daestrom wrote:

I cut my DHW heating by somewhere between 1/3 and 1/2 by installing a
waste-water heat-exchanger. Running hot water for a shower and letting
all
the energy go down the drain (literally), just doesn't make sense. Of
course, this system only recovers heat from *running* water, so baths and
dish washing doesn't affect it.

I leave the dish-water in the sink until it reaches room temperature. It's a
little too low-tech for my taste, but it works :-)

I have one of the largest units and it is a two-pass type so is not the
most
efficient model they have. Mine cost only about $270, did the
installation myself.

http://www.gfxtechnology.com/

I wish I'd known about those earlier. I can't see a way to retrofit one to
work with my main bathroom - slab on grade, all the plumbing through the
slab. I could recover waste heat from the second bathroom & kitchen.
--
derek