How it works
The ground does the heavy lifting.
A few feet below the surface, the soil stays far steadier than the air above it, mild in January and cool in August. A geothermal system takes advantage of that.
- The loop. Plastic pipe buried in the yard, in trenches or in vertical bores, carries water mixed with antifreeze.
- Winter. The fluid picks up heat from the ground, and the indoor heat pump concentrates it and sends it through your ducts.
- Summer. The process reverses: heat from the house goes back into the ground, and the house is cooled and dried.
- Extras. Many units can also help heat domestic hot water.
Your options
Geothermal compared with an air-source heat pump.
| Geothermal (ground-source) | Air-source heat pump | |
|---|---|---|
| Heat source | The ground, through a buried loop | The outdoor air |
| Cold snaps | Output holds steady because the ground temperature barely changes | Output drops as it gets colder; backup heat or a furnace helps on the coldest days |
| Install cost | Much higher, mostly for the loop field | Lower; see our heat pump price ranges |
| Yard work | Trenching or drilling, then landscaping repair | An outdoor unit on a pad |
| Outdoor unit | None; the equipment is indoors | Yes, with a fan you can hear |
Geothermal tends to make sense when
- You're building new, or the yard is already torn up
- You have room for a loop field, or ground suited to drilling
- You plan to stay in the home for many years
- Your heating and cooling loads are large, like a big home or one with long winters at elevation
An air-source heat pump is usually the better buy when
- You're replacing a system in an existing home on a small lot
- The budget matters more than the last bit of efficiency
- You're on Chelan PUD and converting from an electric furnace, where the utility rebate is built around ducted air-source heat pumps
Not sure? Start with our heat pump guide, which covers the air-source options most homes in the valley choose.
Before any price
What we look at first.
- The size, age and insulation of the home, so the system is sized to the real heating load.
- Whether the existing ductwork can carry the airflow a geothermal unit needs.
- Space on the property for horizontal trenches, or the case for vertical bores.
- Your electrical panel's capacity for the new equipment.
- How the cost compares with an air-source heat pump for the same house.
Geothermal questions
Geothermal heat pump FAQ
Does geothermal work in North Central Washington winters?
Yes. The ground below the frost line stays at a fairly steady temperature all year, so a geothermal heat pump keeps working through cold snaps that slow down an air-source unit.
Why does geothermal cost more than a regular heat pump?
Most of the extra cost is the buried loop: trenching or drilling, pipe and backfill. The indoor equipment is closer in price to other heat pumps.
Can geothermal go into an existing home?
Often, yes, if there's room for the loop and the ductwork can handle the airflow. New construction is easier because the loop can go in before landscaping.
Are there rebates for geothermal?
It depends on your utility and the program in place when you apply. Ask us and we'll check what applies to your address before you decide.
Comparing options? Our heat pump page has installed price ranges for air-source systems.
Geothermal consultation
See whether geothermal fits your property.
Tell us about the home, the lot and whether it's new construction. We'll call to talk through geothermal and the alternatives.
Office hours Monday–Friday, 8 a.m.–5 p.m.
- Site visit before any price
- Air-source options compared honestly