"Graham Jones" wrote in message
...
Thanks for all your replies. Luckily the boiler is in the garage and not
in
the house, but I will put a CO detector in there. The outside of the flue
does have a collar and is also sealed with brown silicon. No rain today
and
no leaks, so definitely rain water.

The water is coming from the front right corner of what the installation
manual calls the air box, where the fan and condensate trap are located.
Does this provide any clues?

Also on a side note, why do boilers and fires require flues but not gas
ovens? I have always wondered about this.


Thanks,

Graham


Boilers are usually sealed units. Where the air is drawn in from outside
and expelled back outside through the flue. Not all boilers are like that,
but most today are. This reduces the need to have permanently open vents in
the same room as the boiler, so keep draughts out when you want it warm
inside.

Gas fires and stoves need a permanently open vent from outside, into the
room where they are installed. If you haven't go one on an outside facing
wall, then provision has to be made for a forced air intake and outlet
system into the room where the gas appliance is installed. A gas fire must
also have a flue to the outside, with other safety regulations that go along
with it.

Did you think it was as simple as fitting a stove in a cupboard under the
stairs, and that's it? There is a lot more to gas safety regulations than
that. :-)

I'm sure more knowledgeable others will go into more details for you.
Telling of how the extraction does this, while the Bunsen effect makes it do
that. But I'll leave it there. :-)