Rant about bathroom extractor fans

[Andy]

Just had the bathroom refurbed and the guy installed a 4" extractor fan, which is brilliant for getting rid of the steam and moisture generated when having a shower. However, he tells me that the regs mean that this fan has got to be on the lighting circuit rather than the shower circuit.

Why?

When I'm getting up for work at 6.30am on a sunny summer's morning, I won't need the lights on - but the shower will still be pumping out moisture and steam. Similarly, when I go for a pee in the middle of the night I won't be putting the shower on so don't need the fan running, but because I need the light on, it'll run.

Surely it would make more sense for the regs to insist on these fans being fed from a fused spur unit on the shower circuit?

Rant over.

[MM]

You may wish to continue your rant later on a slightly different aspect of the extractor fan, namely when it's windy outside the slats keep flapping and drive me crazy when I have a bath (fan switched off). I keep meaning to build a shield or something to cover it up in windy weather, with maybe a step motor to open and close it from within the house. Why oh why couldn't the designers have thought of a lock mechanism to keep the slats rigid when the motor is off!

MM

[ARWadsworth]

So use a seperate pull switch for the fan and you get to decide when the fan is on or off.

Adam

[The Natural Philosopher]

Indeed. Mine runs straight off the lighting circuit, but not ONLY via the light switch. It *also* has a humidistat. So steamy daylight showers still cause it to cut in.

Other fans in windowless rooms are on timers. Run for a minute after the light goes out.

[geoff]

Because it costs money

[Andrew Gabriel]

What you describe exists, normally a few models up the range. I have them in my bathroom and ensuite.

[MM]

Yeah, another whole QUID! The house cost me £147k

MM

[Andy Burns]

The phrase to look out for is electrically operated or motor operated backdraught shutter, rather than airstream operated ...

[Toby]

If the guy who fitted it was doing it properly, then you should have a separate fan switch, probably outside the bathroom to isolate the fan. So you can turn this off when you go for a slash in the night :-)

...and if you do not have this, then complain, as it has to be fitted by law.

Not everyone has an electric shower, and you might use it to purge the room after a No2!

Also, if it was connected to the shower circuit, to be of any use it would need to be connected inside the shower unit, so the fan knew when the shower was actually being used, this is not a standard feature of an electric shower, and would have to be improvised, probably invalidating the shower's guarantee.

Toby...

[Mike Harrison]

Why would regs have anything to say about which circuit a fan is wired into? Provided it's fused correctly there isn't a safety issue - I suspect there is some misunderstanding going on here.

[geoff]

In message , Andrew Gabriel writes

There we go, as I said, it costs money

prolly 50p on top of the fiver it costs to manufacture the rest of the fan

[Mike Lane]

Andrew Gabriel wrote on Jan 2, 2010:

Yes, I have a Vent-Axia bathroom fan and the shutters open and close with quite a bang when it's switched on or off. They're obviously not just opened by the airstream, and there's no problem whatever the wind is like

[John Rumm]

Building regs insist that there be mechanical ventilation, but they do not dictate how it is powered.

There is no requirement for it to be on the lighting circuit (although this is frequently the best choice). It would often be difficult to power from the shower circuit.

That would make no sense at all. What if there were no shower circuit? Secondly wiring in extra terminations on a 6 or 10mm^2 cable is not a trivial exercise.

A humidistat operated fan is probably the best all round compromise. The addition of a manual pull switch triggered run on timer would be even better. That way it runs when there is moisture to clear or whn you ask for it.

[MM]

Could you post (here) the make and model so that I don't have to search for ages on Google? Thanks! Maybe it'd be easier to simply swap out the fan for one like yours.

MM

[MM]

The builder (here) must have used a cheapo model, since the fan is definitely not broken. The kitchen has exactly the same model of extractor fan and that beats its slats like billyho in windy weather (when switched off).

MM

[MM]

I don't have that problem, since I'm on my own and smelling your own stink doesn't seem quite so bad. I was with relations over Christmas and visiting the bathroom after someone else can be much more unpleasant. If I've been eating eggs and there's a slightly more whiffy odour than normal, then I just open the window for half an hour.

MM

[Huge]

I changed the "flappy slats" fan in our en-suite for a powered slats version because the back-draughts were unacceptable in windy weather.

[MM]

Meanwhile I've checked mine and it's a Newlec.

MM

[Pete Verdon]

My fan is triggered by a flow switch on the shower supply, or by a stainless pushbutton next to the toilet flush button. When either of these is activated it runs on a timer (adjustable, currently set for ten minutes). The time starts from when the input stops, so in the case of the flow switch the fan runs for ten minutes after you stop the shower (as well as indefinitely during it).

Might give someone some inspiration.

Pete

[chris French]

Sounds a good solution. Esp. the flow operated switch.

I had pretty much the installation that John describes in the old house, though IIRC the fan just stayed on permanently when switched, rather than on the timer.

The humidistat worked pretty well once tweaked to come on at just the right time.. It wasn't perfect - e.g. in heavy rain it would sometimes come on, esp. at night as the temp dropped. but a better stat would probably have managed that better.