As winter creeps in and the temperature drops, homeowners start preparing ways to keep their homes warm amidst the chilly weather. Heat pumps have been a popular solution for HVAC systems, thanks to their energy efficiency, cost-effectiveness, and eco-friendliness. However, a common question that arises among homeowners is whether heat pumps work when it’s freezing outside. The answer is – it depends. In this article, we’ll explore how heat pumps work, when they stop being efficient, and what you can do to ensure that your heat pump operates seamlessly during the winter months.

1. The Ins and Outs of Heat Pumps: A Basic Understanding

Heat pumps are a popular heating and cooling system used in many homes and buildings. They work by transferring heat from one location (the outdoor environment) to another (the indoor space). This way, they can provide both heating and cooling throughout the year.

The basic components of a heat pump system include an outdoor unit, an indoor unit, a refrigerant, and a compressor. The outdoor unit absorbs heat from the outside air and transfers it to the refrigerant. The refrigerant then travels through the compressor, where it is compressed and heated even further. The hot refrigerant is then sent indoors, where it releases the heat and warms up the indoor space.

During summer months, the process is reversed. The indoor unit absorbs heat from the indoor air and transfers it to the refrigerant, which is then released outside, cooling down the indoor space.

Heat pumps have some significant advantages over traditional heating systems, including higher efficiency and lower energy costs. They also have a longer lifespan and require less maintenance. However, they do have some drawbacks, such as limited heating capacity during extremely cold temperatures and higher upfront installation costs.

Overall, heat pumps offer a reliable and efficient option for heating and cooling throughout the year. As technology continues to improve, their capabilities in subfreezing temperatures are also increasing, making them an increasingly viable option for colder climates.

2. Understanding Heat Pump Operation in Subfreezing Temperatures

Heat pumps are one of the most popular home heating and cooling systems used by homeowners around the world. They offer many benefits, including lower energy costs, reduced carbon footprint, and highly efficient heating and cooling operations.

However, many people still wonder whether their heat pumps will work correctly in freezing temperatures. To understand the operation of heat pumps during subfreezing temperatures, let’s explore the basics of heat pump operation.

How do heat pumps work?

A heat pump works by extracting heat from the surrounding air outside your home and, using refrigerant, transferring that heat indoors to heat your home. When the outdoor temperature drops below freezing, there is less heat available outside to extract. At this point, the heat pump must work a little harder to extract heat from the air, but it can still function efficiently.

The defrost cycle

When the heat pump is in heating mode, it creates a buildup of ice on the outdoor unit called “frost.” To combat this, the heat pump goes into a defrost cycle where it reverses the refrigerant flow to melt the ice. During this cycle, the heat pump briefly switches to cooling mode so that it can heat the refrigerant and melt the frost. Once the frost is melted, the heat pump turns back into heating mode to continue heating your home.

It’s important to note that the defrost cycle is a normal part of a heat pump’s operation, and homeowners should not worry when they see their outdoor unit go into defrost mode.

3. Advantages and Disadvantages of Using Heat Pumps in Cold Climates

Heat pumps are an attractive option for homeowners seeking an efficient alternative to traditional heating systems. However, many wonder if they can depend on heat pumps to generate warmth during freezing temperatures. Below are some .


  • Efficiency – Heat pumps are more efficient than traditional gas or oil furnaces because they don’t generate heat; they transfer it from one place to another.
  • Versatility – During warm weather, heat pumps can switch to cooling mode, making them a versatile choice for year-round comfort.
  • Safety – Unlike combustible fuels, there is no risk of carbon monoxide poisoning or gas leaks with heat pumps.


  • Performance limitations – As outdoor temperatures drop, heat pumps have to work harder to extract heat from the outside air. When the temperature reaches around 35 degrees Fahrenheit, heat pump efficiency decreases, and it becomes necessary to supplement the heat with auxiliary systems.
  • Higher upfront cost – Heat pumps have a higher initial cost than traditional heating systems, and installation may require additional expenses for ductwork and electrical upgrades.
  • Maintenance requirements – Heat pumps need regular maintenance, including filter changes, outdoor unit cleaning, and annual inspections to ensure optimum performance and longevity.

