I have a holiday home which I rent and have problems with people not using the shower fans which results in condensation build up. Each bedroom has an ensuite shower room equipped with good quality shower extractor fan and a wall label requesting people to use the fans but they are being ignored and I get a mould build up on the bedroom walls.

I think the only way to overcome this is to make them operate automatically. I hate the idea of them coming on everytime the lights are switched as not only a pain if as I do you have to get up for a pee in the night but also you dont always need a light on when taking a shower. So was thinking that if I fitted a humidistat in each bathroom I could wire them to operate the fans. Is this possible and what would you recommend.

Many thanks

I fitted one in my dads bedroom and really a failure. It just would not switch off. Since I have heard of others with same problem.
Now off at isolator so not used at all.

I had a feeling this would be the case and this is just what I needed to know as they are not cheap and the last thing I want to do is cause myself more problems with complaints the fans wont switch off. I guess I just have to make BIGGER print signs. Thanks

or just put your shower and power to the fan on the same switch??

Not possible as the showers are not electric. I have huge HW & CW tanks and they are driven from one 3.5 bar pump which drives all the water feeds.

get a fan with a overrun timer on it, and wire it with perm live and the switch live from your lights, so when ever someone turns the light on the fan comes on and runs for at least 5 mins after the light has been turned off

Thanks I already thought of that but I do not want the fan on for 5 minutes each time someone gets up for a pee in the night.

I've been installing a new fan today, at the moment its on a pull cord but when the bathroom gets refitted I'm intending to fit a flow switch to the hot water pipe supplying the shower to switch the fan on.
Has anyone done it this way and if so do you have any recommendations for suitable double pole switches.
Don't intend to hijack your thread! but as our requirements are similar thought I'd post it here.
Ta

Most of the flow switches I have used are reed switches basic a magnet on a flap and the flow raises the magnet closer to switch. They are very low current rating and extra low voltage. Even the more expensive types tend to be 24v often 5 - 20ma designed really to connect to a PLC not as a stand alone unit.
Also use current switches but again designed to be inside an enclosure not as a stand alone unit.
From what I understand the more expensive humidistats have an adjustment so one can set the level at which they switch off. These may work better. But I have seem posts asking for advice on how to set up so it seems not trouble free.

I wanted a flow switch for the shower in our new loft conversion but was advised against it,possibly for ease of the builders.Heres a link to my questions:- bathroom-extractor-fan-t41141.html
And a link for the flow switch:- bathroom-extractor-fan-t41141.html
Wish I had perservered with the flow switch idea as I'm not very impressed with the humidifan.