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  1. #1
    Join Date
    Aug 2012
    Location
    Central VA
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    Ceiling fan speed controls

    What's the difference between the pull cord on the fan, a light dimmer, and a dimmer designed for ceiling fans? The ceiling fan I bought said not to use it with a dimmer but are dimmers made for ceiling fans ok to use?

  2. #2
    Join Date
    Jul 2002
    Location
    Centerville, Iowa
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    432
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    Light dimmers use triacs and phase angle control, basically they only let through a portion of each alternation of the sine wave. The sudden voltage change instead of a smooth ramp up is hard on induction motors and makes them overheat and buzz.

    The built in speed switch works one of 2 ways:

    1 is just like a PSC furnace blower, taps in the run winding act as an autotransformer and undervolt the motor on the lower speeds.

    The other is a fixed single run winding and a dual run capacitor, lower value capacitance is low speed, higher value is medium, and both values in parallel is high.

    Fan specific dimmers may just have extra filtering to help suppress the hum.

    To get the degree symbol ° on Windows hold down the Alt key and type 0176 on the keyboard number pad. It is also available via the character map, and on Windows 8.1 devices with a touchscreen via the on screen keyboard.

    There is no "E" in either BluVac or Blu-ray Disc.

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  3. #3
    Join Date
    May 2006
    Location
    Ft. Worth, TX
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    3,573
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    The ceiling fan I installed about a year ago had multiple taps on the secondary and by selecting the tap at the control box, you could reduce the RMS voltage going to the fan motor. You would not want to use a dimmer in series with this setup because it would reduce all the voltages on the taps too much. The same goes for a fan that has a pull cord to change the speeds. BUT, if you put the light on a separate circuit from the motor, it's just fine to use a dimmer switch on the wall to control the brightness of the light. I'm talking about an old school dimmer that is just a simple rheostat.

  4. #4
    Join Date
    May 2006
    Location
    Ft. Worth, TX
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    3,573
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    But why couldn't you just leave the fan on high and use the dimmer (rheostat) to control both the fan and light? I'm glad you asked. I don't see any reason why you couldn't.

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