 of IC741 just becomes low or zero volts.
Now removing the light from the LDRs should make the output high or equal to the supply voltage, check this a few times to confirm the results.
That’s all, the IC is all set…..now reconnect D1.R17 back in position.
Remember the LDR should not receive light from any external source, otherwise the whole circuit will malfunction.
Feedback: Thank you! Going to work on it this weekend.
I might have messed up something up today, as i had the first 3 stages working perfect with the correct values for the timings on each stage,now i get no response, i am new to this as my job has nothing to do with electronics, i think i might stick with the 3 stages, can you please edit the schematic so i can ask help from a friend of mine, who actually makes a living from this repairing electronics…
Solution: OK Vasilis, in that case you can eliminate stage4 and 5 completely. Let pin4 of stage3 IC be connected via R13, that’s all….no other amendments would be required.
Feedback: I wanted to let know that i am ready to test the circuit on the burner these days, as the first 3 stages work flawlessly with some slight accidental changes, pin 4 from stage 3 is now connected to positive leg of C4 at stage 2 with a 4.7k resistor also pin 8 from stage 3 is now connected to the collector leg of T4, I also removed the two 100K resistors as they preventing switching i guess from one stage to another, really happy with the outcome as it made me more excited to continue building the rest of the circuit, i hope you can guide me from now on with the rest of the circuit when you have some spare time!
I am greatful for all!
Reply: That’s great Vasilis, but I think pin#4/8 of stage#3 IC should be connected exactly as I have shown otherwise the system might malfunction.
Removing 100k is OK, alternatively you can replace it with a 1M resistor.
Feel free to question if you have any doubts!
Feedback: I get the same result over and over when i connect the ic the way its shown on the schematic, when power is applied to the circuit first stage gets activated and within the predetermined time second stage gets activated as well, the problem is that both stages stay connected for ever. Also by changing the 100K resistors with 1M it made a difference the circuit works properly, only when its connected the way i reported it works as it should.
Thanks for your fast reply
have a nice day.
Answer: OK Vasilis, thanks!
Let’s see how things work out finally.
Feedback: Well, it didn’t work as i thought it was, i have stage 1&2 working properly with the timings and all set, problem is with stage 3, it’s connected the way it’s shown on the schematic, the problem is when it’s switched on to stage 3, when off it’s going back to stage 2 continuously this is the kind off problem i had since i started putting the circuit together!
I hope you have a solution for this, also thanks for your patience with me!!
Solution: Stage3 has no connection with stage2 so there’s no possibility of the above thing to happen so it’s difficult to understand the situation, may be it’s producing false triggering of stage2. You can try connecting a 1uF/25V capacitor across base of T1, T3, this might stop from stage two or stage 1 from false triggering.
Feedback: I only have 2.2/50v will they do?Also when pin 8 from stage 3 when it is connected to the positive rail stage 3 comes up momentarily and stops, other than that it switches stages alright without the need of the extra capacitors, this would have worked out fine, running out of patience today as i have the burner all the wiring ready to test it..
Analysis: Stage3 is an astable meaning it will switch ON and OFF (oscillate) at some specific rate determined by its R/C values. For checking you can connect its pin8 to positive but you should connect it back to where t is connected after checking. Yes 2.2uF/25V will do.
Feedback: You didn’t fully understand , language gap here, when power is applied to the circuit and pin 8 from stage 3 is connected to positive it’s gets activated only once along with stage 1, when time elapses from stage 1 and 2 (2-3 min period) then stage 3 gets activated like its suppose to, i hope it’s more clear now, i don’t wont to bother you again today, i am just looking for a solution to my problem so i can troubleshoot this issue!!
Reply: yes, when power is applied stage3 might only momentarily activate. But as soon as stage1 relay driver activates, the transistor instantly grounds pin8 of stage3 making it dead.
If you want to avoid this, you can try adding 2.2uF capacitor which you have already have across positive and base of T2 via a 1K resistor. So now you don’t have to connect the cap across the transistors which I had referred before.
Feedback: Thanks for all your help so far, i think i might stick with the first tip, having the two 2,2uf caps connected to base and ground solved the problem, stage 1,2,,3 are connected as shown on the schematic and working like a charm, also i will keep on working with the rest of the circuit as i don’t like to quit that easily..
Reply: That’s great news Vasilis, surely you will be able to complete it
Feedback: I have tested the other day the burner with the first 3 stages on the breadboard, the circuit so far works like it’s suppose to work,i have a question if it’s possible, when stage 2 elapses which is the glow plug, stage 3 gets activated. problem is pellets don’t ignite within the predetermined time most off the times, with the result that the burning chamber gets filled with pellets and they go out, so here is my request, how to connect the op-amp to stage 3 so when the ldr’s detect light only then to activate stage 3 and completely discard stage 5 which is over kill for my project, this way its more trouble free as it takes time for me to disconnect it from the boiler, take it apart and clean it, so it can start over again.
Analysis: For this to happen you will have to do folowing steps.
Remove D1, D2, R17, R25, R13, T7 these won’t be required now.
Connect pin#6 of IC741 directly with pin#4 of stag3 IC.
Connect pin#7 of IC741 to T4 collector.
Use the LDRs in parallel and not in series as wrongy shown in the diagram.
Swap the pin2 and pin3 of IC741 with each other, this is IMPORTANT.
Once you do these, your circuit will respond as you have mentioned.
Make sure the LDRs do not come in contact with any external light.
Feedback: hanks for replying back ,a quick question just to make sure so i don’t mess anything up, were do the ldrs and R19 connect now? Along with pin#7 that connects to the collector leg of T4? or to the positive?
Reply: It would be better to connect them to pin#7 so that all get the positive supply from a common point.
Feedback: I hope everything is well, i am having trouble with the op-amp as everything it’s connected as you mentioned i don’t get the expected results, pin#4 is connected to the output of the ua741 ic, the output is down to 1.9v but it keeps oscilating at power on, whenever i connect pin#4 via a 4K7 resistor to the collector leg of T4 the astable stays grounded, reply to this please when you get some spare time, i hope you have solution to this.
Solution: I would suggest that you isolate the 741 stage and test it separately first for studying it’s performance. You can use artificial light source on the LDR to see how the output of the IC responds. Connect an LED with series 1K resistor across pin#6 and ground to see the output response.
Please refer to this link to know exactly how you need to configure the stage:
www(dot)technologystudent(dot)com/elec1/opamp3.htm
As shown in the link, you may try adding a transistor stage at the output of 741 for powering the astable.
Feedback: That did it, all 4 stages working like they are suppose to, I can’t thank you enough for the time and effort, cold weather is on it’s way, I will post a small video of the finished project soon!
Response: Congratulations Vasilis, that’s great news!
You are most welcome!
Feedback: Hi Swagatam, I have a question regarding the 4060 ic wired as “one short timer.” If it can power on the two monostables from the pellet burner circuit, output will be taken from pin #3 which is the last to count to the C1 stage, will that work?
When power is applied to the circuit, the first 2 stages should stay low until the time has elapsed. Pin #3 should be set to activate the cycle, so when I leave home in the morning, I will be starting the timer via the thermostat. Then when I get home, the burner should be running. Thanks so much for your help.
Analysis: I could not understand this “first two stages should stay low..”can you explain the procedures a bit elaborately.
Feedback: As per the circuit design there are 2 monostable circuits(Stage 1&2) when power is applied via a room thermostat it activates the cycle (Stage 1&2), my request is when power is applied after the predetermined time of the 4060 has elapsed, is to activate the cycle(Stage 1&2), as there is no need for the burner to run when no one is around, plus this would be ideal as it takes about an hour for the water temperature to reach at 75 celsius , I hope this is more clear now!
Reply: Please check out this post:
https://www.homemade-circuits.com/2013/10/simple-adjustable-industrial-timer.html
TESTED&WORKING, really happy with the outcome, i used the 2nd circuit with the relay as i didn’t have that specific transistor, that would be my last request for you, i hope i wasn’t that much of a pain, again really thankful for all the help and effort, god bless you!!
I have put both circuits on a pcb board, everything is working like a charm, ready to burn some pellets soon, i am looking for a 220 vac to 12 vdc transformerless power supply for both applications, can you recommend me one?
Thanks in advance!
