EcoDrain heat exchanger makes good use of warm waste water
By Darren Murph 
posted Mar 26th 2009 5:59AM
posted Mar 26th 2009 5:59AM
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I live at a ground level apartment, I doubt they could install that. The drain is already close as it is to the ground. But sure, good thinking. Another excuse to stay longer in the shower. :D
User installed ? So you connect it to the drain , where do you connect the heat output too ?
I feel a plumber should be involved, you will also need a hot water tank.
Why would you need a tank? It transfers the heat to the cold water that is headed into the shower.
The cold water pipe probably runs beside the hot drainage pipes, which heats the cold water before coming out of your tap.
I think.
So according to your logic you need to be flushing hot water down the drain to heat your shower water LOL
stop laughing cause he's right.
If you use a shower then you mix 10 degree cold water with 60 degree hot water to get around comfortable 30 degree warm water out of your shower. When this water flows down your body and finally down the drainage then it's still warm, maybe 25 degrees.
This warm water do you use to preheat your 10 degree cold water, before you mix it. Because it's then maybe 5 degree hotter, and has 15 degrees instead of 10 degree, you can reduce the amount of hot and expensive water to get the same 30 degree.
In reality you'll start to shower like always and after maybe 30 seconds you can reduce the amount of hot water, because the cold water got a bit preheated by the warm waste water.
mmm, warm waste water
Seriously? This isn't that complicated. The warm, already-been-used water going down your drain transfers some of its otherwise-wasted heat to the incoming cold water, thereby reducing the need for hot water. Not eliminating it. The cold water is just less cold than it otherwise may be.
I dont know about you guys, but I occasionaly pee in my shower!
Aim for the hole! :D
I too pee in my shower - every morning. Standing there groggily wiping the sleep out of my eyes, no handed pissing into the shower, will get me hot water a few minutes faster.
The only problem with this is maintaining a constant temperature of the water coming out of the shower head. (..cause the cold water temp will be fluctuating from cold to warm, making the shower water hotter, then cold, then hot, then warm)
Major4play is right. you still need a tank. mixing hot water with cool water gives you warm water. using only you waste shower water to heat the incoming water would cause the incoming water temp to drop very quickly (not to mention without a hot water heater you wouldn't have any hot water to start with).
It's clear neither of you bothered to go to the read link and look around. No one implied the tank was to be eliminated. The whole fricking point is if you start with warm water, you need LESS hot water. Period.
Wow... I thought engadget had a smart reader base... but watching this thread tells me otherwise. Nay-sayers, this is really, really, really simple. go read and think for a like 10 seconds.
There are two inputs and two outputs (internally in the aluminum brick in the picture)> Usually these are designed counter flow meaning the incoming cold (city water) will flow say up towards the water heater (its pressurized so you can have it go against gravity) and the hot water shower drain will flow down (gravity system) towards the sewer. The counter flow design offers better efficiency compared to parallel flow.
You will see scavenger reheat systems like this in industrial refrigeration applications also. Not that I know anything about this stuff.
Yes, I'd imagine you connect it to the cold water supply for the heater. The water heater then doesn't have to heat the water up from maybe 15°C to 40°C but from 25°C to 40°C.
Great idea.
You don't need to guess, they have diagrams for connection on their site, go look. You hook it up to the output of a cold water line, then feed the warmed up output from this device to the input on the shower body. That is where the warm and hot water mix, thereby requiring less hot water to achieve your desired temp. Now, this would scuk as a technology if you like taking cold showers, as water will pick up heat from the air and you, thereby warming the water leaving the tap.
SEE ? http://www.ecodrain.ca/en/how-does-it-work
Not a bad idea.
Absolutely nothing new. I've noticed these things installed in YHA hostels in New Zealand
only way to travel..
This is actually a rather old principle, I´ve seen them around about 4 years ago. It´s a sort of heat-exchanger which costs around 350 euro. The idea sounds nice though only usable in area´s where the water doesn´t contain to much chalc. I always wonder though how effective they are, there are plenty of green solutions but most aren´t efficient enough to be profitable.
Yeah.. heat exchangers have been around for years now, and so has their application in showers, under drains, and other places that drain warm waste water. Why is this news? Is it drastically cheaper than the ones that are already available?
