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EcoDrain recycles the heat in used hot shower water

EcoDrain recycles the heat in used hot shower water
The EcoDrain uses outgoing hot water to heat incoming cold water
The EcoDrain uses outgoing hot water to heat incoming cold water
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The EcoDrain uses outgoing hot water to heat incoming cold water
The EcoDrain uses outgoing hot water to heat incoming cold water
A diagram illustrating how the EcoDrain works
A diagram illustrating how the EcoDrain works

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.

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.

A diagram illustrating how the EcoDrain works
A diagram illustrating how the EcoDrain works

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.

Source: EcoDrain via Treehugger

How to save energy in the shower with ecodrain

Since the current trend is to use less water, with more efficient showerheads etc, plus more households are using solar heating, I'd like to see the warm waste water being diverted into radiators throughout the house, to use solar power to warm the house.
Mark A
Great idea but that price tag takes the green out of my wallet.
Doesn't appear to use any heat pipe technology as such, though that would help.
In reality, if you drill two channels through a solid aluminium block, and thread both ends, you could make one of these contraptions.
Just have to insulate it appropriately. The concept obviously only works if you put it on the incoming to your heater unit. Though how this can be done economically is the next thing, as you would either bring the drain to the incoming feed or vice-versa. Probably the latter. A lot of plumbing. To be undertaken on a new build, or a raised house without concrete foundation so you can get at the pipes. Will put it on my list of projects :)
Mark C
It's a simple idea apparently done well.
However it shares the main disadvantage the existing products have. And that is a ridiculous price for something that you can make yourself for less than $100 in plumbing parts.
Like the others, they're gouging simply because the individual home owner/ handyman can't ameliorate the certification cost across multiple units.
Brian M
Seems a lot of effort to recover very little energy - showers are meant to be relatively energy/water efficient anyway (unless a power shower!).
Might be better to look at recycling the used water into the same shower, after the first soaking the waste water becomes relatively clean with some filtering and remixing with fresh. Perhaps a recycle switch for when you are just enjoying the water showering on you rather than washing!
Jose Americo
This idea is good, but the price of this device is very hight.
In Brazil, the people use electric shower and a company called REWATT made a simple device that recover the heat and use it imediatly in the shower.
The address for this company is and it is not expensive like that.
This is most effective for households of 2, 3, or more who take long, hot showers every day. There are far better and cheaper ways to save energy by modulating its use more efficiently.
Nuff said.
two things:
1. One can get the same thing done for under $100. for sure!!! - that price tag is ridiculous!!!....what is the dude smoking???? (use outer PVC and inner copper tubing)
2. The idea is to use LESS water....not: "..will let you shower for 33 percent longer, using the same amount of power that you would have used without it."
-no mention of the wastage of water here in the additional 33%!!!
Then again....I live is a very dry part of South Africa where each drop of water is appreciated.
So how does the unit cater for clogging by materials such as hair, sud, etc? which will accumulate with time. And the price...come on...nobody in their right mind would buy this if you can quite easily make it with local plumbing stuff..... What if the system was turn on its head - Hot water pipe within a larger cold water pipe with say a 5-10mm variance in the large outer pipe diametre????
You have the hot, waste water flowing through a COPPER pipe within a larger diametre AL -PEX pipe where the fresh cold water is sent to the shower under normal municipal pressure. The heat will dissipate from the hot waste water via the copper tubing it is travelling through into the the cold water passing in the opposite direction and as a result of the inner AL-Pex piping having a layer of plastic making it a poor conductor of heat, the cold fresh water will warm up as it heads to the shower. The catch however, is what length of time and exposure is necessary for the cold fresh water to be heated to any significant level? There is an entry point and exit point for the fresh cold water within the larger pipe surrounding the inner waste pipe. Guess mixing of the water and should the waste water clog - just power drain it and wha La...system is good to go again!!!
that return on investment has to be wrong way wrong
i doubt it would pay for itself by the time it wore out
you also have to pay for the more complicated installation
and replace when it starts leaking in about 8 years
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