Vasilis K
Response:
That’s great Vasilis!For power supply i think it would be better to go for a ready made 12V/1amp smps adapter for this, because making a capacitive type cheap transformerless power supply could be risky and dangerous for your circuit.
Regards.
Feedback: I think this may be my last question for you regarding the pellet burner circuit. I was wondering if I can connect a simple latch circuit at the junction of T2 and C4, I want the relay to latch right after the time from the first monostable elapses, is this possible? Thanks.
Vasilis K.
Solution: yes it’s possible. Actually you won’t need an additional latch circuit because the first stage itself can be effectively used as a latch. You just have to integrate another transistor relay driver stage with the collector of the first relay driver transistor. Do the connection via a 10k resistor and that’s it, as long as the first stage stays activated, the added relay driver will remain switched off, as soon as the first stage time lapses and it switches OFF, our second relay stage will latch up for the intended change-over actions.
Final Thoughts and Results
My pellet burner project is finally complete, everything works the way its suppose to work thanks to you. I have tested it several times with no problems at all.
I have used pins 1&2 from the 4060ic, pin#1 activates the fan blower and pin#2 is responsible for powering the pellet burner circuit.Pin#1 is connected to the fan as a normally open connection.
When it gets activated it runs for about 2min(Cleaning the ash).Then when pin#2 is latched, the fan gets disconnected and the 1st stage is running.
This is the auger feeder, for 30 sec, feeding pellets to the combustion chamber(with no air blowing the pellets away).
When time elapses from the 1st stage, the new relay driver you recommended, activates the fan blower along with stage#2 which is the glow plug(igniting the pellets), it runs about 3min.
Stage#3 is diactivated until fire is detected by the (LDR) which is placed behind the combustion chamber detecting light through a small hole.
I will build another timer with the 4060 ic which will power both circuits for greater time delays!
I made a short video of the burner running, you may see it here!
Homemade pellet burner
Really greatfull for everything!
Thanks again
Vasilis K
Wood and Pellet Heating | Department of Energy
Energy Saver
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Today you can choose from a new generation of wood- and pellet-burning appliances that are cleaner burning, more efficient, and powerful enough to heat many average-sized, modern homes. Pellet fuel appliances burn small pellets that measure 3/8 to 1 inch in length.
Choosing and Installing Wood- and Pellet-Burning Appliances
When choosing a wood- or pellet-burning appliance, it’s important to select one that’s properly sized for the space to be heated. When an appliance is too big, residents tend to burn fires at a low smolder to avoid overheating, which wastes fuel and is one of the biggest causes of air pollution. An under-sized unit will not provide sufficient heat. You should discuss your heating needs with a reputable dealer. A good rule-of-thumb is that a stove rated at 60,000 British Thermal Units (Btu) can heat a 2,000-square-foot home, while a stove rated at 42,000 Btu can heat a 1,300-square-foot space.
Wood-burning appliances and fireplaces may emit large quantities of air pollutants. Wood smoke contains hundreds of chemical compounds including nitrogen oxides, carbon monoxide, organic gases, and particulate matter, many of which have adverse health effects. In many urban and rural areas, smoke from wood burning is a major contributor to air pollution. Because of this, some municipalities restrict wood heating appliance use when the local air quality reaches unacceptable levels. Others restrict or ban the installation of wood-burning appliances in new construction. Before installing a wood-burning system, you should contact your local building codes department, state energy office, or state environmental agency about wood-burning regulations that may apply in your area.
If you have an older wood-burning appliance, consider upgrading to one of the newer appliances certified by the U.S. Environmental Protection Agency (EPA). Some include a catalytic combustor that allows combustion gases to burn at lower temperatures, thereby cleaning the exhaust gas while generating more heat. All woodstoves sold today should bear an EPA certification sticker. Higher-efficiency appliances usually have lower emissions and are also often safer, because complete combustion helps to prevent a buildup of flammable chimney deposits called creosote.
The location of the appliance (and chimney) will influence how well heat is distributed and conserved in your home. Most wood- and pellet-burning appliances are essentially space heaters, and should be put in the room where you spend most of your time. Ideally, there should be a way for heat to circulate to the rest of the house, such as a fan or blower assembly.
For safety and to maximize efficiency, you should consider having a professional install your wood- or pellet-burning appliance. A professional will carefully evaluate everything from your chimney to your floor protection. A certified professional can also help you choose the best appliance to heat your home. The National Fireplace Institute maintains a list of certified industry professionals.
Types of Wood- and Pellet-Burning Appliances
The following is a brief overview of the different types of appliances available.
High-efficiency Fireplaces and Fireplace Inserts
Designed more for show, traditional open masonry fireplaces should not be considered heating devices. Traditional fireplaces draw in as much as 300 cubic feet per minute of heated room air for combustion, then send it straight up the chimney. Fireplaces also produce significant air pollution. Although some fireplace designs seek to address these issues with dedicated air supplies, glass doors, and heat recovery systems, most traditional fireplaces are still energy losers. When burning a fire, you should turn your heat down or off and open a window near the fireplace.
High-efficiency fireplace inserts have proven effective in increasing the heating efficiency of older fireplaces. Essentially, the inserts function like wood stoves, fitting into the masonry fireplace or on its hearth, and using the existing chimney. A well-fitted fireplace insert can function nearly as efficiently as a wood stove.
Studies have shown that proper installation of fireplace inserts is very important. Have a professional installer examine the fireplace and chimney to determine if they are suitable for an insert. Inserts should be as airtight as possible. The more airtight it is, the easier it is to control the fire and the heat output. The installer should use only approved fireplace insulating materials to fill any gaps between the fireplace mouth and insert shield.
Moving an insert to clean the chimney or liner can be difficult, and is a job best left to a professional chimney sweep. In some situations, a clean-out door can be installed above the insert connection so the insert does not have to be moved as often. Some models have wheels to simplify installation, cleaning, repairs, and other adjustments.
Some modern fireplaces heat at efficiencies near those of wood stoves and are certified as low emission appliances. Although designed to include the fire-viewing benefits of a traditional fireplace, this generation of fireplaces can effectively provide heat as well. Through vents under the firebox, room air is drawn in, heated through a heat exchanger, and sent back into the house either through vents at the top of the fireplace or through ducts leading to nearby rooms. Some of these fireplaces are approved to route heated air to a basement auxiliary fan. The air then travels through ducts to other rooms in the house. The fireplace should have a dedicated supply of outside air for combustion.
Flues leak heated and warm air out of your home. If you have a fireplace that you don’t use, plug and seal the flue. If you use the fireplace, be sure to close the flue when the fireplace is not in use. You could also use an inflatable stopper, available commercially, to temporarily seal the chimney and avoid air leakage through the flue.
Catalytic Wood Stoves, Advanced Combustion Woodstoves, and Centralized Wood-Burning Boilers
Wood stoves are the most common appliance for burning wood. New catalytic stoves and inserts have efficiencies of up to 83% HHV (higher heating value).
Advanced combustion woodstoves provide a lot of heat but often only work efficiently when the fire burns at full throttle. Also known as secondary burn stoves, they can reach temperatures of 1,100°F—hot enough to burn combustible gases.
These stoves have several components that help them burn combustible gases, as well as particulates, before they can exit the chimney. Components include a metal channel that heats secondary air and feeds it into the stove above the fire. This heated oxygen helps burn the volatile gases above the flames without slowing down combustion. While many older stoves only have an air source below the wood, the secondary air source in advanced combustion stoves offers oxygen to the volatile gases escaping above the fire. With enough oxygen, the heated gases burn as well. In addition, the firebox is insulated, which reflects heat back to it, ensuring that the turbulent gases stay hot enough to burn. New advanced non-catalytic combustion stoves often have efficiencies of 65 t0 75%, HHV.
Another benefit is that the secondary channels funnel hot air toward the glass doors, keeping them clean for viewing the fire. They can also be slightly less expensive than conventional woodstoves fitted with catalytic combustors. Like wood stoves, centralized wood-burning boilers have been improved over the years. Some modern, centralized wood heaters use wood gasification technology that burns both the wood fuel and the associated combustible gases, rendering them up to 80% efficient. In addition, systems are available that can switch to oil or gas if the fire goes out.
