Ducted bathroom extractor fan

[Azizi]

Hi all,

I have an electrician coming to fit an extractor fan for a bath/shower room without a window and with approx 3m duct horizontally to the outside world. 2 previous axial fans (regular DIY store jobbies) have proved worthless with excess condensation and mould hanging around after the shower. I had planned to get a centrifugal fan but was told by one electrician it had to be SELV - making them very expensive as far as I can see - but have otherwise read that as long as it is IPX4 and states suitable in zone 1 this is okay. Currently the transformer is also in zone 1 and has been for many years so this will be moved too! Centrifugal fans seem very bulky although I am yet to see one in the flesh, and aesthetics although low on the list are important. A further electrician plans to install another axial. Finally a third, who is doing the job, recommends an inline shower fan but these appear to all be ceiling mounted and we have a flat above. I'm utterly confused.

1. Will any axial fans be sufficient for the duct length? The bathroom is only approx 2.5 x 2m
2. Can we install an IPX4 fan without SELV?
3. What type of fan would you install?!


Many thanks in advance

 

[Des 56]

Axial fans are designed to cope with longer airflow than standard fans

It does not have to be selv.230 volt suitably IP rated is fine,you can then ditch the transformer

Xpelair are the kiddies as far as I am concerned,but you get what you pay for
http://www.xpelair.co.uk/media/literature/A5_PRICE_GUIDE_OCT11.pdf

 

[Johnboy78]

U can fit a 230v ipx4 or above rated fan over a bath provided its 2.25 m from floor level- in line fans are a joke and can't see how u could have one anyway as ur duct runs horizontally thru the wall- if uve got damp and mould issues u might be best off with a trickle fan that runs constantly, maybe try an envirovent type fan.

 

[Des 56]

U can fit a 230v ipx4 or above rated fan over a bath provided its 2.25 m from floor level- in line fans are a joke and can't see how u could have one anyway as ur duct runs horizontally thru the wall- if uve got damp and mould issues u might be best off with a trickle fan that runs constantly, maybe try an envirovent type fan.

Maybe time to start ripping out thousands of fans throughout the country

Johnboy where have you got this idea from ? it certainly contradicts what is permitted by the regs

 

[FrankUK]

First of all, make sure that your electrician is a registered 'competent person' to install the fan. Electrical qualifications alone are not sufficient to design, install, test and commission the fan, in accordance with Part F Building Regulations. NICEIC Certification | Competent Persons Scheme

Next, make sure that the installation is in accordance with this document.

 

[JulianC]

Replacing an existing fan with a similar type is not notifiable under Part F and does not require membership of another CPS. How you define 'similar type' is open to interpretation. Installing non-adjustable fans is not notifiable either. I would not be telling Building Control if I was swapping a bog standard (pardon the pun) single room intermittent extractor, whether it be to an axial, inline or centrifugal fan of the same or better performance. Continuous run trickle and boost is a different matter of course.

 

[FrankUK]

Replacing an existing fan with a similar type is not notifiable under Part F

Quite true so long as the existing wiring is being re-used. If a new supply is provided then section 7.32 does not apply

 

[thomas-1981]

what about a fan with a humidistat if your having constant problems with condensation and damp.

 

[JulianC]

Would probably be my first choice too - humidistat controlled centrifugal fan with plenty of poke. If you're worried about aesthetics, the Vortice Quadro looks quite nice. For a fan.

 

[TAZ]

I think your options are limited on this one. The inline fan ( which would have been the best option) is out of the question as these would be be ducted out through the loft space. As Des quite rightly said you can in deed fit a 230 volt fan in zone one provided it is designed to go in that zone IPX5 if jets are likely. The centrifgal fan is probably you only option as the little axle fans are designed for short lengths ie straight through the wall They are also prone to back pressure where the pressure outside is to great for the fan to overcome. The centrifugal fan will cope better if ducted but like every fan the longer the run the less efficient it becomes so it will only produce the required extraction rates if it is installed correctly The minimum rate for a bathroom is 15 litres l/s & as there is no window it will need a 15 minute overrun to comply with building regs. There are centrifugal fans which have humidity stats incorporated into them & this might be the only viable option OSG page 82 must be fixed & RCD protected

 

[Des 56]

Axial fans are designed to cope with longer airflow than standard fans

It does not have to be selv.230 volt suitably IP rated is fine,you can then ditch the transformer

Xpelair are the kiddies as far as I am concerned,but you get what you pay for
http://www.xpelair.co.uk/media/literature/A5_PRICE_GUIDE_OCT11.pdf

I was just reading through this thread again and have decided my brain must need some new cells
What I intended writing was the opposite of what I am now reading
I meant to write Centrufiugal fans for the longer distances

Sorry if I have caused any confusion,for a moment my hair may have turned blonde

 

[TAZ]

I was just reading through this thread again and have decided my brain must need some new cells
What I intended writing was the opposite of what I am now reading
I meant to write Centrufiugal fans for the longer distances

Sorry if I have caused any confusion,for a moment my hair may have turned blonde

I know the feeling my friend i am the same myself sometimes, the cogs are all there they just take a little longer to engage