A wood stove fan distributes heat from a wood burning stove throughout the rest of the home. Some fans are electric, but more recently the trend has been towards self-powered fans that work on heat alone. The added expense of running an electric fan many be nominal, but some owners have discovered that electric motors and radiant heat sources don't always mix well. Early stove fans tended to malfunction after constant exposure to unregulated heat and fire.
Wood stoves work on the principle of radiant heat, much like the fireplaces they may have replaced in homes. A crackling fire in a typical fireplace may look attractive, but much of the useful heat is lost up the chimney or trapped in the ceiling airspace. A ceiling fan may send some of that heated air back to the living area, but it adds to the electric bill and may not be very efficient.
A solid metal wood stove, on the other hand, is designed to become a radiant heat source. Very little heat energy is lost up the chimney, which also becomes a source of radiant heat. The difficulty with such a system, however, is even distribution of that heat. Those sitting near a hot stove may feel comfortably warm or even hot, but others may experience cold spots and drafts. One solution to this problem is to use a fan.
Manufacturers of wood burning stoves incorporate hollow metal tubes around the body of the stove. These tubes have adjustable vents on one end and an opening for an electric blower on the other. Early wood stove fans resembled industrial-strength hair dryers, with a side turbine providing airflow into the tube, and the owner's only options were "on" or "off." The electric blower would force the heated air through the vents and into the room. This did provide a better exchange between hot and cold air levels, but the added utility expenses and potential for accidental meltdowns negated the money-saving benefits of a wood burning stove.
A recent innovation in wood stove fan technology actually reached into the past for a more energy-efficient solution. Modern fans use the radiant heat from the stove to heat hot air in the engine, sometimes referred to as a Sterling Engine. A piston turns the blades of a fan, which is responsible for blowing the excess heat above the stove into the living space. The parts of a self-powered fan are engineered to withstand the high temperatures of a wood burning stove, so the possibility of a meltdown is significantly reduced. No additional electricity is needed to run it, so the savings in energy costs are measurable over a three or four month winter season.