Bathroom Extractor Fan Hose.

[1581960]

I'm going to fit a new inline extractor fan in the loft above the bathroom and I'm usure about routing the 4" dia spiral hose. My concern is the possibility of condensation forming in the hose and dripping back down into the bathroom, should I route the hose as vertically as possible or should I have an horizontal section before going up to the fan?
Any help would be appreciated, many thanks.

[The Builder]

You're doing the right thing. Most people (including tradespeople) don't take this into account.
If you're connecting to a ventslate in the roof, then suspend the hose so that there is a "drip loop" (much the same as electricians use with external cables to stop water running down into an outside socket or similar.)

It's really just a kind of "U-bend". Any condensate will collect in the "U" and eventually evaporate.

If you're connecting horizontally to a "wallvent" or a soffit behind the guttering, then the problem does not arise.

[1581960]

Thank you The Builder, I'm in a bungalow and just going a short distance to an outlet in the soffit, if I fix the fan as low as possible there will be hardly any rise in the ducting and hopefully I shouldn't experience any problems.

[The Builder]

Ok.
While the fan is running, damp air will all be expelled.
While not running, it's negligible, so no problem.

I must say though, that I wouldn't even bother with an inline. Just a normal extractor fan on the bathroom ceiling.

No matter though. Wire the fan into the ceiling light, so that it comes on with the light. Do remember to wire it to give an "override" after you switch the light off (adjustable.)

[1581960]

Thanks, a well deserved best answer.