Why Does Aux Heat Keep Turning On?

What is Aux Heat?

Auxiliary heat refers to your heat pump’s backup electric resistance heating. Aux heat should only kick on when the heat pump can’t produce enough heat to warm your home on its own. This is typically caused by one of three factors: when it’s below 35° outside, you’re trying to heat your home by 3° or more, or your heat pump is in defrost mode.

Heat Pumps and Heat Pump Balance Point

Heat pumps are more efficient than most other heating systems, but they typically take a little longer to heat your home the colder it gets outside. Since heat pumps can only keep up with a relatively small amount of heating in a short amount of time, they are paired with AUX heat to help heat your home in a hurry.

When your heat pump needs help heating your home, it is below the heat pump balance point. The balance point is based on your system’s capacity and the current load demand. The heat pump balance point is when the system capacity and load demand are equal and for most homes that is around 30 degrees, but it varies depending on how energy efficient your home is.

Auxiliary Heat vs. Emergency Heat

Many homeowners get confused when the temperatures start to drop, and they see either “aux” or “em” heat on their thermostat. So, what is the difference between auxiliary heat and emergency heat?

  • Auxiliary heat is when the secondary heat source turns on automatically. This means, when the temperatures start to drop and your heat pump cannot produce enough hot air to warm your home the aux heat will turn on.
  • Emergency heat is when you turn on a secondary heat source manually.

Does Auxiliary Heat Cost More to Run?

The auxiliary heat setting is more energy and cost-efficient than emergency heat. In aux mode, your heat pump will continue to use outside air to warm your home to assist the secondary heat source.

When switching your unit to emergency heat, you’re forcing the backup heat system to do all the work.

Heat Pump Stuck in Aux Heat Mode

If your heat pump seems to be stuck on auxiliary heat mode and the temperatures outside are above 35 degrees, you should call the professionals at Precision Heating & Air. Auxiliary heat is less energy-efficient than your heat pump, and it is meant to only run for short periods of time when temperatures drop. Prolonged use of aux heat can cause your utility bill to be much higher than it needs to be.

Contact Precision Heating & Air for Heat Pump Repairs

If you’re having problems with your heat pump or furnace, contact Precision Heating & Air. Our team has been servicing and repairing heating units since 1985. We can help you determine the source of your problem and guide you toward the most energy-efficient, low-cost solution. Give us a call at 770-445-0870 or schedule service online.