I'm starting a New Zealand rabbit farm. I have a 40x100 barn for the rabbits. I have to keep it warm enough mainly to keep the water from frezing( around 45 or 50) I'm thinking of useing a hay bale heater. 6'x15'x1/4" pipe fire box with forced air on the fire on a thermastat 55 gallon drum as a heat reclamer. The only thing I do not understand is how to build the door.... It is going to be on the out side of a roon in the weather so I have to isulate it but still have it so it will easly open( so my wife can load the stove) How could I do this with out woarping and able to keep a seal and open enough to get a 4x5 rould bale in it. Thank-you..