A Guide for Geothermal Retrofits

A Guide for Geothermal Retrofits

If you’re considering a geothermal retrofit for your home, the three most important factors are the size of your home and yard, its geology and hydrology, and the adequacy of your existing ductwork system to deliver the conditioned air. A geothermal heat pump harvests or replaces heat to condition your home by using an underground loop field as the heat exchanger.

Geology and hydrology

A significant part of a geothermal retrofit is the soil analysis of your yard. Soils have different thermal properties, so finding out what’s below ground, along with your home’s size, will help the installer calculate the size of the loop field you’ll need. If you have access to a body of water, you could opt to have the loop field placed at the bottom of the pond to take advantage of the least expensive way to install a loop field.

The more costly type of installation is a vertical loop field because the field has to go deeply underground. This type is an option if your yard is small or if you have landscaping you don’t want disturbed. The most common installation is horizontal, which may go five feet down or more.

Home and yard size

The HVAC contractor will calculate the heating and cooling load of your home using Manual J, which factors in home size, the energy efficiency of your insulation and windows, and the air infiltration rates. Homes that are more energy efficient and have low air infiltration rates are easier to condition. Improving insulation and sealing air leaks may result in your needing a smaller HVAC system, which results in a smaller loop field and less disturbance of the land in your yard.

Existing ductwork

A geothermal heat pump won’t produce the same hot temperatures that a forced-air combustion furnace does. As a consequence, the ductwork system in your home may need to be enlarged for quiet and comfortable heating and cooling.

For more information on a geothermal retrofit, contact Roth Heating & Cooling. We’ve provided HVAC services to Portland area homeowners since 1976.

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