Masonry Heaters
Masonry heaters are also known as “Russian,” “Siberian,” and “Finnish” fireplaces. They produce more heat and less pollution than any other wood- or pellet-burning appliance. Masonry heaters include a firebox, a large masonry mass (such as bricks), and long twisting smoke channels that run through the masonry mass. Their fireboxes are lined with firebrick, refractory concrete, or similar materials that can handle temperatures of over 2,000°F (1,093°C).
A small hot fire built once or twice a day releases heated gases into the long masonry heat tunnels. The masonry absorbs the heat and then slowly releases it into the house over a period of 12 to 20 hours. Masonry heaters commonly reach a combustion efficiency of 90%.
Most are intended for burning wood, but they were historically designed to burn almost any type of solid fuel. The relatively small but intense fire also results in very little air pollution and very little creosote buildup in the chimney. Because most of the heat from the fuel is transferred to the masonry and slowly released into the room over the day, this type of heater does not need to be loaded with fuel as often as other types of wood heating appliances. In addition, if the masonry heater is built where sunlight can directly shine on it in the winter, the heater will absorb the sun’s heat and release it slowly into the room.
A wide variety of masonry heater designs and styles are available. Larger models resemble conventional fireplaces and may cover an entire wall. Smaller models take up about as much space as a wood or pellet stove. They can be custom-built or purchased as prefabricated units. Some large designs may cost $5,000 or more. Plans and kits are available, but they are not easy do-it-yourself projects and require masonry expertise.
In addition to their expense, masonry heaters have one significant disadvantage when compared to conventional wood stoves and fireplaces—they cannot provide heat quickly from a cold start.
Pellet Fuel Appliances
Pellet fuel appliances burn compacted pellets usually made of wood, but they can also be derived from other organic materials. Some models can burn nutshells, corn kernels, and small wood chips.
Pellet fuel appliances are more convenient to operate than ordinary wood stoves or fireplaces, and some have much higher combustion and heating efficiencies. As a consequence of this, they produce very little air pollution. In fact, pellet stoves are the cleanest solid fuel, residential heating appliance. Pellet stoves that are certified by the EPA are likely to be in the 70% to 83% efficiency range. Pellet stoves have heating capacities that range between 8,000 and 90,000 Btu per hour. They are suitable for homes as well as apartments or condominiums.
Most pellet stoves cost between $1,700 and $3,000. However, a pellet stove is often cheaper to install than a conventional wood-burning heater. Many can be direct-vented to the room and do not need an expensive chimney or flue. As a result, the installed cost of the entire system may be less than that of a conventional wood stove.
Pellet fuel appliances are available as freestanding stoves or fireplace inserts. Freestanding units resemble conventional wood heaters in that they generally heat a single room well, but not adjacent rooms unless they have a fan to force the warm air into those other spaces. Pellet-fireplace inserts fit into existing fireplaces. Several companies now make pellet-fired furnaces and boilers for replacement of, or a supplement to, gas- or oil-fired furnaces and boilers in residential space heating systems.
All pellet fuel appliances have a fuel hopper to store the pellets until they are needed for burning. Most hoppers hold between 35 and 130 pounds (16 and 60 kilograms [kg]) of fuel, which will last a day or more under normal operating conditions. A feeder device, like a large screw, drops a few pellets at a time into the combustion chamber for burning. How quickly pellets are fed to the burner determines the heat output. The exhaust gases are vented by way of a small flue pipe that can be directed out a sidewall or upwards through the roof. More advanced models have a small computer and thermostat to govern the pellet feed rate.
Pellet appliances usually require refueling only once a day. However, because the fuel is compressed, the bagged pellets can be difficult to lift. Some models use bulk-filled storage systems and are fully automatic.
Most pellet appliance exteriors (except glass doors) stay relatively cool while operating, reducing the risk of accidental burns. Pellet stoves burn fuel so completely that very little creosote builds up in the flue, posing less of a fire hazard.
Unfortunately, pellet appliances are also more complex and have expensive components that can break down. Moreover, they need to be cleaned by the homeowner on a weekly basis and by a professional on an annual basis. They also require electricity to run fans, controls, and pellet feeders. Under normal usage, they consume about 100 kilowatt-hours (kWh) or about $9 worth of electricity per month. Unless the stove has a back-up power supply, the loss of electric power results in no heat and possibly some smoke in the house.
Chimney Placement and Sizing
Chimneys harness the heat of the fire to create what’s called a stack effect. As the warm air from the fire rises, cooler house air rushes into the wood-burning appliance through vents, providing the oxygen the fire needs to burn. Starting a fire with a good hot burn will encourage this healthy draft to flow. Also, between the higher and lower pressure zones of the home lies a neutral pressure zone. The neutral pressure zone tends to move toward the largest air leak. When the top of the chimney is located above the home ceiling (as it should be), the chimney’s neutral pressure zone is above the neutral pressure zone of the house. Such proper chimney placement creates a gentle flow of air into the appliance and out the chimney even when no fire burns.
If you are designing or building a new home, consider placing the chimney inside your home. A more traditional chimney, constructed along the outside of a home, will lose valuable heat to the cold, outside air. If the chimney air temperature falls below that of the inside air, the cold, smelly chimney air will be pulled into the house by the low pressure of the stack effect. In such a scenario, the house has become a better chimney than the chimney. So when a fire is lit, smoke fills the room.
Chimneys must match the size of the appliance, meaning the flue size should match the stove outlet. If the chimney is bigger than the stove or fireplace outlet, exiting exhaust slows, increasing creosote buildup and decreasing efficiency. High-performance chimneys are also insulated. Older masonry chimneys can be relined to safely and efficiently connect them to newer high-efficiency, wood-burning appliances. Again, the chimney liner should be continuous from the appliance outlet to the chimney top. It is not uncommon to pay as much for the chimney as for your appliance.
Free-standing woodstoves exhaust into a connecting pipe, which then connects into the chimney. If the connecting pipe is longer than 8 feet (as in a vaulted ceiling), you should consider investing in double-layer pipe with 1-inch airspace between pipe layers. Efficient modern stoves produce large amounts of heat. Much of this heat can radiate from a longer length of single-layer pipe, slowing down the draft, which can impact the overall efficiency of your wood-burning system.
Maintenance
To keep your wood- or pellet-burning system operating efficiently and safely, you’ll need to maintain it on a regular basis.
Every year, preferably before each heating season, have a chimney sweep certified by the Chimney Safety Institute of America inspect your wood-burning system. In addition to cleaning the chimney, a certified chimney sweep should have the knowledge to help make sure your appliance, hearth, connecting pipe, air inlets, chimney, and all other components are functioning efficiently and safely.
Catalytic combustors need to be inspected after every two cords of wood burned, and replaced according to the manufacturer’s recommendations. Most catalytic stoves or inserts have a place for a thermometer to help you check the combustor. The catalytic cell is removable and replaceable and costs between $75 and $160. Catalysts in new models, especially those made since 2005, should only need changing once every 5–8 years if burning seasoned wood. Older catalytic stoves made prior to 2000 need to be checked more often and catalysts need to be replaced more often.
Cleaning out the inside of a wood stove with a wire brush periodically will also help the wood-burning appliance heat more efficiently. Even one-tenth of an inch of soot can drop the heat transfer efficiency of the metal by 50%.
For pellet-fuel appliances, it is very important to follow the manufacturer’s instructions for operation and maintenance. Inspect fans and motors regularly, and maintain them properly. Manufacturers advise removing unused pellets from the stove hopper and feed system at the end of the heating season. This reduces the chance of rusting, which can cause expensive damage to the appliance. It also minimizes difficulties in lighting the appliance at the start of the next heating season. Clean the flue vent on a regular basis to prevent soot buildup.
Selecting and Storing Wood
All species of wood have similar heat (Btu) content on a per pound basis when completely dry. Therefore, denser woods will generally cost more and burn longer. Woods like oak, hickory, and pine will burn overnight.
Because a lot of energy can be wasted burning wet wood, you should use wood that has been properly seasoned. Properly seasoned wood is harvested in the spring and allowed to dry throughout the summer. Look for wood that is of even color, without any green. It should have a moisture content of 20% or less by weight.
Store your wood away from the house in case termites discover the woodpile. The top of the pile should be covered, but leave the sides open so air can circulate. If possible, store the wood a foot off the ground (on concrete blocks, for example) to keep it dry.
