One Last Parting Shot at Tankless Water Heaters
Published at 10:35 on 26 January 2012
The up to 34% greater efficiency cited for them is a bogus number if you live in a cool climate where the energy you consume heating a home is significantly more than that spent cooling it.
Most of the heat energy wasted by a tankless heater literally goes down the drain. In contrast, most of the energy “wasted” by a tanked heater escapes to the environment around the tank. Since the heater is almost always in an interior space, this means that during the heating season, that energy is not, in fact, “wasted” at all — every therm of natural gas a tanked heater ends up spending on heating its surrounding environment is a therm of natural gas the furnace does not have to consume toward that same end.
If you live someplace like Texas where energy consumed on cooling dominates, then it’s the other way ’round, of course. But for those of us that live in cool climates (I live in a place where the vast majority of residences do not even have air conditioning), the efficiency gains of tankless heaters (which we have already established are mostly bogus even without this latest insight) are perforce inflated.