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Heat Pumps: Frequently Asked Questions

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To Our Heat Pump Customers

Below, you will find information that answers common questions about the operation of a Heat Pump system:

  • A heat pump will run continuously when the outside temperature drops below 25°-35° F. Don’t be alarmed, this is normal and not a sign of trouble.
  • When a heat pump cannot maintain the inside temperature on its own, the thermostat turns on the backup electric heater intermittently to maintain the inside temperature.  Many thermostats indicate when this is happening, and an AUX HEAT icon appears on its screen.
  • During very cold temperatures, the thermostat may read 2°-3° F below the setting. This is normal and does not indicate a malfunction of the thermostat. On very cold days, you can raise the temperature 2°-3° F higher to offset this.
  • A heat pump will accumulate frost and ice on the outdoor unit during operation. Cold, damp and rainy weather exacerbates this condition. Thus, heat pumps have an automatic defrost cycle. During this cycle, your system may make a sudden hissing sound and the outdoor fan motor may stop. The outdoor coil will then heat up to melt away the frost and ice, which in turn causes steam or mist. This is not smoke, don’t panic!  It should only last about 6-10 minutes.
  • The thermostat on a heat pump has an emergency heat option. Regardless of the outdoor temperature always set the thermostat to heat – do not set it to emergency heat!  In the emergency heat mode, the heat pump shuts off and only the backup heater is energized, which results in substantially less heat being delivered to the house. Emergency heat should only be used when the outside unit is broken.
  • Because heat pumps have such long running times, it is important to keep your filter and outdoor coil clean. Letting the filter or coil get dirty reduces the efficiency and can shorten the life of the system. Heat pumps should be cleaned and tuned up twice yearly.

Have more questions or need assistance with your heat pump? Contact the heat pump experts at Stan’s Heating, Air & Plumbing. Emergency service is also available.