This is my gravity fed pellet burner.

The air intake and the feeding rate can be adjusted depending on the intensity of heat needed.

Set to the minimum feeding rate,  i get over 8 hrs of heat with a 40 pound bag of wood pellets.

Together the rocket stove and the burner work better then i expected,  

Wood pellet are cheap and easy to find.  

Since wood pellets are made from recycled wood, i guess this is somme kind of green way to heat my garage..


Step 1: The perforated plate is the key to success

- Pellets will fall on the perforated plate, slide down and form a pile. Fire wil waken the pile and make it crash.  This will allow other pellets to fall into the burner.  This process will continue as long as there are pellets in the container.

- The angle of the perforated plate is about 45 degres.  The holes act in two ways, they allow air to feed the fire and hold the pellets as they fall.  After a few minutes of burning the plate is red hot and every pellet that comes in contact with it quickly ignite.   

- The space between the plate and the interior side of the square tube il about 1/4 inche so air can get in at all time. 

You  can see it work there:


This burner could be install on different kind of heat exchanger device, it could just be an extension of the square tube ending to a chimney.  

Any questions???

<p>Hi again,</p><p>Based on the experience I got from my Sauna heater, I made this concept. Not <br>tested it yet, but I'm sure this will be worth of trying. Both of the sides <br>have similar air intakes as in my previous version. </p><p>This one has also a throttle at the exhaust. This will be a powerful way to control <br>the heating power. It will control the overall gas flow through the burner <br>without altering the fresh air flow and pellet feeding settings.</p><p>Cheers</p>
<p>Hi</p><p>Have a look at my hobby project. Its a controller unit for biomass.</p><p>https://github.com/sedevc/openBC</p>
<p>Hi Seniortrader,</p><p>I have been trying to develop the concept further, and here is my latest <br>design. Unfortunately the concept might violate Wiseway patent, since the <br>secondary burn chamber is a crucial part of the design. </p><p>The idea of the design is let the airflow go across the burning pellets. By <br>this way the air channels in the grates, does not get blocked by ash, and the <br>heating power stays constant. Constant heating power wiht tent heaters is more <br>important than with mass-heaters. I believe this can be a new invention, which <br>has not been published anywhere else before this?</p><p> There are two chokes at the in-take: The upper-one (Primary <br>Choke) controls the airflow over the pellets on the Primary Grate. The lower <br>one (Secondary Choke) controls the airflow below the Primary Grate, and <br>over the glowing pellets on the Secondary Grate. The Secondary Choke also adjusts <br>the pellet flow into the secondary burn chamber a bit. This seems to <br>affect to the heating power a lot. I believe this kind of Choke design/application <br>may also be a new invention with this kind of pellet burners?</p><p>I used 80x80mm 4mm thick square tube this time, since the previous burner <br>was bit too powerful for my application.</p><p>I slept in my Swedish army tent last night. Outside temperature was -7C (19F) <br>and inside the temperature was staying in between +8....+13C (46&hellip;55F), which <br>was quite nice. Pellet consumption ~13kg in ~8hrs. </p><p>Cheers</p>
<p>wow! Grate (:)) work.... Even if the 2 grate concept already exist i believe the way you use them in your projet is unique. Is there anyway to stop the pellet flow from your silo?</p>
<p>Hi Seniortrader,</p><p>I haven't implemented any stop to the silo yet, but it&rsquo;s in <br>the work queue. </p><p>I forgot to mention that in the new design, the pellet <br>feeding tube needs some heat insulation. Since there is no airflow through the <br>primary grate, as there is with your original design, the primary burn chamber <br>heats up the tube too much, and the pellets start to burn too early inside the <br>tube. Therefore I put the tube inside another <br>tube, and put some stone-wool in between them. You can see the double tube <br>structure in the 3D-CAD pictures, but wool is missing there.</p><p>By the way, your original design works very well with my <br>house heating stove. I&rsquo;ve been using it for 8wks now and very satisfied with it. <br>The draft in the chimney is better than in my tent, and in addition 1-2hrs burning <br>time is enough for heating up the stove. Therefore the second burn chamber is <br>not needed. </p><p>Based on my experience the second burn chamber is needed <br>with longer than 4hrs burning times. It seems the burning temperature in the <br>primary grate is so high that the ash &ndash;particles starts to sinter together. <br>That produces relative durable material on the grate, which blocks the air channels. <br>When that happens the heating power reduces gradually. If the primary grate is <br>open enough, the pellets drop trough it before they produce ash on it. Burning event <br>on the secondary grate seems to produce less heat, and the ash seems to sinter bit <br>less on it. </p><p>My next step is to try the older burner shown in the video <br>clip I uploaded earlier, with my sauna stove. Let&rsquo;s see if it is powerful <br>enough for that purpose.</p><p>Cheers</p>
