How do we stop extractor fan coming on with bathroom light?

apples1

In our bathroom the extractor fan comes on when we turn on the bathroom light (using pull cord). When we turn the light off the fan remains on for AGES! Can we change it so fan is only on when the light is on and stops when we turn the light off?

If so - how?

tooconfused_2

The fan is on a run on timer on the body of the fan somewhere there might be a little Knob or screwdriver slot to enable the time to be turned down but if you want to turn the fan on independantly you would have to wire it through its own switch or dependant on the model of fan you might be able to wire it just when the light comes on .This type of fan will have 3 connections a neutral a permanat live (which powers the timer when the light is turned off ) and a switched live from the light switch

mercurystar999

You would usually have to take the front off the fan to turn the timer down. You would need to change the cables in the fan around to have it on solely when the light is on.

How confident are you of doing this?

FilthyLuka

Also before you start making changes consider the reason the fan on a timer has been installed - you dont want to make yourself a problem

normally the fan comes on with the light and stays on a little while longer because the bathroom doesnt have an opening window that you can let steam and toilet smells out of.

if you dont have an opening window then you may be left with stinks hanging around a fair bit longer and you could get condensation if the steam isnt ventilated out

I suppose you could leave the fan on to get rid of these but then you would be using more light and have to remember/hang about to turn it off again

MarkyMarkD

I believe that it's a building regulations requirement to have such a linked fan for any bathroom/toilet without a window for the reasons that others have mentioned.

It's not a very simple wiring job to get it to operate separately; you need to put in a new switch (pull-cord as it's a bathroom) and connect the power to the fan via that, rather than via the light switch.

mercurystar999

No new switch required.

Cagey

If the room does not have a window then you must have a run on timer on your fan but it should be a simple task to turn the fan to the lowest setting ,probably about a minute. It is easy to convert the fan to only run when the light is on but I would not recommend anyone who is not qualified to do it.

ollyk

Cagey wrote:

If the room does not have a window then you must have a run on timer on your fan but it should be a simple task to turn the fan to the lowest setting ,probably about a minute. It is easy to convert the fan to only run when the light is on but I would not recommend anyone who is not qualified to do it.

From 2005 it is also illegal for any layman or even a fully qualified non part p regestered electrician, to touch bathroom electrics now due to new [STRIKE]tax's[/STRIKE] regulations.
But anyway by removing the permenant live supply, and only connecting the switched live (from the lights, via a FSU of course) to both the live and switched live input of the fan you will get a fan that switches on with lights and off with lights. simple. But not if you don't know what you are doing and not if you don't want to have a bathroom full of black grout / sealent and a stench of mildew.
The trimmer for timing is normally within the unit behind a small hole, near all the wires, as people have said but you need to be absolutly sure everything is dead (supply and switch live) before you touch this. Also is the fan a posh one with humidity control?

YorkshireBoy

ollyk wrote:

From 2005 it is also illegal for any layman or even a fully qualified non part p regestered electrician, to touch bathroom electrics now due to new [STRIKE]tax's[/STRIKE] regulations.

Not strictly true. Part P covers only 'extensions' to circuits in special locations (of which a bathroom is one). The home owner/DIY'er is allowed to 'maintain' and 'repair' the accessories within the bathroom. This would include the replacement of a switch or light fitting (crazy I know!) - and may even include the like-for-like replacement of an extractor fan.

But anyway by removing the permenant live supply, and only connecting the switched live (from the lights, via a FSU of course) to both the live and switched live input of the fan you will get a fan that switches on with lights and off with lights.

It's possible that, on some models, simply removing the permanent live from the fan terminal block will suffice. Whether this contravenes Part P's alteration criteria is a grey area in my opinion.

simple. But not if you don't know what you are doing

Agreed.

The trimmer for timing is normally within the unit behind a small hole, near all the wires,

Adjusting this would best/safest option, but only after isolating as stated below.

...you need to be absolutly sure everything is dead (supply and switch live) before you touch this.

A lot of people are killed or seriously injured because they didn't 'realise' that there was a permanent live in the ceiling rose/on the fan etc. So, the essential safety message here is to switch off the main switch at the consumer unit - not the light switch. There may/should be a fused connection unit (FCU)/3-pole switch outside the bathroom door and normally above it, but I'd always recommend the DIY'er isolates at the consumer unit instead (just in case another DIY'er installed this FCU/3-pole switch! :eek:).