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Drainwater Heat Recovery - Page 2

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Posted by DJ on February 15, 2007, 3:34 pm
 
On Feb 15, 9:11 am, nicksans...@ece.villanova.edu wrote:


That's certainly one of the options. These "power pipes" come in a
pretty wide variety of diameters, up to 4"; I contacted these guys
before Christmas to get more information, as my company, as well as
being a licensed electrical contractor is are also licensed plumbing
contractor, so this type of equipment is within our purview, as well
as being within our self-imposed mandate of only doing work regarding
renewable energy projects.
You could easily put one on the main sanitary drain and recover that
heat into a pre-heat tank via direct input or via thermo syphoning,
exactly like solar thermal. However, if you DID have solar thermal as
well, you'd want to install something like this as a pre-heat tank to
the SOLAR pre-heat tank to your conventional hot water heater.


It certainly is. They're "long term return items", much like SDHW is,
really. On a new home, however, it would certainly disappear into the
"noise" of the plumbing rough-in.


The pipes are anywhere from 500-1000$ (prices listed on their
website). Payback, Power-pipe calculates is 1-5yrs, which it could be,
yep, depending on install costs.


It's actually a pretty simple install for most houses, assuming some
room to work around the main outgoing drain. Otherwise, it's just
plumbing.


Not necessary. The heat exchanger doesn't have any internal baffles or
such, so, to the plumbing pipes, internally, it's just another pipe.
Which, of course, is also why the efficiency is lower than it could
be. A fair trade, I'd say ;-).


Again, not an issue with power-pipes, as there's no reason "chunky
water" would hang up.


Agreed, if you have the roof or the initial price of SDHW. Power pipes
are alot cheaper. And, of course, they can both be used.

DJ


Posted by Brian Graham on February 15, 2007, 3:12 pm
 



cold side? <<

My buddy said the extra heat showed up in the shower within 30 seconds.


the hottest) thing until I started thing about:

1) The cost of the commercial product. It's many hundreds of dollars for
just one liine.  <<

My buddy constructed his own for about $00 in materials.



It was a 6' length, 2" copper inner and 3" copper outer shell. It really wasn't
hard to install, coming down a basement wall. Obviously if your basement is
finished..



The concept works only when the hot & cold taps are both running. And you don't
run the kitchen tap like you do a shower. But yeah, I'd NOT put it on the
kitchen line.


This is not in lieu of Solar, its a compliment, effectively enlarging your
storage by 30%.

To me, a great idea if the price is right..
--
Brian

Posted by daestrom on February 22, 2007, 12:50 am
 

Bought a ready-made GFX unit for not much more than that.  IIRC, about $70
including freight.


GFX is a four inch straight bore on the grey/black side, and two 1/2" copper
coils wrapped around it.


Have mine in the whole house drain stack.  Not a problem with a four inch
copper pipe that is straight as an arrow.

But such units only recover energy when both the supply and drain water flow
at the same time.  Things like showers are just the ticket.  But 'batch'
mode things like a dishwasher don't do much at all.

daestrom


Posted by Brian Graham on February 15, 2007, 3:14 pm
 My friend built his own for about $00 in material. Maintenance should be nil.
And what you're getting is effectively a 30% larger storage tank.

Every little bit helps.
--
Brian

On Wed, 14 Feb 2007 11:01:51 -0500


    That depends on how much gas purchase is saved and how much the
device costs to install and maintain.



Posted by Brian Graham on February 15, 2007, 3:21 pm
 I see what you're talking about maintenance. A GFX commercial unit uses a pump.
:-/

My buddy's setup doesn't use a pump. The cold supply line is the outer shell to
the heat exchanger and thus circulates the transferred heat only when the cold
water is running.  This obviously doesn't work with a bathtub as nobody runs the
cold water while draining the tub..
--
Brian

My friend built his own for about $00 in material. Maintenance should be nil.
And what you're getting is effectively a 30% larger storage tank.

Every little bit helps.
--
Brian

On Wed, 14 Feb 2007 11:01:51 -0500


    That depends on how much gas purchase is saved and how much the
device costs to install and maintain.





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