Wood Boiler

[Amber Gold]

A friend of mine just bought a H.S. Tarm wood boiler for his house and he's looking for a tank to store water in as a thermal mass. I guess the most effecient way to run the boilers is you run them flat out until they're out and circulate water into the holding tank. There would be another circulating line in the tank to pull the heat out of the tank to heat his hot water and house. The tanks the manufacturer reccommend are 6' round insulated tanks and they're pretty expensive. I was thinking he could use a milk tank and connect the boiler to the cooling lines to heat the tank and install a roll of copper tubing in the tank to pull the heat out. Does anyone have any experiance with anything like this or have an idea how well this may work? I have no experiance with it and was just thinking of it last night. I told him he could use a round bottom tank, but then he'd have to insulate, cover and install all the tubing. I thought the milk tank would get him most of the way there.

Thanks

[Fred Henderson]

A milk tank is only insulated on the sides and bottom. Do what the manufacturer says or buy a very large (150gal) hot water heater and don't wire it up. Just use it for storage.

[Haynes Forest Products]

Fred has it right use a elec hot water heater as a storage tank. You do not need a big one for the domestic leg for the house. I just got a plate heat exchanger off Ebay ond its a dandy. Most heat exchangers are 3.5 X 7 and have 10 20 30 plates. Andersons in Wisc. have 5X12 and they go from 20 plate to 100. I baught a 20 plate for $207.00 and they upgraded me to a 30 and with a gallon of my best syrup they sent me the 50 plate its a monster!!!
If you use to big of a storage tank you end up back to how you started heating alot of water that sits around waiting to be used. Im going to use it for my prheater on the evaporator and with my new set up i hope to have 180 degree sap in the flote box all day long

[kirkhedding]

They are using bigger tanks for more heat retention. Most are using at least 500 gallons and all the way up to 1500 gallons. Depends on the size of boiler and the heat loss of the building. If you have a fire in the boiler and the house isn't calling for all the heat, the rest goes into the water storage tank for later use. It actually works great. You can heat a home with a medium to large heat load and domestic hot water on 1-2 fires a day in the coldest month here in MI. During the summer time you can have a fire once a week and heat all your domestic hot water. Water holds a lot of heat and properly insulated, it will hold for a long time.
Kirk

[adk1]

for you wood fired evaporators out there, what is the best type of wood to use. from what I have already heard, many like pallet wood. For me, most of my wood will be white pine and hemlock which is very abundant on my property..Other people use it around here and they say that the pine burns real hot and real fast. I dont mind having to re-load often.

[Lyle]

I use soft woods because I have them in plenty and because they burn quickly. When I'm done boiling the fire dies out quickly, no waiting or removing the coals. You will fire more often but you will also get a good hot fire. Pallets work very well also; just clean the nails out as they tend to plug up the grates.

[DS Maple]

I know someone who did exactly what you talked about with the milk tank. I believe it was 1000 gallons with 200 or 300 feet of copper pipe running inside of it. The wood furnace heated the water in the milk tank and hot water for the house was heated by pumping through the copper pipe. The whole tank assembly was set in an insulated chamber below ground level. He told me that even if the power goes out, which causes the wood furnace to stop, the tank holds enough heat to supply hot water for at least 48 hours. After this the blower on the furnace can be run with generator power to bring the tank water back up to temperature for another two days of service.