Outdoor wood burning boilers became very popular starting in 2007 due to the escalated gas prices that the United States experienced during this time. Wood burning boilers are extremely efficient and keep the mess of the wood outside and away from the house. This appeals to many rural homeowners. Here is the breakdown on how these boilers operate.
Wood Burning Boiler
Wood burning boilers have a heat exchanger that surrounds the fire chamber where the wood is burned. The heat exchanger tubes are filled with water which when heated, in pumped to the house through an insulated hose that goes directly into the boiler in the home, or a plate heat exchanger in a forced air furnace. In either case, the heat is then distributed around the house. When the water cycles through the plate heat exchanger, it goes back to the outdoor boiler and gets reheated. This cycle is thermostatically controlled by temperature controls within the outdoor boiler. The boiler will pump the water through the tubes when the water reaches a certain temperature.
Heat Exchanger Setup
The heat exchanger in an indoor boiler is used in conjunction with the outdoor boiler so that no other equipment is needed for a boiler to boiler installation. This is the most efficient setup for an outdoor wood burning boiler system.
Plate heat exchangers are add on heat exchangers that all have different BTU (British Thermal Unit) output ratings bases on material, coil composition, and the size of the heat exchanger inlets and outlets. The plate heat exchanger sits directly above the heat exchanger for the original forced air furnace. When air blows across it when the heat exchanger is hot, the air distributed around the house is warm. This is not as efficient as a boiler, but still works very well. One advantage to this type of system is that it is generally not as costly because forced air is used for both heat and air conditioning. Multiple heating and cooling systems require more parts and labor and typically cost 1 1/2 times more than just a forced air system.
If you live in a rural area and are looking to reduce your propane or fuel oil use this winter, an outdoor wood burning boiler can take care of approximately 80% of your heating needs during the winter, paying for this unit in 2 to 3 years. That is a great return on investment and will continue to save you money for years to come.