Generally-speaking, when there's something that we're trying to conserve, we don't just put it down the drain. For those of us who are trying to save power, however, that's just what happens when we let hot water from our showers or baths run straight into the sewer. The EcoDrain is made to address that problem, via a unique design that allows outgoing hot water to warm up incoming cold water.
First of all, there are indeed other drain heat exchangers that do the same basic thing – they absorb heat from the used hot water, and deliver it to the about-to-be-used cold water. Although that incoming water probably still won't be warm enough to bathe in on its own, less hot water will need to be mixed in with it, thus saving power.
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In the case of most of those other systems, however, they need to be located along a relatively long stretch of vertically-oriented drain pipe. Not all existing homes have such a setup, meaning that the heat exchangers can't be installed in those homes ... or at least, not without a lot of work.
The EcoDrain, by contrast, can be installed horizontally. This means that it could go under the bathroom floor immediately adjacent to the drain, thus catching the waste water at its hottest.
It contains no moving parts, requires no electricity, and takes the form a double-walled pipe – it's a pipe within a pipe, really. Incoming cold water runs through the inner pipe, while the outgoing hot water runs in the opposite direction through the outer pipe, completely surrounding (but never entering) the cold one. This means that the cold water pipe gets heated from all sides by the hot water.
Additionally, in order to allow more of the cold water to be exposed to the warmth, a series of baffles in its pipe create turbulence in its flow. This keeps it from just shooting straight through, with only the outside of the stream getting heated.
The EcoDrain has been in development for several years, although its designers inform us that it received US building code approval just last December, and was officially launched within the past few weeks. It's priced at US$439.95, and is claimed to offer a return on investment ranging from 17 to 43 percent per year – based on the energy costs in various American cities.
Looking at it another way, the company also claims that installation of the EcoDrain will let you shower for 33 percent longer, using the same amount of power that you would have used without it.
More information is available in the video below.