Bathroom Fan - Cold Air

[Jnr_81]

I have an extract fan in my bathroom, when the wind picks up or when it is cold outside the bathroom is absolutely freezing after a while. Has anyone else experienced this and how did you go about fixing it? I was thinking of some sort of one way blocker but nor sure where to find such a part?

[stoneyboy]

Jnr_81,
Fit a backdraught flap either in the extract hose or directly on the extractor, if mounted horizontally the spindle must lie vertically.
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