You've probably heard the saying "like pouring money down the drain." Well, the innovators at EcoDrain say that's exactly what you are doing every time you take a shower -- unless you have installed their high-performance water heat exchanger, that is.
The EcoDrain device (the little gray rectangle in the illustration) circulates heat from your "used" hot water, and transfers it to the incoming cold water. Here's how it works: when you turn on the shower, hot water comes from your storage tank and cold water comes from the municipal supply. As you shower, the "waste" water is sent through a drainage pipe. EcoDrain is attached to this pipe, and transfers heat from the hot water to the incoming cold water supply. Hot water and cold water rush past each other separately inside the device to prevent mixing. Bottom line: the water will be warmer without you needing to turn up the heat.
You are essentially heating up the cold water coming into your shower for free, and therefore use less of the super hot (read expensive) water from your tank. With this device, you can continue to heat your water using 25 percent to 40 percent less energy.
So if you are remodeling, building or retrofitting, I'd say it would be worth your time and money to check out their FAQ page.
I'll be interested to see how EcoDrain's device functions in practice. Aside from its horizontal format, it seems less elegant than the several other products based on the original GFX design, generically called DWHR devices, drain water heat recovery. The GFX and its equivalents are not limited to grey water.
Even better would be to combine this with a tankless heater (which doesn't keep reheating the same water).
Maybe devices for showing should rather recycle some of the water.
Heat isn't the only resource that gets used while showering.