Fan Light Dimming - Aeon Labs Aeotec Z-Wave Micro Dimmer

My wife enjoys having a fan in the bedroom (it helps her sleep). My project this last weekend was to install the fan. This was not a major undertaking but it made me rather sad as I had the light hooked up to a evolve dimmer and an aeon minimote to be able to turn the light on in off as I lay in bed (yes when it comes to getting out of bed I’m incredibly lazy).

After installing the fan and realizing that turning the light on and off at night would require me to stand on the edge of the bed and reach up to the pull string to turn the light off, this scenario quickly became unacceptable. So I looked for a solution and found this:
Aeon Labs Aeotec Z-Wave Micro Dimmer:

To install this I put the device up in the fan box and attached the light line and load and attached a neutral. Then on the side that normally attaches to the switch (per installation instructions) I just simply looped a wire back, like as if the switch was always on.

I held the button down and paired the device and it immediately showed up as a z wave dimmer.

After that I cut all my dimmer commands over to the new device and bingo a fan with a dimming light.

Be careful because I just installed a fan that had a warning about dimmers that can go 0-100% causing damage to the motor or fire. There is a GE fan module that’s recommended for the actual speed control, for some reason it’s ok with three steps.

Something about avoiding dimmers with “triacs.” A little over my head other than don’t use. @JDRoberts is a smart guy maybe he can chime in.

Thank you for the warning. My use is just dimming the light. But it is good to know that a dimming function on the fan is not recommended.

I renamed the title of the thread to be a little more clear.

Thanks for the shout. Yeah, basically you need to read the manufacturer’s directions for the fan, and check that against the manufacturer’s directions for the dim control.

Rate controls For home use are usually either TRIAC or VFD (Variable frequency drive). A TRIAC controller varies only the voltage. This is what’s typically used for a dimmer light because that’s exactly how you make the light brighter, you give it more voltage.

A VFD varies both the voltage and frequency.

But more importantly in this context, is how the dimmer knows to turn itself on. The short answer is the dimmer switch itself, if it uses a TRIAC, is very sensitive to changes in the voltage, and basically it can get confused and send the wrong amount of current at the wrong time. This is what’s responsible for flickers. The problem is that kind of “flickering” in a fan motor control can cause the motor to overheat.

Most of the time, it’s just not a good idea to use a dimmer intended for light switch as a motor control. There are almost always warnings on both the dimmer switch and the motorized device install guides.

There are variable speed controls that are made specifically for fans or other motorize devices… Sometimes they are using a TRIAC switch, but they include other circuits which control the actual amount of voltage sent. There are different ways to do this but they’re all designed to keep the motor safe from variations in the TRIAC distribution. However as you undoubtedly noticed when you start looking around, these type of controls are more expensive, and usually, noticeably bigger than the light switch dimmers. So I know it’s tempting to just grab a light switch dimmer instead, but it’s probably not to code, and it’s probably not safe.

None of this has anything to do with Zwave or zigbee or network protocols. Or SmartThings. It just has to do with the part of the switch that controls the current to the fan. It’s possible to use a networked relay to send current to a VFD switch which then controls the fan and still maintains safe control. So a lot depends on the exact wiring set up.

Which is also why it may be possible to do something with just the light portion of a fan that also has an independent light. It just all comes down to the details.


I knew you would have much better technical insight than myself. :grinning: This should be like a PSA for people thinking about doing this with regular dimmers.

And @jjhtpc I thought you had a dimmer for the fan and the lights, I guess I misread, I need to stop doing that.

Great info JDRoberts, thanks. I don’t suppose you know if there is any danger to taking a box fan or a standalone plug-n fan, putting it on it’s highest setting and using a VFD z-wave 3-speed fan controller to control it?