Air Source Heat Pumps
You might be hearing the phrase “air source heat pump” more and more in Minnesota. These heating and cooling systems are becoming increasingly popular in the northern climates — but how do you know if an air source heat pump (ASHP) is right for you? Keep reading to learn about the factors involved in deciding to install an ASHP in your home.
Air Source Heat Pump FAQ
Depending on your existing heating and cooling systems, ASHPs can help residents save money and reduce household greenhouse gas emissions. An ASHP may also be an option for parts of the home that may be challenging to heat or cool with your existing system.
An air source heat pump differs from a ground source heat pump. Ground source heat pumps, also called geothermal systems, pull heat from the ground rather than the air, and the installation process differs from ASHPs. Find out more about ground source heat pumps from the Minnesota Department of Energy here.
ASHPs provide cost savings for households that currently heat their homes using either electric resistance, propane, or fuel oil systems.
Many homes in Minnesota have natural gas-powered furnaces and boilers. Because the historic cost of natural gas tends to be lower than using electric resistance heaters and the cost of propane, air source heat pumps typically do not provide cost savings for homes heated with natural gas. If the cost of natural gas were to increase, ASHPs may become more affordable than natural gas-only heating systems.
However, if you are concerned about greenhouse gas emissions and want to reduce your household’s reliance on fossil fuel-based heat sources (such as natural gas, propane, or fuel oil), air source heat pumps can be a great option. Because they run on electricity, their greenhouse gas emissions can be lower. If you want to reduce your emissions even further, you can sign up for a renewable energy program offered by your electric utility.
The Minnesota Air Source Heat Pump Collaborative’s Cost of Heat Comparison Tool shows the cost savings associated with conventional vs. electric backups, and also shows how costs vary depending on the “Switchover” temperature. This is the temperature at which you switch from using the ASHP to heat your home to using the backup heating system.
If you have a propane heating system, an ASHP tends to be more affordable in lower temperatures. If you have natural gas, ASHPs can be particularly affordable during shoulder seasons when temperatures remain above 40 or 45ºF. Below 40º, natural gas furnaces tend to be more affordable given historical gas prices. As gas prices fluctuate, the cost savings of an ASHP can also rise and fall, and if the price of gas remains elevated, as it is in 2022, this calculation could change.
In addition, if you use electric resistance heat, ASHPs are generally more efficient and can help reduce your household’s total energy use.
Most utilities offer rebates for ASHPs, and the Minnesota air source heat pump Collaborative has a map to help you find rebates in your area.
If you qualify for income-based energy assistance and the federal weatherization program, an ASHP could be installed at no cost to you (or to your landlord, if you rent your home). Your eligibility varies depending on your primary heating source and may only be available to households heated by electricity.
Air source heat pumps can also reduce the greenhouse gas and other emissions due to a home’s energy use.
ASHPs can be quieter than window A/C units and also effectively dehumidify air. If you are already thinking about installing ASHPs for heating, they also have benefits for cooling.
One key difference between air source heat pumps and conventional heating and cooling systems is that ASHPs usually work best with the “set it and forget it” approach during the winter. You might be used to adjusting your thermostat during the day or in the evening, but because ASHPs are most efficient when maintaining a continuous temperature, it’s best to keep them at a consistent setting throughout the day and night, especially during the winter.
Efficiency Maine provides more user-friendly tips about temperature and fan settings for ASHPs here.
In cold climates like Minnesota, you will need to decide when to switch from heating with an ASHP to using your backup heating system. As previously mentioned, ASHPs in Minnesota tend to be cost-effective when switching to backup heating around 40º or 45º F. This switchover temperature varies depending on the type of heat pump you have and your backup heating source, so check with your installer and user manual for recommendations. Try testing out different switchover temperatures to see which you prefer in terms of energy and cost savings.
Because ASHPs have an outdoor pump component, be sure to keep this exterior unit clear of snow, leaves, and debris to ensure maximum efficiency (just as you would a central A/C unit). Also clean the interior units regularly (every few months or so) to prevent dust buildup.
In addition, make home energy efficiency improvements by weatherizing your home, upgrading other appliances as needed, and even getting a home energy audit. ASHPs work best in well-insulated homes that are already efficient.
Once you’re ready to install, look for qualified contractors. Ask questions about their experiences with ASHPs, because not all HVAC companies have previously installed ASHP systems. The Minnesota Air Source Heat Pump Collaborative and this article from the New York Times. provide suggestions about what to look for in an ASHP contractor.
Make sure the contractor discusses sizing the ASHP correctly. Heat pumps that are too large or too small for your home will not work as efficiently.
Check for rebates from utilities using the Utility Rebate Map.
Additional Air Source Heat Pump Resources
- Minnesota Air Source Heat Pump Collaborative
- Clean Energy Resource Teams ASHP Guide
- New York Times Heat Pump Buying Guide
- Center for Energy and the Environment’s Beneficial Electrification Cost Comparison Tool
- U.S. Department of Energy Air Source Heat Pump Resources
- Efficiency Maine Heat Pump User Tips