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Making Extractor Fans smart with Shelly

Discussion in 'Electrics UK' started by brettuk, 31 Jan 2020.

  1. brettuk

    brettuk

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    Hey,

    I'm looking to smartify my extractor fans in toilets/bathrooms for two reasons really
    1) I currently leave the light on the let the fans run to bring humidity down, I'd rather it did this automatically
    2) I want to smartify my lights, and I don't want the fans to be on permanently.

    I've been looking at the Shelly 1's - https://shelly.cloud/shelly1-open-source/ which look great and would be perfect for this IMO.

    So I have two different types of extractor fans, Timed and Simple

    The Timed extractor fans come on with the light, and then when the light is switched off run for a few minutes. They all have Isolation Switches next to the fan.

    The wiring should be something like: http://www.ultimatehandyman.co.uk/how-to/electrics/install-shower-extractor-fan

    I propose to wire the Shelly in, post-isolation switch (but in the same enclosure) like this: https://imgur.com/a/ZwQUxT6

    Because I'm proposing to replace the bulb with a Hue bulb in due course, the Switched Live will always be on, so in my diagram I've wired it in to live and ignored the Switched Live input on the Shelly (SW) Although I may decide to wire it into the SW pin, I haven't decided yet.

    The Shelly will be POST isolator switch, so turning off the Isolator switch will still kill all power to the fan and the shelly.

    Will this work as I expect?

    The second type of fan is a simple on/off switch fan with no timer. I've had a look at it's wiring (see my link below) and from what I can tell the switched live and neutral are hooked into the fan, which makes sense. What I don't understand though is what the purpose of the yellow wire is that isn't hooked up - it doesn't appear to be earth, so I wonder if this is the Permanent Live? If so I can use that to power the Shelly, I'd rather not have the Shelly on the switched live as then if someone accidentally turns off the switch, the Shelly will go offline.

    The switch that controls this extractor fan is unlike the rest in the house - the rest in the house have the wires attached to the switch which is part of the casing. This switch has the switch attached to the internal housing, I haven't removed it as yet to take a closer look - but I'd be surprised if it had a neutral in it, the rest of the switches in the house don't have neutrals.

    https://imgur.com/a/cY0i2z8


    Thanks!
     
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  3. oldbutnotdead

    oldbutnotdead

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    So what are you trying to achieve here? Runon fans are common and cheap, some use timers, some use humidistats, some use thermometers.
    Your IOT thing is just a remote controlled switch. The apps with these things vary in usefulness.
     
  4. EFLImpudence

    EFLImpudence

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    That won't work. You also need Switched Live to SL terminal to switch it on.

    How can we possibly tell from here?
     
  5. brettuk

    brettuk

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    The shelly doesn't require the SL to work, I'd be connecting the SL from the extractor to the Live so it would get power.


    Obviously I appreciate you cannot say if it is, but is it likely to be? It's either a Perm Live or a cable that does nothing
     
  6. 333rocky333

    333rocky333

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    If the yellow wire at the switch is the same one as at the fan, then surely it can be used for any purpose, a continuity check would confirm its the same core, but its highly likely that a 3 core and earth was originally installed for a timer fan and it is the same core.
    Not that it matters but most would connect Red as a permanent live and the Yellow as a switched live when used for a Timer fan, with a Blue Neutral nowadays sleeving both Red and Yellow with Brown is best.
     
  7. EFLImpudence

    EFLImpudence

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    Ok. Sorry. Your row of connector blocks mislead me.

    upload_2020-2-2_22-43-33.png

    However, if this means the same in that the two reds and the yellow are connected together,

    upload_2020-2-2_22-45-36.png

    then the light will never go out while isolator is on.

    Exactly.
     
  8. DIYnot Local

    DIYnot Local

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