<p>Hi, <br></p><p>Confirmed, it works well as a sauna heater. (The first picture) <br></p><p>I made also a pellet heated sauna stove for my tent sauna. Also that works well. </p><p>Adding <br> some holes to the side of the primary burn chamber (the red circle on <br>the second picture) improved the burning event a lot. Adding similar air <br> inlets as I have with my tent heater, to the both sides of the burner, <br>would probably be a good solution for constant power tent heater. I <br>believe this kind or structure would be bit simpler. Perhaps I will try <br>that some day... <br></p><p>Cheers</p>
<p>great job</p>
Im Finninsh guy nr.2, and im allso building tentstove (sorry my english) i had problems with you burner design, because i think i made it too tight (ari dont pass anywhere else ), pellets bocked &quot;down air intake that size is abut 1cm&quot; and result was great smoke and unburned pellets. Next i make stop vertically longer that pellets stay on that (allso drilled), and cut upper side on the stop about 5mm so air can go over the stop. <br>I'm using 8mm pellets and 8mm holes 100x100 tube <br> <br>When i looked your design it's not so tight so air can get sides
Hi, be sure to create an air flow through the system by heating the chimney before lighting the wood pellets. I used a propane torch. Simply heat the air inside the chimney to create this stream of air. The burner must receive as much air as possible, adjusting the intensity of the flame is done by adjusting the amount of pellets entering the burner. With some pictures i could help you more! Cheers!
Igniting is no problem... I ment that afther while about 1hour when the holes is blocked by ash and air can't get thru &quot;stop&quot; and my case it can't get sides either. <br>I think your system works because &quot;stop&quot; is very loose and air can get sides and over&quot; im not sure but i find out today when i make modifications...
Hi, <br>i would like to make such a stove. But i have a few questions. First, the little holes in the plate (through which the pellet falls), how wide are they (in mm), and how large are the pellets? Also the burner (square tube) where the pellet fall in through the perforated plate, is this burner deep in the chimney and if yes, how deep? What are the dimensions of the burner? Is the burner conected to any tubes inside the chimney, if yes to which tube? <br>And also is there anything inside the chimney or is it empty? Does the chimney have any isolation inside on the wallas? <br> <br>It would be great if i could ask you anything else if i need help. Thank you very much. <br> <br>Best regards, <br>M.T.
Hi, i think most of your questions could find answers on my second instructable the rocket stove mass heater witch is more like a rocket stove without much mass. If you have any questions after viewing this i will be please to help you!<br><br>Cheers! ST
Hi, <br> <br>I tried a couple of different stops and I came into same conclusion as you. If the stop is open enough not to form too much ash on the plate, it gives only marginal help during the ignition phase. After about 30 minutes of operation, the stop seems to lose its purpose as you state. <br> <br>First I used too small diameter for the feeder outlet. That made the feeding unreliable and too pulse-like, which also made the rolling worse. It seems the minimum diameter for reliable feeding is about 57mm with D8mm pellets. That results about 3lbs / h pellet consumption without any air block at the air intake. <br> <br>Your design just work as it is. It could not be any simpler and still it has all what is needed. <br> <br>Sure I'll send some pictures once I figure out how to upload them here. <br>
I made a direct copy of your design, and I have to say I'm positively surprised how well it works! So far I have made about ten trial burns with different settings. The movable 45deg angle plate assy seems to be functioning well for adjusting the pellet feeding. I used constant pellet volume, and so far I have been able to variate the burning time between 45mins and 2 hours. <br> <br>Only disadvantage in the design I can see is the fact that at least in my unit, the pellets seem to roll quite far away from the plate towards the exhaust. Those pellets are not probably burning optimally. Have you considered / tried to make some kind of stopper to the lower edge of the perforated plate to prevent that? <br> <br>My intention is to integrate the burner to a rocket stove and use it for heating up my 12-person Swedish army tent (In Finland you can get those tents relatively cheap nowadays). In order to make as light construction as possible, I want to leave the mass around the central-pipe away . Does anyone have any opinion does that cause any problems?
