How to Recover Waste Heat from Drain Water

What is Drain Water Heat Recovery?

Here is one energy saving device you may not have discovered yet; it can be used in both domestic and commercial drains to recapture thermal energy that usually goes literally down the drain.

RenewABILITY Energy Inc. (REI) designs, manufactures and sells the patent pending Power-Pipe™ Drain-water Heat Recovery System. The Power-Pipe™ is an instantaneous and passive water heater that recycles thermal energy that would otherwise be lost down the drain.

The Power-Pipe™ is a ULC approved heat exchanger for potable water that recovers heat from warm to hot drain-water because it doesn't plug up. Because it has no moving parts, the Power-Pipe™ will typically last for 50 or more years, according to the manufacturer.

HOW IT WORKS

In the Power-Pipe™, the drain-water clings to the inside pipe wall and falls quickly, creating a thin “falling-film” which transfers its heat to the pipe wall. Since copper is used for both the inner pipe and outer tube, the contact between the two has an impressive heat transfer rate that is 4-6x greater than other classes of heat exchange on a surface area basis.

A key advantage of the heat exchanger is that it is absolutely safe (and approved) for heating potable water. This system can help reduce green house gas emissions by up to 1 ton/year in a family of four.

REI says that the Power-Pipe™ can also reduce water-heating costs by up to 40% for home owners.

Here is a case study from the manufacturer that illustrates how the device saved energy in a commercial application:

The turnkey engineered heat recovery system was supplied by RenewABILITY Energy Inc. at a cost of about $27,528 to the Unilever Ragu facility in Peterborough Ontario, Canada. The system saved them $26,136 in the first year of operation resulting in a payback in under 1.1 years. The system also reduced their greenhouse gas emissions by over 130 tons/year.

Learn more about the Power-Pipe™ at their website.