Drain waste heat recovery is a heat transfer system that preheats water before it gets to the hot water tank.
A section of the main drain for the house is replaced with a device that winds a tight coil of copper tubing around a copper section of drain pipe. As someone uses hot water (for example, during a shower) water from the main water supply is circulated through the coil, and is preheated by the hot water running down the drain. This preheats the water supply to the hot water heater, raising its temperature and lowering the amount of energy needed to heat water.
The transmission rate for heat for the installed drain waste recovery system is 53%. It can raise the temperature of the incoming water 10-30+ degrees.
Many thanks to GFX Technologies for their product and their image!
This system not only allows less energy to be used to create hot water, it allows a smaller hot water tank to be installed as it heats water faster.
The house was designed so that all upper floors drain to a single main drain. This requires planning prior to construction with the plumber…it can actually be a little more challenging than you think!