🚀 go-pugleaf

On Sun, 18 May 2008 16:40:09 -0700, Joerg
<notthisjoergsch@removethispacbell.net> wrote:

>I know those, they also come within single-lever shower/bathtub control 
>valves where you just set a temperture instead of a percentage. I think 
>Grohe makes them. But most aren't fast and when you have the situation 
>that Jeff saw in Israel the water coming through the pipes can turn from 
>barely warm to scalding in milliseconds. Unless you have a point-of-use 
>recirc but most houses are not that modern.

One solution that I saw was an inverted siphon between the mixer
output pipe coming out of the wall, and the shower head.  The pipe was
about 6 ft long.  There was a bi-metallic thermometer clamped to the
entry point.  My guess is that it would give about a 3 second warning
of impending thermal excess.  The installation looked commercially
done and may have been part of aftermarket kit.  As I was a visitor, I
didn't give the shower a proper test flight.

It would be fairly trivial to build a proper mixer, with electronic
(or bi-metallic mechanical) temperature control and independent flow
control.  There were some on sale in Israel in the early 1970's when I
was there.  It's just that the apartment where I was living didn't
have one and apparently nobody thought the cost was justified.  People
can get used to almost anything.

I once had my bathroom sink setup as in a medical office or surgeons
wash room.  Limited manually adjustable temperature (to insure self
sterilization) and foot switch operated flow control (to prevent
contaminating the hands).  It saved considerable water and by
implication, considerable energy heating the water.  My ladyfriend at
the time found it "inconvenient" so I reluctantly removed it.
<http://www.faucetcontrol.com>
<http://www.stepflow.com>
<http://www.pedalvalve.com>

An IR faucet adapter:
<http://www.ezfaucet.com>

The same device could easily be installed in a shower, with foot valve
operation.  Set the temperature with a controlled mixing arrangement
and adjust the flow (or more crudely on/off) with a foot switch.  It's
even patented:
<http://www.google.com/patents?id=6uMvAAAAEBAJ&dq=4729135>

So, what's preventing such installations in the home?  I once
discussed the issue with a local doctor, who was building a new house
at the time.  The Uniform Building Code for residential dwellings
won't allow such innovative plumbing.  It's perfectly acceptable for
commercial and hospital, just not residential.  I'll supply a suitable
conspiracy theory when I have time.

Hmmm.... I still have the parts of the foot operated sink valve
somewhere.  I should try to resurrect it.

Incidentally, one of the old but fun problems with hospital water
control is selecting the temperature.  One set of regulations demanded
that the water be hotter than 52C in order to minimally self
sterilize.  Another set of regulations from a different agency,
demanded that water be no warmer than 52C to prevent scalding.  This
was about 10 years ago, and hopefully a suitable compromise has been
reached by now.

"Control of nosocomial Legionnaires' disease by keeping the
circulating hot water temperature above 55 degrees C: experience from
a 10-year surveillance programme in a district general hospital."
<http://www.ncbi.nlm.nih.gov/pubmed/11886198>

Google couldn't find anyone using a rooftop solar water heater as a
drinking water purifier or pasteurizer.  Stand alone yes, but not part
of the water heater pretzel:
<http://solarcooking.org/plans/spasteur.htm>
<http://solarcooking.org/pasteurization/puddle.htm>
Yet another opportunity ignored.


-- 
Jeff Liebermann     jeffl@cruzio.com
150 Felker St #D    http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann     AE6KS    831-336-2558