deep–stores the sun's energy at a more or less constant level, with temperatures keyed to latitude. In contrast, a ground-source heat pump, with its underground piping loop, is able to tap a warmer, more stable heat source. The colder it gets, the less heat is available and the less efficient the system becomes.
Even within a heat pump's effective operating range, efficiency is directly tied to ambient temperature. Unlike conventional furnaces, heat pumps don't have to create heat, they just harvest existing heat–and therein lie the savings.īelow about 10 degrees Fahrenheit, however, too little heat is present in the air and a backup heat source is needed to make up the difference, or, in many cases, take over entirely. The compressor is located outside the home, and, in the heating mode, it's able to extract some of the heat present in cold, outdoor air and deliver it indoors to a condensing coil. A conventional heat pump is really just a central air conditioner that can reverse the flow of its refrigerant. While this equipment may sound exotic, its operation is fairly easy to understand when compared to that of conventional air-to-air heat pumps. Significantly, the heat pump is located indoors, like a furnace, which provides advantages we'll get to shortly. The water piped through this loop uses soil temperature to warm or cool the heat pump's refrigerant. The heart of a typical geothermal system is a ground-source heat pump that cycles water through an underground piping loop. Add impressive durability and less-intrusive trenching methods and the scales begin to tip, at least in the new-home market. And once the system is paid off, the annual return on investment can approach 20 percent. You'll pay several thousand more up front, but in many cases, the payback can come in as little as two or three years. Commensurate savings are common for larger homes. home can be heated and cooled for about $1 a day. In a technology defined by numbers, here's a fact that everyone will understand: With a geothermal system–they're also called geo-exchange systems–a reasonably tight 2000-sq.-ft. What's so compelling about geothermal technology? Energy efficiency. Slowly but surely, homeowners are beginning to take notice. When the numbers for the '97-'98 season are tallied, the industry expects similar gains. Though the number of geothermal systems sold today is still less than 1 percent of the domestic heating market, sales for fall 1997 through spring 1998 were up nearly 22 percent from the year before. And now, thanks to improved equipment and changing attitudes, doors are beginning to open.
Proponents of geothermal heating and cooling systems have been pounding on the door of public acceptance for almost two decades.