[Greenbuilding] whole house DHR retrofit

Nick Pyner npyner at tig.com.au
Sat May 14 18:01:10 PDT 2011

I submit the only "best practice" is the bleeding obvious. The only devices
you connect to the heat exchanger are devices that you can be sure will
always make a contribution. In the domestic arena, this invariably means
showers, and nothing else. The last thing you want is a cold water rinse
from the laundry getting into the act while you are having a shower.

Only you can make a proper assessment of the plumbing situation, what's
viable and what's not, but I don't think there is usually much of a (ahem!)
grey area in matters of viability. I suspect an installation is usually easy
and obvious, or either entirely impractical, or entirely undesirable.

I would be chary about installing a pump and its attendant automatic switch
gear. One of the great joys of a heat exchanger is their utter simplicity.
Having said that, a pump doesn't have to do much to pay for the power input!

Sensible compromises can always be made.

This afternoon I am driving down south about 300 miles from here to retrofit
a heat exchanger in a small ski lodge. We expect some pretty dramatic
results, by Australian standards, as this will handle up to nine showers
simultaneously, but only six drains can be sensibly connected. I would not
contenance any pump system. However, the other  three showers will still be
drawing fresh water through the heat exchanger, and thereby will make some

Similarly, but 500 miles in the opposite direction, I have installed a heat
exchanger which has the toilet connected in tha same line as the cold tap to
the shower. This means that pre-warmed water does occasionally get flushed
down the can. We know it, and aren't going to change anything.

Nick Pyner

Dee Why   NSW

-----Original Message-----
From: greenbuilding-bounces at lists.bioenergylists.org
[mailto:greenbuilding-bounces at lists.bioenergylists.org]On Behalf Of
Haudy Kazemi

Are there any "best practices" for whole house drain heat recovery (DHR)
retrofits?  By whole house, I'm also including the basement drains that
serve basement bathrooms and laundry.  Sometimes upper floors also drain
into pipes that are embedded into the basement slab.

Is a small catch basin + sewage sump pump that lifts the drain line to
drop back through a DHR a viable solution?  This would ideally include a
overflow bypass in case the sump pump fails for whatever reason.

Any comments/opinions are welcome.
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