Very good idea. Incoming water being to cold is the biggest problem of the lack of performance on electric showers.
Price and availability?
What is an electric shower?
For example this - http://www.tritonshowers.co.uk/triton-for-the-homeowner/triton-products/electric-showers/topaz-t100si.aspx
Very common in Britain. It heats incoming water by electricity (duh!). Most commonly available is 9kW. Most powerful available is 10.5kW.
I have a 10.5kW one and it is crap in winter.
Wow, never seen those before.
Definitely not something you commonly find in America.
I poo in the shower. Who is going to clean the heat exchange fins inside this closed thing once they get fouled. I would assume this will be a common complaint.
not poo... but hair.
Gross. You have hair in your poo?
Brilliant! But where you place it is harder to get it right.
I would put one in my main shower, so the waste water warms the cold feed. But ideally with a constant temperature mixer valve so I don't have to keep adjusting the temperature during shower.
i have thought of that, and then i realized that it wasnt worth my time unless you are scalding yourself in the shower, but when i googled it they were already out on the market. anyway, why not use the warm water for in floor heating instead by just running copper conduit in the concrete when you pour the slab seems more reasonable and less of a hassle to me:P
One of my colleages at work told me they do exactly that in one of the Scandinavian countries... that is also a great idea. The heat from the shower drain becomes radiant heating in the floor. Good thinking on yourpart. :p
I thought of this a while back (maybe a year ago) and did some thermodynamic calculations. It's only effective if you have very cold incoming water, which I don't -- it's about 50F in the winter and 70F in the summer. Using a small heat exchanger I'd get < 10F preheating in the winter and only a couple degrees in the summer.
The sparger that the water comes out of mixes the water with the air and causes it to cool very fast. I measured about 80F at the drain.
You are in a different situation from me, my cold water is freaking cold, in the winter I think it actually gets below freezing sometimes and only the absence of some startup to crystallization prevents it from going solid, I had times I washed my hands and felt physical pain from the cold.
There is more to be saved from insulating your hot water pipes, surely. This is cheaper and easier to do...and still alarmingly rare. When we built a house about 8 years ago, the builders had no interest in any of this stuff. I had to insulate the pipes myself. Grey water collector? Forgetaboutit.
ah ha, it's called grey water. I was talking with my wife about why isnt the shower, sinks, bath, clothes and dish washer drains augmenting my sprinkler system? I am in florida and I waste a huge amount of water on the stinking grass just to keep my home owners association happy. Thanks for the search term.
I saw people on the BBC that do that, use their bathwater to water the garden, and it worked as a charm, but the way they did it was a bit labourintensive
This is a not a gray water collector, it is a heat exchanger. The incoming water doesn't not physically mix with the outgoing line, only the heat is transferred, much like a radiator.
But yes, insulating hotwater pipes are very important. In my area of the country, where temperatures occasionally get down to -15 F, everyone has to insulate all of their incoming and outgoing piping, or else you'll have a frozen pool under your house.
And not just showers, but dishwashers and washing machines... What a great idea.
And some commenters seem to be very confused. You're not reusing the hot water. You're reusing the heat.
Do dishwashers and clothes washers actually heat the water though? Do they have a thermometer that would take advantage of warmer water? I thought that they just used the hot water supply until full.
Not confused but maybe I was responsible for the thread drift. I just thought there were easier hits in the saving money/heat/water space.
Dishwashers most definitely have heaters in them.
My tankless water heater cost 8.00$ a month to run....... it would take 20 years to see any gain from this thing after you figure in cost of the heat exchanger, and a plumber to install it. BUT if they could be incorporated into new dishwashers, washing machines, and showers this could be a nice energy saving device.
Are you serious? Only 8 bucks? Wow, you must either be a real lover of using cold water and taking cold showers or you got some cheap power there, but we aren't all that fortunate I fear.
40% savings? From showering? I don't think so. Not even close. Unless you shower 8 hours a day... or are othwerwise living with a lot of immigrants in a small home therefore using a lot of shower water.