Pellet Fuel
Pellet fuel is normally sold in 40-pound (18-kg) bags at about $3 to $4 each or about $180 to $250 a ton. Most homeowners who use a pellet appliance as a main source of heat use two to three tons of pellet fuel per year. Pellet fuel appliances are almost always less expensive to operate than electric resistance heating, oil, and propane-fueled appliances.
Most pellet fuels have a moisture content of 5% to 10%. Well-seasoned firewood is usually around 20%. A few pellet manufacturers contain either petroleum or non-petroleum lignin used as a lubricant in the pellet production process, though most contain no additives.
The Pellet Fuels Institute launched the PFI Standards Program, a third-party accreditation program providing specifications for residential and commercial-grade fuel. This standard assures the consumer of the highest quality pellet when certified pellets are purchased.
You can also check pellet fuel quality by inspecting the bag for excessive dirt and dust, which can form clinkers in the stove. There should be less than one half of a cup of dust at the bottom of a 40-pound (18-kg) bag. Pellet stoves designed for low-ash content (typically top-fed stoves) tend to operate poorly when used with pellets of a higher ash content. Many pellet appliance manufacturers are redesigning their products to burn pellets with varying ash contents.
Most pellet fuel appliance dealers either maintain a supply of pellets or recommend a supplier. You may also check the local telephone listings under “Fuel” or “Pellet Fuel,” or inquire at a local tree nursery or at home and garden supply stores.
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Pellet boilers
Energy Efficiency Week 2021 /
Monday
Level 3: Get ready to move to renewable heating – pellet boilers
Modern pellet boilers are the ultimate convenience wood fuel appliance. While they are not going to be the right solution for everyone, they can be a good plug and play renewable alternative to an oil boiler.
If you have images of rolling up old newspapers and getting out the matches to get your boiler going then think again. Modern pellet systems have automatic fuel feed and ignition. They can be operated in much the same way as your standard oil or gas boiler with programmers and timers.
However, there are several differences that need some consideration in order to smooth the switch over of your home heating system.
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Will you be getting ready to move on to renewable heating? I already have | I absolutely will | Not for me |
1: Footprint / space requirements
Without doubt you are going to need a bit more space for a wood pellet system. The space requirements are often the main point for determining if a wood pellet system can be a practical renewable alternative in a home.
The boilers can be up to as much as 50% bigger than the oil boiler you might be replacing. If you are tight for space in the garage you may want to look at a system that can go outside or see if you have room for a self-contained shed.
In addition to the boiler, many systems work in conjunction with a buffer tank. This is a large store of water, sometimes as much as 500l or 1000l. The buffer tank allows the pellet system to operate at its most efficient. It will reduce the amount of fuel you use and reduce wear and tear on your boiler.
Last, and by no means least, is the space required for storing the pellet fuel. Oil is three times as dense as pellets when it comes to the energy it contains by bulk. If you want to store the same amount of energy you will need a store three times larger than your oil tank. However, you could just opt for more frequent deliveries.
The standard store size for a home in Ireland will hold 3.5 tonnes of pellets. This allows you to avail of bulk deliveries and brings down the fuel costs as opposed to buying bags of pellets. This size of store will generally mean one to two deliveries a year for most homes. There are lots of off the shelf solutions for pellet storage.
2: Ash removal
Unlike oil or gas, wood fuels produce ash which needs to be removed from the ash pan on average about once every three weeks. It’s also important to brush down or vacuum out the heat exchangers as ash builds up here too and will reduce the boiler efficiency if not removed. It is a simple DIY job but you can make it easier by ensuring access to the boiler is good and one of those ash hoovers can be handy. The ash can be put in the bin when it is cool. You can also compost it (if you have apple trees, they will love it).
3: Servicing
As with all boilers (fossil fuel or renewable) they will need regular servicing by an experienced engineer. If you want your boiler to operate safely, efficiently, and not break down just when you need it most then an annual service is just as important as it is for any other type of boiler.
When it comes to finding a pellet boiler engineer there are just fewer of them about, so it tends to cost a bit more and you need to plan ahead. It is well worth talking to your potential installers to see if they can also service your boiler.
4: Clean air zones
Although wood heating offers a renewable, lower-carbon alternative to fossil fuel-based systems, to ensure there is no trade-off between decarbonisation and air quality, policy support may increasingly require that wood heating systems limit air pollutants to acceptable levels.
Pellet boilers produce fine smoke particles and other air pollutants. Although they are significantly cleaner than burning solid fuel on open fires or in stoves, they still produce higher levels of particulate matter than gas fired alternatives. This mainly becomes an issue in urban areas where smoke control zones will mean that the boiler you install must be approved as an ‘exempt appliance’.
Using good quality wood pellets and regularly servicing your boiler will also help to keep emissions of air pollutants to a minimum.
5: Costs
There are running cost savings to be had compared to fossil fuels. Wood pellets are not as affected by the global markets as oil and gas are. According to SEAI 2020 wood pellets are circa 31% cheaper than oil per unit (kWh). Oil at 8.53 cents per kWh and Wood pellets (bulk delivery) at 5.94 cents per kWh.
Biomass boilers can cost anything from €2,000 to €20,000 depending on what you are looking for. They tend to be more expensive than the equivalent oil or gas boiler but the lower running cost will save you money over the lifetime of the system.
Grants for residential pellet systems are not available as an individual measure. However, grants for pellet burning stoves are available when included as part of a wider energy efficiency upgrade under the Community Energy Grant Scheme and the National Retrofit scheme (One -stop-shop development).
Will you be getting ready to move on to renewable heating?
I already have | I absolutely will | Not for me
Manage consent
1 ton of pellets is equal to |
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120 gallons of heating oil |
16,000 ft³ of natural gas |
170 gallons of propane |
4,775 kilowatt hours of electricity |
Do-it-yourself pellet boiler
Minimizing housing maintenance costs is one of the most important tasks today. The search for cost optimization tools is ongoing. Heating at home, with regularly rising tariffs, is a significant item in the family budget.
It can be reduced in several ways. With the help of energy-saving technologies in the construction of a house and the use of efficient heating systems. A pellet boiler is more economical than gas-fired counterparts, not to mention electricity and other energy sources. The reason lies in the low cost of consumables and the high energy efficiency of the device.
Principle of operation
Principle of operation of a pellet boiler (click to enlarge)
Among the energy carriers delivered centrally to the consumer, the most economical type is gas.
However, it is seriously competing with alternative heat sources, among which a pellet boiler for home heating is the most profitable solution. There are no fundamental differences at first glance. In the heat exchanger, which is built into the combustion chamber, water is heated, which heats the house.
Why are the most productive gas boilers made using innovative technologies economically inferior to self-made pellet-fired counterparts? The answer is simple, the cost of 1 kW of energy when burning gas will be higher than the same amount of heat when using alternative fuels.
The raw material for pellets is wood waste, the cost of which is minimal, since the issue of their disposal is very acute and the production of fuel pellets is one of the ways to get rid of unwanted products of the main activity. Pellets can be made with your own hands, but this will require special equipment.
Device
Device of a pellet boiler with the designation of the most important elements and assemblies (click to enlarge)
Before starting work, you should evaluate your strength. The production of a boiler requires good training, knowledge, skills, and making it much more difficult than gas or electric. It is no coincidence that finished products of this class are very expensive.
In addition to the pellet burner for the boiler, which is almost impossible to make at home, all other structural elements will have to be done by yourself. It will take a lot of work to achieve the desired result.
Having experience in similar work, assembling a heat exchanger and laying out a combustion chamber from fireclay bricks is quite feasible work. The burner installation can also be handled, but the fuel supply system will have to work hard. This most important node in each case is exclusive. It is necessary to ensure uninterrupted and reliable supply of fuel pellets to the burner (read about boilers with automatic fuel supply here).
The density of pellets is high, and a large number of pellets cannot burn at the same time.
Please note: the supply of fuel and air in pellet boilers is always forced.
It is almost impossible to ensure the correct mode in manual operation, unless you are constantly nearby. Therefore, the device is equipped with automatic systems, and they cost a lot.
This is a factor in the high cost of the whole structure. One or more programmers cope with the task without outside interference. Even a small fuel bunker is able to heat a house offline for up to three days. If you assemble a more solid structure with a large supply of pellets, then the period of use can be increased significantly.
