Hi Everyone,
I joined this site awhile ago and have been mostly just reading. After much research, reading the book, and planning, my husband and I built and modified a Harbor Freight Greenhouse kit to incorporate a rocket mass heater. After 3 days of "real world" use, I can mark the project as a success.
The RMH functions perfectly at a thermal mass temp of 90F and the pot on the top of the barrel steams extra humidity into the GH. We did not use conventional cob and rather used a brick/mortar for the thermal mass frame. The mass is a combination of ubanite and pea gravel. We used a high temp refractory cement (that we got for free) for all of the connections and the heat riser build.
The temps dipped to 32F over the last two evenings and the RMH and thermal mass kept the GH at 55F with no problem. Additionally, the condensation on the GH helped to keep the humidity up (we need to stay above 50%). Last night we were able to sleep through the night with no restocking the feed tube. The thermal mass combined with the heat from the barrel kept the temperature from dropping below 55F.
For a fire barrier, we used cement board in the corner. This protects the GH poly panels from melting. Yes, the barrels are coated with high temp stove paint.
Here are a few pictures.
