Twisted bathroom extractor hose

[Antony100]

Hi folks
Before we moved in the surveyor noted the extractor hose was twisted in the loft so may allow mould growth - see pic. So I was going to just cut it and put in as a straight run but...is it curved up and twisted for a reason? To reduce condensation getting through or ingress from the roof vent? How should it run?
Thanks

 

[Leofric]

These uninsulated extractor ducts going vertically through the roof in a cold roof space are not a good idea because of condensation which can cause gurgling in the fan as happened in my house before they rerouted the duct horizontally in 100mm plastic pipe covered by insulation to discharge through an external wall .The bend in your duct would not be much use as a condensation trap near the top of the ducting anyway.

 

[foxhole]

The hose should be kept as short and low as possible to minimise condensation build up which if it runs back into fan will cause failure .
Depends on fan power , the more powerful the less chance of condensation.
A trap can be added if it becomes a problem.
https://www.ukhps.co.uk/mcalpine-co...MIi7Tpyrzg5gIVF-DtCh2BOgYMEAUYAiABEgKvk_D_BwE

 

[Leofric]

and use insulated extract ducting.

 

[Antony100]

Ouch so more effort than I hoped for then! Can you insulate the ducting with anything or do you have to buy specific pre-insulated ducting?

 

[Leofric]

You can get insulated ducting.