When we talk with homeowners about geothermal heat pumps, we often encounter misinformation, misperceptions, and myths. One of the most common misperceptions is that geothermal heat pumps won’t provide enough heat for their home in the dead of winter. So we thought we’d put this myth to rest once and for all and answer “how does geothermal work in cold climates?” We’ll start with a look at the science behind geothermal heating in winter, and some of the reasons that have contributed to the incorrect belief that geothermal heat pumps don’t work in cold climates.
The Difference Between Air Source Heat Pumps and Geothermal Heat Pumps
The confusion about geothermal heat pump efficiency in winter stems from confusion about the difference between an air source heat pump and a geothermal heat pump. Air source heat pumps are very similar to geothermal heat pumps but differ in one fundamental aspect: their energy supply source.
Air source heat pumps harvest heat from the outdoor air. This energy supply source has pros and cons, and one of the cons is a loss of efficiency as the outdoor temperature drops. Here’s how it works: When the temperature drops in cold climates, there is less heat in the air, which means the air source heat pump has to work harder to harvest enough heat for your home. This decreases the heat pump’s efficiency. In some parts of the country it will get so cold that the air source heat pump can’t harvest enough heat from the air, and has to rely on backup heat sources such as electric baseboards to supplement.
The scenario above does not apply to geothermal heat pumps. Keep reading to find out how geothermal heat pumps maintain their efficiency in cold climates.
How Does Geothermal Work in Cold Climates?
In contrast to an air source heat pump, a geothermal heat pump harvests heat from the ground, which maintains a steady temperature below the frost line year round. This means that as the outdoor air temperature drops, your geothermal heat pump maintains its efficiency and continues harvesting heat as it normally would. You never have to use backup heat, and you’ll never be cold.
Now that we know how both types of heat pumps work in cold climates, let’s look at some of the reasons there is confusion about geothermal heat pump performance in winter:
Sizing a Geothermal Heat Pump for Winter Heating
One cause of confusion comes from how heat pumps are sized for winter heating in comparison to traditional heating systems like furnaces. Geothermal heat pumps are sized to provide just enough heat on the coldest day of the year and no more. So, on the coldest day of the year, the heat pump will need to run continuously to meet this demand. This won’t hurt your heat pump and is completely normal. This is very different from traditional furnaces, which are often over sized and so do not run continuously even on the coldest day of the year. Having your heat pump run continuously when you are accustomed to a traditional furnace can be off putting, but it’s entirely normal.
When Geothermal Heat Pumps Aren’t Properly Sized for Winter Heating
One of the biggest causes of the misinformation around geothermal heat pumps and winter heating is improperly sized systems.
There is a scenario when a geothermal heat pump would have trouble providing your home with enough heat in the dead of winter. This occurs when the heat pump or ground loop is not large enough and cannot provide enough heat to keep your home at a comfortable temperature, even when running continuously. In this case, you would need to rely on backup heat to stay comfortable. Since this backup heat is less efficient, you’ll see a corresponding spike in your utility bills.
This can occur if a geothermal heat pump installer does not select a heat pump that is large enough for your home, under sizes the ground loop, or both. This is occasionally done to save money or decrease the cost of the installation. We don’t recommend this practice and you should ask your installer whether this is a practice they engage in.
A geothermal heat pump can be a great asset to your home in cold climates. It will provide comfortable and efficient heat to your home, even in the dead of winter. In addition, there are no moving parts exposed to the outdoors, so you don’t have to worry components getting covered with snow or ice. Finally, they don’t lose efficiency and when sized correctly they don’t require backup heat. This makes them a great choice for cold climates. To learn more about whether geothermal is right for your home, find a dealer in your area.