Drain-Water Heat Recovery—sometimes referred to as heat recovery units (HRU) or grey water recovery units—systems operate with all types of water heaters, especially demand and solar types. In essence, the system “captures” some of the heat from hot water traveling through the pipe as it goes down the drain. The system then uses this heat to pre-heat the incoming cold water that goes to the water heater or a fixture, such as a shower.

Source: UF/IFAS Energy Efficient Homes: Water Heaters; Wendell A. Porter, Hyun-Jeong Lee, and Kathleen C. Ruppert, 2008.

Additional Resources

EnergyStar®  - http://www.energystar.gov/

Progress Energy  Home Energy Check-  http://progress-energy.com/

UF IFAS Energy Efficient Homes: Water Heaters- http://edis.ifas.ufl.edu/FY1025

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