GEOTHERMAL HEAT PUMPS CUT POWER COSTS

Jumping on Geothermal; These homeowners took the heat-pump plunge to save the planet—and a lot of money, too.
Martha Thomas, March 2010 (Baltimore Magazine)

"…Bill Davidson finally decided…it was heat-pump time…[and] to temporarily destroy his backyard…to dig four 200-foot-deep holes… to install water pipes at a depth where the temperature is a steady 55 or so degrees year-round. The pipes, with the help of a pump, bring the temperate water back to the surface, where it helps to keep his 2,400-square-foot home toasty warm in winter and cool throughout the summer. The project virtually eliminated the noisy oil furnace (which Davidson keeps as a backup) and means annual savings of more than $1,700…

"…The cost of retrofitting his house—installing duct work in the downstairs, tunneling pipes in the yard and putting a heat pump in the basement—was about $30,000…[I]n the 1980s, [and again in the 1990s] he looked at a little-used technology—geothermal heat transfer—that involved extracting warm air from the ground with a pump. But he decided installing a system, which requires ducts throughout the house, was too expensive…But, eventually, Davidson, who has a master's degree in environmental management and works in renewable energy as a manager in Montgomery County's solid waste division, felt his conscience intervene—it was about the health of the planet…"

A geothermal heat pump system at minimum depth. (click to enlarge)

"For Kelly Palmiotto, the decision to install a geothermal heat pump didn't take quite so long. When she left her job at the Maryland Department of the Environment five years ago to renovate a house—and embark on raising a family…She learned about geothermal heat pumps…and had one installed [in 2005]…[H]er home heating and air-conditioning bills are about a third of what they would be with conventional systems. And the system also provides hot water—free of charge.

"…The air-source heat pump, which most [Marylanders] are familiar with…[p]opular in the 1970s and '80s…[consist] of a unit installed outside that relies on outdoor air—exchanging warm air for cool, and distributing the conditioned air through ducts. They are…noisy and inefficient…Today's geothermal systems are considerably more efficient (with a Seasonal Energy Efficiency Ratio, or SEER, of up to 30 compared to the 1980s air-source figure of about 8…), and they are good for the planet…"

Geothermal heat pump system at greater depth for greater temperature moderation. (click to enlarge)

"Moreover, costs for installing the systems—$20,000 and up—are mitigated by a 30 percent federal tax credit, a deal that's good until 2016…There are also state rebates for geothermal heat pumps, which fall into the category of renewable energy systems like solar panels and wind turbines.

"…[T]he ideal customers are those who already have duct work in their homes. A unit about the size of a small refrigerator—the geothermal heat pump itself—uses electricity to pump water into, and back out of, the ground, through pipes that run through borings in the yard. The typical home will have two to four underground loops…though they will all connect to the indoor system through two pipes. In most cases, air will be circulated through ducts, though in newer homes…the heat can be used in radiant floor systems…[And] the muddy upheaval of [the backyard is] an excuse to do some much-needed landscaping…"