From what I understand there are 3 ways to wire a bathroom fan:

  1. Together with the lights (both are on or off);
  2. Individual switches for lights and fan;
  3. Put the fan (and maybe the light) on a presence sensor (which usually have a timer).

Now what I would like is to have a switch to turn the fan on and when the switch is turned off it remains on for a while. Is there a way to setup that?

  • 2
    Can you explain why you'd want the 'delayed off' switch rather than your standard timer switch? I'm not sure if what you are looking for actually exists.
    – DA01
    May 7 '16 at 15:56
  • Because my wife asked if it was possible. She doesn't like that the fan turns on every time someone just enters the bathroom (the 3 setup above). I don't know enough to know if this is feasible... May 7 '16 at 16:24
  • 1
    So what you want is your option #1, but with a delayed off in the fan circuit?
    – FreeMan
    May 7 '16 at 16:30
  • @FreeMan Yes, something like that. May 7 '16 at 16:35
  • 2
    If the wiring is there to support it (separate switched hot for light and fan), a humidity sensing switch could be installed for the fan. Then the fan will automatically run whenever the humidity in the room is too high.
    – Tester101
    May 7 '16 at 17:51

There's no such thing as too many wires between the bathroom switch and the bathroom light/fan/heatlamp/whatever the future may bring. I would run at least 3 hots and a neutral, with 1 hot and 1 neutral being 12ga for a high current device. Even better, install conduit and pull whatever as needed.

I personally hate fans which turn on with the light. I fear I'll wake others during a 3AM bathroom run. It also wastes energy by ejecting nice warm/cool air, forcing the HVAC system to work harder.

This forum is not for "shop for you", but there's no problem getting a single switch that turns off the fan some period after it turns off the light. the fan with a delay. on light+fan, and turns off light and adand continues the fan for a designated period.

There's also no trouble getting rundown timer switches if you want to manually trigger the fan. However if you also have a heatlamp (commonly put on rundown timers), this will be a confusing UI.

They even make fan controls which detect humidity. The question is whether they have, um... VOC detection.

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