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Discuss Adding a run on timer to an existing fan in the Electrical Tools and Products area at ElectriciansForums.net

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littlespark

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Is there such a thing?
Job i'm looking at has a bathroom with no window. There is a 230v inline fan in the roofspace, vented from above the shower cubicle to... well... the extraction doesn't go anywhere, but that's another problem.
Taking the grill down I can see the fan, but its screwed to the beam and I cannot access the connections but can reach the T&E supplying it.
The fan just comes on with the lights, neutral at the switch just outside the door.
I've mentioned to the homeowner that the ceiling might have to come down, but he's not keen.

I have seen an add on timer unit for a 12v fan, but not 230
 

That says it needs live, switched live and neutral .... and the op thinks he only has switched live and neutral

If the owner can cope with a small variance change the fan for a 12v unit, and mount the transformer / driver near the switch and run a new cable from the switch to the transformer ...
 
Yes. I’ve only got a sw and n. What I need is the fan to be powered from a timer unit which is triggered by a light switch, not from the light switch itself.
I realise I need a 3 core to operate the timer... but that is straightforward from the switch as there’s a live, sw an neutral there.

Swapping out the fan for a timer version or 12v is impossible without taking down the ceiling.

It may be I could use a humidistat?
 
If you've got permanent live, switched live and neutral at the switch, then that timer would work for you, surely or am I missing something?
 
How about a fan with a built in pir ?
It’s an in-line fan in the roofspace....
He could add a ceiling PIR..But if he can reach the T&E he still needs to get a permanent live for the PIR.

Whatever the solution for the fan, it still needs venting. I doubt there’s a workable solution without some ceiling carving.
 
The way I read it is that he's only got SL and N at the fan and a nice ceiling he doesn't want to cut holes in!

Absolutely, but none of the solutions are going to work without a permanent live. But he does say this:-

"I realise I need a 3 core to operate the timer... but that is straightforward from the switch as there’s a live, sw an neutral there."

It's obviously impossible to say without being there, but from how it's been described, it doable.
 
I agree SC. If the fan T&E is at the switch, then adding the unit you linked to would be the easiest way.

If it comes from the light fitting, it depends on the light wiring. No problem if there’s a perm live there. Need input from the OP.
 
I’m trying to convince customer to take down ceiling in bathroom and kitchen for other works.
See my other post in The Arms

It’s not ideal. The fan is inaccessible for maintenance and vents nowhere.

I haven’t checked that link yet SC to see if it’s suitable, but I will.

Edit: just had a look. That unit will do the job fine. Thanks. And not too expensive.
 
If access to the ceiling will be restricted after the works, it may be better to have a surface ceiling fan and not an in-line one. Your customer will have the same problem in a few years time when (and not if) the fan fails.
 
While not just tap into the PL going to the switch and run it to fan?? If its in a loft space you'll have everything visible going to and from switch... Or am I missing something.
 
You've missed something; - flat roof above bathroom. I cant access the fan, but can see it.
The switch is under an attic and I can get access to that, and push a cable through into the roofspace where the fan is.

The flexy duct that comes from the fan and goes nowhere yet could come down into the kitchen and run in a pipe box above the wall units and through an outside wall.
 
You've missed something; - flat roof above bathroom. I cant access the fan, but can see it.
The switch is under an attic and I can get access to that, and push a cable through into the roofspace where the fan is.

The flexy duct that comes from the fan and goes nowhere yet could come down into the kitchen and run in a pipe box above the wall units and through an outside wall.
Ahhh. I c, you say you can push a cable from the switch to the roof space. I cant see how difficult it is to access.
 
The light above the shower has the intake vent around it. Taking this down reveals a 100mm hole.
From here I can see the in-line fan screwed to the beams above the ceiling, but cannot access it to get at the connections.
I can pull the cable back to this hole and fit a timer unit to feed the fan, leaving the other lights on the switch wire.
All I need is a perm live from the switch to the timer. Just as easy using a 3 core from the switch to the fan and putting in a 3 pole isolator while I’m there.
The main house has an attic. The bathroom and kitchen are in a flat roofed extension. The switch for the bathroom is in the main house.
 

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