John Stumbles wrote:

I thought that was frowned on and you were supposed to fit them as close
as possible to the point of use? (But then, maybe that's the TMV
manufacturers' association recommendation? :-))

The idea was to minimize the length of the blended water pipework,
because it was a greater legionella hazard. You'd use one TMV to supply
a group of fitings.


There is a rather poor site I inherited at
http://www.davidsemporium.co.uk/norscreen/ but I haven't finished making
the replacement and it does have illustrations of the covers.

Oh dear they are very NHS-looking aren't they? This is for a Steiner
school and they'd never wear anything with that sort of aesthetic :-)

Hudevad
http://www.hudevad.co.uk/
and Runtal (now Zehnder?) used to be the main UK suppliers of LST rads.
They all looked a bit NHS, 'cos the NHS was the main purchaser. You
also had to ensure that any accessible pipework or valves were
insulated, which was a PITA if the building was not designed for such
special-needs use.a purpose

"Owain" wrote in message
...
nightjar nightjar@ wrote:
"John Stumbles" wrote
This is for a Steiner
school and they'd never wear anything with that sort of aesthetic :-)
They are all made to order, so we can do pretty colours,

RAL, or Farrow & Ball? :-)

Hand painted pictures of local landmarks, if that is what the customer
wants. RAL colours would be cheaper though.

Colin Bignell

On Sat, 01 Apr 2006 11:31:14 +0100, nightjar wrote:

The problem is, would you know if home made covers gave the proper level
of protection?

I meant the sort of wooden grille-type covers you get for prettifying rads
in houses. Obviously they'll cut down output a lot but in the main area
concerned the rads would still cope if the room weren't haemmoraghing
heat :-(

"John Stumbles" wrote in message
news
On Sat, 01 Apr 2006 11:31:14 +0100, nightjar wrote:

The problem is, would you know if home made covers gave the proper level
of protection?

I meant the sort of wooden grille-type covers you get for prettifying rads
in houses.

You still ought to verify the surface temperatures achieved. It is
surprisingly easy to end up with local hotspots.

Colin Bignell

Aidan wrote wrote:

If you have a 'Duty of Care' and you ignore L8, whether about cooling
towers, H&C water systems, humidifiers, etc., and there's is an
outbreak, then the HSE will sample all suspect systems and will be able
to link the strain of bacteria to the infected persons. They will drag
you through the criminal courts.

Funnily enough one of few the things you can just about guarantee in a
legionella outbreak is that the HSE will NOT sample anything. What they
do is look at your risk assessment and whether you have correctly
identified and implemented the precautions required, including
monitoring and record keeping. If you have done all this, then even if
you have killed people, you are not in breach of the law as perfection
is not required only "all that is reasonably practicable".
Complying fully with L8 is taken as doing this.

Whether there are, or ever were, actually any legionella present is not
really relevant, it is the risk you must control under the law, not the
actuality per say. They have established case law on this (over the
BBC's London outbreak). As all biological sampling is a bit hit and
miss it is better legally not to sample, so they do not. You would be
sampling a dynamic system at least a week too late anyway. In any case
the first thing any half intelligent building manager would do at a
hint of legionella problem would be to superchlorinate their system,
(purely to protect the public from any possibility of ongoing risk of
course and not with the intention of destroying potential evidence,
which would be entirely coincidental).

The people who do tend to sample are the local Environmental Health
department as part of the Outbreak Control Team, as their primary
interest is in trying to establish the source to protect public health
and not prove legal culpability. But only positive results mean
anything, negative ones disprove nothing. That is why routine sampling
is not recommended (except for very high risk situations such as
cooling towers or systems that cannot be fully controlled for some
unavoidable reason) as negative results give a false sense of security.

There was also a comment that TMC's do not need to be maintained as
they fail slowly and you do not get sudden scalds, but rather water
that is unacceptably cool. I am sorry I cannot recall who said this.

While this may be true, the scalding risk is not the only risk. From
the legionella viewpoint maintenance is critical as TMC's inevitably
get scaled (or attacked by aggressive water) and then present internal
surfaces ripe for biofilm colonisation. Without maintenance the
colonisation gets heavy resulting is significant levels of discharge.
This is also why the TMC needs to be as close as possible to the outlet
- as the system will probably get colonised, the shorter the run the
lower the number of legionella that someone can then be exposed to,
(minimising a risk you cannot completely eliminate).

This is also why you should not routinely sample downstream of a TMC,
if you are seeking to establish if the system as a whole is OK, as all
you end up testing in effect is the TMC and downstream pipe run. This
you already know is at a risky temperature, so showing legionella
presence does not really tell you much, unless there are vast numbers.
Even then it probably only means the TMC and outlet are not being
maintained properly and you should know if you are doing this already.
Thus why spend the money on testing when it is better to spend it on
doing the maintenance properly in the first place?


Patrick