It has been estimated that 80 to 90% of the energy used to heat water in our homes ends up being sent right down the drain, but a new drain heat exchanger could effectively recapture some of that energy, reducing our energy consumption in a cost-effective manner.
The cost of energy required to heat water is one of the biggest energy expenditures at home, right after cooling and heating, and considering that most of that energy essentially gets wasted by flowing down the drain, harvesting heat from our showers could be a simple way to save energy and money.
Waste heat recovery, and drain heat exchangers, are not new concepts, but haven't really been viable on the small scale, due to design and installation limitations, and have mostly been targeted to larger commercial applications. However, a new model of heat exchanger for waste heat recovery for residential buildings promises to be the first practical version for home shower use, recovering up to 45% of the waste heat from shower drains, and offering a good return on investment.
Earlier heat recovery models were designed to be installed vertically, which limited their installations to new construction or bathrooms with at least 5 feet of vertical drain runs.The Ecodrain can be installed horizontally, which allows it to be mounted right near the source of hot water (the shower drain), and is said to be easy to install (assuming you are comfortable with doing basic plumbing).
"Ecodrain has no moving parts and requires no electricity to operate. Inside, a specifically engineered piping configuration transfers heat energy from the hot shower water to the incoming fresh water supply. And, a patent-pending device optimizes turbulence in the fresh water supply for maximum energy recovery." - Ecodrain
According to Ecodrain, the payback on the installation of one of their heat exchanger units can be as soon as 2 years (in areas with high electricity costs), or up to five years (in areas with low electricity costs), and because the units are made to last for up to 30 years, this investment could continue to pay off for a long time.
Here's a short video that helps to explain how the product works, and why it's effective:
One of the distinctive elements of the Ecodrain is the inclusion of their own turbulator design within the unit, which generates turbulence in the water in order to increase the rate of heat transfer without significantly reducing water pressure for the user. The units, which have a rugged double walled design, keep drain water and fresh water completely separate, so there's no chance of cross-contamination, and can be easily installed by any plumber or experienced DIYer, as long as there's access to the shower drain pipe.
The company claims that by using one of their heat exchangers, users can effectively take longer showers (up to 33%), without increasing their carbon footprint or their electricity costs. The base price of the unit is $439.95, and because of the high rate of energy recovery possible with the device, Ecodrain says their product is one of the simplest and most cost-effective home improvements you can make. The units can also be installed any place that uses a lot of hot water, such as gym or pool shower facilities, hotels, laundromats, or on commercial dishwashing machines.