Humidity problem

["egelbeertje" <r_d_k@xxxxxxxxxxx>]

Hi,

Our bathroom is located at the innermost part of the house - so no
windows - which created the need of forced ventilation.
Currently this is done by walking into the bathroom - knowing that
you are going to take a shower or bath - and swith on the 20 minute
timer that drives a fan sucking the air out through a vent hole and
pipe it through the loft to the outside.
The timer (a din-module in the loft) is controlled by a pulse switch -
push it once and you get 20 minutes, push again it switches of. I
could change the setting so that every push extends the timer by an
additional x minutes but then I have to wait until it reaches the end
of the timer cycle.

So I want to automate this one and link it to humidity detection but
haven't been able to come up with an easy solution - preferrably
hardwired - something like "hey it's x% humidity - I will click my
relay and give a pulse to the timer so it can work for 20 minutes -
then I will measure again and repeat this cycle" without going into
pulling wires back and forth to a home control device since I don't
have one (yet).

Anybody out there with some bright idea would be welcome to comment.
Also some guidance on where to find humidity detectors would be a
good start.

rgds Rob