Anybody convert a wood furness to boiler?

[captainkirk57]

I have a indoor wood burner located about 6 feet from a forced air furnace.The stove is not big enough to completely heat my big old house as a sole heat source when temp drops to zero. I was wondering about using a water coil to heat water and circulate to water heater and then pump it to a heat exchanger located in the forced air furnace like outdoor boilers use, and then I would have two heat sources using the same batch of wood. How can this be accomplished?

 

[KYErik]

Kirk- I hate to rain on your parade, but if the stove is not putting out enough heat to heat your house, then taking away some of that heat to heat your water and put it into your duct work will not help your situation- you really need a bigger stove.

If the stove overheats the room it is in and you want to redistribute the heat to the rest of the house, then the easiest way would be to have the "cold air return" suck hot air from around the stove and blow it out to all areas of the house.

The outdoor wood furnaces have a firebox that is surrounded by a water jacket- the best you could do is run a coil of expensive copper pipe inside your stove- but then you would need to buy a $120 Taco 120 volt electric pump to circulate the water and a heat exchanger to install in your ductwork. Too hot of a fire could boil the water in the copper coil and be dangerous/messy.

The only way to get more heat out of your stove would be to add one of the flue pipe heat extractors (a little heat exchanger built into the flue pipe) or possibly you could install a power draft to blow air into the air inlet vent of the stove. The power draft would need to be small- too much draft and you could overheat/damage/melt down the stove. Your buddies might call you "blacksmith" because you heat your house with a forge....

 

[magicheater]

Kirk, Is your indoor wood burner a radiant stove or a furnace type somehow hooked to your plenum? What I get from your post is how to effectively move the heat to the extremities of the house using your wood stove's output, is this correct? Air is the least efficient medium for heat transfer but ironically the most common. A chunk of wood has a fixed BTU value, it cannot be multiplied through division. KYErik is correct in that the only waste heat you have to capture is going up the chimney. I have a hybrid heating system that relies on mass for heat retention so I can relate to what you are trying to do.

The goal for most people is to extract the most BTU's out of their fuel source. Easily metered fuel's such as gas and liquid are most commonly applied to forced air systems, i.e., easy thermostat application and just pay the bill. Pellet stoves offer nearly the same convenience but are radiant. Wood boilers are popular because they can keep the mess outside, are easily tied to forced air systems but in this manor are energy hogs to the max. Having the proper thermal storage can increase the overall efficiency of your boiler, an idling boiler is wasting energy. Boilers are perfect for in floor heating but not so perfect for forced air systems.