I am installing a humidity sensing fan (Delta GBR80H) into a bathroom where no fan existed before, only have a light switch. What is the best way to accomplish this?

  • 2
    Do you have access from above in the attic? You'll need a spot to put it, run power to it and then run a duct to exhaust the air outside.
    – Gary Bak
    Commented Sep 14, 2018 at 21:50
  • Hi Richard, I think your question has not gained much attention since it lacks a bit of detail that is required for us to help. Describe the bathroom, your access from above and provide a picture, perhaps of the ceiling and the attic. This will go a long way if you are truly stuck from moving forward.
    – Gary Bak
    Commented Sep 15, 2018 at 16:44
  • Hi Gary, thanks for your input. I have plenty of room in the attic to do the install and running the ducting and I have no questions about the physical installation my question is more about the electrical hook up. I can install switches and run electrical if necessary. In my case it appears the humidity sensor needs constant power and another switch for the intermittent fan, just not sure with way to get started. I've also heard about using a smart switch but I'm a couple of decades behind that technology but I do have an Echo plus with a built in hub. Commented Sep 15, 2018 at 19:22
  • You can hit "Edit" (it's right underneath your post and the tag bathroom-fixtures) in the row of text that says "share edit delete". Commented Sep 15, 2018 at 21:24

2 Answers 2


You'll have to check the light fixture and the switch to see where the hot wire is. It can be in the ceiling, with a wire running to the switch to break the circuit, or at the switch and a wire running to the light to power it. If the hot is in the ceiling, you are in luck. You can tie into that for power. If the hot wire is at the switch, you'll have to run a wire down the wall and into that box. Not impossible, but not easy either, it will be much easier if its an interior wall. I am an amateur and have done it many times.

I would suggest cutting the power at the breaker, pull off the light fixture from the ceiling, and the switch from the wall. Then turn the power back on and with the light turned off, carefully probe the wires with a contactless voltage meter to see where the power is coming from.


I have installed a couple of these I think they were delta fans, I’m not sure but the one that I installed I did as follows.

The fan does not need to be wired for constant power. It should be wired with a normal switch.

When you flip the switch up once it activates the fan to run like a normal fan, if you flip the switch up once back down and then back up again quickly it puts the fan in humidity mode. In the first scenario you will see a little yellow light just inside the grill cover of the fan telling you that the fan is on, and in the second scenario you will see a little blue light which will tell you it is in humidity mode.

On the ones that I’ve installed there have been two switches, one for the light and one for the fan. But if I remember in the instructions there may be an option for one switch wiring.

  • Thanks Alaska Man, after checking out the Delta website again there is a schematic for a one switch installation that is not included in the instructions that come with the fan. I think I can get it running, will let you know in a couple of days. Commented Sep 16, 2018 at 20:43

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.