Gravity fed pellet burner

Hi, 

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:

 http://www.youtube.com/watch?v=rEosHNLZJek&feature=g-upl&context=G2e8c2daAUAAAAAAAAAA

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???

Comments

[JasonInSD]

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.

[Seniortrader]

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!!

Cheers!

[Atar]

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!

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.

I would end up making a cob bench though, something like described in here:
http://www.richsoil.com/rocket-stove-mass-heater.jsp

I like the idea of sitting on a heat mass battery, reading a book :)

Thanks for the inspiration!

[Seniortrader]

Hi,

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.

If you make your stove would you be kind enough to send me a link to you're stove.. Thank you!

ST.

[Seniortrader]

I ment a link to your photos...

[Jerrod j]

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.

[Seniortrader]

Hi,

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.

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.

Cheers!

[scbron]

great design.

two questions.

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?

Also, how do you determine and control the correct airflow?

Thanks for sharing your elegant design.

[Seniortrader]

Hi,

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.

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.

Cheert

[achong0]

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?

I am not quite sure how you have managed to get the burning and the ventilation separate from the feed tube.

Thanks

[Seniortrader]

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.

I hope to have answer your questions !!!

ST

[kretzlord]

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?

[Seniortrader]

Hi, thank you!

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.

I also use the front door to ajust the air flow...

Cheers!

[jimvoth]

may i ask, is the air convection or pushed mechanically? and... how does one start this heater? :)

love it... i want to learn more.

[Seniortrader]

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 ...

I used this stove all winter in my garage with the pellet burner and I'll do it again the next winter.

Cheers!!

ST

[canucksgirl]

I see how this project would work very well with your other instructable for the "Rocket Stove Mass Heater".

Very cleaver design. :)

[Seniortrader]

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.

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...

Cheers!

[Seniortrader]

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.

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 à 48 inches clearance in my 16 X 24 feet working space!!!!

[canucksgirl]

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.

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.

Thanks for sharing your work!