I have been searching for something to automate this (Shelly sadly only has a 2 switch variant) and a product that looks rather promising is: https://zencontrol.com/smart-fan-controller/ however it doesn’t seem to be available in my region (Germany) and requires something called DALI / DALI 2 which I am not sure about.
You just need 3 standard switches/relays or similar.
I’d wire them with some sort of interlocking between them so you can’t power everything up at once and kill the motor. I’d also clarify which it is that is correct, the function description says mid speed is L-1-2 but the diagram shows it wired as L-2-3.
I will step out from this project using what you mentioned because the problem is you don’t have mechanical locks in place to mimic what the switch in the picture does otherwise you can ruin your ventilator.
Best is to either use esp plc etc with relays that interlock in certain positions.
No what in the world is that. What I mean something that has 3 relays that you can interlock their positions either via software or hardware if that thing you posted is something where you can program the interlock no problem go for it.
Yeah now you are talking. If you can set the interlocks correctly then go for it. Just make tests with a multimeter before not directly on the fan and try different combination low then high the low then medium them high turn off the power put power back on. You get the ideea make sure no matter what it defaults in a safe all outputs off and no other combination of outputs on then the ones stated in the first post with the picture. Also very important transitions from low to high make sure when you define that it then all outputs off then switch to new position.
Afaik, the default interlock is for single relays, not like L12 case. I wonder if it would work with just L2. With esphome (and possibly also with tasmota) you could code your own custom interlock, so you can achieve the L12 case.
As much as I think modifying the fan switch directly is not the best approach for many reasons but one big reason is due no manual alternate way to use the fan if openhab is down unless you have something like the board I listed that has a alternate remote and still I think this is still not the best approach but this board it has 4 relays and a interlock feature as well as zigbee and a programable remote for a secondary way to control the fans.