Expert tip: It is very important to accurately calculate the air supply. With a lack of air, the pellets may not burn, but smolder, and with an excess, there will be heat losses that will be blown into the atmosphere.
Additional costs will also apply for the purchase of the motor for the auger mechanism and its automatic connection. Before assembling a pellet boiler with your own hands, you need to draw up drawings of the future boiler, calculate its dimensions depending on the area of \u200b\u200bthe available space for its installation.
Materials
The main part of the pellet boiler is the burner
The decision to make a pellet boiler with your own hands is not cheap, but the finished product will cost even more. The main element of the device is a burner, which is purchased separately.
Similar to factory models, the focus is on assembling the body and fitting all components. Assembly kit includes:
- Sheet steel 4-6 mm for making the boiler body.
- Bunker material. It can be made from sheet metal (1-2 mm thick will be enough), plywood, wood.
- Auger. It is selected according to size or, with existing skills, it is done independently.
- Chimney pipes. Metal or asbestos and mounting kit.
- Control system. Provides automatic control over the operation of the boiler.
- Motor for driving the auger mechanism.
- Tubes for heat exchanger. Square sections are recommended.
- Pipes and fittings for connecting the heating system.
- Firebrick, if the combustion chamber is made stationary.
- Grate. It will provide air access to the place of combustion.
Advantages
Do-it-yourself pellet boiler
The main obstacle to installing pellet boilers is its price. It is noticeably higher than analogues using other types of fuel.
Significantly reduce costs by making a pellet boiler with your own hands. If, on average, a factory model pays off in 2-3 years, then a home-made boiler will justify itself about twice as fast. A significant help for the family budget.
A good design solution can be another advantage. The shape and configuration of the device can be optimally integrated into the home. It will be more convenient to use it than the factory model.
Operating tips
A correctly assembled pellet boiler does not require any special care. Everyone can use it, regardless of gender, age and training. What you should pay attention to is the storage and loading of fuel pellets.
Despite the fact that they do not absorb water well, prolonged exposure to a damp place impairs their consumer qualities. Especially if the pellets are made by yourself. It is not recommended to store them outdoors. Only on a pallet and better in airtight bags, as for example they are supplied by many major manufacturers.
Please note: when purchasing pellets, you should pay attention to their color. The lighter they are, the better. Dark granules indicate a high content of bark and undesirable impurities that impair heat transfer.
How to make a pellet boiler with your own hands, and how it will work, see the following video:
- Author: Natalia Florya of 5)
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Pellet burner and do-it-yourself boiler
Ready-made burner
In recent years, it has become economically justified to purchase various heating systems that run on alternative fuels. For example, pellet boilers are very popular, which are easy to install and operate. Especially where there is no gas pipeline, and electricity is very expensive. The main disadvantage of such a boiler is the high cost, so the idea of purchasing only a pellet burner and making a heating device with your own hands is quite justified. Despite the fact that it costs a lot, in the end the entire unit should cost much less than its counterpart in the store.
Content
- On the advantages of using pellet
- On the advantages of pellet boilers
- The principle of operation of the boiler and its constituent elements
- Creation of a pellet boiler
- Conclusion
On the advantages of the use of pellet
. from wood waste and peat. Outwardly, they resemble cylindrical granules with a standard size of 10 mm. Among the advantages of such biofuels it is worth noting:
- Pellets are produced without the use of chemical components, they have no smell, unlike fuels such as gas, coal or diesel fuel. In addition, pellets do not absorb moisture, which makes it possible to maintain their calorific value for a long time under normal conditions.
- Unlike other types of fuel, such pellets do not ignite, they do not contain dust, which often causes allergies, and even surpass coal in their thermal properties.
- High efficiency, while the amount of ash does not exceed 2% of the total volume of the pellets.
- Pellets save space compared to other wood fuels and are easy to transport.
- Pellets are an economical type of fuel in terms of financial costs.
About the advantages of pellet boilers
Pellet boiler is a kind of solid fuel boiler, which has an automatic fuel supply mechanism for continuous operation of the unit. As a rule, the combustion chamber in such a device is relatively small, since the main heat removal is carried out in a well-developed multi-pass part of the boiler. The boiler is equipped with a special volumetric pellet burner, which provides a higher coefficient of performance (COP) when burning pellets, compared to other types of similar burners operating on solid, liquid or gaseous fuels.
Fuel supply is carried out from the bunker in automatic mode, so that the boiler can work without human effort for a long time. For example, if the bunker is loaded in full, then this will be enough for 5-7 days of uninterrupted operation of the boiler.
Among the advantages of pellet boilers it is worth noting the following:
Simple scheme
- If necessary, not only pellets, but also firewood or coal, as well as other plant waste can be used as fuel.
- Presence of an automatic burner ignition system.
- Device fire safety.
- Reduced costs due to the low cost of pellets, no maintenance costs.
- High efficiency heating device.
- The average life of such a boiler is 20 years.
- Independence from centralized fuel sources and tariffs for similar services.
How the boiler works and its components
So, if all the advantages of pellets and boilers operating on this type of fuel were appreciated, and a decision was made to create such an element as a burner with your own hands, then it’s time to get acquainted with the general principle of building such a design.
Another method
Fuel from a special container for storing pellets enters the combustion chamber with the help of a transport auger. Considering that the boiler does not have a direct source of natural draft to maintain combustion, it is necessary to provide such an element as a burner in it. It will act as an air blower with the help of a special fan, and will ignite the fuel at the moment the boiler is turned on.
The heat energy is then transferred to the heating medium of the system via the heat exchanger, and the flue gases are discharged through the chimney. At the same time, an insignificant content of mineral elements in pellets forms an equally small amount of ash . Its removal is carried out through the grates of the grate into the ash pan chamber. As the pellets burn out in the combustion chamber, the temperature drops, which can be recorded by a special sensor. Then, with the help of an auger, pellets are automatically fed from the loading tank.
Creating a pellet boiler
At first glance, the system may seem too complicated, but with great desire and due skill, everything can be done by hand. To do this, you will need to develop a project with detailed drawings, select the necessary materials and tools, as well as purchase additional ready-made components.
Materials for work
The first stage is the creation of a project, which must contain thoughtful and accurate drawings, diagrams and the order of assembly of all elements. It is not recommended to build a structure without a project, as there is a high probability of error.
To create a boiler with your own hands you will need:
- Pellet burner – it is best to purchase such an element factory-made, since it will be problematic to make it on your own. The burner is not just an element where the fuel is ignited, but it also performs the functions of regulating the flame.
- Sensors and several programmers that help you save fuel and keep your home at the most comfortable temperature.
- The body must be made horizontal to make efficient use of the heat from the combustion fuel. Sheet steel, bricks or cast iron can be chosen as the material for the body. It is necessary to give preference to the material that will allow you to retain heat for a long time, and guarantees its high-quality transfer to the next structural element, i.e. heat exchanger.
- Heat exchanger – mounted inside the housing, and is made in the form of several rows of pipes or a coil, which are connected on one side to the building’s heating system. In addition, an inlet for pouring cold water into the heat exchanger must be provided.
- Ash pan.
- Combustion chamber – the diameter of its opening must be equal to the parameters of the purchased pellet burner.
- Chimney.
- Fuel bin – the place where the fuel will be stored and from where it will be fed to the burner.
- 100 mm auger, metal outer casing and electric motor that will be connected to the pellet boiler control unit.
Pellet inlet
Insert the auger inlet into the tank outlet. Then, a plastic pipe is fixed on its other part, through which granules will flow to the pellet burner. When a signal is received, the electric motor starts and runs until the combustion chamber of the heating device is filled with the required amount of heat.
As a result, a complex of individual elements, ready-made and made by hand, together is an efficient pellet boiler.
Conclusion
Having decided to create a pellet boiler with your own hands, you should remember that such a decision will not always be more profitable than purchasing a ready-made design, especially since economical device options are also offered today. To do this, it is necessary to calculate the full estimate of materials, all costs for the services of a welder and other expenses. Therefore, if in the end the amount is significantly lower than the cost of acquiring a finished complex, then you can safely proceed to the manufacture of the boiler with your own hands.
Read more:
Do-it-yourself pellet boiler drawings and working principle. Description of the design of the boiler
Contents
- Do-it-yourself pellet boiler drawings and the principle of operation. Description of the design of the boiler
- Do-it-yourself pellet burner controller. Why use a pellet burner
- Video pellet boiler with their hands – a test! Pellet boiler with their hands.
