CONTROLLING YOUR HEAT PUMP
More advanced controls are now available that will determine when the heat pump should operate based on your current fuel prices - leaving you with little to worry about. One thing to keep in mind is not all thermostats are able to control a heat pump. Heat pump specific thermostats may be needed to take full advantage of all their features and capabilities. Be sure to work with your contractor to ensure you have the right controls for your heat pump.
The switch over temperature, which is the most common means of controlling a heat pump, may be configured based on comfort, economics, or the thermal balance point. The thermal balance point is the temperature at which the heat pump can no longer meet the heating needs of the home. In an all-electric centrally ducted system, the backup electric resistance heat should be locked out until the outdoor temperature is below the thermal balance point. Below the thermal balance point, the electric heat runs simultaneously with the heat pump to supplement and meet a home’s heating needs. In this scenario, the goal is to use the least amount of electric resistance heat to operate and maximize the heat pump’s economic advantage during the coldest days of the year. If the lock out is not set up properly, electric resistance heat will cycle on more often than needed causing higher electric use and higher bills. Dual-fuel applications of heat pumps pose additional considerations regarding the switchover temperature. Gas furnaces typically can’t run at the same time as the heat pump. The temperature you want the gas furnace to run may be different than the thermal balance point.
FIGURE 8. DUAL-FUEL SYSTEM WITH GAS FURNACE BACKUP HEAT
FIGURE 9. ALL-ELECTRIC SYSTEM WITH ELECTRIC RESISTANCE BACKUP HEAT
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ELECTRIC HEAT PUMP CUSTOMER BUYING AND OPERATION GUIDE FOR SINGLE-FAMILY HOMES
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