Around the end of December we installed a Central Boiler in our backyard (thanks to my father in-law David for help with cement and neighbor Bruce for the cement mixer and his electrician help). We have a lot of standing dead wood around the farm site that we weren't sure what to do with. So we decided to heat our home and water with it.
It's a fun experiment. And I would say with 3 months under our belts- a success.
The Central Boiler heats about 300 gallons of water and has some magic mechanisms for calling up and reducing the flame and so is very wood efficient-- we can go a couple days without needing to add more wood. We have hot water heat in the house and run the wood heated water right through our furnace boiler and a heat exchanger heats the water in our hot water heater. We've:
1) Turned off the electricity to our hot water heater, saving about $60 per month on our electric bills
2) Have hardly used any propane since we fired the stove up around the 1st of January (saving about 1,500 to 2,000 gallons of propane per year)
A conservative estimate is a 3 year payback on the investment. Wow! Plus, I believe it is pretty carbon neutral since the wood was decomposing and releasing its carbon naturally before we burnt it and released the carbon faster. Plus we'll be planting more trees than we use.
Aside-- I can be borderline cruel about conserving energy- like making my kids wash their hands in cold water. Now I'm like "FREE HOT WATER" --take a long hot shower, fill the sink with hot water to wash the dishes, let the kids have warm water hand washes! Makes me smile just to turn on the hot tap. I said this Mike and he says "uhh... yeah it's free except I'm the one cutting and loading all the wood." A small price to pay.