ThermoDrain, A Unique Drain Water Heat Exchange Technology
The ThermoDrain drain water heat recovery unit is composed of a copper drain section around which a copper pipe is moulded and wound. As hot water drains down the central copper pipe, an important heat transfer occurs thereby preheating the cold water circulating in the outer coil. This incoming cold water may be preheated by more than 18 degrees Celsius (32 degrees F) before entering the water heater.
What makes the ThermoDrain so unique is that it is the only style of heat exchanger that is allowed to be used for potable water due to its double wall leak proof design.
The ThermoDrain is the only drain water heat recovery unit that has a very low pressure drop through the use of a single 3/4" coil. Other manufacture designs require splitting of the flow into 1/2" or 3/8" thin walled channels and headers. Designs that do not improve performance but may impact longevity of the unit.
ThermoDrain's is constructed using potable copper tubing with walls that are 0.045" thick and a 0.75" in diameter
Clogging of the ThermoDrain is not possible like other heat exchangers.
The ThermoDrain heat exchanger works under the principle of gravity film exchange. Due to the superficial tension present in liquids, the waste water clings in a film-like fashion to the inside wall of the drain pipe as it undergoes gravity flow in the open drain. This greatly improves the effectiveness of heat transfer from the falling drain water to the water inside the copper coils that winds around the central pipe. The heat exchange is thus completed with no contamination risk to the incoming cold water.
A superficial film forms on the interior wall of the ThermoDrain as hot waste water transfers its heat energy to the copper drain tube.