Do-it-yourself pellet boiler drawings and principle of operation. Boiler construction description
If you purchase automated equipment for heating your home with pellets, you can spend up to 3 thousand USD. e., which is very costly. More budgetary, but reliable designs will cost about 500 USD. You can make them yourself, which will save you a lot.
But before you start working, you should have a good understanding of the structure of the pellet burner. Its key task is to ensure flame stability and uniform burning of sawdust. Attention should be paid to adjusting the intensity of combustion.
The main structural elements of the product are as follows:
- combustion chamber;
- solid fuel hopper;
- screw conveyor for fuel supply;
- fan for blowing air into the chamber.
How long the automatic boiler will be serviced depends on the volume of the hopper. The fan is controlled by an electronic control unit. The rate of combustion of fuel is directly affected by the rate of air supply.
You need to be well prepared in order to properly assemble the sawdust burner with your own hands, the drawings can be found in open sources. The device is volatile, without electricity the unit, fan and conveyor will not be able to work.
The principle of operation of the pellet burner is as follows:
- at the first feed, sawdust that enters the chamber is ignited under the condition of minimum air supply;
- when the first portion of pellets burns, the air supply increases, the fire intensifies, due to which the combustion chamber warms up;
- fuel is supplied in small portions, air pressure is normalized, the flame is evened out;
- when the burner starts to work stably, the fuel will disperse in small doses and heat up the boiler efficiently.
Bulk fuel is supplied to the burner in two ways. In the first case, you need to put a large bunker, pellets are immersed in it from consumption for 10 days, subject to continuous operation of the equipment. In order to supply fuel to the nozzle, a screw conveyor is mounted. It has a length corresponding to the distance between the boiler and the hopper. In the second case, it is placed directly on the burner, and the fuel enters the auger under its own weight. This type of burner is called gravity.
Do-it-yourself pellet burner helps to significantly diversify the functions of a solid fuel boiler. There will be an opportunity to save coal and firewood. It is also easy to maintain. Fuel will need to be laid only once a week.
DIY pellet burner controller. Why Use a Pellet Burner
Pellets are a material for burning. We are not talking about conventional pallets for transportation. Pellets for the burner are pressed wood in the form of small cylinders. Their diameter reaches 25 mm. They successfully broke into the market and do not stop conquering it. People who have used such fuel note its high quality and use only it.
However, if pellets are the same wood that is loaded into the firebox, why spend money and effort on creating an additional mechanism? Although this is logical, but in this case, the solid fuel material will burn out by 80 and even 40%. The rest is simply disposed of. As a result, the efficiency of such a furnace is reduced significantly. If you use a burner, then the combustion of the material will be 98%. The difference is significant.
Please note! Pellets are not suitable for pyrolysis boilers. During operation, they harm him, and the equipment has to be serviced more often.
It is also important that the temperature inside the burner reaches 1,000 degrees Celsius as the pellets burn! That is why it is worth considering whether it is possible to install a pellet burner for your boiler. This is quite rational if you understand the principle of operation of the pellet burner during assembly, and also follow the instructions. Then the burner will be a great addition to the boiler, improving its efficiency. At
The main task of the burner is to organize a powerful torch that will heat the boiler. A pellet burner is used for the same and consists of a small combustion chamber in the form of a wind tunnel. Pellets are fed into it from the bunker. Under the influence of the air flow, a directed flame is formed. The combustion chamber is made rectangular or round. The outer part consists of a screw conveyor. Fuel from the bunker is supplied through the inlet pipe. The next indispensable element is the fan. It will supply air to the bottom of the chamber.
The principle of operation is as follows: the pellets enter the chamber where they are ignited. The fan turns on, supplying a minimum amount of air. As the flame ignites, the fan spins faster, pumping in more air. The result is a smooth and powerful torch. Factory burners are fully automated. The controller of the pellet burner allows you to regulate the supply of pellets, air, etc.
Video pellet boiler with your own hands – a test! Pellet boiler with their hands.
Do-it-yourself homemade pellet boiler
Of all the hot water heating installations that burn various types of solid fuels, the pellet boiler is rightfully considered the most perfect. And it is not surprising, because the efficiency of burning pellets is very high, and the degree of automation of the unit allows you not to interfere in its work for weeks, if only there was enough volume of the loading hopper. But all these advantages also turn into another side – a decent cost of equipment, which includes not only the heater itself, but also a fuel hopper with a screw conveyor. However, there is an opportunity to become the happy owner of such a high-tech unit, paying half the price for it. To do this, you will have to make a pellet boiler with your own hands, we will analyze this topic in this material.
The design and principle of operation of pellet boilers
To mount such a solid fuel installation on your own, you will need to work hard, but first you need to figure out how it works and what it consists of. The heart of the pellet unit is the burner, which performs almost all the main functions and is connected to the boiler controller, acting on its commands. Pellet burners are of two types:
- retort;
- flare.
The difference between them is as follows. A retort pellet burner is a bowl (retort) filled from below with fuel by means of an auger, and air is supplied to the combustion zone by a fan through holes located on the sides of the bowl. During operation, the flame column is directed upwards, which should be taken into account by the design of the boiler. The flare burner device is a pipe, it is also a combustion chamber, where pellets are fed from one end, and a powerful horizontally directed flame comes out of the other. This is achieved by forcing air into the chamber from the same side as the fuel.
Flare-type burners are used more often than retort ones, as the latter have problems with supplying poor quality pellets. To assemble a boiler plant with your own hands, it is also preferable to use a torch burner, below we will justify why.
In the following, we will consider the operation of the unit with a flare burner, since this design is better suited for our purpose. So, the combustion chamber in the form of a pipe is located inside the boiler, and the outer part of the burner consists of a housing with a feed screw and a fan for blowing air. For the operation of electric ignition and maintaining the flame, the design also includes a control board, a photo sensor and an incandescent element. In the upper part of the body there is a fuel supply pipe.
The process is as follows: at the command of the controller, the auger feeds a small amount of pellets into the chamber and stops. The incandescent element and the fan are switched on at the same time, causing the fuel to ignite. The appearance of a steady flame fixes the photo sensor, and notifies the control unit about this, and it turns off the incandescent element. Then work begins in normal mode, the screw conveyor resumes supply, and the fan pumps the required amount of air. At the command of the same controller, pellets are poured into the burner through the nozzle, moved there from the hopper by an external screw conveyor.
Many manufacturers use a fuel tank mounted directly above the burner nozzle, which allows the pellets to fall into it on their own without an additional conveyor.
Now it is worth considering the device of the pellet boiler as a whole. The design of the body of the unit is typical for all solid fuel installations, it is an internal chamber made of steel or cast iron, enclosed in an outer casing filled with water – a water jacket. To extract heat from flue gases, the design can provide 2 types of heat exchangers:
- fire tube;
- water pipe.
In a water-tube heat exchanger, the heating medium flows through pipes that are washed by the combustion products and transfer their heat to it. But such a device is rarely found in solid fuel boilers, usually the opposite is true in them: flue gases pass through the pipes, giving combustion energy to the water jacket, this is the fire-tube heat exchanger. In order for the boiler to be efficient, the heat exchanger is made two- or three-way. This means that the flue gases, passing through the flame tubes, change their direction to the opposite twice or thrice, making 2 or 3 strokes. This allows you to give them maximum heat to the water jacket, and at the exit to the chimney to get a temperature of no more than 150 ºС.
The working process is as follows: the burner burns fuel and heats the walls of the chamber, and they warm up the coolant. In turn, the combustion products, under the influence of natural draft and fan operation, pass through the flame tubes, also giving off heat to the water jacket, and are thrown into the chimney. The intensity of combustion is controlled by the controller by a signal from a temperature sensor immersed in the coolant at the outlet of the unit. This is the principle of operation of pellet boilers in order to automatically regulate the combustion process and, if necessary, increase or decrease the supply of fuel and air to the burner.
Recommendations for the manufacture of the boiler
The first thing to do is to choose the design of the unit. Here the recommendations are as follows: do not complicate your work and choose a boiler device taking into account the future. In simple words, it is worth separating those elements that you can make yourself from others that you have to purchase. The latter include a burner with a set of automation.
