Extractor fans not working

[midknight]

Hi

I have just moved into a new build house. The extractor fan in the cloakroom is Silavent SDF1001B axis model it has a 2.9 metre flexible trunking. Although it sounds like it is working the external backdraught shutter rarely opens and it does not remove smells. The builder contacted the electrician and said that the shutter did need to open. Is this right?

I also have the same fan fitted on a ensuite and a bathroom - one has a 3.5 metre hose and the other 4.5 metre hose. These also do not seem to work and sometimes with a wind outside there is a considerable draught from them - enough to make the fan spin in reverse when switched off. Can anything be done to improve matters.

Thanks for any advice.

 

[midknight]

Re: Extractor fans not working
Posted: Sep 8, 2008 7:57 PM Reply


sorry my mistake

The electrician was quoted as saying "the back draught shutter does not need to open"

 

[Spark123]

You can edit your posts by clicking the edit button at the top right hand side
If the backdraft stopper isn't opening then there isn't any airflow going through it, it needs to open to allow the air flow through it!
Is there a high wind resistance?

 

[midknight]

thanks for that - will do in future

there is no wind the shutter opens about 20mm any wind and the shutter does not open.

I seem to rember reading that hose length on axis type fans should not exceed 2 metres

 

[Spark123]

You can get ones which can move air a bit further without needing to up the size of the pipe, is there an instruction book with the one which you have fitted? Worth looking in it to see if theres any restricitions on duct length. If it is no good then it might be worth trying a centrifugal fan such as the manrose one - £25 in screwfix normal and £30 for a timed one.

 

[midknight]

Thanks - an electrician fitted it as new house

Checking Silavent website it states only suitable up to 2 metres of ducting.

Is there a building regulation that this contravenes as the fans do not remove the smells?

 

[TicklyT]

There needs to be sufficient airflow into a room for an extractor fan to work. if the room is practically airtight an extractor fan will be about as much use as a vacuum cleaner with a blocked nozzle.