Extractor fan works but doesn't vent any air

LlamaKarma

We have an extractor fan in our bathroom which has never worked since we've had it. We should have got the builders back but never did. So.....

We've done some investigation and discovered the fan itself works fine when it is taken down, but when it is reattached to the ducting it doesn't work any more.

So I'm assuming that either:-
1. The ducting is blocked (although we have tried putting the hoover up there) or torn
or
2. There is a kink in the ducting
or
3. Maybe the ducting doesn't actually go all the way outside.

We can't see any problem with the portion of ducting that is visible.

Any advice on how to proceed would be very welcome.

Thank you!!

phil24_7

Is the ducting in the attic? If so get up there and see if there is anything obvious.

Regards
Phil

MX5huggy

If the duct route has corners and is long enough not to be easily inspected. Plus is made of flexible duct even if the duct is not blocked, then the fan, which will be the cheapest available, will not be powerful enough to actually move the air through the duct.

Can you put a proper fan in the loft with a grill in the bathroom?

Le_Kirk

LlamaKarma wrote: »

We've done some investigation and discovered the fan itself works fine when it is taken down, but when it is reattached to the ducting it doesn't work any more.

When you say "doesn't work any more", do you mean the fan blades don't spin or do you mean it doesn't pull air through?

Xeorix

Le_Kirk wrote: »

When you say "doesn't work any more", do you mean the fan blades don't spin or do you mean it doesn't pull air through?

LlamaKarma wrote: »

We've done some investigation and discovered the fan itself works fine when it is taken down, but when it is reattached to the ducting it doesn't work any more.

LlamaKarma - Get into the loft and see where it goes

LlamaKarma

Thank you for the replies!
The extractor fan is in the loft - it's in our ensuite in our loft conversion and is vented out to the roof. So it's not possible to look at the ducting.

When I say it doesn't work any more I mean that the blades turn but no air is pulled through.

Thank you.

forgotmyname

Get some flexible rod and push it through, not fitted it backwards with a one way valve in the duct? Or the one way valve is fitted backwards?

Is it spinning up fast enough, not a trickle speed? Mine tricles but boosts when moisture is detected.

LlamaKarma

Hi,
It does seem to be spinning fast enough when not attached.
Does anyone have any recommendations as to a better fan if that's the solution? The extractor fan we currently have is 100mm diameter. Looking online, most other fans seem to have a similar spec.

Le_Kirk

Did you check that it is not fitted backwards? Did you check the flap valve? If that is backwards, the extractor will be blowing it closed not open.

LlamaKarma

Thanks for your response. I've just had to look up what a flap value is ! I'm not able to see a flap value in the portion of ducting that's visible. As I said it vents onto the roof so we can't see all of the ducting.

Le_Kirk

The flap valve is normally situated just after the fan exit or on the inlet to the duct and is to prevent draughts being created by wind blowing down the duct from outside.