Replace light fixture with fan

Just getting started with ST – I have a few test devices, and will be getting some in-wall dimmers soonish. However, there’s one thing on our home-improvement list that I’m not sure how to approach.

Our house is two-story, and the upstairs gets… quite warm at times. One idea I had was to replace our stairwell’s ceiling light with a lighted ceiling fan that can help pull the warm air back downstairs. The light is currently controlled by a three-way switch (top and bottom of the stairs, of course). Where I’d like to wind up is:

  • Motion-controlled lights: If it’s dark and someone’s on the staircase, turn the lights on automatically.
  • Temperature-controlled fan: If the upstairs is X degrees warmer than the downstairs, turn the fan on automatically.

I’m assuming that I’ll need to run (or more likely, pay an electrician to run) a second wire to the ceiling to control the fan speed alongside the light. There seem to be numerous threads about a single fan/light switch concluding that there aren’t any good ones, so I’ll probably be needing to either expand the existing switch locations (each double-gang) to triple-gang, or move them to a new, separate, double-gang location. That’s a pity, and I’d love to be wrong.

I’ve looked at the GE 26933 motion + switch units for other places in the house, but the current switches aren’t ideally placed to catch stairway use (they look down the hall, not at the stairway). I could move the switches, or I could put a motion sensor on the stairs. Would a single motion sensor be enough to look both up and down the stairs, or would I actually need two?

I’ll probably use a SmartThings Multipurpose Sensor as the temperature upstairs to trigger the fan.

i recommend buying one motion sensor to start with the stairs. play with it for a week. see if you have missing spots then buy a 2nd if necessary.

the fan wires, i think it is quite easy to replace. just buy 14/3 guage electrical wire. go into attic and pull wire and re insert new wire. you will have ground, white, black, and now…red. black or red can be used for light or fan. doesnt matter which. but then to make double gang…
buy a little hand saw. cant think of name. kinda like a long blade. saw the nails from the side of the single gang. remove. use drywall saw, make double gang box size hole , insert new gang box. after running wire

I recommend trying to figure out your wiring configuration first. There are way too many 3 ways wiring out there and it could be costly if you going in blind with an electrician. Of course if you don’t feel comfortable then leave it to the pro. Here’s a ref site for 3 ways Config.