Any reason NOT to use a GE Fan Control for Bathroom Exhaust

I have four bathroom exhaust fans throughout the house and in this area the temperature/humidity outside can easily swing 40 points in a day. I have an accurate outdoor air and humidity sensor installed outside my garage that’s fed into SmartThings (Bringing in Analog Sensors & Misc Items to SmartThings using ST_Anything - My Writeup). I would like the ability to turn on and off my exhaust fans in the morning (and potentially late afternoons) based on indoor temperature, outdoor temp/humidity, and current thermostat mode (cooling). In other words I want to pre-cool the house for the cost of running some exhaust fans instead of later running AC. I also want to be able to auto turn on our master bedroom exhaust when the humidity is high (I have a temp/humidity sensor in the space).

Is there any technical reason (bad for fans, etc) that I can’t use a GE fan control switch on the bathroom exhaust fans and run them at a lower speed in this mode? I would think since the fan controls are made to run ceiling fans at low speed without burning them up it would work the same for bathroom exhausts. I have found multiple bathroom exhaust speed controllers that do the same type of thing so I would imagine it’s possible (,, etc).

Most Washroom fans are not multi stage or variable fans so it requires constant 120v for venting. Anything less than full voltage is definitely not good for the fan. I have mostly Panasonic vent fans and a couple have motion sensor for low speed but still require 120 to operate.
So check your fan to be sure it’s a multi stage or variable fan. Most likely the controller you posted is for a typical ceiling fan.

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Interesting…I have 5 exhaust Fans that I use a regular GE Switch to control on/off. A couple of them sound like jet turbo engines! I though about just replacing them with quieter ones like the other 3.

I am now curious as well if I can run them at lower speeds using the Fan Controllers. Also wonder if it is possible, will they still do a decent job at pulling the humidity out of the air at lower speeds…

The controllers I posted are listed as “Variable-Speed Fan Control for Ventilation Fans”. In fact the controller is made by Broan and I know at least one of my exhausts is a Broan.

Think I’m going to need to pull the covers on all mine and get the models it sounds like. I would think if they models say they are compatible with the variable-speed controller from the same company that they also should be compatible with the GE fan controller?

I was thinking that manually turned on/off it would be high speed, on humidity it would be medium, and on “pre-cool” all would go to low. But that’s of course assuming I can even do it based on above response. If I can’t then I can’t and I might just swap out the two fans on the second floor with on/off switches since heat rises and that would be the most efficient thing to do.

Since they are multi speed fans, you just have to check the exact specs and make sure the GE fan switch can handle the load.

As @Navat604 mentioned, many bathroom exhaust fans are not variable speed – – they are just on/off. In that case you would use a different switch.

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The majority of these fans, as well as Broan kitchen exhaust fans, have one of those motors that I first saw in a 1950 era record player. Not sure what you call it but I many here have seen them.

They can be controlled by simple voltage reduction. Fact is I just bought one that is for 4" inline duct and a 10$ rheostat for it for a project. Current bathroom is a Broan, but I replaced the variable speed control for full on and a timer.