My appartment has a mechanical ventilation system. When switched on, it works in all rooms at the same time (being the toilet, bathroom and kitchen). This system is controlled by a physical switch in the kitchen that has 3 possibilities: off, low, high.
In my currect appartment I have replaced this switch 2 years ago with a wemos d1 mini and a relay. It’s a binary switch so the ventilation is either on (high) or off. There’s a bunch of automations based on me cooking, pooping or taking a shower. So far so good.
Now I’m moving to a new place and this place happens to have the exact same system.
I would like to upgrade however: I want to be able to control all 3 options (off, low, high). I don’t need to keep the original switch really since home assistant takes care of all my needs.
What product do I need to achieve this? Bonus point for wiring help but I assume that would be included in the documentation.
pic related: the switch. Again, I don’t need to keep the switch as long as I can control the 3 options in HA (off, low, high).
Thank-you!
Crap… Turns out there’s no neutral in the wall. Are there any options left? I have some shelly 1l’s and a shelly 2.5 and a sonoff. The mechanical ventilation system is running on 400v. Would a zigbee of wifi power plug for this be an option? Again, I’m happy to lose control of the switch and regulate everything in HA and have it just either be on or off
I solved this in my previous apartment with a d1 mini and relay but because I also need to convert 230 to 5v it looks bulky because I need to use an adapter. I rather have a solution that I can squeeze in the wall and cover it up with a white plastic cover.
Can’t you just get a neutral from the outlet? You can use an 18-gauge wire (white is neutral in the U.S.) since the smartswitch only draws at most 100 mA.
and this is where my knowledge is too limited I have a shelly 1l. Can I use that? Here’s the schematic. Sorry if asking too much, I really try to figure out as much as possible myself but in this case I just lack some basic knowlegde to read these images.
You still haven’t shown how you connected your Shelly. If you did connect it as your text describes, then that would smoke the Shelly as soon as you turned the light on through the switch. This is what you described:
The switch should go between Sx and SW1. If you only connected one side of the switch, then the Shelly would never try to turn on the light, and there shouldn’t have been any smoke.
Okay, so the brown wire from the switch goes to L, the blue one to N. The switch I connect to sw1, sw2 and sx. What happens to O? And where do the 2 black switch wires go to?
Thank you. Just before I’m going to connect live, can you check this picture to see if I’ve interpreted it correct? When connecting the black wires, the fan turned on already.
Normally when I let the brown wire touch one of the two black ones, the fan turns on. Low or high depending on which of the two black ones the brown one is touching
Edit: connected live. So far so good, shelly powers on. Go to Shelly’s webinterface. Switch relay on, bang, shelly gone. 2 more Shelly’s left. Any suggestions on how to proceed?
The only thing I understand is that a brown wire is called live, a blue one neutral and black switch. When I then look at the picture I don’t understand what I’m seeing. I see a wire labeled blue going to N and O.
Also, the hole in the wall where the original switch was located has 3 wires: brown (live), 2 x black (switch).
When brown touches black, the fan turns on (let’s say low). When brown touches the other one, it turns on high.
I really would like to make a schematic for you, but I’m afraid I can’t because I’m not even capable of reading one.
There is probably a third position where neither black wire is connected. Let’s call this “off”.
You cannot use this switch on the Shelly.
What you want to do is possible, but not with a Shelly and not with the switch wired as I have interpreted. However, your lack of understanding electrical circuits at the basic level of drawing a schematic would frighten me from any further advice.
Sorry to be so blunt, but working with mains power can be blunt. And unforgiving. You’re lucky that you have only blown up a couple of Shellys. (Likely just the relay inside).
I have a shelly 1l. Can I use that? Here’s the schematic. Sorry if asking too much, I really try to figure out as much as possible myself but in this case I just lack some basic knowlegde to read these images. 
