Even when it’s cold outside, a heat pump is designed to use refrigerant to transfer heat from the air outside of the home and displace that heat indoors.
As crazy as that sounds, it actually works really well in moderate climates. Unfortunately, when those outdoor temps get below freezing, a heat pump does lose capacity and efficiency. Although, they do still produce heat, it may not be enough to satisfy a thermostat setting without extended run times and some help. That is why it is necessary to have the electric back-up heater cycle on to assist the heat pump. Most of us know this as “AUX HEAT”, as labeled on most thermostats. Most heat pumps use an air handler with an electric strip heater in it.
This electric heater has 3 main functions:
- Assist the heat pump when needed.
- They will automatically turn on when the heat pump goes into defrost.
- They will be deemed the primary source of heat if your thermostat is switched to “EMERGENCY HEAT”.
Some think that shutting down a heat pump and switching to emergency heat when it is really cold outside is beneficial, but in all reality, the best way to heat the home is to allow the system to run. Of course, for better results, the heat pump system needs to be healthy and running at its best.
Here are 5 signs that your heat pump system may not be reaching its peak performance:
1) Thick layer of ice forming on the outdoor unit: As temperatures fall, a thin layer of frost may develop on the coil. All heat pumps have an automatic function called defrost that will assist in melting the frost. This is a timed function and the frost levels may differ. But, if the frost continues to form without melting, ice will begin to accumulate. Ice will impede airflow on the heat pump and the system will lose even more capacity and efficiency.
2) Heat Pump not running: There are many parts in a heat pump that may cause it to fail in the winter time. There are different switches and sensors that ensure safe operation of the heat pump. For instance, a system that is low on refrigerant may cycle off and not come back on unless repaired by a professional.
3) Electric heat not functioning properly: Often times we get calls from customers who notice during colder weather that they cannot reach set point on the thermostat. A heat pump may heat fine during moderate temperatures, but without the assistance of the strip heater, a noticeable problem may arise. Some possible causes of electric heater failures include defective relays or sequencers, bad heating elements, tripped breakers, and/or improper wiring to the heater.
4) Reduced Indoor Airflow: As with air conditioning, proper indoor airflow is crucial to a heat pumps performance. Dirty filters, dirty indoor coils, and/or a dirty blower wheel can reduce the amount of air needed to operate your heat pump satisfactorily. With longer run-times during the cold winter months, it may be necessary to change your filters more often than non-peak seasons like the spring or fall.
5) Leaking Ductwork: One thing that usually doesn’t come to mind for most homeowners is leaky ductwork.
I can’t say that I know anyone who would be willing to generate heat with their system and lose a good portion of it to the attic or crawlspace. The reality of this is that MOST duct systems have significant duct leakage.
In conversation, I often ask homeowners, “What would happen if their water lines leaked 30% or more in their attic, walls, or crawlspace?” Obviously a water leak of that proportion would cause terrible damage and an airflow loss of that kind may not be that noticeable; but nonetheless, heating and cooling the outside world hurts your wallet. Duct leakage in my professional opinion has a direct relationship to extended equipment run times, comfort issues, and poor indoor air quality.
If you experience any of these problems or have any other questions or concerns about your heating equipment, please feel free to give us a call. We work hard with our technicians to identify and resolve heating or air conditioning issues that reduce efficiency and comfort.