Some craftsmen offer to make a burner with their own hands, but this assembly is quite complicated, you can spend a lot of time and effort on it, and as a result, the operation and consumption of a pellet boiler will be unpredictable. It’s probably easier to buy a finished product and put it in a home-made unit, but everyone decides this question for himself.
To choose a design with perspective, you need to make it universal. That is, it is proposed to make a home-made pellet boiler in the image of a conventional solid fuel unit, in which it is possible to burn wood and coal. In essence, the heat exchange processes occurring in both types of heaters are identical, only the fuel and the method of its combustion differ, which is shown in the figure:
So, we boldly accept the design of a traditional solid fuel boiler with the possibility of being built in instead of the loading door of the burner device on the mounting plate. This will provide the following benefits:
- Since the production of pellets is not yet very common in our country and fuel shortages are possible, you can remove the pellet burner at any time and heat your home with wood or coal.
- It will be possible to use natural gas or diesel fuel by installing a gas or diesel burner instead of a pellet burner.
It is best to take heat-resistant steel 5 mm thick for the boiler furnace. The ideal option is steel alloyed with chromium and molybdenum (stainless steel), but it is quite expensive, and special skills are required for its welding. For this reason, pellet boilers are made of ordinary carbon steel St20, and St3 grade 3 mm thick is suitable for the water jacket casing. From the same metal as the combustion chamber, it is preferable to take blanks for the doors and flame pipes for the heat exchanger. The grate is cut out of 10 mm thick steel or simply bought ready-made. Well, for the chimney and coolant pipes, you will need pipe sections of the appropriate diameters.
Assembly is carried out by welding, using the drawings of the pellet boiler. Particular attention should be paid to toughening the walls of the water jacket with pieces of steel strip or angle, as well as the removable design of the loading door. Upon completion, the welds must be tested for permeability and the defects eliminated.
Pellet boiler piping
In practice, the installation of a pellet boiler is not much different from the installation of other solid fuel “brothers”. Here the main task is to correctly place all equipment together with fuel supply devices. Remember that between the units of the units it is required to observe passages with a width of at least 700 mm, and there must be a space of 2 m in front of the front panel of the unit.
If, during the ignition of any solid fuel boiler after stopping, the coolant is supplied from the heating system, then toxic condensate mixed with ash and soot is formed on the inner walls of the furnace. In order to prevent this process, which destroys the metal over time, during installation, piping schemes for pellet boilers with a mixing unit are used.
Here the main role is played by a three-way valve, whose task is to prevent the coolant from the system from entering the jacket of the unit until it warms up. At this time, water, driven by the pump, circulates in a small circle from the supply pipeline directly to the return through the three-way valve. As soon as it reaches the set temperature, the valve will start mixing water from the system into the return line, eventually blocking the movement in a small circle. At the same time, the piping of a pellet boiler should provide for the installation of a pump on the return, and not the supply pipeline. Do not forget about the safety group with a safety valve and a pressure gauge, which must be installed on the heater outlet pipe.
Conclusion
As practice shows, home-made pellet boilers are inferior to factory-made plants in terms of efficiency, but they surpass them in affordable cost and reliability. The latter is achieved by the thickness of metal structural elements.
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Equipment -1 :: Equipment -2 :: Equipment -3 :: Equipment -4 :: Equipment -5 ::Operating principle and wiring diagram of the pellet boiler
For those who decide to switch to heating with pellets, the question is already settled – why they do it. Now it is important for such an owner to understand the principle of operation of a pellet boiler, what is the connection scheme for a pellet boiler and how pellet boilers are installed in new or existing heating systems.
The very fact that a person has to install just such a heat generator that burns pellets usually indicates that the main gas is not available, and when heating on electricity there is no night or rural tariff and it is too expensive to heat with an electric boiler.
Otherwise, the installation of pellet boilers looks like just a whim, a desire to “play around” with a new expensive toy.
Because if you have access to mains gas at a reasonable price or you can heat your house with electricity at a price of 0. 85 rubles per kilowatt, then heating with pellets at a price of 2 rubles per kilowatt looks, to put it mildly, incomprehensible.
But if you don’t have either, then connecting a pellet boiler to your heating system is just a matter of time. Because in the absence of cheap gas and cheap electricity, only automated and uninterrupted operation of a pellet boiler can provide the house with normal heat in batteries and hot water in a tap.
Let’s briefly consider the structure of a pellet boiler, its principle of operation and connection diagram.
How the pellet boiler works
The basic principle of operation of a pellet boiler is the metered supply of fuel to the combustion chamber in the amount that is needed to obtain a given amount of thermal energy at a given moment.
In contrast to a solid fuel boiler on wood, where the entire fuel load is already in the firebox and either burns all or burns on one side, fuel is supplied in portions to the combustion chamber of a pellet boiler.
This is done through the mechanism of a pellet burner, which can be of three types:
- blast or flare,
- retort or volumetric combustion,
- flow or conveyor.
Flare burners can be with forced feeding of pellets by an auger and gravity, in which the pellets “fall” under their own weight into the working area of the burner to the space vacated from the already burnt pellets.
Pelletron burner is a prominent representative of prefabricated gravity burners.
Each of the above types of burners needs a separate description, so each of them has a separate article – see them on the website in the “Burners for boilers” section.
As for the boilers equipped with burners with forced feeding of pellets, fuel is supplied to them by auger or pneumatic supply from the hopper to the burner in precisely measured portions by the controller. The size of the portions depends on the temperature that is required to be maintained at the moment in the house and on the temperature of the outdoor air.
The burner fan forces air into the combustion zone. The amount of air is also calculated by the controller.
The heat from the burnt pellets is removed by a tubular, plate or fire tube boiler heat exchanger, depending on the design of its furnace. The best pellet boilers use vertical tube heat exchangers and horizontal multi-pass heat exchangers.
In general, the concept of “the best pellet boiler” depends on many factors and in different conditions the best boiler will be one or another heat generator.
For example, in the absence of electricity, the best boiler would be a non-volatile pellet boiler Pelletron. Under these conditions, only the simplest pellet boiler scheme will work.
And in conditions of tough fuel economy, the best pellet boiler will be an expensive boiler with good automation, which allows you to fine-tune the combustion of pellets.
After the flue gases have given up their heat to the heat exchanger, they are discharged into the chimney. A chimney for a pellet boiler is a topic for a separate discussion, see also it on our website.
Pellet boiler connection scheme
Pellet boiler connection scheme to the home heating system is identical to the connection scheme of any heat generator, whether it is a gas boiler or a diesel fuel boiler.
The bottom pipe of the boiler cuts into the return, the upper pipe cuts into the flow. The combustion of pellets in the boiler burner is strictly controlled by two factors:
- auger fuel supply,
- air supply by fan.
Therefore, overheating of the boiler in a normal situation is impossible. This means that there is no need to tie the boiler supply with metal. The scheme of a pellet boiler with polypropylene or metal-plastic pipes has worked great for many owners for many years.
And for emergencies caused by accidents in power lines or failure of the boiler controller, it is worthwhile to provide an emergency shutdown scheme for the supply of fuel and air to the combustion chamber of the boiler. The amount of pellets that will be in the boiler furnace at the time of the accident is no longer able to cause overheating of the coolant in the heating system.
Naturally, a safety group with a pressure gauge and an emergency valve must be on the boiler supply.
With such ease of tying, the installation of pellet boilers can be carried out not by a specialized organization, but by any construction organization with a license.
Just do not trust the installation of pellet boilers to the first comers. This is a thermal device designed for burning wood fuel, it is a source of increased fire hazard. And therefore, they may be able to install a pellet boiler. But to set it up and ensure fire safety is unlikely.
Installation of pellet boilers – some features
Most pellet boilers are made using boiler steel, the share of cast iron pellet boilers on the market is small. This is due to the fact that the high combustion temperature of the pellets is localized either in the flame of the blast burner or in the cup of the retort burner. Therefore, there is no need to make the entire boiler out of cast iron, as is the case with coal or wood boilers.
This means that a separate foundation or reinforced floors are not needed to install a pellet boiler. An ordinary boiler with a capacity of 20-40 kilowatts weighs from 150 to 300 kilograms, which allows it to be installed on the floor of the most ordinary boiler room, without any reinforcement.
