Installing a wall vent fan
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Gad-Westy

Original Poster:

16,193 posts

236 months

Friday 17th September 2010
quotequote all
Our bathroom gets fairly damp and being a ground floor flat, we can't really leave the windows open during the day. I want to install a wall vent (can't use a ceiling vent as there is another flat above us) that operates on a timer connected to the light wiring. I have a reasonable idea of what is involved but have a few questions on the details if anyone can help. Bear in mind I can't access the ceiling void from above.

My rough plan is:

Use core-drill to make appropriate sized hole for fan unit roughly in line with the ceiling light fitting through external wall to the outside world.

Cut away a large access hole in the ceiling above the fan hole so that I can drill a second small hole into the wall cavity above the height of ceiling.

Feed wiring from light fitting in centre of ceiling through to my access hole and then down into wall cavity until it appears at my fan hole.

Wire fan up and install on wall.

Connect fan wiring to light fitting.

My questions are:

1. Does the above look like sound methodology?

2. In terms of the legalities of wiring this in myself, I presume I would have to get the wiring work signed off by an electrician with the appropriate qualification? Or can I not do the wiring myself full stop?

3. Are the timer units built into the fan units by convention or do I need to find a home for one of those as well?

4. How do I repair the great big hole in the ceiling that I will have cut out?


andye30m3

3,496 posts

277 months

Friday 17th September 2010
quotequote all
Timer units are built into the fans,

You'll also need to put an isolator switch outside of the bathroom, often found above the bathroom door in new builds.

Gad-Westy

Original Poster:

16,193 posts

236 months

Friday 17th September 2010
quotequote all
andye30m3 said:
Timer units are built into the fans,

You'll also need to put an isolator switch outside of the bathroom, often found above the bathroom door in new builds.
Feck, more holes!

Smiler.

11,752 posts

253 months

Friday 17th September 2010
quotequote all
andye30m3 said:
Timer units are built into the fans,

You'll also need to put an isolator switch outside of the bathroom, often found above the bathroom door in new builds.
And OP in case you're not aware.

For the run-on timer function, you need a non-switched feed as well as the switched feed from the light.

The above isolators are 3-pole.

Gad-Westy

Original Poster:

16,193 posts

236 months

Friday 17th September 2010
quotequote all
Smiler. said:
andye30m3 said:
Timer units are built into the fans,

You'll also need to put an isolator switch outside of the bathroom, often found above the bathroom door in new builds.
And OP in case you're not aware.

For the run-on timer function, you need a non-switched feed as well as the switched feed from the light.

The above isolators are 3-pole.
I don't know how I didn't think of that. Presumably the live feed can come from the light switch? The wiring is all starting to sound a little involved I must admit. Maybe I should get a quote from a pro.

B17NNS

18,506 posts

270 months

Friday 17th September 2010
quotequote all
As said the fan will need an iso, outside the bathroom door is a good place.

Should really be installed by a pro. All work in bathrooms is notifiable.

Might be worth spending a little extra and gettingva fan with a humidistat built in.

Shame you can't squeeze an in-line fan in through, quiet as a mouse.

hairyben

8,516 posts

206 months

Saturday 18th September 2010
quotequote all
Solid Wall mount fans are normally fairly quiet. hollow walls, ceiling etc are where the noise issues begin.

For evan quieter try the airflow quietair range.

Isolation can be provided using a ceiling mounted pullcord isolater anywhere convenient which can save mess when retro fitting.

Electrical work in a bathroom needs approval, best to use a spark if you're not sure, a decent spark won't mind you doing the prep work/making good and just connecting the thing.

smn159

15,102 posts

240 months

Saturday 18th September 2010
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B17NNS said:
Might be worth spending a little extra and gettingva fan with a humidistat built in.
I would do this. You only really need the fan when someone uses the shower or bath, and to have it running every time the light goes on can be a pain in the arse.

DrDeAtH

3,678 posts

255 months

Saturday 18th September 2010
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....and then test and notify the job as it falls under part 'p' of the building regs......

rfisher

5,050 posts

306 months

Saturday 18th September 2010
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Do you need an isolator switch for a fan in a downstairs toilet?

Smiler.

11,752 posts

253 months

Sunday 19th September 2010
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rfisher said:
Do you need an isolator switch for a fan in a downstairs toilet?
Yes