bath fan "dimmer"

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Coppersmith

Coppersmith

Senior Member
Location
Tampa, FL, USA
Occupation
Electrical Contractor
I have a client who want to control the speed of his bath fan. (I have no idea why.) I know they have speed controls for ceiling fans. And there are light dimmers. Anybody know if either of these will work or is there something designed for this purpose?
 
I would think that a fan control would work on either a ceiling fan or a bathroom fan. Just don't use a lighting dimmer.
 
A light dimmer will not work. A fan control could work but there is just a tiny shaded pols motor inside the bath fan and it's got just enough hp to move the blades at full speed or not at all.

What he needs is a quieter fan and those cost too much for some customers.
 
ah, get a Fantech inline ($60) that has two-speed control built in. or nope, his fan runs at one speed.

or, is the faceplate metal by any chance, he could flip-on magnetic vents covers, having several covers with different cutouts in them to restrict airflow in various ways, that will slow down the fan and reduce noise.

is the issue CFM or just noise?
 
Hey, some days he is gassier than others...

99.999% of the time you can just get a fan speed pot and for those little Shaded Pole motors, it works fine. But as said, don't use a lighting dimmer. Some older types MIGHT work, but most of them now are too different. For a motor, you need an old "pot" (potentiometer) or rheostat type. Those are still sold, but are specifically called "fan speed control".

https://www.zoro.com/broan-wall-control-120-v-white-57w/i/G2586613/
Not an endorsement, never used one nor bought from this outfit, it's just an example.
 
Jraef said:
Hey, some days he is gassier than others...

99.999% of the time you can just get a fan speed pot and for those little Shaded Pole motors, it works fine. But as said, don't use a lighting dimmer. Some older types MIGHT work, but most of them now are too different. For a motor, you need an old "pot" (potentiometer) or rheostat type. Those are still sold, but are specifically called "fan speed control".

https://www.zoro.com/broan-wall-control-120-v-white-57w/i/G2586613/
Not an endorsement, never used one nor bought from this outfit, it's just an example.
Click to expand...

"Except Ceiling Paddle Fans"

so there it is $20 part, install. nice. assuming fan only unit, or hot leg to fan motor.
 
Pop the cover and take a look at the fan. A dirty fan will make more noise than a clean one. if there were any valid reason to vary the speed of the fan, bath fans would come with variable speed control. if it's making too much noise, he needs a better fan or larger duct work. if it's sucking too much air, then he needs a smaller unit.

you should find out why he wants a fan speed control switch. I believe there is a high chance it will not solve the problem.

Eta: there is also the issue that bathrooms have to be ventilated at 50 CFM or greater.
 
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JFletcher said:
Pop the cover and take a look at the fan. A dirty fan will make more noise than a clean one. if there were any valid reason to vary the speed of the fan, bath fans would come with variable speed control. if it's making too much noise, he needs a better fan or larger duct work. if it's sucking too much air, then he needs a smaller unit.

you should find out why he wants a fan speed control switch. I believe there is a high chance it will not solve the problem.

Eta: there is also the issue that bathrooms have to be ventilated at 50 CFM or greater.
Click to expand...

I think that's a great point. They do make aftermarket speed pots as I pointed out, but the reasoning does still escape me.
 
Ok, so I did the job today (wiring the fan) and told the HO I didn't have a good solution for a fan speed control. He didn't seem too concerned. After I was done and turned the fan on to test I could hardly hear the fan at all. It was very quiet. Not sure what he needed a control for at all.

Thanks for all the input. I'll try that Zoro fan speed control next time this comes up.
 
since interior walls are seldom if ever insulated, he was probably concerned about noise. The last bathroom fan I installed, the homeowner didn't even realize it was on... that's how quiet it was compared to his old fan.

And ty jraef.
 
Yeah, I put in an old Broan fan/light in my bathroom 20 years ago and the bearings are shot now, so it screams at me every now and again. But the wife remodeled another bathroom and I just "paid the man" to do the whole thing. Code requires newer energy efficient fans now, so he installed one and I can't even tell it's running it's so quiet. Now I'm jealous...

But to put one in my bathroom I'd have to cut into the ceiling, and I am disinclined to work that hard at it. So I just pulled the motor out, intending to replace it, to make the screaming stop. But the new motor was going to be $24 and it would still be noisy. So I just cleaned it really well, lubed it up and put it back in. Now it only screams about once a month and I figure I can put up with the noise for anther 10 years or so.
 
Jraef said:
Yeah, I put in an old Broan fan/light in my bathroom 20 years ago and the bearings are shot now, so it screams at me every now and again. But the wife remodeled another bathroom and I just "paid the man" to do the whole thing. Code requires newer energy efficient fans now, so he installed one and I can't even tell it's running it's so quiet. Now I'm jealous...

But to put one in my bathroom I'd have to cut into the ceiling, and I am disinclined to work that hard at it. So I just pulled the motor out, intending to replace it, to make the screaming stop. But the new motor was going to be $24 and it would still be noisy. So I just cleaned it really well, lubed it up and put it back in. Now it only screams about once a month and I figure I can put up with the noise for anther 10 years or so.
Click to expand...

as long as its not a wobble noise issue, clean it and put a drop of Mobil-1 synth on the shaft, 20yrs old, probably has sintered bronze sleeve bearing? it should quiet up.

i replaced all my ceiling mount vent fan units (new home in in 2008, replaced in 2011) with inline Fantech's in the attic. super quiet operation, two speed capable (only wired for one speed).
 
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