kenneth tallent

Thanks for the reply Thomas, I had a feeling I was about to screw up just needed a second opinion. I was wanting to hold a bench height of 18" due to physical reasons. I guess I could build a step in front of bench and take the bench up higher to keep lines  off the floor. I will cob the heater and would possibly like to cob bench internally and top, I wonder if it could work if I put expansion joints around the inside of the cinder block. I wanted to use cinder block because it is easier and I am a 1/2 man army whittling away at a much larger project than normal  one day at a time.

I have been testing my new 6" rocket mass heater with bench, my radiant lines are running 180 to 210 deg on hot side 150 to 190 on low side after it heats up. I have not filled bench yet and I am wondering how deep to bury them. I saw that for a 8" heater the depth was 5" -6 " on the hot side and 4" to 5" on the low side. I have no idea if the temps for exhaust are the same as a 6" heater. I will be using pea gravel for fill above pipe maybe a  grouted paver top, bench has cinder block frame . I love my heater and the heat it produces. I  just want to warm my buns not fry them.lol  Any guidance would be appreciated thanks.

Thank you Glenn Herbert, I will proceed as planned thanks

I was wondering if raffia grass would work for base coat in cob for a rocket mass heater. All the straw around here is chopped 6" or less, mainly less for use in a spreader.