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My Heat Pump is Smoking! What’s Going On?

With winter in full force, you want to make sure your heat pump is working properly. But what happens if you see smoke rising from your heat pump? Is there something wrong with it? Let’s explore what is happening when your heat pump is smoking and why you shouldn’t sweat it.


Steamy Situations: Heat Pumps and Heated Moments

Toasters shouldn’t shoot sparks, washing machines shouldn’t rumba across the room, toilets shouldn’t run endlessly, and when it comes to heat pumps, they probably shouldn’t have steam rising from them in the middle of winter, right? This can be especially frightening if the steam is first mistaken for smoke! Although it can be an alarming sight at first, this is a perfectly normal part of your heat pump working through a cold winter day. 


Spark Some Discussion

Let’s address the first fear of seeing white, puffy clouds from a heat pump smoking: it is most likely not smoke at all. The sight of “smoke” rising out from a heat pump can be very alarming, but you can easily discern the difference by noting that the rising steam is white, not gray as ashy smoke from a fire would be, and there is no evidence of flame. You can step outside and examine your heat pump to assure yourself that there is no smell of smoke and that the heat pump is still functioning. 

This is also the ideal moment to take some time and assess the fire safety of your home by making sure you have enough smoke detectors and fire extinguishers in your house, as well as an escape plan for everyone living in the house. 


So What’s with the Steam?

During bouts of cold weather, Heating, Ventilation, and Air Conditioning (HVAC) service providers stay busy with calls from folks claiming that their heat pump unit is on fire. What’s actually happening is that the heat pump is too cold and has moved into its defrost cycle to maintain proper operation. 

A heat pump functions in the winter by extracting heat from exterior air and using it in warm interior spaces. Although this seems counterintuitive in cold weather, a heat pump can and does so with great efficiency, using the same refrigerant that keeps you cool in the summer to warm you through the winter. Heat pumps are amazing machines!

The process of extracting heat from the outside air, especially when there is moisture in the air, can cause ice to build up on the exterior condenser coils of the heat pump. This ice build up makes it difficult for a heat pump to function, but don’t worry, because heat pumps are built to handle this issue with ease. When necessary, a heat pump will enter a defrost phase to melt any ice build up before it forces the heat pump to stop working correctly. People inside a home that have a heat pump going through a defrost mode might notice that air vents will temporarily blow cooler air. This will only last a moment before heat returns. 


Stop, Children, Whoosh That Sound?

If the sight of steam rising from a heat pump isn’t enough to scare you, maybe hearing a completely unexpected sound might give you a fright! When heat pumps move into a defrost mode, the exterior fan turns off until the process is complete. This makes a heat pump sound different than normal, with the sound often described as a “loud whooshing noise” that is not heard during typical operation. While it’s always good to be familiar with how the appliances in your home operate and be aware when they are doing something outside the normal bounds of their functions, this noise during a defrost period is perfectly normal. 


Ice, Ice, Maybe

During the winter season, especially when freezing temperatures reach your area, it is always good to keep an eye on your heat pump. As you cover your exterior hose faucets and cover vulnerable plants, heat pumps and air conditioning units also need protection from ice. It is best to keep an exterior unit entirely free of ice.

Turn the heat pump or air conditioning unit off before manually clearing any ice or snow to prevent injury or damage to the unit (never put your hands near the moving fan blades of an ac unit!). If ice is firmly frozen onto the unit, don’t force it off. Most sources of help recommend using a garden hose to wash the ice away. The key thing is to remove the ice without causing any scratches, dents, or other damage to the unit and to keep yourself safe. If a heat pump completely freezes up, that’s when it is time to call your local, licensed HVAC service provider so they can make sure your home stays warm for the winter. 


The Hard-Working Heat Pump 

Cold weather can cause heat pumps to go into defrost mode, which is often accompanied by a loud noise and steam rising from the exterior unit. Even though it looks like your heat pump is smoking, this is a normal part of operation and should not be a cause for alarm. It is very important to keep a heat pump free of ice and snow, which can hamper its ability to function. Although the defrost mode can look and sound alarming, it is just a heat pump’s way of dealing with cold temperatures and is in fact a very clever work around when dealing with unfavorable winter conditions. 

So the next time you see “smoke” rising from your heat pump, take a moment to assess if you are just witnessing the defrost mode of this fantastic piece of technology. By being HVAC aware and scheduling bi-annual maintenance and cleaning appointments with your local, licensed HVAC service provider, you can stay cozy all winter long while your heat pump works at its peak efficiency.

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