What type of extractor fan ?

[ss]

History: Small 6 x 6 foot shower room mostly used by my wife (I use main bathroom) the room has black mould issues due to condensation, the only window is approx 2 feet tall x 6 inches wide and normally she will forget to open it, and rarely sqeejes down the tiles in the enclosure as she dashes off to work. it is due a remodel and I want to install an extractor fan. this to be located as part of the top of the window which will be next to the shower enclosure. Other options not reall viable, like directly above the shower enclosure. Now can someone explain the humidity sensor as that is what I am prefering as my understanding is the fan will be switched on through the lighting circuit but only come on if humidity is present and also have a delayed timer as in a shower but not if just using the loo, is this correct? Should I just get a timed extractor fan that always comes on when the light is turned on? Noise factor not an issue.

Any guidance appreciated.

[Tim Watts]

Either way is good.

The humidistat will avoid the problme of the fan coming on at night when you nip in for a pee. If noise is not a problem, that might be anon issue.

A humidistat might need a manual pull cord for when you really want to run the fan for a bit for other reasons.

[meow2222]

Just ensure you can override automation in both directions.

A dehumidifier works better & doesnt chuck heat outside.

NT

[ss]

This room will not be used at night as `activities` will be transferred to the upstairs loo so possibly the humidistat not required then?

[Andrew Gabriel]

I'm about to do one that will use a pipe stat on the hot water feed to the shower. It effectively gets a run-on timer by the length of time the pipe takes to cool down after the shower, followed by the fan's own (shorter) run-on timer.

Part of the reason for this is the light is operated by a motion detector, but it isn't going to work through the shower screen, so it needs something else to keep the light on whilst someone is using the shower. However, I like the idea of a longer fan run-on if the shower is used, versus just clearing toilet smells, as drying the room needs many more air changes than just clearing a smell.

[Johny B Good]

That looks like an opportunity for someone to invent the stinkidistat! :-)

[ARW]

The opposite. The humidistat is used to turn the fan on when the humidity rises ie shower time. Most humidistat fans can also be wired to also be turned on via a separate switch should you require that function.

[Martin Bonner]

I disagree. If you can tolerate noise from having the fan on whenever the light is on, not having a humidistat will increase reliability and capital cost.

[John]

Motion detector? ;-)

[John]

You probably only need a humidistat fan. Heads-up: BES do them a *lot* cheaper than anyone else I've come across. Also install an isolating switch (ideally just outside the bathroom, high up out of the way where it won't get operated accidentally).

[ARW]

But is the light always turned on when she has a shower?

[ss]

Yes, as its taken around 6.00 am and the only window is a narrow 2 feet x 6 inches.

[ARW]

Then a timer fan should do the job nicely and I agree with Martin.

[Johny B Good]

I'd imagine that would be an expensive item (IP66 or better rating :)

[sm_jamieson]

I just fitted a separate humdistat to our fan (vent in ceiling and inline f an). It takes some fiddling to get the correct balance between nuisance tri ps and running long enough, and if you want to totally dry out the bathroom you might need a run-on timer too. I took the approach that to totally dry out the bathroom with air flow would lose too much heat from the house, so did not include a run-on timer. So it just clears moist air. In practice this means the fan runs for a bit, switches off, runs again, etc. whilst the room dries out. It also does thi s during a hot bath or if the hot tap is running for a whilst and someone i s in there breathing (I hope they are !). I have also heard that the through the wall fans with built in humidistat c an be more susceptible to nuisance tripping if the outside air is moist sin ce the sensor is closer to the outside air.

I would also have considered a dehumidifier in there if the bathroom was la rge enough. Someone could do a calculation to compare humidifier running co sts to costs due to chucking out hot air ...

Good luck ! Simon.

[PeterC]

Definitely needs more time. Mine /should/ change all the air in the 20-odd minutes but, of course, it doesn't, although I've arranged the flow to reduce 'channeling'. The humidistat is a bit so-so: certainly works, but is slow to come on and to quick to go off in cold, dry weather when there could be water on the walls; comes on just for a piss, or even spontaneously, in warm, humid weather. I had trouble in remembering the run-on timer and kept leaving it on, so now I let the humidistat do it's job when I'm having a shower then use the pull-switch for 5s after I'm dry. After getting dressed etc. I open the bathroom door to allow normal circulation - so far, so good. As to losing heat: I used to open the window and close the door for 30 min. or so in cold weather and in warmer weather just have the door open and let throughflow work. I guess that lost more heat.

[Alan Braggins]

ITYM "increase reliability and decrease capital cost" :-)

[ss]

Thanks all for the replies, I reckon I will just go for a timer model. That in itself is an improvement on not currently having one. I will also go for a cheaper model so if I want to upgrade it is no big loss. I expect the airflow should be reasonable as it will be fitted on to the top of the window so no ducting as such required.

Rightly or wrongly thats where I have arrived.