A heat pump works best in a building that is weather protected. Therefore, seal and insulate your home heating system's ducts and stop air leaks around windows. Also avoid frequently adjusting the thermostat upward. It takes longer to heat a house with a heat pump than an oil or gas furnace, and a sudden upward adjustment of the thermostat will activate the backup heater to meet the jump in demand. The resistance heater is two to three times less efficient than the heat pump, which means energy use goes up sharply every time it comes on. The desire to suddenly raise the thermostat is compounded by the relatively cool (90F-100F) air the heat pump produces.
One of the keys to an efficient heat pump is the proper selection and operation of a thermostat. Usually a two-stage thermostat is used for heating, and a one-stage thermostat is used for cooling. During the heating cycle, one stage of the thermostat controls the compressor and fan, while the other stage activates the supplemental heater when necessary. Some systems are equipped with an outdoor thermostat separate from the room thermostat. This limits supplemental heating and minimizes electricity demand, particularly when the room thermostat is suddenly turned up.
In case of compressor or general system failure, many thermostats have an emergency heat switch that bypasses the thermostat and activates the supplemental heater. Following a power outage, the supplemental electric resistance heater should run for a time equal to the outage to allow the heat pump's crankcase oil to reheat.
While setting back thermostats at night reduces energy consumption in oil or gas furnaces, it is usually not recommended for heat pumps with two-stage thermostats. The sudden upward adjustment of the thermostat in the morning would activate the supplemental heater, negating overnight energy savings. Two-stage units with an outdoor thermostat or adaptive recovery thermostats, which automatically raise the setting less than 2 at a time, can take advantage of setting back the thermostat at night or during the day. In any case, check the owner's manual for specific guidelines.
Closing air registers and vents to conserve heat is not recommended with heat pumps. The heat pump system is sized to meet the entire house's heating requirements and blocking off vents can reduce mechanical performance and efficiency. Also make sure the vents are not blocked by furniture, drapes or other obstructions.
Filters should be checked monthly for dirt build-up and cleaned or replaced as needed. The manufacturer's instruction booklet should indicate when and how to lubricate fan motors and how to adjust the blower unit and drive belts. Indoor heat exchanger coils should be cleaned periodically with a vacuum or brush, and outdoor coils can be washed with a garden hose. Do not surround the outdoor coil with shrubs, tall grass or enclosures that would impede air flow around the coils. If the outdoor coil is exposed to the summer sun, shading it with an awning or overhang will improve the heat pump's cooling efficiency. It is a good idea to contact a qualified, licensed contractor every 12-18 months to perform routine maintenance.