Ever wonder if it would be possible to recapture heat from drained shower or dishwasher water? A new product called ThermoDrain offers the ability to do just that. We love this ingenious technology for conserving heat that would otherwise just drain away.
The way ThermoDrain works is simple: a copper drain pipe is wrapped with a coil of copper tubing that has fresh potable water flowing through it. As the hot water drains from the source, it transfers the heat to the cool water in the copper coil. This pre-warmed water is then directed back into the hot water heater or into the cold-water flow in the shower. The pre-warmed water reduces the demand for heated hot water from your water heater and can save as much as 40% of your 
water heating costs.
ThermoDrain drain water heat recovery has some real benefits for homeowners with on-demand tankless water heaters. Tankless water heaters can be limited in their supply of hot water and often take some time to recover during a longer duration event like a shower. The ThermoDrain preheated water speeds up recovery and increases the supply of hot water from the tankless water heater. These tankless water heaters are already efficient and preheating the water can really add to the savings!
ThermoDrain tubes come in lengths from 12 feet to 100 feet, though 42 feet is the most commonly employed. ThermoDrain is installed to replace a portion of the drain stack from showers, dishwashers or clothes washers—any drain where hot water is draining away. The single coil design provides minimal pressure drop and is virtually maintenance free.