Home & Garden: Using the Earth as your Furnace [View All]

Home & Garden: Using the Earth as your Furnace

Candace Renalls
Duluth News Tribune - 11/17/2007

Unlike most of us, Dale Burgess doesn’t mind his heating bill.

He pays less than $400 annually for heat, air conditioning and hot water in his 2,200-square-foot home. His average monthly bill of $31 also pays to heat an attached two-car garage and airplane hangar.

Instead of a conventional gas, propane or oil heating system, he and his wife, Linda, rely on the constant temperature of the Earth, which is warmer than the air in winter and cooler in summer. The house they built in 2005 has a geothermal heating system.

Rising home heating costs are prompting more people to look to geothermal systems instead of burning fossil fuels. Burgess estimates he would pay $2,000 to $2,500 a year to heat and cool his house with fuel oil.

Summit Mechanical Service in Duluth is installing 40 geothermal systems this year, more than previous years, said Kevin Kaski, one of its geothermal designers.

“There’s definitely been an increase in geothermal, and there’s a lot of talk about it,” said Dean Talbott, energy specialist with Minnesota Power. “As a heating system, it’s the most efficient heating and cooling system on the market.”

Even in the Northland, where the ground freezes, the temperature of the underlying earth remains a relatively constant 45 to 50 degrees year-round. That’s where coiled pipes are laid to absorb heat. An electric heat pump, which replaces a furnace or boiler, moves fluid carrying that heat through a system of underground or underwater pipes to the house. Then the heat pump’s compressor raises the fluid’s temperature and the heat is distributed through the house, typically through a forced-air duct system. In the summer, the system works in reverse, moving heat from the house back to the Earth where it disperses. Adding a “desuperheater” provides hot water for free in the summer and saves heating costs in winter.

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