Extractor fan with humidity stat question

[danrich123]

Hi,
I've been supplied with a fan that has a humidity stat and timer which i've fitted in two kitchens in two flats.
I didn't have any access to a switch live so I ended up putting the fan on its own circuit and put a link across the live and sw live.
The fan will not switch off (unless turned of at isolator)... I put the setting to 40 it stays on constantly, I put it all the way up to 85, and it stays on constantly.
Any ideas as to why the humidity stat doesnt turn the fan off.
The instructions are vague, but i presumed that when the sw live was live the fan would come on until the humidity was correct.
Any help?

 

[TicklyT]

More likely t'other way around - the fan will run under control of the humidistat without a link between live and switched live, the switched live giving an option to bypass the humidistat.

How does it behave without a link?

I have seen a humidistat controlled fan apparently responding to random changes in atmospheric humidity as well as moisture in the room, but that was in the Welsh valleys, where it does rain most of the time.