Bathroom fan turning on via PIR

[vala]

Hi @aptsys , thanks for your reply.
I have already bought the fan which has a timer built in. Had I thought/known that this and the PIR would clash over the timer, I would have purchased the non timer version.
I did think early on in this thread to have the PIR set to 10secs then set the fan to something longer for the overrun, however this would then mean the mirror demisters would turn off sooner.
So now liking your suggesting about linking the fan L and SL to SL at the isolator, and leaving the PIR to control the timings so as not to affect the mirror demisters.
So the latest drawing is like this, ok?

 

[Taylortwocities]

Not quite. As the fan will not use its timer function then it does not need a permanent live. Just a switched live with the SL & L terminals linked at the fan itself.

 

[Harry Bloomfield]

Hi all,
Looking to have my bathroom extractor fan turn on via a PIR instead of on with the light switch.
Main reason for this is the bathroom gets lots of light in during the day and if showering at that time there's no need for the light, and so an extractor fan wouldn't turn on.
I also have a fan isolator mounted above the bathroom door outside the bathroom.

The extractor fan is this
https://www.extractorfanworld.co.uk/envirovent-silmv250100t-ultra-quiet-inline-fan--timer-4358-p.asp

And I was thinking of this
https://www.cef.co.uk/catalogue/pro...VEc53Ch3-jQP4EAQYBCABEgLbF_D_BwE&gclsrc=aw.ds

to trigger it.

Can anyone confirm if this would work?

Just ensure that the photocell can be completely deactivated - the photo cell is included, when it is used to switch lighting, so the lights are inhibited when the room has some natural light.

 

[vala]

Hi @Harry Bloomfield
Just checked the manual for the PIR and it notes the photocell range is 100 to 1000 lux, and inactive.

 

[vala]

So redone the drawing and now looking like this taking into account the L & SL link. I’ve done the drawing using the cables I would use, hence the shading around cables I’ll be sheathing.
Does this look correct?

 

[EFLImpudence]

Why have you two Browns entering the top?

Otherwise it is correct.



I would advise you to use 3core&E from isolator to fan, just in case you decide to do something else in the future, so you may as well wire the fan as you would for a timer but connect both L and SL to SL (L1 in your drawing) at the isolator.

 

[vala]

@EFLImpudence
The 2 browns going into L2 are the feed in to the isolator and feed out to another switch on my lighting circuit. There’s supposed to be a second blue neutral, but I just forgot to put that in.
I think to reduce the amount of connections in the back box I’d like to stick with the T&E if that’s ok. All cabling in the house has been redone In conduit and the distance from this isolator to the fan itself is at max 2-2.5m so swapping over to 3 core if needed in the future wouldn’t be a hassle.

 

[EFLImpudence]

@EFLImpudence
The 2 browns going into L2 are the feed in to the isolator and feed out to another switch on my lighting circuit. There’s supposed to be a second blue neutral, but I just forgot to put that in.

Ok.

I think to reduce the amount of connections in the back box I’d like to stick with the T&E if that’s ok. All cabling in the house has been redone In conduit and the distance from this isolator to the fan itself is at max 2-2.5m so swapping over to 3 core if needed in the future wouldn’t be a hassle.

Up to you.