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Because it involves significant excavation to install, Tesoro says geothermal technology is impractical for existing structures and suburban homes that will be built on small lots. He says that homeowners who cannot use geothermal can get the next best thing by installing an air source heat pump. As opposed to geothermal technology, air source heat pumps draw the heat from the surrounding air, instead of the heat energy stored in the ground.
“Both types of heat pump operate using the same kind of heat-exchange technology that makes your refrigerator operate, or a window air conditioner for that matter, by the circulation of a refrigerant chemical through tubes or coils,” Tesoro says. “In a geothermal system, that circulation is happening belowground, and the circulation is happening in an environment of constant ground or water temperatures. In an air source heat pump, that circulation takes place outside the house, in the system’s condenser unit—which looks like a big metal box, usually right next to the home’s foundation.” The air source heat pump system is similar to the workings of a refrigerator, where that circulation takes place at the very bottom of the unit and you can feel warm air being blown out from under the fridge, he adds. “That heat has been displaced from inside through the same basic heat-exchange technology.”
By using the heat pump as a secondary heating source, homeowners can save money by avoiding the burning of oil until below freezing. “Think how much oil you save by only burning oil in a cold snap,” Tesoro says. “It’s very easy to install in any home that has central air-conditioning and has ducts.” The pumps need ducts and will not work in a home that with baseboards or radiators.
RADIANT HEATING: THE FLOW UNDERTOE
Radiant heating is a distribution system that can work in tandem with most energy sources and help lower energy consumption and cut costs in the long run. “Radiant floor heating is a heat delivery or distribution system that delivers heat to the home by heating the entire floor surface,” says John Abularrage, owner of Stone Ridge’s Advanced Radiant Design. “By heating the entire floor surface you have warm feet, for one thing, and no matter where you move in the space you have direct exposure to very even heat. The heat transfer is much like the sun’s, and you can be more comfortable at lower temperatures.”
Radiant heat is installed using a system of plastic tubing called PEX (cross-linked polyethylene), which is embedded into concrete slabs or on framed floors in an underlayment that goes directly under the finished floor. Heated water flows through the PEX tubing, warming the floor. Radiant heat can be used with a variety of flooring materials, including wood and carpet, with some minor limitations. For example, certain types of carpet padding would be avoided because they are too insulating and would inhibit the flow of heat.
Radiant heat is more efficent and comfortable than baseboard or forced air heat because it heats directly—Abularrage says general industry statistics show that radiant heating is 20 percent more efficient than baseboards and up to 40 percent more efficient than forced air. The lower temperatures associated with this system also take stress off of heating systems and can save in oil and related costs.
“It’s a very low-temperature delivery system,” Abularrage says. “You can heat a home with certain types of radiant floor heat with water as low as 100 degrees, where the conventional system would require water temperatures of 160 to 180 degrees. Those lower water temperatures can increase the efficiency of the boiler system, depending on what your boiler system is, by as much as 10 percent. For geothermal systems, which are quite popular now, using the low temperature distribution system of radiant floor heat can increase the efficiency of a geothermal heat pump by 50 percent, which is significant.”
Though radiant heat is a pricey option when compared to baseboard and forced air, Abularrage reiterates that it’s the most effective, and will pay for itself in savings over time. It works best with new construction, but existing buildings can be retrofitted, especially if floors can be easily accessed from below.