My HVAC System Froze In The Winter Weather… Now What?
MY HVAC UNIT IS FROZEN… WHAT SHOULD I DO?
Your heat pump is frozen; It’s Wintertime and you’re not sure what to do. First, check to ensure that your outdoor unit has proper airflow. Too much overgrowth or recent snowfall can impact your unit’s ability to breathe.
Recent snowfall, overgrowth, or drifting snow can impede your unit’s airflow. Be sure to clear the area around your outdoor unit by shoveling snow and trimming any nearby vegetation to keep the airflow unrestricted.
If you do not see anything blocking your unit’s room to breathe, don’t fret just yet. Although seeing your heat pump frozen on a cold day can be alarming, it is likely completely normal. So, how can you tell if the amount of ice buildup on your outdoor unit is normal or not? First and foremost, it’s important to understand how a heat pump works when it’s set to heating mode.
HOW DOES A HEAT PUMP WORK DURING THE WINTERTIME?
Contrary to what some may think, heat pumps don’t generate heat themselves. Instead, they transfer heat from the air or ground by circulating a refrigerant between the indoor air handler and the outdoor compressor." The resulting heat is then redistributed throughout your home. To understand how this works in more detail, check out the following video from This Old House on how a heat pump works in both heating & cooling modes. To see how a heat pump works in heating mode skip to 4:18 in the video below.
It is well known that heat pumps are versatile, highly efficient heating & cooling systems. Simply put, when your heat pump is set to cooling mode, it pulls heat from inside your home and pushes it outside. In heating mode, your heat pump will absorb heat from the ground or outside air (including cold air) and then release it indoors.
WHY DOES MY HEAT PUMP FREEZE?
As mentioned earlier, when your heat pump operates in heating mode, it uses a refrigerant to move heat from outside into your home. During this process, the cool air expelled outside can lead to condensation forming on the coils. In cold weather, this condensation may freeze on the coils.
If your heat pump doesn’t enter defrost mode as scheduled, it can hinder its performance. Which is why nearly all heat pumps are designed to have the system switch to defrost mode every 30, 60, or 90 minutes. During defrost mode, warm air is blown over the condenser coils in your outdoor unit to melt any frost buildup. This cycle typically lasts an average of 10-15 minutes but no longer than 30 minutes. You might even see steam rising from the outdoor unit during defrosting — this is completely normal and is not cause for concern.
HOW MUCH FROST OR ICE ON A HEAT PUMP IS NORMAL?
Now that we have gone over how a heat pump works in both heating and cooling modes. We can better understand why frost/ice can easily accumulate on your heat pump on cold weather days. While this accumulation is completely normal as discussed, you should only see a thin layer of frost that does not cover your entire unit. This is a good indication that your heat pump is likely functioning as it should and will cycle through defrost on its own.
As noted by NACHI “a heat pump unit will defrost regularly when frost conditions occur. The defrost cycle should be long enough to melt the ice, and short enough to be energy-efficient.”
However, there are some instances where a frozen heat pump could be cause for concern, indicating a problem with your unit. For instance, if you see a significant amount of frost/ice buildup covering your entire unit. This is a clear signal that your heat pump is not able to properly defrost on its own.
Not Cycling Through Defrost & Needs Service
Fully Frozen Over Unit In Need Of Service
Your unit should never appear as though it’s trying to create its own personal snowman. If you step outside and see a large amount of ice buildup encapsulating your entire unit, you may have a more serious problem on your hands and it’s time to call in a professional like the ones at Air Dynamics HVAC. A trained, qualified technician will be able to identify the underlying issue and address it in order to get your unit back to functioning as it was designed.
HOW DOES A HEAT PUMP PROTECT ITSELF FROM FREEZING?
Your heat pump is designed to handle the possibility of ice buildup in cooler weather. In fact, your heat pump’s built-in defrost cycle is designed specifically to handle frost accumulation as a part of its normal operating cycle. This built-in defrost cycle will temporarily kick on in order to allow your unit to use the heat from the refrigerant to melt the frost/ice away. This process should only last an average of around 10-15 minutes.
Defrost mode usually lasts about 10-15 minutes, before the unit will start to heat again.
While your unit is in defrost mode, it will automatically switch into air conditioning mode for a short period of time until it thaws itself; at which point it will be able to return to functioning in heating mode once more. But don’t worry, you’re not likely to notice the difference. While all of this is happening, a backup heating cycle will automatically kick on. Keeping you and your family warm until it has finished. If, however, your unit is still frozen after 30 minutes and you feel the temperature dropping in your home, it’s time to consider calling a professional.
PROBLEMS THAT CAN LEAD TO A FROZEN HEAT PUMP
There are several things that can cause a heat pump to freeze unexpectedly. One of the most common causes is restricted airflow. This is why it is imperative to ensure your unit has adequate breathing room. Aside from simply ensuring that the area surrounding your outdoor HVAC unit is clear from snow and other debris. You should check your unit’s HVAC filter and ducts. Clogged air filters or debris can add to restricted airflow. Choking your unit of the air it needs to function properly. Without adequate airflow, ice can build up and cause your outdoor unit to freeze over.
Check your HVAC filters, and change them every 90 days as needed. This will help to keep your unit functioning as it should. Avoiding unexpected issues caused by restricted airflow.
Another thing you can do is to check your ducts for airflow. Do you feel air blowing from your vents when your unit is running? If not, then you may have a bad blower motor or other part that has gone bad on your unit. You should also check the fins on your outdoor unit. If you see any dirt or debris be sure to remove them.
HOW DO YOU UNFREEZE YOUR HVAC UNIT?
When your HVAC unit freezes over it’s understandable that you may be worried. Especially if you’ve now determined that this is more than the normal ice/frost accumulation that your unit is prepared to handle. So, how do you unfreeze your HVAC unit when this happens? First, avoid the temptation to pour hot water over your unit or manually scrape away excess ice; we do not recommend this.
If your unit is fully frozen over, turn your unit off completely and contact a professional like the ones at Air Dynamics HVAC.
Instead, turn your unit off completely and call in a professional. This will allow your unit to defrost on its own naturally while you wait for the technician to arrive. Avoid the temptation to speed up this process by scraping at the ice with a sharp object or taking any other means to speedily defrosit it on your own as these actions have the potential to cause unexpeted damage to your HVAC unit. As we mentioned earlier in this article; your unit should never look like the image above. This is not normal and is a clear signal that it’s time to call in help.
WHEN SHOULD YOU CONTACT AN HVAC PROFESSIONAL?
If you’re still struggling to get your HVAC unit to defrost on its own, contact a professional at Air Dynamics HVAC today. Our knowledgeable HVAC professionals can assist you in getting your heat pump back to functioning as it was designed.
