Drain Water Heat Recovery

The purpose of a “drain water heat recovery unit” is simply to recover the thermal energy we normally throw away down our drain, particularly during a shower. The Watercycle model DX 4048 (the brand I chose) is a water to water heat exchanger designed for use with drain water.

Water is the most expensive natural element to heat and carries a significant amount of energy. Any hot water that goes down the drain carries away energy with it. That’s typically 80–90% of the energy used to heat water in a home. Drain water heat recovery systems capture this energy to preheat cold water entering the water heater. This drain water heat recovery technology works well with all types of water heaters, but especially with my demand (instantaneous Navien water heater) and my future solar pre-heater.

Water will enter our home between 5C– 12C and is heated to 50C in my water heater. Showerhead temperature is approximately 41C and this warm water is going down the drain.

This energy will be brought back into my home to substantially reduce hot water heating costs. The Watercycle is a drain waste heat exchanger which will heat water coming into our home by 12C (43.5% effective) using energy from the water going down the drain.

It’s very simple, there are no moving parts and it consumes no energy; it just saves energy and money since I will now require less energy to heat my water.