It doesn't say 40% savings. It says "cutting water heater usage by as much as 40 percent," and implies that the 40% reduction is during shower operation, compared to using the same shower for the same without.
Actually, now that I think about it, I wouldn't be surprised if they meant 40% reduction in heater use over-all, considering how much hot water use in the average household is dedicated to showering compared to all other uses.
How much hot water a household uses outside shower use is very much dependant on the lifestyle and appliances you have I'd say.
If you don't have a dishwasher for instance you'd use much more hot water (but less electricity).
And I like to fill the pot with hot water when I'm cooking pasta so it boils sooner, to name another example, not that I eat as much buckets of pasta as the water I use to shower, I'd be the size of saturn.
And you can't use this effectively in the kitchen since it only helps for extended use of medium-warm water I imagine, on a temp-controlled tap so it auto-adjust the output-input interaction.
excellent, same principle as in my HX espresso machine - but now I would have to descale my plughole...
It's called cross-current exchange. Your body does the same thing in the capillaries to maximize the amount of O2 going into tissue and C02 coming out of tissue. Score one for nature.
Not a new idea
http://gfxtechnology.com/contents.html
http://www.retherm.com/HowItWorks.htm
How about one that connects up to my CPU heat exchanger?
This idea has been done to death but no-one has come up with a trully affective design. Also, its only effective if you've got a cold water supply being used at the same time as draining hot water from somewhere.
The savings are difficult to quantify, and I think 40% is ambitious. I've designed something similar for a university project, and theyre quite easy to make yourself if your DIY inclined, items such as car radiators would be perfect for such an aplication
I like the idea, but how exactly are you supposed to control it?
It doesn't directly decrease the water heater usage, it just heats cold water. Personally, I always turn the hot water all the way on and leave the cold water off (my water heater sucks). Wouldn't that eliminate the usage of this thing?
Also, won't a lot of people just turn UP the cold water to cool it down rather than turn DOWN the hot? Which would also defeat the purpose, correct?
Plus, even if you do turn DOWN the hot water because the cold water is making it overall too hot, then the cold water gets colder too. I imagine the savings would be something more like 10% if you used it at maximum efficiency.
The water going down your shower's drain is likely around 100* F, the incoming water (to your hot water tank) is likely around 50*F. By piping your hot water's incoming pipe through this heat exchanger, you'll transfer a portion of that outgoing heat into the incoming water, so the temperature of the water going into your hot water tank is now ~65* F.
The hot water tank has to less hard to heat the water up to 120* F from 65* F, both increasing the length your hotwater will last and decreasing your utility bill.
Counter-current heat exchange had been used industrially for at least 50 to 60 years. It works well when there is constant flow of both streams, but does not work consumer situations because the shower is on only for 5 to 10 minutes. The heat loss by the cold pipes is one inefficiency. Another issue is the "sludge" build up. If you don't have constant flow of water to flush them out, the calcification of the soap and hair, skin etc will clog up and you'd have a hell of a time cleaning the inside of the exchanger (you can't run a snake through it).
That's quite a good point the build-up of slurry, but you can coat it with some non-stick material and add a cleanable filter before the intake I guess.
Site says:
"EcoDrain™ is installed directly in the shower drain line and features a double wall of separation between fresh and waste water to eliminate the possibility of mixing, plus an interior non-stick coating to prevent soap, hair or debris collecting inside."
So I was right about the coating.
While I like this in theory it just seems like one more thing to clog up.
It looks like they're using stainless steel construction. That's a pretty poor choice of material considering it's thermal conductivity.
Probably zinc, and inside there should be a radiator-style construction possibly made from copper, you only see the outside.
Zinc + Copper = sexy anode/cathode combination. I'd expect zinc plated copper to lose its plating very quickly.
Wow... I thought engadget had a smart reader base... but watching this thread tells me otherwise. Nay-sayers, this is really, really, really simple. go read and think for a like 10 seconds.
This is like.. a turbo for your shower.. Awesome!
As others have said, heat exchangers are nothing new. They have been around a long time... just applying them to a small scale residential use is sorta newish. That being said, this sounds like a good idea. Maybe in a few years, California will require heat exchangers in new residential/commercial construction as part of their title 24 building code standards.