"Why is my heat pump not working?!"

With the recent cold snap we just had the last week, we received many calls from our customers who  said things like, “My heat pump is blowing out cold air,” or “My heat pump is constantly running!” This article is to help you better understand exactly how heat pumps operate.

“My heat pump will not reach the temperature I have set on my thermostat.”

Let’s say you set your thermostat at 71 degrees in the winter and your home only seems to be getting up to 69 degrees. Don’t fret! This is normal. Sometimes, this may be caused by a genuine problem, but unfortunately in extremely cold weather, even a properly working heat pump may have trouble maintaining the desired temperature. Why is this, you might ask? When it gets below a certain temperature outside, normally 25 degrees (depending on what you have it set at), the heat pump loses efficiency and cannot keep up with the heat loss of the home. When the temperature in the home drops approximately 2 degrees below room temperature, supplemental heat comes on to assist the heat pump. When it gets to within 1.5 degrees of room temperature, the backup heat cycles off and the heat pump continues to run, trying to reach the desired temperature, but cannot. This usually happens when the temperature is at its coldest: 0-30 degrees. This is, however, the way heat pumps were designed to operate. So, if it is bitterly cold outside and you desire your home to be a certain temperature, you might have to raise your thermostat by 2 degrees to maintain it.  If it is only mild outside and your heat pump isn’t maintaining the temperature, this might indicate a problem and you should call your local HVAC company to come look at your unit.

What is auxiliary heat?

Auxiliary heat is the technical term for “heat strips.” Most heat pumps have heat strips inside the air handler to compensate for the cold air produced when the heat pump goes into “defrost cycle.” During the defrost cycle, the heat pump reverses. It circulates cold refrigerant through the inside coil and hot refrigerant through the outside coil to melt the ice off the outside coil. Without heat strips, cold air would be blown into the home during this time. Heat strips/auxiliary heat is also sometimes referred to as “backup heat” which is used to supplement the heat produced by the heat pump to assist during extreme cold weather. 

Another thing to note is that if your heat pump is running consistently more in colder weather, this is normal for a properly installed heat pump. If it is running constantly during mild weather, you may have a problem.

Some heat pumps may automatically kick on the back up heat when needed, but some require you to manually do this yourself. You should check with the HVAC company that installed the unit to determine what situation yours is if you do not already know.

“It feels like cold air is coming from my registers.”

Sometimes a conventional heat pump delivers heated air that is actually cooler than your body temperature. If moving air that is less than your body temperature strikes you while you’re warm, it tends to feel cold, when in fact, it could be several degrees warmer than the room temperature. It might help to relocate furniture so that you do not get a direct draft from the registers.  Also check to see if the fan switch on your thermostat is set to "ON". If the fan switch is set to "ON" the fan will never stop running. This is used to circulate air on mild days or to continuously filter the air inside your home. If you want the fan to run only when there is a need for A/C or Heat, set your thermostat to "AUTO". This could also be a cause of any colder air coming from your registers.

While maintaining your heat pump and air handler, be sure that the outside unit is free of debris and clutter. Also, it might be a good idea to have some sort of roof over top of your unit to prevent snow and rain from getting on the unit, which can cause the unit to freeze up more often and not be able to properly defrost, causing long term damage to your unit. Be sure to not restrict any air flow from the outside unit when doing so.

Always remember, if you suspect a bigger problem and none of the recommendations have helped with your situation, call your local HVAC company and get a qualified technician to your home to determine and fix your problem.