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Old 10-08-09, 08:50 PM   #14
Christ
Apprentice EcoRenovator
 
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Quote:
Originally Posted by Daox View Post
They're placed vertically to maximize efficiency. The water clings to the walls of the pipe giving you the most surface area. IMO, 40% efficiency is pretty darn good. However, a few of the places posted claim up to ~70%.
I was thinking about something like this after seeing it in use on Planet Green (I think it was that channel). My first and only thought was to use an actual heat exchanger, water-water style. In essence, my idea was to box in a heater core from a car, flow my cold water through the fins, and flow my wasted warm water through the normal fluid passages.

My only problem with this whole idea is where do the savings come from? Sure, you're heating up some cold water. If your water heater is set efficiently, you don't need the cold water on anyway, do you?

Ok, so the best two uses I could think of after that are heating the home, by running the drain water through a heater core, and placing it somewhere in the HVAC ducting, easily removable. Great, but that only extracts heat when the HVAC system is working, right?

Awesome! Well, last idea, then I'm ditching it if this one won't work out...

Let's do the water/water heat exchanger thing again, but run the water heater's inlet through it, pre-heating the cold water that would normally go in bone cold. THAT'S IT! This way, I"m using less (insert fuel source) to heat my water...

Maybe that was the original intention?

Oh, damn. I planned on solar thermal water heating. I guess I'm still wasting fuel, but it's a potentially infinite fuel that I can't control whether or not it will run out, nor does it really make a difference how much I use for what...

Back to the drawing boards...

(The HVAC idea is actually sticking in my side... I might have to do that one anyway, if it's feasible for me.)
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