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Re: Water heater capacity for occational use ski cabin

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Posted by nicksanspam on April 13, 2006, 7:20 am

There's probably not a lot of room for a greywater heat exchanger either.
The one Gary Reysa and I are working on would be about 3' diameter x 6' tall,
with the greywater I/O near the top. If the 4" x 100' black corrugated
drainpipe spiral were flat (eg hung under a basement ceiling), it would be
about 7' in diameter.

That could increase the capacity with good final temperature regulation,
compared to putting the tankless after the tank :-)


Posted by hallerb@aol.com on April 13, 2006, 8:37 am
yeah your best bet is probably putting a tankless, the highest btu your
propane tank will support immediately before the standard tank. you
will likely need to upgrade your propane setup..

with the tankless first this will temper the incoming water, warming it
enough that will allow your regular tank to finish it off for a stable

Posted by Ecnerwal on April 13, 2006, 12:18 pm
  nicksanspam@ece.villanova.edu wrote:

Step one - have a qualified propane service technician check the thing
out and make sure that the burner is adjusted and working properly.

Seems to me that there might (depending on location of shower) be plenty
of room for the copper system where the outgoing shower drain water
preheats the shower cold water supply (or even two of those stacked, one
feeding the shower cold and the other the water-heater inlet cold). This
is a commercial product (I forget the name), essentially consisting of a
copper drainpipe with a soft-copper water line wrapped around it and
soldered to it. By warming the cold into the shower it reduces
hot-water-use per shower.

Simple to install if there's a basement (or first floor) under the
shower, more complicated (wants a pump to elevate the drain water) if
the shower is on the lowest level of the building.

Cats, coffee, chocolate...vices to live by

Posted by nicksanspam on April 13, 2006, 12:57 pm

GFX, but that needs lots of vertical space, and it's only 60% efficient.

Maybe it's time to build a low deck with another fully-enclosed shower
or a hot tub, which would lose less heat with a pump but no bubbles...


Posted by meow2222 on April 14, 2006, 12:16 am
 nicksanspam@ece.villanova.edu wrote:

If space is lacking, suggest making a pancake shaped drain heat
exchanger and fitting it underneath the shower tray. The tray then goes
back 4" higher than originally.

Or a square tray with baffles fitted to control drain water flow
direction, and paralleled microbores running along those channels to
prewarm the cold feed to the shower.

The most primitive possible version, something one could set up in
minutes, could be nothing more than a copper coil placed in the
existing shower tray, with wood strips on it to keep feet off the cold
copper. Could be used as a temp measure while a permanent design was

Also ensure shower enclosure is fully closed to minimise conduction and
evaporation losses.


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