I've read about home made wood fed boilers. It shouldn't be that difficult. Use enough water for heat storage so you don't have to burn all the time. I have a munckin 140m hot water boiler in my house (92.5% efficiency and modulating). It is a very nice unit but I still spent $300 last month for nat gas. I considered a corn fed boiler for the house but it would be a lot of work in town. I think if I built a shop here I would use a hot air corn burner. Corn is cheap and portable. Anyone else hear that nat gas is supposed to go down in price?
