I made a couple small batches of charcoal in the shop furnace t on day. Then I dumped them in the milk can to cool to add some extra BTU’s to the greenhouse this evening.
Look up the seachar TLUD, that puts out some btu’s, and bulk amounts of good charcoal.
I built one last year,a keystone stove but I can’t use it in this greenhouse. I may bury the milk can in the floor for now to store the heat from the cooling process longer. It is still cold enough here to need a second shelter in the greenhouse. To leave the plants out there overnight…This is a new to me solaraim still under construction. It will eventually be heated by hydronic solar. For now some thermal mass will get me through this spring. Cooling will be a problem very soon. I had temps from 31* Ina four foot deep pit to 132* say the ceiling vent at the same time yesterday. It is 21* n there this morning.