Extractor Fan

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Hi all,     I have to install an extractor fan into our upstairs bathroom and have a couple of questions to anyone who might have done this:
    Firstly, should I drill from the inside going out or the outside going in? And secondly are there any unforeseen complications that the novice DIY person like me might miss and should I call a professional?
Many thanks Sam
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Just done this for the first time in my kitchen...
I would start on the outside. Spend some time working out whether both sides of the bit of wall you intend to drill through are actually clear. A drainpipe across the front of your fan will not help! Assuming you have cavity walls, I would make the appropriate size whole in the outer skin from the outside, then drill pilot holes through the inner skin so that you can see where the fan will be. Then, I would drill out the rest from the inside.
A handy hint: get a big cardboard box and duct tape it to the wall below where you'll be drilling. Stone dust is a pig to get out of tile grout etc. The box should catch most of it.
HTH, Al
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The minimum effort/maximum cost way is to hire a core drill and just bore straight through.
Minimum cost/maximum effort is to bore a number of holes then knock the wall out with a hammer and chisel.
As to 'inside out' or 'outside in' you may have to drill from both sides unless you have a very long drill.
Don't worry too much about damage around the hole, as you normally have a plastic surround on both the inside and outside to cover damage around the hole.
Complications - as stated in another reply, make very sure that there are no obstructions inside or out where you plan to drill. Also check that there are no services running down the inside of the wall. Do you have cavity wall insulation? I don't know if this is an issue - just had a vision of loose insulation pouting out of the hole :-(
Be careful working outside - an SDS drill can wallop a big hole in the wall but can also hurl you off the ladder with the recoil :-)
You should be fine DIYing it - just go cautiously.
HTH Dave R
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On 27 Oct 2003 02:56:34 -0800, snipped-for-privacy@conree.fsnet.co.uk (Caher) wrote:

If it is a cavity wall then drill a long thin hole thru first, then you can push the big drill thru from both sides to meet in the middle.
PoP
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On Mon, 27 Oct 2003 18:29:26 GMT, "ARWadsworth"
Right. 110mm or 117mm usually.
PoP
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One more question: Where should the power wire go - between the cavity and up into the loft? Thanks again.
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On 12 Nov 2003 02:35:53 -0800, snipped-for-privacy@conree.fsnet.co.uk (Caher) wrote:

Running power cabling within the cavity is not recommended. Some of the reasons include if the cavity is filled with insulation at some future point in time there could be a chemical reaction between the insulation and cable. There is also a consideration with regard to power rating and heat transfer. Hardly likely to be a major issue with a fan which is almost always low power (I'm assuming this fan doesn't have a heater built in), but could be later.
The fan should be a spur from the upstairs ring main, not the lighting circuit. And upstairs ring mains tend to come up from the floor rather than down from the loft. Note the word "tend", you can't count on it.
So you might want to think about coming down rather than going up.
Furthermore you should have the fan fed via a fused spur which has a 3A fuse. Don't connect it directly to the ring main because it's likely that the fan would burn out before it took the fuse (or MCB) down. It's a low power device.
PoP
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Why not from the lighting circuit? Isn't that the way to wire them if you want them to switch on automatically with the light switch (eg as in the case of an internal bathroom/toilet)?
David
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On 12 Nov 2003 16:11:38 -0800, snipped-for-privacy@hotmail.com (Lobster) wrote:

Actually....you may be okay with this. I was coming from the direction that "appliances" should be fed from ring circuits (or spur...), and lights from lighting circuits. But I haven't seen anything written on tablets of stone to advise that it has to be that way.
Not that a fan is an "appliance", but if it is generating light then I would assume it might have a problem ;)
PoP
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Because Murphy's says that if it is going to fail it will do so at night :)