It’s important to weigh the pros and cons of heat pumps to determine if they are a suitable option for homes in colder climates. While they may not always be the most efficient choice in freezing temperatures, they can still provide reliable comfort with proper maintenance and supplemental heating.

4. Tips to Maximize Heat Pump Efficiency During Winter Months

Do Heat Pumps Work When It’s Freezing Outside?

Heat pumps are highly efficient HVAC systems that can provide heating and cooling throughout the year. However, heat pump efficiency can decrease during subfreezing temperatures, making it difficult to maintain a comfortable indoor temperature. Here are some :

  1. Install an auxiliary heating system. Consider installing an auxiliary heating system, such as electric resistance heating or a gas furnace, to supplement your heat pump during extremely cold weather. This will help your heat pump maintain a comfortable indoor temperature without overworking itself.
  2. Seal air leaks. Air leaks can cause heat loss, reducing the efficiency of your heat pump. Check for air leaks around doors, windows, and other openings, and seal them with weatherstripping or caulk. This will help reduce heat loss and improve overall efficiency.
  3. Reduce heat loss through windows. Windows are a major source of heat loss. Consider installing energy-efficient windows or using window insulation kits to reduce heat loss and improve efficiency. Also, close curtains or blinds at night to help retain heat.
  4. Maintain proper airflow. A dirty or blocked air filter can restrict airflow, reducing the efficiency of your heat pump. Replace or clean your air filter regularly to maintain proper airflow and maximize efficiency.
  5. Use a programmable thermostat. A programmable thermostat can help you keep your home at a comfortable temperature while maximizing efficiency. Set the thermostat to lower the temperature during times when no one is home or during the night, and raise it only when needed.
  6. Get regular maintenance. Regular maintenance is key to keeping your heat pump operating efficiently. Schedule annual maintenance with a professional HVAC technician to ensure that your heat pump is in good working order.

By following these tips, you can maximize heat pump efficiency during winter months and enjoy a comfortable indoor temperature without breaking the bank on energy bills.

5. Alternatives to Heat Pumps in Freezing Conditions

Although heat pumps are effective in heating homes during winter, their efficiency decreases as the temperature drops. For areas that experience extremely low temperatures, alternatives to heat pumps may be a better option.

1. Furnaces

Furnaces are the most common alternative to heat pumps in cold climates. They use either gas, oil or electricity to generate heat and distribute it throughout the home via ductwork or pipes. Furnaces can be more cost-effective in areas that experience sub-freezing temperatures because they are not affected by outdoor temperatures.

2. Boilers

Boilers work by heating water and distributing it throughout the home using radiators or in-floor radiant heating. Like furnaces, they are not affected by outdoor temperatures and can provide consistent heat even in extremely cold conditions. They are also more energy-efficient than furnaces, with an average energy efficiency rating of 85% compared to furnaces’ 60-98% rating.

3. Wood stoves

Wood stoves are another alternative heating option that can be used to heat homes during winter. They use wood or other biomass fuels to generate heat, which can be circulated throughout the home using a blower or by natural convection. While wood stoves can be cost-effective, they require a constant supply of wood and can produce harmful pollutants if not maintained properly.

Overall, choosing the right heating system for your home will depend on factors such as cost, availability of fuel, and the severity of winter temperatures. Consulting with a professional heating contractor can help you make the best choice for your specific needs.

6. Maintenance and Repair of Heat Pumps During Winter

Heat pumps require regular maintenance to ensure optimal performance and prevent breakdowns, especially during winter months when they work harder to heat homes. Here are some tips to keep your heat pump in good shape during the cold season.

