Posted on August 2012
A. Yes. Waste-heat recovery devices, sometimes called hot gas reclaim systems, take heat where it is unwanted—from your air conditioner’s or heat pump’s outdoor heat rejection coil—and move it where it is needed, to your hot water tank. In so doing, these devices can decrease water heating costs substantially while also lowering air conditioning costs. It may sound too good to be true, but it works well, particularly in hot climates. In areas that have high cooling loads and a long cooling season, enough heat may be reclaimed to meet the home’s entire hot water requirements during the summer months.
With a heat recovery device, your air conditioner operates more efficiently because it does not have to work as hard exchanging its waste heat, and the heat deposited in the water heater is essentially free. With the heat recovery device in place, a typical house air conditioner or heat pump produces about 25 gallons of water per hour heated to 130°F. Since heat can be reclaimed only while the air conditioner is operating, the storage tank must have supplemental heating capabilities for when the air conditioner is not on. Even when it does not meet the entire demand, reclaimed heat contributes some heat that would otherwise have to be supplied by the water heater.
Heat recovery devices can be installed during construction or retrofitted to existing water heater storage tanks. Most are enclosed in metal cases and mounted either on a wall outside near the air conditioner condenser or inside near the water heater.
Ask your service technician or your utility representative about the availability and performance of heat recovery devices in your area.