Will Humidistat extractor fan operate properly near open window?

[EddieJT]

I have tenants who seem incapable of opening the bathroom window during/after a shower, so I want to fit an extractor fan. I'm eyeing up the humidistat ones, but how would they work if fitted net to an open window? Would the outside humidity influence the sensor and cause it to potentially never switch off?

 

[Taylortwocities]

If fan is situated near open window then its never going to work properly, but i think you know that.

I guess the fan itself has to go there? If so, buy a standard fan and a remote humidistat, and fit the humidistat in the steamy bit.
https://www.tlc-direct.co.uk/Products/MR1361.html

or use something else to control the fan, switching on of the shower, for instance. The fan could be triggered either by that, or from the water flow to the shower.

Set the fan timer for a good long time.
MAke sure there is a good sized method for air to enter the room, if the door is tight fitting then the fan will never be efficient. If you have a 100mm hole for the fan, you need an equivalent are intake.

 

[EddieJT]

Very helpful. Thanks.