On Sat, 18 Jun 2005 14:08:32 +0100, wrote:

On 18 Jun,
John Rumm wrote:

John wrote:

Glow worm have recognised the plume as being a problem and make a kit to
extend the discharge upwards and away from the flue wall exit point.

I find it supprising that people get so upset at the sight of a bit of
water vapour... They must get really scared when they make a cup of tea! ;-

What I wonder about condensing boilers is whether the low temprerature plume
can spread legionella. Can water sit anywhere at a suitable temperature to
allow growth of the bug. What precautions need to be taken to prevent this.

Several points.

- In the area of the burner the temperatures are considerably higher.

- Flues are normally arranged with a slight slope back towards the
boiler for nominally horizontal runs so that water condensing in the
flue goes mainly back into the boiler. This is also to stop it
dripping out onto the ground outside.

- Internally in the boiler, there is an arrangement for the water to
run down into a trap from where it then drains out. Hence there is
not really a place where it will remain stationary for long.

- The condensate water is mildly acidic.

- Condensing boiler technology has been in use elsewhere in Europe for
20 years and there are not large outbreaks of Legionella reported as a
result of its use.




--

..andy

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