Using dimmer as fan control

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Old 04-19-08, 08:45 PM
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Using dimmer as fan control

I am looking to install a fan control for a new ceiling fan I just installed, I do have a 3 wire running to the fan and there are currently 2 seperate switches, (Fan and Light). The problem is that the control needs to be Black Decora and I have been unable to located such a fan control.
I was wondering what the differences are between a fan control and a dimmer switch and if the dimmer can be used for the Fan.
 
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Old 04-20-08, 05:06 AM
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Dimmer switches dim incandescent loads, they kill fans. So a quick answer, unless you have a fan rated dimmer, No. Check with Lutron or Cooper lighting to see if you can locate a fan rated dimmer to fit your needs. They have dedicated switches for certain applications.
 
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Old 04-20-08, 12:52 PM
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http://lutron.com/skylark/?s=17000&t=17200

You should be able to get this with relative ease.
 
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Old 10-01-09, 10:57 AM
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I know this thread is a bit old, but I always see that regular dimmer's will not work with fan motors, but I never see why, can someone explain it do me?

I know that regular AC dimmers will rapidly turn the current off and on, and this results in a lower voltage, is this what is hurting a fan motor? Why?

How does a fan control work differently that it does not have these shortcomings?

Thanks.
 
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Old 10-01-09, 02:51 PM
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Welcome to the forums! Using a regular dimmer, whether it be an old rheostat type or even a more modern one (not specified for use on fans) reduces the amount of voltage that reaches the armature of the fan motor. This reduced voltage results in more arcing in the fan motor and eventual burn out. The fans were meant to run on full voltage. To jump back up, there are dimmers specifically for fans, so the animal exists, but the OP, and I believe you, were looking for an answer regarding regular dimmers.

Larry
 
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Old 10-01-09, 03:14 PM
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Fan speed controls start at full voltage and reduce down. This allows the motor to come up to speed, kind of like the transmission in your car in first gear.

Dimmers start out with greatly reduced voltage and increase. This is very hard on motors, this would be like starting out in overdrive.
 
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Old 10-01-09, 08:41 PM
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Great. Thanks for the quick responses. I get to go look up more things now

I was actually looking at using a dimmer not with a fan, but with a different type of small electric motor. I had heard that regular dimmers could make the motor have a shorter life-span but wasn't sure why.

Didn't know if using a variable speed fan control would still work in this case without decreasing the life.

I'm not an electrician, but know enough to get myself in trouble, cause I know there are options out there
 
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Old 10-04-09, 10:47 AM
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Need someone with knowledge of the various motor designs to chime in here, (as I'm not one), but having installed a number of ceiling fans with varying controls in days of old, I used to not use the 5-speed controls that came with the fans, but use a common phase-control dimmer switch. (we're talking 1970's here), as the old fan motors were run-capacitor induction motors. Ceiling fan motor design may have changed somewhat in the ensuing years, (they are all reversible now, maybe by rectifying the current and changing the polarity, but are they not still induction motors?)
I wouldn't think of using a dimmer switch on a commutator/brush type motor tho, unless it was designed for the purpose.
Thoughts from motor people?
 
 

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