By Barbara Baird, September 2008

• Introduction
• How does it work?
• Closed & open loop systems
• What's the cost comparison?
• Examples & where to find contractors
• Download the full article as a

A Haywood County residence

When he built his house in Haywood County three years ago, Ken Thomas installed an open loop geothermal heat pump system with pipes running from his water well to a pressure tank, then through the house and ending in a creek on his 3-acre property. He had determined that his 290-foot well could deliver 40 gallons per minute, which more than twice what you’d typically need for such a system. He heats and cools his 2,100-square-foot house for between $60 and $80 per month, using a programmable thermostat. He keeps the place at 72 degrees in winter and 68 in summer, and he has no auxiliary heating system. Summer cooling costs less than winter heating in this mountain country. The water in his system maintains a year-round temperature of about 52 degrees.

“I am amazed at the savings,” says Ken, who is the marketing and communications manager at Haywood Electric Membership Corp. He estimates he’s paying about 65 percent less than he was in his previous house built in 1979 with an air-source heat pump.

A Randolph County office building

Randolph Electric Membership Corp., the cooperative based in Asheboro, incorporated a ground-source heat pump system into its 21,060 square-foot contemporary office building when it was built in 1995. And 13 years later, the system still works like a charm, has required very little maintenance, and has saved the cooperative in energy costs.

A good example of a commercial-sized system, Randolph EMC installed 17 water-source heat pumps working from 80 grouted wells. It is a closed-loop system, with piping running horizontally in a field five feet underneath a parking lot. The pipes circulate water that maintains a year-round temperature of 68 degrees, effectively preheating the building internal space so the heat pump equipment does not have to work hard to get the space cooled in summer and warmed in winter. Unlike conventional air-source heat pumps, the ground-source equipment is housed indoors, increasing its life.

Joe Millkan, owner of Superior Mechanical Inc. of Randleman, was involved in the system’s installation and has maintained it. “It has been pretty much maintenance-free,” he said.

—Michael E.C. Gery

Where to find contractors

The contractor should be certified by the International Ground Source Heat Pump Association (IGSHPA) and should have references from satisfied customers. Check the association’s Web site at: www.igshpa.okstate.edu.