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Air Source vs. Ground Source Heat Pumps: Your Questions Answered



Air source or ground source? That is the question. When comparing ductless air source heat pumps with ground source heat pumps, it’s important to honor their similarities before we unpack their differences. Both use a small amount of energy to move large amounts of naturally existing heat from one place to another, both are fueled by electricity versus fossil fuels, and both cost less to operate than traditional heating and cooling methods. Now let’s explore some questions about how they differ.


How do air source heat pumps and ground source heat pumps work?

Ductless air source systems are reversible, two-way heat pumps that absorb heat energy from the air and move it to other areas. During winter they pull heat from outside air and move it inside, versus summer when they pull heat from indoors and move it outside. Ground source (or geothermal) heat pumps require ductwork and use the constant temperature of the earth to heat and cool spaces. During winter, they pull heat from the ground and transfer it into homes or buildings, and during summer, they pull heat out of the home or building and sink it back into the ground.



Do both methods perform well during extreme weather?  Both systems can heat and cool in extreme weather, however, ground source heat pumps can be more efficient than air source heat pumps in extreme climates. On the other hand, air source systems have an unlimited source of heat and with the newest heat pump technology, they continue to work in very cold weather, as long as temperatures are above -13°F. Which makes air source more than adequate for Western Washington weather.


Which system uses less energy to run? Ground source heat pumps may be up to 30% more efficient than new ductless heat pumps, making them overall more energy efficient than air source systems due to their use of more consistent ground temperatures versus varying temperatures that exist in outside air. However, one must also consider the greater cost to create and install ductwork throughout an entire home, excavate the earth, and install a ground system, as well as addressing unforeseen complications or land clearing that might be needed.


Do equipment, installation, and repair costs differ? Ground source heat pumps are not only more invasive and time consuming to install than air source heat pumps, they also typically cost 2-3 times as much due to the required ductwork, possible land clearing, and need to drill boreholes or excavate trenches. Air source heat pumps cost much less to install as they don’t require special permitting for drilling or trenching extensive ductwork for your home, or disruption to the earth and surrounding land. Additionally, when compared with geothermal systems, ductless air source systems are much easier to retrofit into existing homes, and far less costly regarding repairs and maintenance due to ease of access above ground.


Which heat pump style is easier and more versatile to install? Ground source heat pumps can only be installed in locations with road access for a digger and adequate outdoor space for either vertical pipes requiring a depth of 100-400 feet placed 20 feet apart or a horizontal installation requiring multiple trenches about 4-6 feet deep. The excavated land must be cleared of trees and roots, yet installation can damage existing grass, landscaping, and underground utility pipes. Additionally, duct work must be available or installed throughout the home, and adequate space will be needed for the large indoor heat pump unit. In contrast, ductless air source systems are a breeze to retrofit almost anywhere due to simply needing a 3-inch hole through the wall for installation and minimal surface space for low-profile indoor and outdoor units. They’re easily installed in garages, apartments, tiny homes, home additions, historic houses, larger dwellings, and commercial buildings.


In Closing

At IDHP, we’re proud to install ductless air source heat pumps and find them to be the premier heating and cooling method for people everywhere, especially residents of the Pacific Northwest. To learn more about how our systems can meet the individual needs of those in your household, please contact us today.

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