I looked at an old cast iron boiler the other day it was the type used to heat those old brass radiators in the ’40’s, I think it was originally coal fired, probably weighed 1200 lbs. What I thought might work would be something like this boiler, converted for wood, an insulated jacket around it to keep all the heat contained (I thought of putting the unit in the basement – maybe the laundry room so any excess heat could dry clothes in the winter), feeding a large water tank (also super insulated – perhaps one of those old stainless milk tanks from a dairy farm would work) to be used as the heat storage unit.

Then as hot water was needed the cold water feed would enter separate pipes running through the hot water storage tank and come out heated – apparently this is how the Tarm works and depending on use the boiler may only have to be fired one day per week. Coupled with some type of solar collector for the summer I may be able to eliminate the need for an electric hot water tank. Perhaps a Babington burner could be fitted to heat the water if my wood supply runs low. I’m sure a Tarm would be the solution, but I’m cheap (frugal) and like to learn/do things myself. Does this sound like a viable solution?

Yeah, I’d say it is .. however, in order to do a good job you have to do a lot of thinking about how you are going to heat the water, and how you are going to burn the wood. You can buy boilers like this that run outdoors, but most of them are apparently very poorly designed. If you use a water jacket around the firebox, it will stay cool and quench the flames before you get complete combustion of the wood, and it’ll be very smokey. If you could do something like the TARM, that would be good. They have an insulated firebox and gasify/burn the wood, and then run it through water jacket. This gives you clean, complete combustion and greater efficiency. There’s lots of info on the net about gasification and biomass burning, including the conversations here on efficient wood cookstoves.