In addition to being buried underground, a geothermal loop can be run along the bottom of a pond to exchange energy from the earth. (Photo courtesy of Advanced Air & Metal)

Heating from the ground up

You don't have to live near a hot springs to use geothermal heat to warm your house. Current geothermal technology makes use of the difference in temperature between the ground and the air to heat — or cool — a house.

This "ground source heat pump" consists of a series of fluid-filled pipes buried 5 feet below the ground that feeds an indoor unit that compresses the absorbed heat and distributes it throughout the house.

The underground temperature 5 feet down is a constant 55 degrees throughout the year in the Rogue Valley. With a geothermal system, even if it's frigid outside, the air coming into your house has been prewarmed by the earth, so the heating system inside your house isn't working as hard to warm it up for you.

The same principle works in reverse during the summer to keep you cool for less money. Hot, outside air is cooled underground before being pulled into your house.

The geothermal units on the market today are vastly more efficient than older "air-to-air" electric heat pumps. The pumps and compressors are similar, but today's units save far more energy.

"We use seasonal energy-efficiency ratios (SEER) like gas mileage for heat pumps," says Scott Rosendahl, co-owner of Advanced Air & Metal in Central Point. "The old air-to-air pumps have a SEER rating of 21. Geothermal is 41 — double."

Part of the energy efficiency of this green technology stems from "the startup amperage," which in geothermal installations is about one-third of that needed by air-to-air heat pumps. This is helpful during power outages because most gas generators cannot supply the amperage to start the air-to-air systems but should have no trouble starting a geothermal unit.

"The pressures are lower (in the system)," Rosendahl explains. "It's working against the (constant) 55 degrees and not the extremes in the air."

In addition, newer geothermal systems last longer, says Rosendahl.

"Air-to-air equipment has a 12-year life expectancy. With geothermal, it's 20 to 25 years."

Rising energy costs make geothermal an attractive replacement for other technologies, as well.

"I was on oil, but oil's getting so doggone expensive, and it's not going to get any cheaper," says Bob Turner, a Central Point homeowner who had his geothermal unit installed a year ago by Advanced Geothermal.

Turner already is reaping the financial benefits.

"For the first 10 months, I've made a comparison, and we've saved $1,500," says Turner. "And that doesn't even include the increase in oil prices. When oil hit $4 a gallon, I had oil bills that were $600 a month. Geothermal has cut my total bill by more than half."

Geothermal does, however, require a substantial amount of up-front cash. Rosendahl estimates that most systems cost between $12,000 and $15,000. A federal tax credit of 30 percent eases this pain, and credits from the state of Oregon and Energy Trust of Oregon make this option even more affordable.

"I figure it will probably take eight to 10 years to recover my costs," Turner estimates.

The improvements over oil heating go beyond cost savings.

"My house is warmer, a more constant heat, unlike oil, where temperatures vary when the oil pump kicks on and off," says Turner. "It also charges my water heater with water well over 100 degrees."

Geothermal is not for everyone. Because of the high initial cost, smaller houses — with smaller initial energy bills — have a longer payback period. Most of Rosendahl's geothermal customers have houses of at least 2,500 square feet in size.

The system's underground pipes can be arranged horizontally, like a large refrigerator coil, or vertically by drilling new wells. Drilling adds to the initial expense but is necessary for town or suburban installations with limited lot sizes.

"You have to drill a 200-foot well per ton of output," says Christopher Harrison, who works for Spring Air in Jacksonville. "We put in six wells for the McPhail family," he says, referring to the family who gained local fame when "Extreme Makeover: Home Edition" built them a new house.

The more common horizontal pipe configuration requires a lot of space, making it most appropriate for those with rural acreage.

"For my system, we had 600 feet of pipe buried in trenches 6 feet wide and 5 feet deep," says Peter Stemple, an Applegate Valley homeowner who has had his geothermal system in place for a year.

Stemple's old system was an air-to-air heat pump with firewood as a supplement. He hasn't used his wood stove since installing the geothermal system.

"My old system had an electric furnace with three 50-amp circuits, but now I have only one," Stemple explains. "There's a lot less to maintain. It's an elegant system."

Share This Story