Bathroom extractor fan - advice

[mattysk]

Hi there

I'm planning on installing a bathroom fan. Does anyone have any advice?

I don't really want to cut my window and the external wall is pretty much all window. I think I'll go into the ceiling and then along a bit and out of the soffit.

My specific questions are:

Are ther any regulations? Do I need a professional to do the electrics? I've read that you can't put it above the bath but are there any other rules?

Is it OK to just vent out of the underside of the soffit? Or could that mean the air could condense back up the pipe?

Any other help appreciated!!

Thanks!

 

[mattysk]

Reading around it sounds as though venting through the soffits could cause the water to back through soffit or roof vents. This sounds sensible to me but going through the roof would need a professional. Also it sounds as though the electrics would be "part b" so need a qualified electrician.

Sounds like this may be too expensive to do right now...

By the way, one of the reasons I'm doing this is that I suffered from bad consensation in the loft last winter so I'm being extra careful about what I do with this! I had some great advice on this forum about moisture levels in the house but I'm looking to put this issue to bed.

Appreciated!

 

[JohnD]

if the electric fan is inside the bathroom, then it is subject to Building Regulations and is Notifiable.

If it is outside the bathroom (for example in the loft) then it is subject to Building Regulations but is not notifiable.

A fan in the loft can be more powerful since there is more room for it, and it can be installed in a way that makes less noise.

Any ducting in the loft must be insulated to prevent condensation inside the duct. This can be done by wrapping it in loft insulation. The duct must slope down towards the point of exit so that any condensation runs out of the house and not back towards the fan or bathroom. Rigid smooth duct (such as soil pipe) traps less condensation and fluff than convoluted hose.

 

[mattysk]

Thanks JohnD - its you who has helped me out in the past so thanks again!

Excellent advice about the regs as that was confusing!

I'm going to ask a stupid question here. What stops water from going back down a fan if the fan vents vertically out of the roof or even if it goes up into the loft and then along and out a slope? Is it simply that the water hasn't condensed at that point so gets out before condensing?

Also, do you see an issue with using the soffit? - Would it just try and rise and potentially come back through the ridge tiles or any soffit vents?

I do have a gable end - (about 12 ft away) so perhaps I'd be better running a pipe along there?

(thanks again)

 

[JohnD]

if the fan vents vertically, water will run down. People try to put in water traps and drain hoses.

if the fan is just above the ceiling, the fan and its stub will usually be fairly warm so will not suffer from condensation as much as the duct.

 

[noddy997]

When we got an extractor fitted many years ago, which i checked recently, it goes from the shower room ceiling in to the loft and doesnt go out anywhere, but has a long pipe... is this a cowboy job?

 

[Spark123]

Yes - it needs to vent outside. Putting warm humid air into an unheated loft space is asking for damp problems.

 

[mattysk]

thanks again for the advice JohnD.

Does anyone see a problem with venting out of a soffit. Getting a roofer in to put a hole in roof is a bit expensive.

I am end of terrace but the outside wall is directly next to someones garden so after a 12ft journey from fan to outside, I'm guessing the water would condense and start dripping out?

Also getting through the wall could be difficult?

 

[mattysk]

Oh and "noddy997" - I'm no expert on this but I did have trouble with condensation in my attic last winter so I'd say that adding any more moist air directly into the attic is just asking for trouble.

 

[JohnD]

you can hire a core drill to make a hole in the wall. If you flop loft insulation over the duct, that will keep it warm enough to prevent much condensation. The duct does need to slope downwards towards the hole in the wall.

 

[SaladFingers]

Also it sounds as though the electrics would be "part b" so need a qualified electrician.

Why do you say it comes under fire safety regulations?

Can't see why

 

[mattysk]

@saladfingers and @johnD,

Could you point to anywhere online that says that I don't need a qualified electrician to fit the fan in the loft? It would be good to see what the regs are.

I'm getting a quote from my plumber to install the fan - he's happy to do the electrics but doesn't know what the regs are.

MUCH appreciated!

 

[rjm2k]

What kind of roof do you have? It may be fairly simple to fit a vent tile, since you are talking about cutting a hole in your soffit anyway you probably would be within reaching distance to change a tile over.

A loft isn't a special location part P wise, but It would be interesting to see how you would connect it up without hooking into the bathroom electrics. I guess if the light switch is outside the bathroom and has switched/perm live and neutral then technically you could hook the whole thing up without touching the bathroom electrics at all.

 

[mattysk]

Thnaks, rjm2k - they are redland stonewold mk 2 tiles - I know this as someone kindly told me on another (semi related) thread

[url]//www.diynot.com/forums/roofing-guttering/ventilation-tile.348522/[/url]

It's interesting what you say about the electrics. Ideally, I think I'd actually like an off on switch outside the bathroom with an over timer. That way we can switch it off exactly when we want and don't need to switch the light on.

The bathroom light switch is in the bathroom.

Would this also mean that the electrics wouldn't need to have anything to do with the electrics in the bathroom?

Thanks!

 

[rjm2k]

With the setup you describe, if you use a loft mounted extractor which has ducting to the bathroom ceiling and also takes it's power from say the landing light rose plus has the switch outside the bathroom then as a non-expert I would assume part p wasn't needed since you aren't doing anything in the bathroom itself to do with electricity.

But I'm not an electrician, and tbh it probably wouldn't actually cost that much to get one in if you needed to .

Also, personally I'd go for either a vent tile or hole in the wall rather than going through the soffits.