dhaslam, I hear what you're saying with freezing pipes. I don't really have that problem here, but I can see how warm wastewater could be needed.

I haven't messed with the evacuated tubes yet, but I've heard great things! I'd prefer the passive method over one which consumes electricity, but in certain situations, cooling is needed anyway, so you know...birds...stones...awful phrase. :-P

I'm planning on eventually heating water as a byproduct of power generation, but I still enjoy the subject of heat pumps, and I think there are practical ways to improve them.

Ctgottapee, I guess I wasn't specific enough; I am talking about pumping heat out of waste water, not passively preheating water before it goes to a water heater. Yes, the long copper heat exchangers are not practical for all situations. What I was thinking of was a heat exchanger tank, with either immersed coils, or evaporator coils wrapped around the outside of the metal tank. A clean out port would be necessary to spray it out a bit. Of course, you wouldn't want any blackwater going in there!

The long pipe is the solution. You can't really extract any more heat out of the water without creating issues with the waste water mucking things up. There has been quite of bit of testing put into it. It's an elegant solution to creating a tank the self cleans.

I did see a horizontal shower specific model once, but I don't think it made it to market in any shape.


I've thought about running a cold water pipe inside a waste water pipe to the shower to serve a similar purpose

The easiest way to do heat recovery on waste water is with a vertical drain pipe. Metal dwv pipe conducts heat readily through its wall. Your recovery fluid is directed to flow around the dwv pipe. The waste water naturally sticks to the inner wall of the dwv pipe through surface tension.

Not sure why it weighs so much?

Water is 8.34 lbs. per gallon
Ton = 2000 lbs.
80 gallons of water = 667.2 lbs.

The tank and compressor must weigh a lot.

It's almost 1,000 lbs, not a true Ton; I meant ton figuratively


It's a higher end product so the tank is not gonna be a cheap thin one.
I have a stand alone compressor add on, and it is a heavy mofo in itself

being worth $2400 for the larger unit

see separate HP water heater thread abut how the price has come WAY down,


not spamming, just giving specifics here, but
got a GE Geopsring 50 gal hybrid WH over the weekend at Lowes for $629 -- I get PAID for taking it after rebates from poco and tax credits.

The efficiency of Air pumps are temperature related, and in turn dependent on the refrigerant used -- particularly in cold climates.

I don't know anything about the Steibel, but people living in 4 season climates should strongly consider CO2 refrigerants. I think most of the devices on the market are from Japan but slowly spreading across the world.

Marx,
Years ago I talked with a guy who designed and sold waste recovery systems. I would have employed it but like ctgottapee said you need a decent drop which I didn't have. If you have a second floor shower and a clear path to the waste pipe it's not to hard to build one if your wife and kids don't mind you chopping out a bunch of sheetrock through the kitchen to make a path. Basically you wrap the incoming water copper tube around a 2 to 3" copper pipe (I guess you could use aluminum) and the capillary action that causes to waste water to cling to the inside perimeter of the larger pipe gets recovered... If you've never wrapped copper pipe around larger pipe you're in for a whole new experience though!

AC,
Great Fracking post, one of the reasons I love this site!

Rob

I've wondered more than a few times why drain water heat recovery units are not built with a pump for installation in one story homes. Seems like activation could be either manual or by water weight.

By the way, I'm willing to wager that the least expensive, best savings/dollar on water heat is to first change out the shower head to a low flow, 1.2 or 1.8 gallon/minute type.

Here are a few reviewed;
And the type I am going to buy.

I've wondered more than a few times why drain water heat recovery units are not built with a pump for installation in one story homes. Seems like activation could be either manual or by water weight.

By the way, I'm willing to wager that the least expensive, best savings/dollar on water heat is to first change out the shower head to a low flow, 1.2 or 1.8 gallon/minute type.

Here are a few reviewed;
And the type I am going to buy.