TL;DR: How Does a Heat Pump Work in Winter?A heat pump pulls heat from outdoor air and transfers it indoors using refrigerant and a compressor. Even cold air has usable heat. If temperatures drop too low, the system may use supplemental or emergency heat to maintain comfort. |
During cold weather, many homeowners wonder how does a heat pump work in winter when temperatures drop.
Unlike traditional furnaces that generate heat, a heat pump transfers heat from outside air into your home — even when it feels too cold for that to be possible.
Understanding how this process works helps you maintain comfort, reduce energy costs, and recognize when your heat pump may need seasonal care or repair.
When your heat pump is in cooling mode during summer, it absorbs heat from your house and sends it outside, leaving your home fresh and cool. That’s easy enough to understand since it works the same way as an air conditioner.
A heat pump can work to either heat or cool your indoor space. This means it’s an ideal appliance both in cold and warm seasons.
Now, the big question is, how do heat pumps work in winter when the temperatures are significantly low? Where does the system get the heat to warm your home?
Read on to learn more about how a heat pump works and how you can get the most of it.
How Do Heat Pumps Work in Winter?: Heat Pump Mechanism
A heat pump works the same way in winter as it does in summer, but in reverse. This is possible because a heat pump has a closed-loop system that allows it to work both ways. During winter, it extracts available heat from the outdoor air and brings it to your home.
Believe it or not, the air outside has a significant amount of heat, even at the height of winter. In fact, a heat pump can absorb enough heat to warm your home when the air outside is down to 5° F or lower.
Now, that was the easy part to understand!
So, how does a heat pump work in cold weather?
Think about a bicycle pump. If you release air or pressure from the tires, the gas coming from the tires feels cold. Conversely, once you increase pressure, the tires feel quite hot. Similarly, when a refrigerant moves from liquid to gas and vice versa, its temperature changes too.
For instance, a low-pressure liquid refrigerant passes through the outdoor condenser coils, where it absorbs ambient heat from the outdoor environment. The heat makes the refrigerant boil and turn into low-pressure vapor. From here, this vaporized refrigerant is pushed to the compressor, where it’s pressurized to achieve higher temperatures.
The hot, pressurized refrigerant now moves to the indoor unit (heat exchanger), where it heats up the air blown over the exchanger by the blower. As the refrigerant loses the heat, it turns back to liquid form and is transported out again to start another heating cycle.
Heat Pumps at Very Low Temperatures
Unfortunately, heat pumps are not the best heating option when the temperature outside drops below freezing point. During those days or weeks, your heat pump’s effectiveness also drops significantly.
If it’s only for a day or two, the heat pump will switch to an emergency heating system where it uses electricity to warm your house, but this will cost you quite a penny. For those people who live in extreme climate locations, it is more economical to have a gas-fired furnace for winter instead of a heat pump.
Heat Pumps Defrost Cycle
When it’s extremely cold outside, layers of ice start to cover your outdoor heat pump. For most heaters, this is fine as they are equipped to handle the situation in what is called the defrost cycle.
The defrost cycle takes around 10 to 15 minutes, and you may notice cool air coming from your vents when that is happening.
When should you worry?
If you see a significant amount of ice covering your heat pump, then you should be worried. This means your defrost cycle is not working properly. You should also be worried if your system’s defrost cycle kicks in very often because it’s a sign of a bigger issue.
It could mean your heat pump isn’t working efficiently, and some components need to be checked, especially the air filter. Call an HVAC technician if the heat pump is covered in ice or triggers a defrost cycle too often.
How to Keep Your Heat Pump Working During Winter
To keep the heat pump operating efficiently throughout winter, you need to take care of the unit. Thankfully, heat pumps don’t require as much maintenance as air conditioners, so it’s just a check-up that’s needed here and there.
Here are some tips:
- Schedule regular maintenance of your unit (maybe twice a year) to check the internal components of the heat pump.
- Replace your air filters every month or more frequently, depending on how often you use the unit.
- Always ensure that the outdoor components are free from debris, ice, snow, dust, grass clippings, etc. Periodic checks would be ideal.
- Ensure that no debris or blocking materials, like bushes or grass, are closer than two feet from the heat pump. Also, nothing should be covering the unit.
- If there has been a power outage or a tripped circuit breaker that interrupted your heat pump’s operations, avoid using the system for the next six hours.
Whenever you encounter a problem with your heat pump, contact a qualified HVAC technician to check it out instead of ignoring it.
Is a Heat Pump Right for Me?
The main reason people opt for a heat pump instead of an air conditioner is its dual purpose. Instead of installing an AC for summer and a gas furnace for winter, a heat pump does both at a fraction of the cost.
That’s not all you get from a heat pump, though. Here are some other benefits:
- Energy Efficiency. Heat pumps work on the premise that it’s easier to move air from one place to another than make heat from scratch like a furnace. Essentially, it only moves hot air from the outside environment to your indoors and vice versa during the winter to warm your house. This requires very little energy, meaning that heat pumps are quite friendly to your pockets.
- Durability. While they don’t last as long as a well-maintained AC, heat pumps last longer than most heating systems. Most units have a lifespan of 15 years if well taken care of, and a geothermal heat pump can go up to 50 years with no problems.
- Safety. Last but not least, heat pumps are safer than other heating options, and they require little maintenance. In the long run, you’ll be saving a lot of money with a heat pump compared to an AC and furnace.
But is a heat pump the right option for you? If your climate is moderate, then the answer is yes. However, if winter and summer temperatures are extreme where you live, a furnace and an air conditioner may be better options.