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ojc 02-23-2010 10:52 AM

Drain Water Heat Recovery System
First Post!

I am working on plans to finish my basement. In searching for products, I came across a Drain-Water Heat Recovery System. I found ReTherm and a few others.


This looks like an easy way to recoup some lost heat and since tankless was the way I was leaning, this looks like it would help reduce the work (read: $$$$) the tankless heater would have to do (once the shower got hot).

Has anyone installed one of these and liked it or seen promising benefits?




Bondo 02-23-2010 11:03 AM


This looks like an easy way to recoup some lost heat
Ayuh,... just my opinion,... I'd think the time frame for pay-off would be in the 100s of years....

RegeSullivan 02-23-2010 11:26 AM

I have thought about building that type of recovery system. I could get material for the scrap cost of copper but it still does not seem worth it to me. I am thinking the shower is only place you could get any real return. A tub would fill, then drain while the water is NOT running. The chance of getting any heat to transfer to fresh water is nil. Only if water was running somewhere else would it give back any heat. Same with a dishwasher.

Is my logic flawed....


Chemist1961 10-10-2010 07:29 AM

Drain Water Recovery Success
I know this is an old post but to follow up on the question I have installed two of these, one for a neighbor one for myself so I have some feedback. The "Power Pipe" brand we chose are locally made, not cheap but they work really well in conjunction with a traditional tank style heater. Advertising material on these and similar devices claims they will save 15-40 % on the cost of your hot water heat, but that's a bit tough to calculate. Either way why waste free energy if it's right there and there are government grants available.
It still made great sense to me as we have 4-5 people showering back to back daily, including 3 teenagers who run at least 20 minute showers. We never run low on hot water but have a 50 gallon heater. We also use low flow shower heads but they do have great stream.
The first installation we did was a bit of a chore due to iregular piping layout, but in my home the drain and meter were adjacent within 4 feet of each other. I installed the 66" x 4" pipe section and tapped into my supply with shark bites and was done within 1.5 hours while cleaning up some other pipe at the same time.
Hard to say how much the gas bill consumption has shrunk as we are gradually insulating elsewhere as we go....but the furnace is going on 2 years old and past 6 months versus same period last year, the gas bill is down for sure. Even if its only a 10 year payback, its a permanent one, but with the grants I am thinking we break even by about the end of year 4.:thumbsup: this a slick DIY project even for someone with no soldering skills

Chemist1961 10-10-2010 07:41 AM

You are correct. This unit has the best payback where there is continuous shower use back to back. The gain from dishwasher, laundry or bathtub would be negligeable. But I will have these 3 boys around for a few years so the showers will continue. I also found a blanket for the hot water heater and moved it off the cold uninsulated wall it was resting against for the past 10 years,(Shark Bites again!!!) next project is to insulate that wall...
And it goes without saying for a first timer if you take the plunge make certain there is no one flushing above you... even if you have the water shut off your toilets will flush one last time!!!:laughing:

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