Drain Water Heat Recovery
DWHR is a system in which the thermal energy that is lost down the drain is recovered to heat cold water entering the water heater. By raising the temperature of the cold water before it is to be heated in the hot water tank, the amount of energy needed to heat the water fully is greatly reduced. This requires less electricity and therefore is not only a very energy efficient way to heat water, but cost effective as well.
This simple system routes the drain water from the showers, washer, sinks, and dishwasher through a 60” copper pipe that is wrapped by the domestic water supply line. The heat from the drain water is conducted through the exterior of the supply line to heat the domestic water supply.
Typically: water enters home between 5-12ºC, is heated to 50ºC, loses kinetic energy throughout the plumbing system and enters the showerhead at 41ºC, while draining away at 37ºC. A DWHR system will use already produced energy to warm your water by 12ºC. That’s a minimum of a 35% and maximum 48% increase in efficiency.