Extractor fan installation, Thoughts ?

dnme

I have a very damp bathroom. It has a wall vent which does nothing to alleviate the moisture apart from make the place bloody freezing. I don't really want to fit a fan in the existing wall vent as it is in a poor location away from shower unit. I am thinking of putting in an extractor fan. I am toying with the idea of a fan into the loft, vented out to facia / soffet.

I am just wondering about how I would go about wiring / powering this. The bathroom has an outside light switch powering a single central light and a second mains line powering a shavers light. The walls are drylined and the attic is directly above.

Could I run power from one of these and if so, how? could you describe the cabling run to me? Any other advice greatly appreciated.

Many thanks

Buford T Justice

Use the live and neutral present in the light fitting in the center of the room, that way when you switch on the light, it will switch on the fan too.

There are two types of fans, standard ones and ones with a timer that stay on for x amount of time after the light has been switched off.

If you use a timer fan, you will need to find a permanent live in the attic and use that as well as the above.

If you have difficulty understanding what I have said above, then I would suggest you call an electrician

fred funk }{

Above is correct but personally I'd give the fan it's own supply because they're noisy and late at night when you want just the light on it could be irritating.

I'd take a feed from the shaving light and get a fan with a pull cord.

cnocbui

The fan noise with lights on issue can be solved by fitting a humidity controlled fan. They have a sensor which measures the humidity in the air which turns them on when it reaches a set level - which is adjustable.

I have fitted these in both the main bathroom and en-suite. I took power off the light circuit for each room.

They don't come on just because a light is turned on but they can run for a good while at times of high humidity in summer.

I installed mine on the existing room vents. It wouldn't matter a jot if the existing vent is not near the shower. Mine is as far away from the shower as is possible in a fair sized bathroom - shower is immediately inside the door - and it has no trouble comming on and clearing the whole bathroom.

if you fit a fan that vents via the roof space you could exacerbate the cold air problem as the fan will cause an air pressure drop in the bathroom which will suck cold air straight in via the wall vent, especially if the door is closed.

Step out of the nice warm shower into the rest of the bathroom now chilled to arctic levels - no thanks!

Given how long my humidity controlled fans can stay on for, I would say having one wired to the light switch may not have it on for long enough to do the job properly.

It is pretty easy to get power to the wall vents by chasing a slight channel from the ceiling to vent opening with a cold chisel and then plastering the cable into the channel.

dnme

OK folks but in all the posts above, the fan would be dependent on the light being on no?

I was hoping to have the fan independent and either automatic (sensor) or with it's own switch. Even if I take power form the shaving light, wouldn't that be dependent on the shaving light being switched on?

Buford T Justice

It depends on what way you want it wired. If you get a humidity sensor one you can just use a permanent feed and let it work to its own devices. As with the switch, its just a common way of controlling them

You can also get vents that open and close covers built into them so when they are off they prevent draughts coming in, but the cowl that you fit outside will also be a factor in draughts

dnme

So if I use either light circuit, then it will only work when light is on is this correct? If I use a dedicated circuit, how is this wired?

indie armada

to help eleviate noise you could fit an inline fan kit. the fan istelf is fitted up in the attic on a rafter and one duct goes to the outside and another goes to the batroom. because the fan is on a rafter and not directly connected to the plaster board of the ceiling it is much quieter.
to switch it you should take a feed, live neutral and earth down to a new switch outside the bathroom and use either a fan isolating switch or a 20 amp double pole switch. you could also retro fit your existing switch to become a double and using a grid type system have both switches beside each other on a single plate.

indie armada

dnme wrote: »

So if I use either light circuit, then it will only work when light is on is this correct? If I use a dedicated circuit, how is this wired?

you can take a feed directly from the fuse board or tap into the feed comming from the fuse board to the light. if you take off the switch for the bathroom light and there are only brown wires then there is probably a junction in the attic above the light where the original feed is, if behind the switch you have a bunch of cables with all the blues connected and the browns in the switch then thats where the feed is.
thats a rough idea but if not sure call a sparks or somebody who is sure of what there doing.

cnocbui

dnme wrote: »

So if I use either light circuit, then it will only work when light is on is this correct? If I use a dedicated circuit, how is this wired?

No, I wired my fans to be permanently powered, the light switch plays no part. Iocated the wires for the lights, turned off the power - obviously - cut the wire that feeds the light switch and used junction boxes to add a parallel circuit that runs to the fans.

The fans come with a second way of wiring them so they are constantly powered but will also turn on with the light switch - a manual overide if you like. I personally didn't want that.

paddy147

indie armada wrote: »

to help eleviate noise you could fit an inline fan kit. the fan istelf is fitted up in the attic on a rafter and one duct goes to the outside and another goes to the batroom. because the fan is on a rafter and not directly connected to the plaster board of the ceiling it is much quieter.
.

+1 to the above.

the man speaks the truth here.

The plumber and electrician fitted normal ceiling extraction fans into my new bathroom and ensuite,and they worked via the light switches.

problem was the noise from the fans was fairly noticable,especially at night and going to bed.

So I got them changed over to the inline units that have an adjustable timer in them,where the fan motors themselves are up in the attic space above the ensuite and bathroom,and its just a flexible ductiing pipe and vent in the bathroom and ensuite ceilings now.

Difference is unreal,allmost cannot hear them on any more.

Best thing I have done.:)

dnme

Found this as well which really helps explain circuit layouts. May be of use to others.

https://www.youtube.com/watch?v=0MLshqOmltU