Since the main house is heated with a radiant floor system, it was easy to incorporate an outdoor wood boiler. Click the image for a larger view.

This home is heated with a propane boiler that heats a fully zoned radiant floor system and domestic hot water tank. In addition, there is an outside wood fired boiler that adds economy to the equation. Remember that this boiler system is not the primary heating system. If wood is not added to the boiler and the fire goes out, the propane system in the boiler room will take over. This is especially useful if you're going to be away for a period of time and won't be able to load the wood stove. The wood stove - located midway between the wood shop and the main house - heats water that is circulated through a heat exchanger in the boiler room. This exchanger, located "upstream" from the main boiler, preheats the water returning from the floor or hot water tank in the boiler. The maximum temperature of the boiler is set to 140 degrees F. When the wood stove is active and water is being circulated through the floor or domestic water exchanger, it maintains a temperature above the startup temperature of the inside boiler, and no propane is used. If the outdoor stove drops below a certain point (about 140 degrees F), the indoor propane boiler takes over and heats the home normally.

The first year we operated the outside boiler was a particularly cold year. We estimate that we used around 12 cords of wood. This property will sustain that level of consumption for many years, which would provide economical heating for anyone willing to get a little exercise in the forests in summer. Wood preparation is easy too. The logs are best cut about 2 feet in length. Splitting is not necessary unless the logs are over about 1 foot in diameter. Handling of wood in this size is easy, and the repetitive steps of moving, stacking, and loading wood when these larger sizes are use are reduced. For the money saved, the work involved in using this stove was not an issue.

Remember that this boiler system is not the primary heating system. If wood is not added to the boiler and the fire goes out, the propane system in the boiler room will take over. This is especially useful if you're going to be away for a period of time and won't be able to load the wood stove.

Another plumbing feature that was recently made to the outdoor boiler is a series of valves that allow for easy winterizing. The main reservoir in the outside boiler is quite large, so filling with antifreeze can be a bit expensive. Because if this, it's more economical to drain the system when we're going to be away for a long period of time during the winter. This process is now a reasonably simple matter. All that's necessary is to drain the main tank, then pump RV grade antifreeze (the non-toxic variety) into the pump and pipes that run between the boiler and the house. It takes less than six gallons of anti-freeze to make the whole system winter safe. All the plumbing and pumps necessary are of course included with the house.