Exhaust fan control 2 speed

Hi guys
Hope you can help a newbie like me.
I am looking for a way to control a fan with 2 speed. The motor coil is one coil with a tab for lower speed so it is important that only low or high speed is feed with power and not both at the same time since that will burn the coil.
See more fan details here: TD-SILENT – S&P – S&P
I have being looking around in this forum but have not found any solution that fits my needs so please help.

Use a 2 gang switch. With 1 switch for high and the 2nd for low speed.

I’m thinking a double smart switch, or two smart switches, with one controlling a relay, so the the two don’t collide.

I’ll bet there is already a thread on this…

Or a smart switch with scene control. The switch could provide power, and the scene could trigger a relay like this one? That way only the high or low would be getting power. (though the scene would have to turn one channel off and the other on, and another scene to do the opposite)


I also found a post in a review of this product (The 120v version of the three options is what you would need)…

This seems to be what you are looking to do (I wonder if he is a member here?):

I built a whole house fan years ago. I wired it in to 2 sepearate switches to control the fan. One to power the fan and a SPDT switch for high/low (to prevent powering both windings at the same time or cause possible fire…) I then decided to update to Zwave switch and the same high/low switch but… it kept burning out the zwave switch. twice. I have replaced it so I decided to use these instead (MUCH CHEAPER!!)
I then replaced the high/low switch with a zwave switch and reworked the wiring. I use one zwave to power one of these relay to provide the power for the motor (no motor power through the zwave switch so the back EMF won’t burn it out again)… then a second zwave switch to power the second relay to provide power to the high OR the low speed motor windings. It works perfectly and so far I have ran it all night long several times with out any failure. Both relays are inside a 2 Gang electrical box with a blank cover and it worked perfectly the first time I tried it. Not only that but I can now control the speed of the motor without complicated Zwave macro to switch between the speeds… (which may have caused the previous zwave switchs to die).
Very satisfied and it works (so far) perfectly.

A little short on details, but I’m sure it could be worked out.

Here is my attempt to recreate what the relay reviewer did. If I’m wrong or otherwise have an error, someone please advise, and I will revise.

The stated reason for doing it this way, was that by not powering the relays through the switch, it would prevent damage to the “smart switches” from the Electromagnetic field generated by the fan’s coils/windings.

Hi James

Thanks for your reply.

I have been inspired by your idea and made my own design, I don’t think I will have problems with the fan coils sending back highvoltage to the smartthings relays so I take my chances .
Best regards

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Looks fantastic. That helps to give me other ideas, too.