In this case the fan has two live connectors. One to power the fan and electronics and one connected to the switched live feeding the lamp(s).
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Thats the way we wire them. From the bathroom fitting we take a 3core and earth (6243Y) to a 3 pole fan isolator (outside of the bathroom) then another 3core and earth to the fan itself. The 3 core carries a permanent live, a switched live and a neutral.
--
Gary
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I would have thought that your idea is bloomin' dangerous - by connecting the "permanent live" to the sockets and the "switched live" to the lights the fan is in effect connected across two separately fused circuits and a fault at the fan may not cause enough current to flow to blow both fuses. Also consider the case where the fan actually connects "SL" to "PL" internally, perhaps in a fault condition (who knows what the electronics do?). In this case you have created a huge circuit, partly wired in (usually) 2.5mm cable, partly in (usually) 1mm cable and protected by what amounts to probably a 38A MCB (32A+6A). Not only that, but you have bridged the two neutrals too and this could cause big problems if, as is often the case these days even upstairs, your sockets are wired via an RCD but your lights are not.
The only instance where I would consider spuring a typical run-on fan from a sockets circuit would be where the fan is controlled in some way *other* than via the light switch. It may have its own pullcord, or a door switch, or it may be controlled by a humidity sensor or even a PIR.
Hwyl!
M.
--
Martin Angove: http://www.tridwr.demon.co.uk /
Don't fight technology, live with it: http://www.livtech.co.uk /
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Hi
I think these extractor fans are not a good solution anyway. Theyre not particularly effective, theyre noisy and annoying, and the bearings are guaranteed to deteriorate making them very noisy. And they simply throw your heat away.
Alternatives are:
HRV, which costs very little more, works like a fan but recovers most of the heat.
A window lock enabling it to be locked 1/4" open - good, effective and free for most of the year, but not so good for the coldest few months.
Dehumidifier - a bit more to install, much more efficient, doesnt ventilate or lose any heat.
Finally the simplest option of all, an adjustable vent. Easy, cheap, simple, no run cost, and effective year round.
Anything but a fan, they are just the worst option.
Regards, NT
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"Martin Angove" wrote | > In this case the fan has two live connectors. One to power the fan | > and electronics and one connected to the switched live feeding the | > lamp(s). | I would have thought that your idea is bloomin' dangerous ... | consider the case where the fan actually connects "SL" to "PL" | internally, perhaps in a fault condition (who knows what the | electronics do?). In this case you have created a huge circuit, | partly wired in (usually) 2.5mm cable, partly in (usually) 1mm | cable and protected by what amounts to probably a 38A MCB (32A+6A).
And if the lighting circuit in the bathroom and the socket circuit borrowed from (because there shouldn't be a socket circuit in the bathroom ...) happen to be on different phases ....
Owain
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"Martin Angove" wrote in message

Another reason will become clear if you consider that the ring circuit might be fed via an RCD and the lighting circuit not...
More fundamentally though it violates regulation 314-01-04 which says that the wiring of final circuits must be kept electrically separate.
I can't find the beginning of this thread, but whomever it was that said:

wants locking up.
--
Andy



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On Wed, 3 Dec 2003 07:53:54 -0000, "Andy Wade"

Guilty as charged :)
However, I don't see what you are getting at with your comment.
PoP
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Which comment? Elucidate and we will expand.
Hwyl!
M.
--
Martin Angove: http://www.tridwr.demon.co.uk /
Don't fight technology, live with it: http://www.livtech.co.uk /
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On Wed, 03 Dec 2003 15:59:08 GMT, Martin Angove

Locking up..... :)
I was under the impression that fan circuits would be run as a spur from the upstairs ring. I guess I'm basing that assumption on a previous house I owned where I know that was the arrangement (and I didn't wire that property, it must have been before the 16th ed came out).
Could you please explain what is wrong with running a fan circuit as a spur from the upstairs ring? I would assume from a technical standpoint that providing it is properly fused (that is, minimum fuse rating - 3A?) and appropriate cabling is employed then it would meet the requirements of the 16th edition regs. Having got my 16th edition regs certificate earlier this year I'm wondering what I've missed!
Always willing to learn....
PoP
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On Wed, 03 Dec 2003 16:40:31 +0000, PoP wrote:

Here are two resons: 1) It mmight not be obvious to someone that supply is from the upstairs ring rather than the downstairs lighting. Not withstanding that there ought to be a service isolator for the fan.
2) If the fan is the sort that requires both permenent and switched live supplies (such as timed overrun models) then you will have also to supply switched live from two seperate circuits. Which not only is contrary to the regs but poses hazards for maintainers and might even make two circuts have common live connections through the fan timer circuits.
--
Ed Sirett - Property maintainer and registered gas fitter.
The FAQ for uk.diy is at www.diyfaq.org.uk
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