Loud buzzing from fan after Blue 2-1 + Fan Canopy installed

Switches Wiring Discussion
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1
  • Model # of your smart switch: VZM31-SN + VZM36
  • Neutral or Non-Neutral Setup: Using neutral on both
  • Single Pole, 3-Way, 4-Way, etc: Single Pole to VZM36

Hello,

I purchased a few of the fan canopy + blue 2-1 switch bundles to replace some in-wall Leviton fan switches we had controlling Hunter AC fans. With the existing Leviton switches, we heard little to no buzzing when running the fans. I installed 2x fan canopy and blue 2-1’s today, and after installing those, I have found that both fans are buzzing fairly loud when running them. The model of each fan is different, but I collected a video from the fan which is the loudest.

Note: I don’t hear anything when running only the light. I am using SBM in the Hubitat VZM36 child light controller to provide constant power to the Hue bulb you see installed. It doesn’t seem to contribute to the noise.

For the wiring, I installed the Fan Canopy wired to the Load of the Blue 2-1, and then I enabled SBM on the switch to provide constant power to the canopy module. This was mainly so that I could achieve air gap restart of the fan canopy module. Both the blue 2-1 and the canopy module have neutral wires installed.

Any idea what could cause something like this? This is actually not the first fan canopy module I have installed with these fan models. We have one other fan canopy + blue 2-1 already installed with the same model fan and it doesn’t show this buzzing at all. I am a little confused on what it could be…

2

This is the issue. The Blue 2-1 is not rated to provide power via the load connector to an inductive device (the fan). You should connect the Fan Canopy to the line directly (you can use the second connection on the line terminal on the Blue 2-1).

3

Got it - I went ahead and swapped it, and it significantly reduced that humming noise. I had assumed that SBM would act in the same way, but I was wrong on that. Thank you!

4

The issue is that the 2-1’s run all the power to the load through the dimming circuitry (even when in smart bulb mode or on/off mode). That circuitry can’t handle inductive loads.

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