Putting Geothermal Heating on the Hot Seat

We're through the first winter with our new, efficient heating system, and it saved us some bucks. But it isn't clear how many because of kinks in the new tech. While a geothermal system isn't a new concept, as drawing heat and cooling from the ground is at least as old as the Romans, it's still unusual in American homes. And we've learned there still is a hassle in being the first on your block.

It appears the system cut our heating bills by a little less than half. That's good because it was expensive to install: about twice the cost of a conventional furnace and air conditioner. If geothermal cuts our bill by half, the monthly savings would cover the upfront difference in six to eight years.

We think it can do better. That's because we discovered that on cold days we had problems with the original thermostats, which unnecessarily kicked on our supplemental heat. The expensive supplemental heat is powered by electricity, like a big space heater, and should be tapped only on the coldest days, when the geothermal can't keep up. Most days, with compression, geothermal can heat the house, even though it pulls only 55-degree energy from the ground.

Essentially, the thermostats were confused and had our system backward. They were designed for heat pumps, which are much like geothermal but draw their energy from outside air. In our area, they are powerful enough to provide only supplemental heating or cooling–with another system doing the primary work. Our system is flipped, with geothermal as the primary.

We have new thermostats, and no supplemental cooling is ever needed with geothermal. So the hottest weather should prove our energy bills can be cut by more than half. We hope.