Easiest way to insulate bathroom extractor fan

evoke

I'm looking to make some sort of insulating cover for our bathroom extractor fan, to slip onto the casing at night. The bathroom is located on a corner of the house and is exposed to the wind so it becomes very cold over winter night (down to +12 C). The weak link seems to be the extractor fan.

I have added a butterfly valve to the vent pipe but that's not going to stop a lot of cold air from entering the bathroom overnight.

So, what do I use to make up an insulating cover? Needs to be cheap and cheerful!

dampdaveski

Evoke,
I wouldn't recommend that you cover your extractor fan over, it only take someone to leave it switched on when the cover's on and you've potentially got a fire risk or at best you'll burn it out.
The biggest drop in temperature for your bathroom will be the 2 exposed external walls acting like a cool box, particularly so when the heating is off during the night

Remember also that the fan will be giving a little bit of background ventilation, by blocking it off for most of the time will encourage mould growth etc

evoke

^ Good points.

southcoastrgi

change it for one of these, shutter is closed when not in use & opens automatically when switched on