Humidistat extractor fan wiring

[andyste]

I recently bought a "SwiftAir STY!00H" extractor fan (built-in humidistat and run-on timer) to replace an old extractor fan that is connected to a twin and earth, where the live comes from the switched live of a ceiling pull switch. I would like the new fan set up so that the pull switch is always "on" and let the humidistat turn the fan on and off. (I'll keep the ceiling pull as an isolating switch).

The fan has L/N/SL connections, so I assume I need to connect the existing T&E to the N & SL. But I'm not sure what to do about the L terminal, as there is no permanent live available (without getting into the loft and running one in).

Does the permanent live have to be connected, or is this is only needed for the timer run-on feature (which I'm not bothered about)? If it *must* be connected then could I just run a jumper between SL and L?
[/i]

 

[Taylortwocities]

You must have a premananet live connection to the fan. If you connect the SL & L then the fan will only run when the light is on and you will not get the timer or humidistat functions.

L, N and SL connections may be available at the light itself, depending on how it has been wired.

Otherwise you'll need to get into that loft.

 

[andyste]

I currently have the new fan in situ, with its permanent live connected to the pull switch live (which is always "on"), and the fan's SL not connected to anything. The fan currently isn't working, so assumed I had wired it up wrong, hence my post here.

I've found that the fan comes on if I turn the humidity adjustment fully anti-clockwise. I then tried turning this back up by the tiniest of amounts (just enough for the fan to turn off), thinking this would now be on its most sensitive setting. However the fan doesn't come on when the room steams up. I've also tried a cup of steaming hot water directly under the fan but nothing happens!

Looks like an email to the manufacturer...

 

[Taylortwocities]

Where are you getting th eneutral from?

 

[andyste]

Where are you getting th eneutral from?

It's in the existing twin&earth that the old fan was wired up to. I haven't looked in the loft but assume the T&E goes back to the ceiling pull switch.

As soon as I explained the problem to the manufacturer they immediately offered to send out a new PCB, no questions asked, so perhaps they know something we don't.

 

[Taylortwocities]

I haven't looked in the loft but assume the T&E goes back to the ceiling pull switch.
.

It is unlikely that there is a neutral at the switch.

Whatever, you'll need a 3-core and earth cable with
perm live, neutral and switched live

 

[ban-all-sheds]

It is unlikely that there is a neutral at the switch.

Indeed.

But the fan must be getting a N from somewhere (hopefully the same circuit).

I've found that the fan comes on if I turn the humidity adjustment fully anti-clockwise.

 

[ban-all-sheds]

Whatever, you'll need a 3-core and earth cable with
perm live, neutral and switched live

No - he doesn't want a switched live, he just wants permanent L&N so that the humidistat can do its thing.

Which it sounds like he has, the problem being that the humidistat is not doing its thing.