What are tankless hot water heaters and are they more energy efficient?
A. On-demand tankless (or instantaneous) hot water heaters eliminate the storage tank by heating water directly when there is a call for hot water. These units are growing in popularity in the U.S. The energy consumption of these units is generally lower since standby losses from the storage tank are eliminated. Demand hot water heaters have three significant drawbacks: Large simultaneous uses (two showers and the clothes washer, for example) may challenge their capacity, particularly in winter when the inlet water is coldest. They will not turn on unless the hot water flow is ½ – 3/4 gallon/minutes. Retrofit installation can be very expensive. Finally, because the efficiency tests were not developed with these designs being considered, it is not known if the “EF” accurately estimates energy consumption. If you choose a tankless unit, look for one eligible for 2006-2007 federal tax credits (EF levels).
