A dual fuel system is the most economical heating system available for our climate. The system employs a heat pump as the primary heating source for the home. The heat pump heats the house very effectively down to between 25 and 30 degrees. Below this temperature range, a secondary heat source (usually a natural or L. P. gas furnace) is turned on intermittently to supplement the capacity of the heat pump. The secondary heat is necessary because the heat pump, which is simply a reverse cycle air conditioner, is unable to provide all of the heat your home needs under these conditions.
When outdoor temperatures go down to 25 to 30 degrees and the heat loss of the house causes the indoor thermostat to “call” for more heat, the furnace is started by the indoor thermostat and the heat pump turns off. After the furnace has produced sufficient heat to provide the comfort your home needs, the heat pump will come back on and run to produce a portion of the heat your home needs. As outdoor temperatures rise it will be again able to provide all of your homes heating requirement.
The primary advantage of a dual fuel system is low operating costs. Electric rates are very low in the winter because power providers build plants to meet summer peaks. In the winter they have excess generating capacity and offer power at reduced rates to make heat pump systems attractively affordable to operate. Gas rates, on the other hand, are up in the winter because of high demand.
Knight Air Conditioning has installed many dual fuel systems over the past ten years with excellent customer satisfaction. The heat pump system produces a “warm” rather than a “hot” heat, which most people seem to like. The indoor air retains moisture better and many heat pump owners don’t feel the need for a humidifier. There is really no disadvantage to the dual fuel system. With a gas furnace for backup heat, the homeowner can always run the thermostat up slightly to increase the furnace run time if there is any discomfort associated with the temperature of the air produced by the heat pump.