When it gets cold, you can rely on your heat pump to give you warmth. Just enter the right settings on the thermostat and wait for a few minutes to feel the difference. The system will always do its best to make you and your family comfortable. However, it does have inherent limitations and known issues. By learning about these, homeowners will be able to set realistic expectations and make the right decisions in every situation. In this article, we will tackle a common complaint: that the heat pump doesn’t quite achieve the desired temperature during harsh winters. 

Heat Pump Never Reaches Thermostat Setting In Cold Weather

It happens quite often. Homeowners will aim for a certain temperature on the thermostat and the heat pump will try to reach it. No matter how long the system runs, the indoor air may get stuck a few degrees lower than the target. 

Many won’t mind the gap as they still feel sufficiently warm. Others are bothered by the inability to get an exact match. They might call their local HVAC technicians to schedule a visit. The technicians may indeed find a valid problem that needs repairs. However, it is more likely that the system is doing just fine. Heat pumps simply cannot generate massive amounts of heat in extremely cold weather. 

How Heat Pumps Work

To understand this inherent limitation, let us delve into how heat pumps work. These are versatile machines that can provide both heating and cooling. Households don’t need to have a separate air conditioner for summer and a furnace in winter. The heat pump can regulate indoor temperature throughout the year by itself. This simplifies installation and maintenance. It works by extracting heat from one side and moving this to the other side. Thermal transfer is made possible by a circulating refrigerant and carefully timed changes in pressure. Every heating cycle brings the home closer to the desired temperature. 

In the hotter months, heat pumps can cool down homes by letting the refrigerant absorb the interior heat. This heat is then released outside via the outdoor unit. A fan blows through the coils to speed up the process. The refrigerant is depressurized before starting another round. In the colder months, the process is reversed. Heat pumps warm up homes by moving heat from the outdoors to the interior. This may seem odd given the cold weather but it is possible as long as the temperature does not dip too low in the negative territory. 

Why A Properly-Working Heat Pump May Not Reach A Certain Temperature On The Thermostat

It should be noted that harvesting heat outdoors becomes more difficult the colder it gets. Once the mercury breaches 35 degrees Fahrenheit, heat pump efficiency begins to plummet. Once the outdoor temperature reaches the freezing point, the system will struggle to provide heat. 

This is one of the reasons why heat pumps are typically used in areas with mild winters. For regions with an extreme climate, it is more common to see households with boilers or furnaces. Homes may also implement a hybrid heating model in which they use a heat pump and a gas-fired heater. The former can run in moderate temperature while the latter can kick in during periods of extreme cold. 

Another way to circumvent this limitation is to raise the thermostat setting by a few degrees. For example, the current setting might be 71 degrees but the indoor temperature can only reach 69 degrees. Consider bumping up the setting to 73-75 degrees and see if this results in a more pleasant indoor environment. This is the quickest and easiest way to maintain comfort when winter kicks into high gear. The heat pump is still working properly but it needs a bit of help to provide adequate warmth. 

Other Issues That May Cause Your Heat Pump To Fail To Meet Thermostat Temperatures

1. Frozen Outdoor Unit

heat pump icing up in winter

Heat pumps that do not perform as well as expected may be dealing with certain challenges such as a frozen outdoor unit. If it gets too cold, then the ice can form over the equipment. This can interfere with the airflow and prevent heat absorption. Since it is a common occurrence, heat pumps usually come with the ability to run a defrost cycle. This should be enough to fix the problem and get things back to normal. In case the ice does not melt, seek professional help. 

2. Faulty Outdoor Unit

Even if the outdoor unit is not iced over, there could still be a faulty part causing it to malfunction. If the unit is unresponsive, then check the power supply and make sure that it is turned on. You should also look around the openings and remove any debris that is blocking them. Change the filters if they are dirty. If you do not see any changes after these, then call for an HVAC technician. 

3. Poor House Insulation

insulation for home to increase thermal envelope in winter

Sometimes the reason why the temperature never quite reaches the thermostat settings is poor house insulation. The heat pump may work hard but it can’t keep up with the speed at which heat is escaping through the walls and the roof. Perhaps there may even be open windows that are letting cold air in. They may also be air leaks that require caulking and weather-stripping. HVAC technicians can help you find and seal these hidden leaks to improve the home’s energy efficiency. 

4. Low Refrigerant Levels

image of heat pump with low refrigerant levels

If there isn’t enough refrigerant in the system, then the heat pump will have a hard time absorbing heat. Call the local HVAC specialists to fix a refrigerant leak and get a refrigerant recharge. Check the type used in your heat pump so that they can bring the right one.  

5. Undersized Heat Pump

If the heat pump routinely provides underwhelming performance, then perhaps the problem lies with its size. Maybe it is simply too small for the house so it cannot produce a sufficient amount of heat for the space. HVAC professionals can conduct a load calculation to check whether this is the case or not. If you have an undersized heat pump, then consider replacing it with a bigger unit. 

6. Thermostat Error

The struggle to reach the temperature settings may be due to a thermostat error. Maybe the unit is not properly calibrated. It could also have faulty sensors or a bad battery. You should also check whether there is a heat source close by that is skewing its sensor readings. 

7. Aging Heat Pump

Lastly, you may be dealing with an aging heat pump that has suffered from too much wear and tear. It can no longer operate efficiently so it constantly struggles to generate enough heat for the home. These heating systems last for around 12 years. If yours is older, then you may start to consider a full replacement. Consult an HVAC contractor for equipment selection. 


Heat pumps have a limited capacity to produce heat on extreme winter days. This is a normal consequence of the design. Therefore, it is not a reason to worry about equipment failure. The use of supplemental heating sources can keep the family comfortable until temperatures rise back up. If you are not dealing with extreme cold yet performance is underwhelming, then call HVAC professionals for maintenance, repairs, or replacement.