I had a friend just give me an old longwood furnace. It had a few cracks in the firebox that I had welded up and I hooked it up in my shop and it puts out some serious heat. The propane burner on it doesn't work, but I haven't had to big of problem getting it started or keeping it warm. My shop is over 2500 sq ft with 20 ft ceiling and is insulated, and it will keep it 70 degrees when it is 10 degrees outside. I like the idea of installing this thing in my garage to heat my house, as all the ductwork goes through the garage it would be a simple install, but I am unsure if this would be safe or not. My insurance said that it had to be UL approved and I am not sure if this old thing is , as I am doubtful at how old it is. If anybody know a thing or two about the longwood furnace please fill me in. Thanks