puzzled...anyone help ?

[george765]

The small on-suite to our bedroom has a shower. The shower is humidity contolled. The control is very effective with the in-line fan in the loft coming on within 2-4 seconds of the shower being switched on.
The shower is combi-boiler fed...not electric.
The puzzle is....where have the installers (prior to my house purchasing) located the humidistat ?
I've been up in the loft and located a j/b which supplys power to the fan, switched via a flex which disapears down into the stud wall around the shower, but there is no humidistat/sensor anywhere to be seen in the on-suite.
any idea's guys ?
George

 

[Lectrician]

Flow switch in the shower pipework - actually quite common in commercial installs, and becoming popular in domestics. A humidistat would take more than a couple seconds, and would be visible.

 

[securespark]

Sure it's not on a timer?

 

[george765]

no, no timer, fan doesn't come on if shower not run.
looks like a flow switch is the answer, never heard of them, but do they have a over-run timer ? as the fan would stop when shower turned off and steam wouldn't clear...mine does.
I supose if the fan has a built in timer that would answer that.
thanks guys , mystery solved.