hi all...new mwmber here...I have a "central boiler" brand boiler with roughly 225 gal h2o capacity. With it, I heat a 2500 sq ft house and apmt combo, along with all dom.H/W needs. I burn on average 10 to 15 cords of wood /yr.Inside, I have a standard H/W boiler with a "super stor" hot water heater next to it in my cellar. My total INDOOR system efficiency runs about 86%, while my outdoor burn efficiency is around 30%. I would like to enhance outdoor efficiency, and am considering doing so in the following manner:
I want to super-insulate a one thousand gallon ss milktank and put it about eight feet underground. I have found that I can heat my home/hot water with water temperature anywhere from 90 degrees on up, so my plan would be to bring tank water temp uo to aqround 190 degrees, then shut my outdoor boiler down for a number of days. I would switch my heat source from hardwood to either pine slabs that burn fast and hot, or possibly set up batch deeding wood chips. MY GUESS WOULD BE THAT i COULD GET BY AT RUNNING MY OUTSIDE BOILER only a couple times a week, instead of 24/7. By my calculations, I should be able to cut my wood consumpsion by around70%. Open to any and all comments.

My woodmaster outdoor wood burner heats a 2,000 square ft shop, a 2 car garage, and a 2600 square foot house. It also heats the water for the hot water heater. I have 3 full size furnaces for heat and 3 modine style heaters. It burns an incredible amount of wood. I think it should regulate the wood better but I dont really know have had it for 3 years now and simply put more work into cutting wood. But to me cutting wood is kind of fun and something to do rather than "real" work.

Most of the heat in the storage tank will escape into the ground. Insulation does not stop heat flow, it only slows it down. The system you describe will only work if the heat storage tank is in the basement of the house. I've seen systems like you propose and they never worked.

I have a wood Master! As a matter of fact I just came in from cutting wood for it!
I want to builld a solor hot water heater for it during the summer. I should be able to capture enough heat to turn the pump to the heatexchanger back on and heat my hot water during the summer right? I guess I need to decide how big to build it. 4x8 ? Anyone with some exp. with these?

I use a outside wood furnace also but it is forced air and cheaper than a boiler. has worked for me for the last 20 years in a 1755 sqft house.
www.heatbywood.com