Wiring Stand-alone Humidistat to Bathroom Fan with Timer

[jakehalf]

Hi

My bathroom fan has a built-in timer and presently switches on when the light is operated, then off after a fixed period when the light is turned off. It is connected via a 3-pole isolator.

I have bought a humidistat and want to change the wring so that the fan comes on when the humidity exceeds a certain point, independently of the light. I would also like to be able to switch the fan on manually to remove smells, and have the fan's timer switch it off after a fixed period (unless the humidity is still high). The humidistat has a switch with a permanently on setting. The humidistat should be connected to a 3 Amp FCU.

How should it be wired? A wiring diagram would be most useful. Thanks.

 

[Lectrician]

I would assume you have a three core and earth cable from your light (or switch) to the fan at the moment.

Remove this cable from the light and take it to your humidistat. Take a 1mm twin and earth from your FCU to the humidistat.

Connect the blue neutral from the twin and earth to the neutral to the fan (probably blue if older cable). If the humdistat also needs a neutral, connect these to that, else just connect together.

The brown live from the FCU will be connect to the live in of the humidistat, and also to the permenant live to the fan (probably red if older cable).

The switched live to the fan would go to the switched side of the humidistat (live out). (probably yellow if older cable).

There are so many different combinations of how you could wire this.

 

[Taylortwocities]

Does your fan have a pullswitch as well as the humidity control?

If so, you only need the permanent live and neutral. Then follow the diagram that comes with the fan!

 

[PinkE]

I would assume you have a three core and earth cable from your light (or switch) to the fan at the moment.

Remove this cable from the light and take it to your humidistat. Take a 1mm twin and earth from your FCU to the humidistat.

Connect the blue neutral from the twin and earth to the neutral to the fan (probably blue if older cable). If the humdistat also needs a neutral, connect these to that, else just connect together.

The brown live from the FCU will be connect to the live in of the humidistat, and also to the permenant live to the fan (probably red if older cable).

The switched live to the fan would go to the switched side of the humidistat (live out). (probably yellow if older cable).

There are so many different combinations of how you could wire this.

I did exactly this but for some reason with the lights switch in the off position the lights come on off on off on off repeatedly.
Any ideas why?
The fan+timer was working as expected before the remote humidistat was added.
Sorry to pick up an old thread but wondered if you have any recommendations?

 

[ericmark]

I have now answered your original post, I am guessing the humidistat is a switch without a neutral and was not designed for LED bulbs, but see other reply.