  • Clean the outdoor unit: Dirt, debris, and snow can accumulate on the outdoor unit, hindering the flow of air. Clear away any debris and remove any snow from around the unit. If necessary, rinse the unit with a gentle stream of water to remove dirt and grime.
  • Check the air filter: A dirty air filter can reduce airflow and cause the heat pump to work harder than necessary. Check the filter every month and replace it if it looks dirty. Consider using a high-efficiency filter to trap more airborne pollutants.
  • Inspect the ductwork: Leaky ducts can waste energy and reduce indoor comfort. Check for cracks, holes, and gaps in the ductwork and seal them with duct tape or mastic sealant. Insulate the ducts if they run through unheated spaces like the attic or crawl space.
  • Test the thermostat: A faulty or outdated thermostat can cause inaccurate temperature readings and erratic cycling. Test your thermostat by setting it to a target temperature and checking if the heat pump starts and stops at the right times. Replace the thermostat if needed.

If you notice any issues with your heat pump, such as strange noises, weak airflow, or frost buildup, contact a certified HVAC technician to inspect and repair the system. Don’t attempt to repair the heat pump yourself, as it can be dangerous and void the warranty. With proper care and maintenance, your heat pump can provide reliable and efficient heating for many winters to come.

7. Frequently Asked Questions About Heat Pump Operation in Low Temperatures

If you live in an area where winters are harsh, you may be wondering if a heat pump can still effectively keep your home warm during subfreezing temperatures. Here are some :

  • Can a heat pump work in temperatures below freezing?
  • Yes, heat pumps can still operate in temperatures below freezing. However, as the temperature drops, the efficiency of the unit decreases, and it may struggle to maintain a comfortable temperature in your home.

  • How do heat pumps work when it’s really cold outside?
  • When it’s really cold outside, the heat pump compensates by running continuously, trying its best to extract heat from the outdoor air. The unit will defrost itself periodically as needed by reversing the refrigerant cycle and sending heat from the indoor unit to the outdoor coil to melt any ice buildup.

  • Will my energy bill go up if I use a heat pump during the winter?
  • While a heat pump is more efficient than a traditional heating system, you can expect your energy bill to increase during the winter months. However, by utilizing energy-efficient practices, such as keeping your home well-insulated and setting the thermostat to an appropriate temperature, you can help minimize your energy consumption.

  • Can I use a heat pump as my primary heating source during the winter?
  • It depends on your specific climate and heating needs. Heat pumps work best in areas where temperatures rarely drop below freezing. However, if your home is well-insulated and you live in a milder climate, a heat pump may be able to serve as your primary heating source during the winter months.

By understanding how a heat pump operates during subfreezing temperatures, you can make an informed decision about whether this type of unit is the right choice for your home. If you have additional questions or concerns, it’s always best to consult a professional HVAC technician for guidance.

People Also Ask

Can heat pumps work in extreme cold?

Yes, heat pumps can work in extreme cold, but their efficiency drops significantly when the temperature falls below freezing. However, modern heat pumps have advanced technology, such as a defrost cycle, which helps them to function even in sub-freezing temperatures.

What is the lowest temperature a heat pump can handle?

The lowest temperature a heat pump can handle depends on the model and brand, but most standard heat pumps can work efficiently down to temperatures around 25-30 degrees Fahrenheit. However, some advanced heat pumps are designed to work in colder temperatures as low as -15°F.

Are heat pumps suitable for cold climates?

Yes, heat pumps can be suitable for cold climates if they are correctly sized and installed. Homes in colder climates require a heat pump with a higher heating capacity, and the device must be equipped with a suitable defrost cycle, a backup heating system, and proper air duct insulation.

Do heat pumps use more electricity in cold weather?

Yes, heat pumps use more electricity in cold weather because they need to work harder to extract heat from the outside air, which is colder. Some heat pumps use backup electrical heating systems during extreme cold weather, which increases their energy consumption.

What is the best heat pump for cold climates?

The best heat pump for cold climates is a unit with a high heating capacity, low-temperature performance, and advanced technology such as a defrost cycle, a backup heating system, and hardened components. Popular brands that specialize in heat pumps for cold climates include Mitsubishi, Fujitsu, Carrier, and Trane.


Heat pumps can function in cold weather, but their efficiency and effectiveness drop as the temperature falls. Therefore, it is essential to choose the right heat pump for your climate and home, properly size and install it, and provide the necessary maintenance and insulation. With these measures, a heat pump can provide reliable, affordable, and efficient heating throughout the year.