If you mount a large capacity bunker for 0.5 – 1.5 tons of pellets to the boiler, then you will have to make a reinforced base under it.
Further, since there is very little ash from pellet combustion, there is no need to clean the boiler and remove the ash frequently. It is enough to buy a pellet boiler with a large ash pan and clean the boiler once a week. Some comrades come to their boiler once a month, but this, I think, is too much. The boiler must be monitored and serviced.
Do-it-yourself pellet boiler drawings and principle of operation.
Description of operating modes
Contents
- Do-it-yourself pellet boiler drawings and principle of operation. Description of operating modes
- Homemade pellet burner drawings. Why pellets
- Do-it-yourself automation for a pellet boiler. Making a pellet boiler with your own hands
- Equipment features
The principle of operation of a pellet burner is as follows: a portion of fuel enters the chamber, it is ignited and the minimum air supply is turned on. As the fuel ignites and the chamber warms up, more air is forced in. As a result, a stable, even flame is formed, which heats the heat exchanger with water. In factory burners, the process is fully automated, ignition is provided by an electric incandescent element, its operation is controlled by a photo sensor. The amount of air and pellets supplied to the chamber is regulated by the electronic unit, receiving signals from temperature and pressure sensors. The diagram of a pellet burner will help you understand the operation of the device.
Fuel in the form of wood pellets or seed husks can be fed into the pellet burner auger in various ways:
- should be cleaned once a week. From the hopper, the fuel is moved to the burner by an additional screw conveyor of the required length.
- A do-it-yourself gravity pellet burner can be equipped with a simpler fuel supply. In it, the husks and granules under their own weight are poured into the auger from the bunker installed directly above the burner, and it delivers the right amount to the combustion chamber. Then the power reserve of the boiler will be from 1 to 3 days, depending on the intensity of work.
It is not difficult to select materials for the manufacture of the device. Considering the temperature regime of the combustion chamber, it is better to take a pipe made of heat-resistant steel with a wall thickness of at least 4 mm for it. The flange plate, with which a home-made pellet burner is attached to the body of the boiler installation, can be made of ordinary quality steel 3 mm thick. The feeding conveyor can be purchased assembled, or you can make it yourself from a regular pipe by placing an auger in it. For rotation, a low-speed electric motor, gearbox and bearings are selected. The fan must be bought and fixed on the plate, preparing a seat for it. The plate itself must be made, having studied the drawings of the pellet burner, and depending on the design of the boiler door.
Homemade pellet burner drawings. Why pellets
For those regions where gas is not provided, such biofuel is a salvation. It is very effective and has a reasonable cost. For comparison: burned 1 kg of pellets emit thermal energy equal to 0.5 liters of diesel fuel. They are capable of delivering 5 kW / h. To heat a one-story house in an area with moderate winters, you need 50 kg of pellets per day. The advantage of fuel is that it can be filled up once for several days. It all depends on the model of the boiler. Pellets are loaded into the bunker, and then they are fed into the burner itself. A do-it-yourself pellet burner needs maintenance twice every 7 days.
If we talk about the disadvantages of this solid fuel and burners, then this is the possibility of reverse thrust. In this case, the fire will break out into the bunker. The result is a house fire. The second point concerns the amount and intensity of air supply. Pellets are light in weight, which means that the air flow sometimes blows them off the device. Then they won’t burn. And when the air supply is low, the fuel does not burn completely
In order for the burner and furnace to function correctly, it is important to follow the sequence.
Light the fuel with a ceramic rod lighter. It not only gives direct fire to raw materials, but heats up more than 1 thousand degrees. This is done so that during ignition the flame does not go into the bunker with other pallets. Further inside, air is supplied so that the combustion flame remains stable and even. After that, the operating mode is reached, since a large amount of air is supplied inside. You can stop the process by stopping the air supply to the burner.
Do-it-yourself automation for a pellet boiler. Making a pellet boiler with your own hands
When choosing a heat source for your home, you should pay attention to a pellet boiler. The unique design allows you to heat the house automatically. The device works on pellets – one of the granulated types of wood fuel, consisting of a mixture of peat, wood residues, bark and other waste. If desired, you can always make it yourself.
Features of the equipment
Like any heating equipment, pellet stoves have their own advantages and disadvantages.
Advantages
Pellet heaters gained their popularity due to the following properties:
- fire safety;
- automatic operation that allows fuel supply and burner ignition without the involvement of people;
- low maintenance;
- high efficiency;
- long service life;
- possibility of independent heating of the house.
Disadvantages
Negative moments are associated with the following features:
- large dimensions of the equipment can create certain difficulties when choosing a place for their installation;
- possible difficulties with the purchase of fuel;
- high cost.
Device
The pellet boiler consists of a burner, a hopper and a screw mechanism used to feed the fuel.
Burner
It can be of different designs depending on its technical characteristics and principle of operation.
Volumetric is installed directly in the furnace of the device. It comes in steel or cast iron. Allowed manual (using matches) and automatic ignition. In the latter case, a special electric fan is provided.
Flare is characterized by low power. It has compact dimensions.
Auger mechanism
The mechanism is powered by an electric motor. Has a screw up to two meters long. Geometric parameters within the specified limits avoid the need to clean out sawdust, which often accumulates at the pellet feed point.
Can be equipped with a special sensor that controls the degree of heating of the auger casing. When overheating, the fuel supply stops due to the operation of the machine.
Hopper
The design features of the hopper have a direct impact on the battery life. For longer work, an additional auger is often installed.
Sometimes a pack of pellets is used as a bunker, fixed with the help of special tripods.Such a system not only ensures the timely supply of fuel, but also solves the problem of its storage.
How it works
Fuel is supplied to the combustion chamber via a transport auger from a special container designed for storing pellets. The device does not have a direct source to provide natural draft, so a burner is provided in it. Thanks to the presence of a special fan, it pumps air and ignites the fuel at the moment when the device is turned on.
Thermal energy is transferred to the heating medium via a heat exchanger. Flue gases are removed through a chimney. Due to the presence of a small amount of mineral elements in the pellets, a small amount of ash is formed.
The ash is removed through the grate into a special ash chamber. As soon as the pellets in the combustion chamber burn out, the temperature drops. This is fixed by a special sensor. After that, with the help of a screw, the pellets are automatically fed from the loading tank into the combustion chamber.
Installation
Pellet boilers must be installed in accordance with certain requirements for the installation site.
Choosing a place
It is better to install the unit in a separate room due to its impressive dimensions. The best option is a room with a temperature of at least +10 ° C.
Outdoor installation is not recommended. However, when placing the equipment outdoors or in a garage, pipes should be placed underground below the freezing level to reduce heat loss.
Floor and wall preparation
The floor must be leveled where the equipment will be installed. The platform must be strong enough to support the weight of the machine and the pellet bin. Non-combustible plates should be fixed to the walls and floor. Near the device, a place for pellets is necessarily provided.
Ventilation and chimney
We install ventilation and chimney made of non-combustible material. The latter, as a rule, is displayed on the roof, protruding at least half a meter above its surface. It should be protected from rain and insulated.
The cross section of the chimney pipes must be larger than the diameter of the hole intended for the removal of exhaust gases from the equipment.
Do-it-yourself pellet burner for a solid fuel boiler. About the advantages of pellet boilers
Pellet boiler is a kind of solid fuel boiler, which has an automatic fuel supply mechanism for continuous operation of the unit. As a rule, the combustion chamber in such a device is relatively small, since the main heat removal is carried out in a well-developed multi-pass part of the boiler. The boiler is equipped with a special volumetric pellet burner, which provides a higher coefficient of performance (COP) when burning pellets, compared to other types of similar burners operating on solid, liquid or gaseous fuels.
Fuel supply is carried out from the bunker in automatic mode, so that the boiler can work without human effort for a long time. For example, if the bunker is loaded in full, then this will be enough for 5-7 days of uninterrupted operation of the boiler.
Among the advantages of pellet boilers, it is worth noting the following:
A simple scheme
- If necessary, not only pellets, but also firewood or coal, as well as other plant waste can be used as fuel.
- Presence of an automatic burner ignition system.
- Device fire safety.
- Reduced costs due to the low cost of pellets, no maintenance costs.
- High efficiency heating device.
- The average life of such a boiler is 20 years.
- Equipment features