Q.A customer wants me to install one of the new heat-pump water heaters in the ground-floor utility room of a house built on a slab. I don't have any direct experience with them, but since they work by drawing heat from the surrounding air, won't any energy savings in the winter be at least partly offset by the cost of heating that indoor air to begin with? And could the outflow of cool air from the utility room cause comfort problems?A.Marc Rosenbaum, an energy consultant in West Tisbury, Mass., responds: If the heat-pump water heater (HPWH) is operating with a...

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