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Re: Looking for Hot Water Heater Efficiency comparison - Page 3

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Posted by Solar Flaire on April 9, 2007, 10:30 pm
Very stupid logic, Nick.

With this attitude we should all wear blindfolds when crossing the
road. Tha naser is, ignore your dangerous suggestion to disconnect the
bottom element. You could possibly cause deaths if people listen to

Posted by Derek Broughton on April 10, 2007, 12:52 am
nicksanspam@ece.villanova.edu wrote:

Surely the solution was given - keep the tank over 60C.   Not my preferred
solution.  I have a tank that stays at a nice temp for Legionella (from
solar), and top it up with a tankless gas heater.  It'll probably kill me
one day :-)

Posted by Solar Flaire on April 10, 2007, 11:04 pm
 The way I understand it, when it passes over the heating element in a
gas water heater it raises the temperature much higher and kills the
legionella bacteria.

Legionella is naturally found in ground water and is normally not a
problem. It becomes a problem when you give it a breeding ground and
allow it to accumulate, as below the bottom element of an electric
water heater does. The report shows it wasn't found in gas water
heaters due to bottom heating and intense temperatures where the
colonies accumulate.

Posted by Derek Broughton on April 11, 2007, 1:04 pm
 Solar Flaire wrote:

That may be true when the demand heater actually comes on (I'm not sure the
heating is sufficient - it certainly isn't "pasteurization"), but in summer
I may get enough solar heat that the demand heater never comes on at all.
I'd think it entirely possible that my water never gets to the temperature
levels the health officials seem to think is needed.


Posted by Solar Flaire on April 11, 2007, 11:54 pm
 I think the method today (by code or bylaw) is to always heat your
water to 140 C and then downmix it with the now required temperature
regulator at the output of the DWH.

I don't see a problem with solar heated water as long as it get to
this high temperature, sometime before you use it. Either it will
happen totally solar or in the heat "top-up".

The other item is, I beleive, this is only a problem with ground water
and not rain or chlorinated water, once the Legionella bacteria have
been killed.

The Quebec study has a lot of information about this. Opened my eyes
because I have a guy that wants to run well water through my hydronic
system, where it may sit at 90-120 C for days, and then used for
showering...etc.. His comment was "you don't drink hot water...do
you?". Research shows it to be an inhaled problem in the shower. It's
a form of pneumonia.

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