Bathroom extractor fan

[tommyl18]

Hi im fitting a new extractor fan to a bathroom and want the fan to come on when the shower pull chord is pulled and vice versa.

The instructions state it needs to be on a double pole fused spur with a 3amp fuse

the house has been rewired and the shower is on its own mcb.

Can i wire it straight into the shower pull chord or do I need to have the extractor wired with 2.5mm twin and earth to fused spur then to the pull chord?

Thanks

 

[sparkwright]

There's no simple way to feed a fan off a shower circuit.

The simplest way is to supply it from the lighting circuit;

Either a timer fan than comes on with the light, and runs for a short time after you switch the light off
or
So the fan comes on and off with the light
or
Fit a separate switch (eg pull switch) to control the fan.

The shower pull switch is not really to be used every time you have a shower, it's for maintenance.

Adding things to a shower circuit is a bit of a grey area, and there is never often any need to anyway.

You could supply the fan from a nearby socket circuit via a 3 amp fuse if access to the lighting is difficult.

 

[ban-all-sheds]

Can i wire it straight into the shower pull chord

No.

or do I need to have the extractor wired with 2.5mm twin and earth to fused spur then to the pull chord?

No.

The problem is that you cannot get 2 conductors of the size they need to be into the terminals of the shower switch.

To do what you want you'll need to have the shower switch use the lighting circuit to control the fan and a contactor which switches the shower circuit, or put a flow-switch in the water pipe to the shower.


Are you aware that all of this is notifiable?

 

[ban-all-sheds]

The shower pull switch is not really to be used every time you have a shower, it's for maintenance.

There's no reason why you can't though, if you want it to control something else as well.

 

[ianblue]

Other possibilities are an occupancy sensor( motion sensor). No jokes please , we've had them all before or a humidity sensor. The latter sounds ideal but in actual fact I have tried it and although I used a very good quality humidistat I found that by the time it had cut in the walls were already getting damp.
The flow switch sounds good but sounds a bit difficult to arrange.
The occupancy sensor is what I have at the moment and works well, it has a run on timer and obviousy covers every use of the bathroom

 

[ban-all-sheds]

Bit of a pain, and a waste, to have the fan come on if you only go in there to wash your hands or brush your teeth though....

 

[ianblue]

We have a pull cord so that it could be cancelled if desired but in actual fact when we wash our hands in the bathroom we have usually done something else when the bathroom benefits from a purge. We also brush our teeth after showering in the morning.
Its nice to have a bathroom which always smells fresh even after visitors have used it. So in practice we leave it on standby.
I suppose it all depends on the individuals who live in the house and how they use it.
ps Just thought about what ban-all-sheds said " Bit of a pain". Yes I can understand that if one had a noisey fan it could result in a headache. I have used a centrifugal fan which is actually in the loft some distance from the bathroom and which is ducted. I have a heat recovery setup there, so the fan is barely audible in the bathroom.
The best exhaust "fan" I ever had was in an old victorian house where I tapped into a disused chimney. No fan was needed just a cord operated flap valve and the upward draught did the rest. Silent and ecofriendly!

 

[tommyl18]

to clarify the wc is in another room so only basin and shower in the room and dont want the extractor on everytime i turn the light on. So if I come off the light circuit I can use a pull switch to isolate the fan if I dont want it on then I would need to run it to a fused spur before it goes to the extractor?

 

[ban-all-sheds]

//www.diynot.com/wiki/electrics:fan

 

[cherryred]

Here is another neat little way to operate your exhaust fan when the shower is switched on.
Its a current sensing device which sends out a signal which could switch a low voltage relay.
Its non-invasive (you don't need to come into electrical contact with the main shower cable.) And it would not need to be in the bathroom.
Just something that would interest an electronics diyer.
Only thing I expect you would want a run timer.
Well again that would interest our electronics diyer.

http://www.ebay.co.uk/itm/0-100A-In...ponents_Supplies_ET&hash=item2a165070baCheers
John