Replacing a Bathroom Extractor Fan

[leevis]

Hi All
Another task I have is to replace a bathroom extractor fan, the current one is wall mounted.
The current one that this there is rather noisy and comes on with the light. This would be ok with a new one as I would get one that is silent (or at least quieter than whats there at the moment).

How difficult are these to connect up? I haven't taken the existing one out yet but I am assuming that these are just a straight replace the wire and go if I want it the same as it is as the moment.

I have seen, though, some that have a timed run off, do these require additional wiring?

Also, saw some that have a humidistat which look very interesting in that they only go off when they need to which would appeal to me quite a lot however, this must require some additional (quite a lot) of wiring and I would guess that there needs to be some form of isolation outside of the bathroom for these which might be troublesome. Are they worth the agro?

 

[ban-all-sheds]

If your current fan is 230V, and does not have a timed overrun or humidistat then you'll need to change the wiring, as it will need both permanent and switched L, as well as N & E.

If it's 12V and ditto then only the wiring to the transformer will need changing.

Re humidistats - never had one, but my instincts have always been that they aren't going to work very well, and I've seen quite a few people here confirming that.

 

[leevis]

I think that its a 230V one, but this is based on the fact that there is no transformer.
Would it be a good idea to re-do the whole of the wiring to the new one - I guess it will need to be 12v these days
Also, where does the transformer normally go? above the ceiling and in the void?

 

[Taylortwocities]

A 12v transformer is not necessary unless the fan is located very very close to a bath or shower (see bathroom zone in the WIKI for guidance).
It is not necessary to change the wiring if you are using the same type of fan, and the wiring is OK. An easy option is to pop the cover off the existing fan and report back the connections and make and model of the fan. Or take a photo and post it on here! We could then advise more effectively.

PS I concur with BAS, Humidistat fans are not an exact science. In my experience they seem to be either on too much, or not at all. Humidistat fan not needed unless you have a specific moisture problem (ooh Matron!)

 

[ban-all-sheds]

I think that its a 230V one, but this is based on the fact that there is no transformer.

Unless it's tucked away in the ceiling void?

Would it be a good idea to re-do the whole of the wiring to the new one

Do you want one with a timed overrun?

I guess it will need to be 12v these days

Not necessarily - which Zone is it in?

Also, where does the transformer normally go? above the ceiling and in the void?

Can do, as long as it's accessible, and a future owner can easily find it.

Some are made to fit standard back boxes and can go on the wall or ceiling.

 

[leevis]

Been into the void and didn't see any trace of a transformer

From what I have investigated so far, it will be in Zone 1 although might be Zone 2 as its on the wall where the head of the bath will go but not too sure how high it is as yet.

There is a bit of a problem with moisture in the bathroom, but this is likely to be because the existing fan is rubbish, a timed run off or at least the choice of a timer would be nice (as long as its easy to change).

Probably not going to go down the humidistat route as it looks to be a little problematic from what I have read. Although that being said, there are many times where someone will have a bath without the lights on (during day etc) and having the fan being able to detect this and turn on would be very advantageous so I will keep investigating it. On these humidistat ones, is there a way to turn it off if it becomes a pain?

 

[EFLImpudence]

There is a bit of a problem with moisture in the bathroom, but this is likely to be because the existing fan is rubbish, .

Or not - they are not magic.

there are many times where someone will have a bath without the lights on (during day etc)

That almost certainly implies that you have a window. Open it - far better than a fan.

 

[leevis]

Therein lies another problem, need to get another handle to open it but the spindle is all bent up and cant work out where to get a replacement but that's in another post lol. Difficult for kids to open the window though

 

[leevis]

OK, wife wants fan with Humidistat
Lets say that the current fan is a direct 230V, I can remove all of this but I have read that there needs to be an isolation point outside of the bathroom for these - is this true? Right outside I already have a switch for the lights on the stairs (loft) which I would rather not move if possible so there isn't the room for a switch out there (although it would be great to have these on the outside). Where exactly does the isolation switch have to be? Does it have to be outside the bathroom or can it be put in a different zone?

 

[jj4091]

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

 

[ban-all-sheds]

OK, wife wants fan with Humidistat

Try to resist the "I told you so" when she finally accepts that they don't work well enough to be of any use.

 

[leevis]

Yeah I know, written in the stars but what can ya do.

I still am not understanding where the isolation point needs to be on one of these (outside the room or in a corner)?

 

[EFLImpudence]

The switch may be anywhere switches are allowed.

You do not have to fit one if you don't want to.

As I like to say in theses circumstances regarding humidistats, according to BBC weather the RH here today is 94%.

 

[leevis]

OK, was doing some more investigation on this wiring this weekend and I have found that the metal conduit that I have previously identified as the power coming IN is not and is in fact the conduit going to just the light switch in the Toilet. What I have ascertained and I need to check this is the power comes in from another room.
This kind of makes it a bit easier for me as I can now not worry about the lighting in the other rooms and basically disconnect everything in the toilet/bathroom and start from scratch.
The issue that I have at the moment (and its not really an issue - just my musings) is that the existing Extractor fan is connected up to a junction box and then routed to a switch etc. What am I likely to find when I take the old fan out connection wise? The new one needs a Live, Neutral and Switched Live, I am assuming that this would (or is very likely to have) the same connections in the existing fan - does that sound correct?
What I mean is I don't want to have to chase the wall if not necessary but not sure.
L

 

[jj4091]

No because your previous posts suggest your current fan goes off with the light so you won't have a permenant live for the timed side of the new one.