Large buildings like hospitals have a central hot-water circulation loop. Hot water circulates in the loop constantly. Every hot water fixture is a short length of pipe away from the central loop so that hot water is available as soon as you open the valve. In order to keep from losing heat from the circulation loop, the piping is well insulated. Often “heat tape” is wrapped around the pipe ~ inside the insulation ~ to keep the water hot.
A low-voltage current passes through the heat tape, converted into heat via resistance in the cable. The tape adheres to the pipe, transferring the heat through the pipe and into the water. A thick layer of insulation around the pipe keeps the heat from escaping to the environs.
Heat tape is most often used in residential applications for freeze protection. The traditional “freeze protection” is to drip one faucet in the building (the faucet farthest from the water meter): if the water keeps moving, there’s less inclination to freeze. This technique works in moderately cold weather, although it does waste a lot of tap water. Areas with extended frigid temperatures need more pro-active means, such as heat tape.
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Excerpted from Going Green, available as an eBook at this list of eBook retailers online.
