Humidistate fan switching

[diynovice12]

I want to put an extractor fan in a bathroom that has bad condensation.
There is a window in the room, so I can't rely on the light switch to operate the fan.
If a humidistat fan was connected directly to the lighting circuit so that power was always available to the fan, would that work?
I ask because a post in this forum suggested that a humidistat fan was started by switching on the light, and the fan continued until the correct humidity was sensed, whereas I would want the humidity sensor within the fan to be the only switch.

Thanks

 

[SaladFingers]

Yes that's fine. There are humidistats with a pull cord, so that if you wish, you can start it yourself and have it run until humidity has decreased, or leave it running, or have it come on when it's humid enough to.

 

[Taylortwocities]

Also you can use a humidistat fan with a timer.

this will work when the light comes on and also if the humidity is above the set limit.

Fans need certain conditions to work effectively. The two most important are:

You've got to allow as much air into the room as the fan is extracting, or it will be trying to create a vacuum

Don't have a long duct run. Most fans dont hack it much over 3 metres. Cheapo weedy fans can barely push air through a 9inch wall.

 

[diynovice12]

Thanks for all the replies.
The important point for me was that the fan is switched on automatically depending on the humidity level as I can't rely on the light being switched on.
If some fans will not be strong enough, are there particular manufacturers to look at (or avoid) ?

 

[EFLImpudence]

You say there is a window in the bathroom so exactly how bad is the condensation?

Is it slow clearing after a bath or shower?

If it is there all the time then there may be a fundamental problem somewhere such as a leak or seepage under the bath which never dries.

 

[SaladFingers]

I have a bathroom with window, but I won't leave it wide open when not there.

It's about air flow, so the window alone isn't enough for my bathroom. The condensation builds up tremendously from showers.

I have now a 6" Manrose selv fan with a humidistat on the wall, entirely independant from the lights, so it runs when it needs to and it's made all the difference. Enough air supply will come in if I lock the window in the ajar position.

It's great having it independant from the lights as it'll help keep things clear in the summer when the lights won't be on or if I leave wet towels on the towel rail.

 

[bhm1712]

You say there is a window in the bathroom so exactly how bad is the condensation?

Is it slow clearing after a bath or shower?

If it is there all the time then there may be a fundamental problem somewhere such as a leak or seepage under the bath which never dries.

I have a window in my bathroom but sometimes weather conditions dicatate that the window cannot be left open (or opened at all) for long enough for the air to be replenished!

Mould formed really fast in my bathroom before we had a fan.

 

[diynovice12]

You say there is a window in the bathroom so exactly how bad is the condensation?

Is it slow clearing after a bath or shower?

If it is there all the time then there may be a fundamental problem somewhere such as a leak or seepage under the bath which never dries.

It's bad after baths/showers, and when drying clothes.
There were other damp problems, but I think all of those have been fixed now.