Martin Pajak

Thomas, I'm definitely aware that I could buy a core but they are $400 US. I'm in Canada so by the time it gets here plus the $50 shipping I'd be looking at $700. I may as well have fun with the fire brick and build something.

As for my design I'm definitely going to have a bigger air intake than what that picture shows.

Thanks. Good to know about that particular design not working as well. What is your opinion about a closed top and an intake over the fuel such as this design? I can see how this would solve the problems of the fuel getting too hot. It would allow a closed top while still getting air into the system like a traditional J tube.

I really want to play around with the J tube design due to its simplicity so I think I'll have to test this out for myself. I do have a power engineering background as well as aerospace. So I definitely understand basics of thermodynamics and how this is supposed to work in theory.

As for the cost of the bricks, yeah they are expensive here. It seems everything in Canada is two to three times the cost. New fire brick is $5-6 a brick. I managed to find 60 of them for $100. They are used but in very good shape. I don't think there is quite enough there to build a batch box though. Most are half size (see pic)

I don't want to go too high with my mass nor do I have the bricks available to build a huge bell, also a bell takes a while to heat up. I'm more or less after fast heat instantly refracting off the heat wall I plan to build. This stuff is pretty expensive in Canada so I want to spend as little as I can on it. I just spent $100 on 60 used fire bricks. I guess that's not too bad.

I wouldn't mind having some benches to store wood on or to sit on though. Maybe I can make the benches  36" high and lined with brick to have a fairly large mass on either side of the drum. I still haven't decided on the final design.

Hey I'm new here. I recently got sick of being in the city and moved my place as well as my small shop into the country. I moved the shop into a barn that was split in half and my side is 30L X 40W X 16H

I want to heat it with a rocket mass heater and want to know your opinions on my design. All I know so far is that for something that size to get nice and toasty, I need an 8" system using a 55 gallon drum and quite a bit of mass as well as something to refract the heat back into the room and move it around with the assistance of fans.

So the plan is to put it in the corner of the shop to utilize as little shop space as I possibly can. This will enable me to use an L shaped mass equal on both sides with the drum and exhaust stack in the center of the mass. The drum will be 2-3 feet from either wall.

The interior wall of the barn is going to be steel tin just like the exterior is. In the corner where the heater/drum is there will be a brick wall built up with insulation/an air gap between the interior wall and the brick. On the heater side of the brick will be a steel plate to refract the heat back towards the room.

I drew a preliminary sketch on a post it note to show you what I mean and I intend to design this in sketchup as soon as I'm ready to build it. Should I be doing anything different here?

How big would you guys make the mass for this size shop? Please keep on mind that on the opposite (south) wall I will be using solar air heaters to supplement my heating during the day. I only need the mass to hold about 24hrs worth of heat.

The style of heater will be a simple J tube with a separate air intake and a fuel magazine like the one pictured.