Hi Finnish-guy, <br> <br>Glad you like the design! I thought about adding a stop but I immediately had a problem with the ash. <br> <br>After some time of operation, the ash that accumulates at the bottom of the burner will act as a stop and it will become so hot in there that the pellets that have rolled foreword will burn quickly .. <br> <br>Youre idea of using the burner in a rocket stove is the main reason why i did it that way. The only thing you have to care about is that this burner will work fine only if the air draft is good enough. <br> <br>I would realy like to see some pics of that stove you will build. <br> <br>Cheers!!!
Hy Badjo2, <br> <br>It will work fine with any solid fuel that will act like wood pellet. It has to be able to flow down from the tank to the burner and form a pile. Corn could be a good fuel. I would like it very much if you could post your prototype even if it does not past the test... i'm working on a new desing to.. <br> <br>Cheers!
+++GREAT JOB+++Perfect 'Add-on&quot; &nbsp;for many Rocket mass heaters or stoves. Just the airflow gate - cut two 3.2mm (thickness of cutting disc) equal slots on the vertical sides,+-5mm from the edge and insert 3mm plate. Sliding the plate in or out regulates the airflow very fine and you do NOT need to &quot;hold&quot; it in position. Did you try using anything different then wood pallets. &nbsp;At the moment I am working on &quot;Weld free&quot; 3 pieces &quot;Rocket&quot;.- BBQ,oven and stove. I shall post all details as soon as it past the tests.<br> Cheers&nbsp;<br> &nbsp; &nbsp; &nbsp; Victor
I'm so glad that I found this. My friend was recently looking into <a href="http://www.marshallsinc.com" rel="nofollow">pellet stoves in eugene, oregon</a> and I'm almost thinking that they should follow your instructable and make their own. Yes, I think I will share this with them. Thanks for sharing.
Nice work.I built a similar RMH stove a few years ago. In place of your ramp, I had a wedge shapes stainless steel mesh that the pellets would drop onto. In a 4 car insulated garage, I was hard pressed to burn 40lbs in a 10-14 hr burn. I did not regulate pellets, only the air from below. I am currently working on a smaller version that hopefully won't overheat the space as much.
I think the only way to adjust the heat with pellet heating is by ajusting the flow of pellets in the burner. The airflow must be constent and sufficient to obtain the most complete combustion possible. Hope to see pics of your new stove soon!! <br> <br>Cheers!
I am planning to build a rocket stove mass heater and this looks like an amazing invention to feed your RMH. The only thing is, I would like to have a bit bigger burn chamber for when I am not using pellets. I saw in your other instructable that you basically use the same diameter square 'pipe' but this is a bit small for my liking. All the rest off it seems amazingly well designed! And I like the fact I could get back into welding again, no need for firebricks. Just weld it! <br> <br>My question is: would it be possible to attach a bigger 'burn chamber' for regular wood? I'm thinking: dumpsterdived cargo-pellets cut up small with a chainsaw. <br> <br>I would end up making a cob bench though, something like described in here: <br>http://www.richsoil.com/rocket-stove-mass-heater.jsp <br> <br>I like the idea of sitting on a heat mass battery, reading a book :) <br> <br>Thanks for the inspiration!
Hi, <br> <br>The exhaust must be at least the same size as the input and the pipe from the inlet to the end of the central chimney must have the same dimension. Your rocket stove will work best when you put small size peices of dry wood in it. When the fire intensity is not high enough you will get smoke witch is not an environment-friendly way to make heat. <br> <br>If you make your stove would you be kind enough to send me a link to you're stove.. Thank you! <br> <br>ST. <br> <br>
I ment a link to your photos...
Hello just seen your stove good design. I was thinking that if you mounted your burner a bit higher, and the burn site closer to your heat chamber then your ash may be swept into the bottom of it by the air flow. This way the ash would store on the bottom of the chamber and you would't need to clean it out as much.
Hi, <br> <br>To get the best performance possible, the burner should be placed at the base of the central chimney of the stove. Even if it was placed above, the air flow would not be sufficient to carry the havier ashe particles to the inside of the stove. <br> <br>I light the stove for less than one day at the time and let it go out every night. Cleaning the heat chamber is very easy and gives me the opportunity to check that everything is in good condition. <br> <br>Cheers!
great design. <br> <br>two questions. <br> <br>what happens to the ash? Does it end up clogging the intake and reducing the airflow. How often do you have to clear it out and do you have to put out the fire to clean it out. It looks like you have to open the air gate and pull the ramp out to clean the ashes. Am I not getting it right? <br> <br>Also, how do you determine and control the correct airflow? <br> <br>Thanks for sharing your elegant design.
