We've extended onto a wall that contained the outlet for an internal
toilet extractor fan. So temporarily, this fan ducts into a cavity.

The original plan was to re-route the ducting to the other side of the
house. But this seems tricker than expected - we'd have to destroy a
lot of ceilings, fix a long run of ducting just to get to the nearest
outside wall. Even then - that wall contains the outlet for the CH
condensor boiler so it may not be a good idea to come out too near
that.

We've had the suggestion that ducting into a cavity from a toilet only
room (not a bathroom or shower with moist air) can be acceptable if you
use a fan with a carbon filter for odour control.

But I can't seem to find any such fans - does anyone know if they
exist?

Thanks
Paul

wrote:
We've had the suggestion that ducting into a cavity from a toilet only
room (not a bathroom or shower with moist air) can be acceptable if you
use a fan with a carbon filter for odour control.

No. The purpose of the extractor fan is to extract the air to the
outside, not pump it into the wall cavity and hope it makes its way
outside somehow.

When you flush the toilet, aerosolised fecal matter laden with bacteria
is sprayed into the air. It is this which you need to extract to the
outside, rather than 'odour' per se. Using a carbon filter for odour
control is only of relevance if you are using a recirculating fan; using
one would be an admission that your fan is not extracting from the room
space.

If you can't take the long way across the extension can you go up
through the roof? Or even down and under the floor? Oblong ducting will
run parallel to joists quite easily.

Owain

On Sat, 23 Apr 2005 14:25:28 +0100, Owain
wrote:

When you flush the toilet, aerosolised fecal matter laden with bacteria
is sprayed into the air. It is this which you need to extract to the
outside, rather than 'odour' per se.

Didn't your mum teach you to shut the toilet lid before flushing? ))

cheers,
Pete.

Pete C wrote:
When you flush the toilet, aerosolised fecal matter laden with bacteria
is sprayed into the air. It is this which you need to extract to the
outside, rather than 'odour' per se.
Didn't your mum teach you to shut the toilet lid before flushing? ))

The aerosolised fmlwb then hangs around in the toilet bowl waiting for
the next user to lift the lid.

Owain