How to charge a heat pump in cold weather

Reviewed by Eric Grubbs

Heat pumps use refrigerant to transfer heat between the inside of your home and the outdoors. When refrigerant lines are damaged, refrigerant can leak out of the system. The heat pump will need to be recharged to restore the proper amount of refrigerant necessary for optimal performance.

Only a certified HVAC technician should charge a heat pump or HVAC system. The tech will use one of two methods: superheat or subcooling. In most cases, subcooling is the preferred method, but the solution will depend on the indoor metering device type.

Charge A Heat Pump In Winter

To prevent the home from becoming cold, the auxiliary heating system will run while the heat pump is taken offline for repair.

Signs a heat pump is low on refrigerant

There are three primary warning signs your heat pump may need to be recharged. Look for these symptoms of a heat pump that’s low on refrigerant:

  1. A leaking heat pump. The refrigerant in your unit should last as long as the system itself. That is, unless it experiences a leak. If you notice liquid escaping from the system, typically around connector points, you’re likely low on refrigerant.
  2. Unit is frozen. If the heat pump evaporator coil is frozen over, it’s time to call an HVAC pro. Note that this can also occur in the summer, signaling the need for a charge.
  3. Poor performance. Does your home feel colder (or warmer) than it should? A unit that continuously runs but can’t maintain your desired temperature signals the need for a refrigerant charge.

Stop Reading, Start Talking

When the technician arrives, request that they check the airflow of your unit before charging the refrigerant. If the airflow is off, the unit will not operate properly even with the correct charge.

When to add refrigerant to heat pump

With regular maintenance, your heat pump should operate efficiently for 10 to 20 years. The refrigerant in your unit should not need to be charged or “topped off” unless a leak is detected.

Heat pump maintenance should be performed twice a year: in the spring and fall. Technicians will spot small issues before they turn into major system challenges. Between professional inspections, you can use these simple homeowner heat pump maintenance tips to keep the unit running at its best:

  • Clear away snow and ice build up. The heat pump needs access to outdoor air. Anything that restricts that air flow will cause the heat pump to work harder than necessary.
  • Clear leaves, sticks, and other foilage from the outdoor unit. Plant shrubs at least 18 inches away from the heat pump.
  • Clean or changeyour filters once a month, or as needed.
  • Ensure all registers are open.
  • Clean outdoor coils with a foam spray whenever they appear dirty.
  • Keep the thermostat set above 65 degrees during the heating season.
  • Keep the thermostat set at or below 70 degrees during the cooling season.

DIY or call a pro for heat pump charge?

Inspecting and charging the refrigerant in a heat pump is not a DIY job. Any time coolant in an HVAC system needs to be charged, a certified HVAC technician must complete the work.

Follow a routine heat pump maintenance schedule and have a professional inspect the unit twice yearly. The upkeep on your unit will pay off with a warm home in the winter and a cool space during the summer. If you’ve noticed the symptoms of a leaking heat pump, click below to connect with a trusted HVAC technician.