Geothermal Heating & Cooling 101

In honor of Earth Day later this month, we figured we’d answer every conceivable question about geothermal heating and cooling, our Earth-friendliest HVAC option. Here we go…

Q: How does geothermal work, anyway?

A: A geothermal heat pump, also called a geoexchange or ground-source heat pump, basically just takes heat from the ground in the winter and moves it into your home. In the summer, it takes heat from your home and transfers it to the ground.

Q: Okay, but … how?

A: Starting at about five feet underground (depending on your location), the earth is pretty much always between 50 and 60 degrees Fahrenheit. So, what we do most often is bury a heat exchanger (a loop of pipe that’s filled with water or a water solution) at that depth. During cooler months, the liquid circulates and absorbs the earth’s heat, bringing it back to your heat pump, which uses it to warm the air and then your heating system warms it a bit more before circulating it throughout your house and making you all toasty. This sounds like a lot of warming, but it’s actually not. Since heat naturally flows from warm areas to cooler ones, the heat pump doesn’t have to work very hard to collect heat from the ground and bring it back to your heating system.

It’s possible to use pond/lake loops and well water-provided systems like an open loop instead of burying a heat exchanger below ground, too. If you’re interested in geothermal, we can talk about which option would work best for you.

Q: And it can cool my house, too?

Absolutely. During warmer months, your HVAC system gathers up heat from your home and transfers it to the water (or water solution), which is then circulated through the heat exchanger (the aforementioned underground loop). This deposits the heat back into the cooler ground along the way. The now-cooled liquid travels back to your heat pump to cool the air inside your home.

Q: Will it still work when there’s frost on the grass (or when it’s 110 outside)?

A: You bet. We place the heat exchanger deep enough that the ground temperature isn’t affected by daily temperature cycles — like we said, the temperature down there is the same year-round.

Q: What are the benefits of installing a geothermal system?

Well, for starters, it can reduce your energy bills by up to 65% when compared with traditional HVAC systems, according to the U.S. Department of Energy. That’s because geothermal heat pumps are radically more efficient than gas or oil furnaces. They also burn zero fossil fuels, which means that their carbon footprint is minimal and — bonus — they pose virtually no risk of carbon monoxide poisoning.

Q: How often do they need to be replaced?

A: Not very often. The indoor components are designed to last for about 25 years and the outdoor loops have a 50-year warranty — but can be used for up to 200 years!

There you go. In the unlikely event that you’ve got a question that we didn’t answer (or if you’re just interested in learning more about your geothermal options), give us a call.

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