Hello All,
I am totally new to all of this. I just happened to stumble on this site via some loosely related greenhouse culture stuff. My Mother and I started up a small garden center on her property last year. We have four hoophouses. We do seasonal plants, natives, hybrids,.....we would like to get one house heated so that we aren't beholden to buy annual veggies and flowers in the spring from one the wholesale producers. We are both living on shoestrings, and with the business still in start-up mode, we don't have a lot of cash to throw at a wasteful gas furnace and all the electrical and such that conventional greenhouse heaters require. Not to mention, I think there must be a better way of heating one of those goliaths, than gas!
We would likely need to have it heated starting February 1st. I am in Southern Michigan, it has rarely dropped below the teens here in recent years. Last year we had a zone 7b sort of winter...my rosemary survived in ground (super amazing). I wouldn't want night temps to drop below 50. I am ok with living in the greenhouse for a month or two, to keep fires fed through the night. Daytimes, are obviously less of an issue as long as the sun is shining. I have a bunch of 350gallon water barrels that I was thinking of putting inside the greenhouse...or along the west wall (south wall is obstructed by hill) thinking the mass of water would be additional thermal source of heat....
Questions:
1) How many 55gallon drum style rocket stoves would I need
2) With the aformentioned style of stove, how many lineal feet of in ground exhaust pipe, would be supported
3) In the greenhouse, there will be water penetrating the floor...is that going to rust the pipes out?
4) If rusting from water penetration is a concern, can I cover the radiant channels that the pipes are layed in with polyfilm to divert water? Or would the film melt?
[I am envisioning the exhaust pipes being under the walkways in the greenhouse. Filled with rocks and pearlite, capped with brick or cement paving stones....so that the system can be accessed and repaired in case of rust]
5) Can I build an exhaust system that is entirely a brick tube underground? What would be the problems I would incur with that?
6) How frequently will the fire need to be fed?
7) How often must the system be cleaned to prevent burning my place down?

Has anyone had any problem with rodents moving into their exhaust pipes?
My other thought was to build a lean-to on the back of the greenhouse, hang reflective blankets and put a wood stove in the room (mom has one she removed from the geodesic she built in the 70's). Then just blow the warm air through the house with fans....But I don't have electricity down there and am still using 14g extension cords to run small things like a power drill. Would hate to burn moms house down with a bunch of fans overloading plug at the house.