Drain Water Heat Recovery

I Overview
Drain Water Heat Recovery (DWHR) units use the latent heat from wastewater

to preheat incoming fresh water. They are very similar to water heat exchangers and operate on the same principle.

A typical DWHR unit consists of a narrow freshwater pipe that wraps around the wider drain pipe. Fresh water circulates around the hotter waste water. The waste water transfers its heat energy to the fresh water through the walls of the pipe, heating the fresh water.

II Applications
DWHR is most common in residential and small commercial settings. These units generally yield water heating savings of 25-40%.

III Equipment Options

IV Resources
1. Equipment Manufacturer Database
2. Natural Gas Efficiency Consortium