Hi, <br> <br>This stove does not produce much ash. One reason is that the wood pellets have a low moisture content and an other is due to the intensity of the heat in the burner. However, i clean the heat chamber by taking the grate out of it just the way you say it. I have to do it after every 40 pounds of pellets. The way the grate is made makes it very easy to take out and back in even if the stove is hot. I made a container with a stove damper to stop the flow of pellets in the burner. Now i can stop the pellets to fall in the burner whenever i need to. <br> <br>The burner makes a very nice sound, like a rocket.. When i close the front door i hear this typical rocket sound and adjust it to the level where i know it is at the maximum heat. For all rocket stoves more heat equal less smoke. I could let the door open and let the burner take the air it need. <br> <br>Cheert <br> <br> <br> <br>
Hey, how have you managed to get the flow of the gravity fed pellets to be off to one side? in your pictures it looks like the pipe you are filling with the pellets is directly above the burning chamber. Does this not just burn the whole lot at one go? <br> <br>I am not quite sure how you have managed to get the burning and the ventilation separate from the feed tube. <br> <br>Thanks
HI, look at the grate, it has a 45 degree angle and ti can't go all the way in the burning chamber. The feeding pipe end inside the burning chamber make's it stop in the minimum burning rate position. This is wy the pellets are going from the feeding pipe to the inside of the burning chamber. Prior to lightning the fire inside the burner it is important to build a good air flow to the exaust pipe outside the garage. The flames will follow the airflow to the inside of the stove. In the feeding pipe the pile of pellets prevents air from passing through the feeding tank and that make's it impossible for the flames to catch in the pellet tank above the burning chamber. <br> <br>I hope to have answer your questions !!! <br> <br>ST
awesome idea!!! One question, how do you adjust the flow of pellets? From what i see, it seems like you move the grate in or out to change the flow rate. Is this correct?
Hi, thank you! <br> <br>Yes this is the way to ajust the flow of pellets. When closed all the way, it is still burning but at the minimum rate. This is the setting i use for long time burning. <br> <br>I also use the front door to ajust the air flow... <br> <br>Cheers! <br> <br>
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may i ask, is the air convection or pushed mechanically? and... how does one start this heater? :) <br> <br>love it... i want to learn more.
Hi, Before lighting the fire, I heat the chimney with a propane torch for about 10 seconds. This induces a movement of air in the stove to the outside. Then I light the fire in the burner with a small amount of wood. It's always best to use small stick of wood than larger blocks. When i use the gravity pellet burner, after heating the chimney i place a small piece of fire starter juste below the burner and let it start by it self. There must be a much better scientific explanation for this phenomenon ... <br> <br>I used this stove all winter in my garage with the pellet burner and I'll do it again the next winter. <br> <br>Cheers!! <br> <br>ST
I see how this project would work very well with your other instructable for the &quot;Rocket Stove Mass Heater&quot;.<br><br>Very cleaver design. :)
HI! After two week of testing and great heat in the garage, i have decided to make another one for my hunting camp. This time, the gravity pellet burner will be made directly on the heat chamber. Winter is here with day temps down to -20C and i get all the heat i need to work in the garage. <br><br>In the coming days I will show the stove to the local fire department. I hope to get there approval and maybe convince others to convert there oil or electric furnace to a gravity pellet stove...<br><br>Cheers!
Already had an answer from the local fire department. All heating device have to meet CSA standards. Otherwise, the stove must be installed with a clearance of more than 48 inches. This standard applies to Quebec and probably all Canada. If you decide to fab one you should first talk to your local fire department. This heating device could void your home insurance. <br><br>Well, i had a lot of fun makin it and share it with Instructables members, now i have to take the decision to get it out or to keep it in and move it to &agrave; 48 inches clearance in my 16 X 24 feet working space!!!!<br><br>
When you had mentioned you were going to speak to the Fire Dept. I had my suspicions... I understand the rule, but if the design is done properly (or some safety measures were put in place), I think this could still be a safe and effective design. <br><br>I found what you created very interesting (that and the Rocket Stove Mass Heater) and will share the projects with my father. He has a hunting cabin as well, and although they have a heater in the main cabin, they may be interested in this.<br><br>Thanks for sharing your work!

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