Which GE zwave switch did you use? I have the same kind of switch on an old whole house fan, with a timer dial and a hi/off/lo switch.
There are only 3 wires in the box: red, black and white. The white came into the timer dial on LOAD, the black had a wire nut connected to the off position wire on the switch and the white and red wires were wire nutted to the other switch positions.
The current wall plate/switch combo looks like this one - http://jetfanusa.com/media/timer-two-spd--front-ivorythumb.jpg - except it’s a small switch on the right instead of the big paddle.
I want to replace this with one of these http://www.homedepot.com/catalog/productImages/1000/dc/dc1101b2-5cf5-45ea-b257-ea3c314da1cf_1000.jpg for the 2 speed fan motor and then replace the dial timer with a GE on/off zwave switch.
The problem is, I’ve only got 3 wires in the box (Hot, low and high). What are others doing for this scenario? I imagine there are many of us with old houses and old whole house fan (wiring).