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If you have a heat pump and have ever noticed an "Aux Heat" message on your thermostat, you might be wondering exactly what this means and whether it's something to be concerned about. Old Glory Air Conditioning and Heating explains how auxiliary heat works.
Auxiliary heat, often abbreviated as aux heat, refers to a backup heating source, typically electric resistance heating elements, built into many heat pump systems to provide additional heating support when needed.
Since heat pumps work by extracting available heat from outdoor air, their efficiency naturally decreases as outdoor temperatures drop significantly. Auxiliary heat provides a backup source of warmth for the relatively rare occasions when the heat pump alone can't keep up with heating demand.
Auxiliary heat usually engages during unusually cold outdoor temperatures, when there's a large gap between the current indoor temperature and the thermostat's set point, or during the defrost cycle when the heat pump temporarily can't provide heating.
Since auxiliary heat typically relies on electric resistance heating, which is generally less efficient than the heat pump's normal heat transfer process, running on auxiliary heat for extended periods can lead to noticeably higher energy bills compared to normal heat pump operation.
If you notice the aux heat indicator activating frequently, even during relatively mild weather, or running for extended periods, this can indicate an underlying issue with your heat pump that's preventing it from operating efficiently on its own.
A struggling heat pump, whether due to refrigerant issues, a failing component, or general system inefficiency, may rely on auxiliary heat more frequently than it should, essentially masking an underlying problem that needs professional attention.
Some thermostat settings or programming choices can inadvertently trigger auxiliary heat more often than necessary, particularly if the system is asked to make large temperature adjustments quickly rather than gradual changes.
If you notice your auxiliary heat running frequently or for extended periods, especially during relatively mild weather, it's worth having a professional inspect your heat pump to determine whether an underlying issue is causing excessive reliance on the backup heat source.
Our team helps Arlington area homeowners understand their heat pump's auxiliary heat function and can diagnose any underlying issues causing it to run more than expected.
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