John Reese

I am testing out a 4" J-Tube for a small rocket mass heater. It does seem to have limitations on burn velocity inside of a 55 gal steel drum. I do not know if a secondary air supply needs to be used to help burn hotter, or how that would be accomplished if it were needed. Thermal mass inside the drum is through cement pavers (free) and I'm thinking of using clay/gravel mix to fill gaps between pavers.

This is the one I was looking at, the Minnie Mouse Heater.
https://permies.com/t/62190/Peter-van-den-Berg-inch
I did look at this batch box cook top version, but it didn't seem quite suited to a small structure with weight restrictions.

Thank you for forwarding links to the batch box versions.

Hi all,

I had been living in a 30' bumper pull camper for the past four winters, and decided to start work on a heat system for this small space. When I saw the Mouse heater post for the love shack it looked to a reasonable answer to my needs. Space is very limited, so I pulled out the bench seating for the dinette that is centered along the entry wall to make room for the Rocket Mass Heater. Because this camper is on wheels total weight is a concern, and I've salvaged 1/2" plywood to reinforce the floor and cover over 2" rigid foam insulation under the heater and up the wall.
I have a 30 gallon steel barrel to place over the J-Tube exhaust and tapered fire brick to line the bottom of the J-tube.
As a student in a welding class I have the means to build the J-tube, but could use some advice for dimensions, thickness, and actual layout for the barrels to be joined. The photos in the article were helpful, but there is a lot of guess work at this point that I would like to eliminate.

Thanks for your insight!

John