At What Temperature Do Heat Pumps Stop Working?

Heat pumps are popular heating, ventilation and air conditioning (HVAC) system components, particularly in locations with mild climates. One benefit of a heat pump is that it works year-round to help keep your home comfortable. Because heat pumps help transfer warmth, they can move heat from the outside in (helping warm a home in winter) or from the inside out (helping cool a home in the summer).

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You might wonder what temperature heat pumps stop working at, given that they rely on some amount of heat to transfer. The answers might surprise you.

Can It Get Too Cold for My Heat Pump to Stop Functioning Properly?

Eventually, it may get too cold in some areas for heat pumps to function effectively. Extremely low outdoor air or ground temperatures can make heat pumps work unusually hard to convert any remaining thermal energy into warm air inside your home. This can cause heat pump problems, such as freezing up or not keeping your home warm enough.

How Cold Is Too Cold to Use a Heat Pump?

It depends on your heat pump efficiency. Old heat pumps didn't keep up well in cold climates and were mostly used in moderate climates where winter months didn't bring ice or snow.

Temperature Range for a Heat Pump

Modern heat pump units can keep up with cold weather and typically function well in freezing temps. If winters in your area rarely drop to freezing — remaining at 40 degrees Fahrenheit (4 degrees Celsius) or above — a heat pump will likely chug along and keep your home as toasty as you like. Newer traditional heat pumps can even function decently in temps as low as 0 degrees Fahrenheit (-18 degrees Celsius), but you lose some efficiency as you dip further below freezing.

Heat Pump Temp Limits

Cold-climate heat pumps are designed to work well at lower temperatures. You can expect them to work decently in weather that drops to -15 degrees Fahrenheit (-26 degrees Celsius) or lower.

Every heat pump has a point it will struggle at. That point is simply lower for cold-climate heat pumps. If your winter weather often drops below that threshold, it can be a good idea to install a backup heat source for your home. Popular options include gas log fireplaces, electric heaters and gas heaters.

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How Do I Keep My Heat Pump Working in Colder Weather?

To ensure your heat pump can keep up with cold weather, you should start by checking that you have the right model. A heat pump that's ideal for a homeowner in northern Georgia probably won't work well for someone in upstate New York, for example.

Once you know your heat pump model can work well in the winter temps you experience, the next step to keep it working all year is proactive heat pump maintenance:

• Make sure the outdoor unit is kept clean and has several feet of clearance. Debris that builds up around your unit, including snow, leaves, ice or even dirt, can block airflow and reduce the efficiency of your unit.

• Change your air filter. Changing your air filter periodically is critical to supporting long life for all types of HVAC components. Refer to your manufacturer's documentation, or ask an HVAC professional how often you should change filters.

• Get a professional inspection and maintenance. Call in a pro to check out your unit, make necessary small repairs and ensure your filters and fluids are ready to support optimal operation over the winter.

How you run your heat pump can also support efficiency and longevity. Avoid changing the thermostat setting constantly or making wide temperature swings — such as setting it to 60 degrees Fahrenheit (16 degrees Celsius) while you're at work and bumping it to 72 degrees Fahrenheit (22 degrees Celsius) when you get home. A 12-degree temp hike puts a lot of burden on the system, which can lead to more wear and tear and repair needs.

If you notice your heat pump doesn't work ideally during the coldest weather, talk to an HVAC professional about adding insulation to your home. Adequate insulation in areas like attics reduces how hard heat pumps have to work against exterior conditions. You could also install a backup heat source like a furnace to kick in when your heat pump can't keep up.