Square Barrel Design

I would like to build a unit with a square barrel... i.e. home made barrel, made with 1" angle and sheet metal (18 ga.). Does anyone know of a problem with such a design.

The heat riser will be square fire brick with a square insulating can. Then a square radiant can over top with a gap of 1.5 inches between the two cans. The burn chamber is about 6.75 inches square from entry to the top of the heat riser. The gap btw the heat riser and outer can is two inches.

Cheers...
Rod

Hi Rod; Lets see, first, nothing wrong with building your own barrel although a removable lid is very nice. second , I would increase the top of the barrel gap to at least 2" but 1.5" may work . Third , a gap of only 2" alongside the inner and outer barrel seems to tight 2.5-3" would be better. Are you using 6" pipe in your mass ? 8" ? Do you have a copy of ianto evans book rocket mass heaters If not, then you should have one ! Add your location in your profile so we know what part of the country/ world, that you are in.

Thank for your answers Thomas... I have updated my profile as suggested.

... Yes, I do have a copy of the book. I picked it up at the university of Guelph organic conference last February.

I can include plans to incorporate a "top of barrel" gap to 2" , and increase the barrel to barrel gap to 3".

I was thinking an 8" pipe through the mass would be best....

I ran a test burn last night with just the burn chamber and everything worked good ...

I am setting this up as a portable unit also ... A base has already been welded up with a raised carriage to hold the burn tunnel and heat riser above the base . I will be putting insulation under the burn tunnel.

Rod

Hi Rod ; Sounds good an 8" system should have a 2" top gap and a 3" side gap is also good . If your rocket is portable, what are your plans for the mass ? In missoula, MT they built and transported one with bicycles , but i'm not sure what they used as a mass, possibly small gravel. water tanks could also work as a portable mass but your water temps would have to be monitored constantly when the dragon was roaring to avoid boiling ! Is this unit being made portable to be used as a demonstration ? The more people that learn about RMH,s the cleaner our air will be !

The inner barrel and outer barrel will be welded together at the bottom with 4 pieces of 4" x 25" piece of bar stock. So, when the combusted gases exit the heat riser they will be trapped between the two barrels with only one way to go, through the transition zone and into the flue pipe. I am thinking of using a 10" flue pipe which will pass through a river rock raised mass before exiting via the house chimney. We will need to reinforce the basement joists for the mass unit. The rocket heater will not be that heavy - I am guessing 350 lbs. see the attached picture for the progress. I am redesigning the combustion unit so it is missing from the photo.

Did this stove ever get finished? How well did it work out?