Extractor fans

"Trevor Smith" wrote | I am fitting an 4" extractor fan in the bathroom wired from a junction box | on the lighting circuit so does it still need a double pole isolator | switch?.

Yes, it needs an isolator for mechanical maintenance.

If you are using a run-on timer you will need a triple-pole fan isolator switch. You might as well use one anyway, as they have a little fan symbol on and can be locked off, which is required if they are not 'under the control' of anyone working on the fan.

Owain

If you have no external wall there you need one, but otherwise I wouldnt bother. People often fit these in the hope it will clear smells or damp, but really theyre fairly useless. A far more effective alternative is a locking mechanism that allows the window to be locked securely 1/2" open when wanted. 4" fans get noisy over time, waste electricity, throw heat away, and are simply ineffective.

Regards, NT

If you have no external wall there you need one, but otherwise I wouldnt bother. People often fit these in the hope it will clear smells or damp, but really theyre fairly useless. A far more effective alternative is a locking mechanism that allows the window to be locked securely 1/2" open when wanted. 4" fans get noisy over time, waste electricity, throw heat away, and are simply ineffective.

Regards, NT

Have you had experience of humidistat control? If damp is the issue, it should be the cure and I'm thinking of fitting one, but I completely agree with your point about wasted heat.

As I see it there are three ways around the heat thing:

2: use one of those rather expensive in-wall heat-exchanger things. Looks like an ordinary 4" (or 6") from the inside and outside, but in reality is an air exchange unit which uses the heat from the outgoing air to pre-heat incoming air;

Hwyl!

M.

On Tue, 18 May 2004 00:58:36 +0100, in uk.d-i-y Martin Angove strung together this:

They're not that expensive actually, I usually get them for about £120ish.

Well, its upto you of course. I was just saying that IME 4" fans are rubbish at controlling damp.

The advantage with the window option is that it uses no lectricity, is silent, and will last a lifetime. Yes you still lose heat: a dehumidifier is the only way to not lose heat.

I'd consider putting a dehumidifier in the room. Cheaper than £120, no heat lost. Be sure to observe the extra wiring requirements for electricals in a bathroom.

Regards, NT

I didn't really look to hard at these things because of the price difference (I will probably fit 4" humidistat cheapies from Screwfix - £29.99) which adds up to quite a lot if you are fitting more than one or two, but I'm sure I saw a model which was 4", some manufacturer beginning with "B" on a stand at the 2003 NEC H&R show.

Great idea, will have to save up for a few when we build :-)

Hwyl!

M.

Mmm... but under what circumstances? A 4" on a 10 minute run-on timer isn't going to shift any appreciable amount of humidity from anything except the smallest bathroom, but unless the room is very large or the installation very leaky (so that air is short-circuited around the fan) surely a humidity controlled fan would work, eventually? At £30 and requiring nothing more than a DP switch from the lighting circuit it's a bit cheaper and easier to install and maintain than a dehumidifier too.

As you say, personal preference, though in my case budget counts for a lot too :-)

Hwyl!

M.

The basic problem is that it doesnt work.

The secondary problems are noise, energy waste due to run power plus throwing all your warm air away several times over, which is the only way these could ever dry the room out.

Regards, NT

I've never seen the equivalent in the UK, I don't understand why.

Regards Capitol

On Fri, 21 May 2004 21:37:36 +0100, in uk.d-i-y "Capitol" strung together this:

No I didn't.