On 28 Jul, 15:41, (Andrew Gabriel) wrote:
In article ,
John Stumbles writes:





On Thu, 26 Jul 2007 23:21:21 +0000, Mike Holmes wrote:

I am about to convert my standard open vented DHW system with indirect
tank to a HeatBank system following the wiki @

http://wiki.diyfaq.org.uk/index.php?...DIY_Heat_Bank- many thanks
to John Stumbles for that.

While trying to figure out what specification I require for the plate
heat exchanger, I happened upon this article, which suggests hot water
should be *distributed* as well as stored at 60degC.

http://www.bsee.co.uk/news/fullstory...ding_safe_hot_...

Seems to be pitched at commercial-type installations. Obviously legionella
is possible in domestic ones too but AFAIK the outbreaks that have occurred
to date have been in larger ones. I don't know what the incidence of
legionella in domestic installations is

There are none.

This came up here some months back. A few weeks later, I went to
a wedding and found myself sitting next to a bacteriologist or
virologist or immunologist or some such. With this fresh on my
mind, I asked about it. Answer was that we tend to be immune to
the bacteria in our homes as we're continually exposed to them.
The problem starts when you eradicate them, and hence lose your
immunity. That's fine in your home where they no longer exist,
but if you then go into an institution (such as a hospital)
where they are still the norm, or walk past a water-cooled air
handler with them in, you are now susceptable. He's not an
expert on Legionella specifically, but the appearence of it as
a disease over the last few decades does tie up with attempts
to clean our homes of bacteria, i.e. closing down the training
classrooms for our immune systems (as he put it) which is
widely recognised as a cause for some previously harmless
bacteria to have become recognised illnesses.

What would be interesting would be to see if there's any
correlation between those who've caught legionares disease
(and had previously been healthy, not immune suppressed),
and those who've been eradicating their exposure to bacteria
at home (in this case by using water systems which are
designed to minimise Legionella, rather than by explicitly
spraying disinfectant everywhere).

--
Andrew Gabriel

There are no recorded cases of Legionnaires disease in domestic
premises because they are not investigated. Legionnaires disease is
not reportable as such. However, if there's more than two cases it
becomes an outbreak and is investigated but only as far as commercial
premises are concerned. Private houses are not checked. As always
finding out about these cases can be difficult especially if they're
not in the same area.

I suggest your ?ologist needs to gen up on Legionella. The disease was
discovered in the 1970's. That doesn't mean it didn't exist before
then. As medical awareness grew, more cases have been discovered.
It's believed that most cases are contracted on holiday where
temperatures are higher and water hygiene not is so well established.
The victim also returns home to a system that's been sitting at a nice
temperature for a few weeks so Legionella has had lots of time to
multiply. The first shower releases a lovely aerosol of contaminated
water which they breathe in. By the time any symptoms appear 10 days
later, the system has been flushed many times and so all traces are
gone.