Relay for exhaust fan 3-way switch

I have an exhaust fan with a three way switch: two speed settings and off. is there a smart device like a relay from Shelly that i can wire into the fan to control the three switch settings from home assistant

If they are indeed switches, a 2 pole (relay) would work, but the control logic would be tricky.

Now keep in mind most ceiling fan’s have a 3 way switch, so a smart fan control that does the standard capacitive dropper speed control would likely work as well.

Thanks for the info! I really dont have much knowledge on how this would work, so thanks for your patience…

I’ve opened the wiring box for the switch and also found a recommended wiring diagram.

I read online that a suggested way to hook this up would be a ‘shelly switch with a relay module’ but this seemed complicated, involving a PCB. I was hoping for an off-the-shelf solution if it’s out there. :pray:t3:

Could something like this Shelly Plus 2pm work?

I think probably.
I’m still going to cover my butt and officially advise you to have an electrician do it for you because you have not had a lot of experience with mains wiring, but I bet it would work.

excellent thank you. and wise words

i do have an electrician coming next week for other work so ill grab the shelly device and get them to wire it at the same time

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Note that Shelly recommends that you use an RC snubber if you’re going to be controlling an inductive load such as a fan.

Also, it’s important to consider that if using a Shelly 2PM, there is the possibility that both the switch lines (L1 and L2) can become active at the same. I don’t believe the Shelly software itself has an option to disallow both outputs being on at the same time. You would want to use software controls within HA to make sure you don’t switch both outputs on at the same time. I don’t know how the fan might get affected if the two lines ever do get activated at the same time. Your electrician might be able to answer that.

Alternatively, if you don’t actually need power monitoring, you could use two separate Shelly 1 Minis instead of using a 2PM. These are proper relays with dry contacts, and you could wire them up to mimic the setup in diagram 14. The cost of two Minis is about the same as one 2PM, and you also won’t need an RC snubber, since these are dry contacts.

EDIT: I think I was in a bit of a rush when I made this suggestion. Using two 1 Minis wouldn’t actually work.

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That is true, I agree.
Make sure since you are controlling a motor the switch will handle at least 50% more current than the listed amps on the fan. The switch rating are almost always on resistive loads, and inductive loads (motors) are a bitch to start.
So if the fan is rated at 10 Amps, the switch better be rated at 15 or more or it won’t last long. (20 is better)

All back to the ‘make sure a real electrician is involved’.

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thanks to all for the great advice. i’ll go with a Shelly 2pm (2ch relay). Shelly 2pm is rated max 18A

the fan apparently is rated at 0.20 / 0.23 amps (low/high speed). it is 230V.

i did have an electrician say that a Snubber in this case won’t be needed because of such a small fan, so i will opt out for now.

thanks again to all. i’ll update this if it doesn’t work. the electrician will install at the end of the week

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