I can see an answer where it suggests a 3-wire run from the fixture but I'm hoping to use existing wiring and it only has black and white wires coming from the bathroom fan to the old timer switch.
The new modern timer switch has red, white and black wires out (and green of course).
Which wires connect to which wires please?
and thanks Scott
You got the wrong timer switch. You grabbed one of these digital jobs because you're too cool for school. Unfortunately your wiring is not.
What you need is the trusty dusty mechanical model, available in any "max time" you like. That one's an hour, you can get 15, 30, 2 hours, all the way up to 12.
The black wire on the timer would connect to the power (hot) wire in the junction box, the red wire is the switch leg to power the fan and the white wire is combined with the 2nd wire from the fan and is connected to the neutral wire in the junction box. The green wire is the ground connection.
