Kim Woodson

The room is not so tight that air does not get changed out. I have some leaks at the sides of the overhead door. This past week I had a old wood 80K BTU stove running for about 10 hrs with a 18 inch fan blowing on the 6 inch flu and stove to get all the warm air I could in the room. The walls are 8 inch solid concrete along with the concrete ceiling. 8 inches of styrofoam insulation on outside top, then a sheet of 30 mil visqueen and 2 foot of clay on top of that. out side air was 25 deg F and the inside of the garage pretty well maintains between 52 - 55 deg F with no heat. After 10 hr of hot burn it raised the temp inside to 61 deg. It takes a while to heat up the concrete walls which have earth back filled agaiist them. I really don't need the drafty air being pulled through the room. My question is can I pull air down from the annular space between the 12 inch hole in ceiling and the 6 inch exhaust pipe ?

My room is a underground Concrete garage that is very tight. I do have some leakage around the doors i'm sure but was worried also about pulling todays air of 25 degrees in and defeating the efficiency of the RMH.

I have a 12 inch pipe thro my ceiling. I plan on building a 6" MRH. Has anyone ever tried piping in make up air thro the annular space between between the 12 inch hole and the 6 inch pipe?

Second: the average 6 inch Batch MRH would equal to how many BTU of heat?

Thanks

UPDATE:

I cut off the feed chamber and added 2 more inches to the burn chamber making it 15 inches now it draws much better. I guess I proved to myself that this will work so on to the RMH.

My question is now when I build the RMH I will have to have the Feed chamber so what measurements do I use for the Real RMH? I have a Larger underground concrete garage so space is not a problem with an existing 12 inch hole thro the roof 12 ft from the floor.

Big Al,

for some reason Only half your post displayed on my computer. I am reading your reply now. Thank you so much for the dimensions.


Kim

Thanks guys for the reply. I understand that Mild steel is not going to work. I was just interested in getting my lengths right before
i went to the trouble of building the RMH to find that my burn tube is to long/short or what ever. Today I built my first fire in it and at the top of the riser temp only got to 340 deg F. i
then took 1.5 inches Mineral Wool and wrapped the riser only and it brought it up to 550 deg. I still consider that a failure. I guess I bought the wrong book. i see lots of designs on here but I did not see dimensions.

So is 1 foot feed tube, 2 foot burn chamber, and 4 foot riser what I should work towards?

Thanks,
Kim

My ultimate goal is to build a rocket mass heater. I have purchased and read the Book "Rocket Mass Heaters" by Ianto and Leslie

I decided to build a rocket stove first (which i Have ) to verify it works before I build the Mass heater

The rocket stove works but not as good as I thought it would. I built a J Tube out of 6 inch square tubing 3/8 inch wall

Feed tube is 13 Inches deep total
Burn chamber is also 13 inches long total and is raised 2 inches up from the bottom of the feed tube to keep hot coals at the bottom of the feed tube.
Riser is 34 inches tall.

5.25 opening all the way start to finish

Not much of a rocket sound. it draws but fire trys to climb up the wood in feed tube.

I would appreciate any help from you guys that already made this work.