Outdoor wood furnaces can be hooked up to almost any existing heating system and that definitely includes a forced air furnace. To install an outdoor wood furnace to heat your house using your existing forced air duct work system is really quite simple and can be accomplished in a single afternoon or weekend.
Just follow these simple steps.
1. Set your outdoor boiler on a level surface. Paving stones, bricks or wood blocks can work wonders, making almost any spot level.
2. Hook your insulated underground line and pump(s) to the supply and return ports in the back of the boiler. See image below.
3. Install a radiator heat exchanger in your forced air furnace ductwork. See image below.
4. Attach supply and return lines to the radiator.
5. Using an aquastat, wire your forced air furnace to only operate if the water temperature in the outdoor boiler lines is below a specified temperature.
Installing an outdoor wood fired boiler in this way is a much better option than using a forced air outdoor furnace with duct work through the wall. Here are a few reasons.
1. With a forced air outdoor furnace you must cut a large hole through your wall, often up to 20 inches in diameter; with an outdoor boiler, you only need approximately a 6 inch hole which can be below ground level in many situations.
2. A forced air outdoor furnace must be placed directly outside the wall from your furnace due to the massive size of the duct work it requires, while an outdoor boiler can be as far as 300 feet from your house. This keeps fire, smoke, and mess associated with fire wood safely away from your house and from the people you love.
3. Efficiency. Heat transfers much more efficiently from steel to water than it does into air, making an outdoor wood boiler burn much less wood than a forced air outdoor wood furnace.