Ecodrain. Save energy on hot water for showers


The EcoDrain™ is a unique patent-pending heat exchanger which transfers heat from hot shower waste water to cold incoming water. This cuts water heater use by 25%-40%.

This is for showers only. The hot shower water that goes down the drain is used to heat incoming cold water for the shower, thus saving hot water usage.

They say it hooks up easily. Perhaps for a first floor shower where you have a basement under it, but it would be difficult to retrofit in, say, an apartment building. Still, this is a great idea. The more ways we have to save energy, the better.

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  • Huh. I see from their diagram that they’re assuming that your water heater is set to 140F. I rather suspect that you could get more savings for free by turning it down to 120F. (And notice that a device like this becomes less efficient (thermally) as hot water temperature drops.)

    • Also, the cold water that gets heated by waster hot water will eventually cool off if not used quickly, I think.

      • That part is OK, I think. The idea is that you’re heating your shower water “in real time”, so some of the recovered heat will indeed be wasted when you shut off the shower. But it would have gone down the drain regardless.

        Here’s another problem, though. Shower drains clog, regularly, because we’re sending down a nasty mix of hair and soap. A heat exchanger needs relatively small passages to create a lot of surface area to get any kind of efficiency, especially with a relatively small delta-T. This thing is going to clog like crazy.

        Here’s what I want, btw, along these lines. Free idea, just list me on the patent. I have to run order of 3-5 gallons to get hot water in my shower, because of the run from the heater to the bathroom. I’d like to capture that water for toilet flushing.

        • They say it has a special slippery lining to prevent clogs, but if it’s narrow, that makes it even more likely to clog.

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