Low-wattage extractor fan and touch switch - incompatible?

[Inchiquin]

I have an Envirovent extractor fan with run-on timer, i.e. it has neutral, switched live and an extra unswitched live to power the run-on. I want to use it with a touch switch but it doesn't work. It will switch on OK but automatically switches off after a couple of seconds. The run-on works as it should so the fan keeps running for a minute. I've tried it with both a Livolo and an iLumos switch and both are the same. If wired up to a conventional on/off rocker switch it works perfectly so there's nothing wrong with the fan.

The fan uses 8w. Do you think this means there is insufficient current for the switch to detect that it's on, which is why it switches off immediately? The specs for the Livolo say it works with 3 - 1000w but I'm sure I read somewhere that other people have had trouble with low-wattage appliances and touch switches.

Alan

 

[JohnD]

It sounds more likely that the timer has been adjusted to minimum.

Why do you want to use a touch switch?

 

[Inchiquin]

It sounds more likely that the timer has been adjusted to minimum.

Why do you want to use a touch switch?

Yes, it is set to the minimum which is a minute. But that's not the problem. The timer works correctly, which is to run on after it's switched off. But it's switching off immediately without being touched, so I can only ever run the fan for a minute at a time. As I said, it works correctly with a rocker switch. I guess my next step is to see if it works with a light in parallel. I don't really want to do that as the room doesn't need extra lighting but I will if it's the only way to go.

I should have added that the touch switch works perfectly with an 18w LED panel.

The only reason I want a touch switch is for aesthetic purposes. I'm creating a modern room.

Alan

 

[Harry Bloomfield]

I would guess, that the touch switch derives its power from being in series with the fan and it's control system and it is not getting enough of a charge to properly trigger the fans control. If you add a light in parallel with the fan - does that work?

If it does, could you maybe add a light permanently in parallel with the fan?

 

[EFLImpudence]

I would think that the timer circuit is less than 3W.

However, I do not know how these switches work at all without a neutral with LED lamps.

 

[JohnD]

but if the PL of the fan is live, and the neutral is connected, then the fan (once started) should continue to run for its timed period.

The fan, when running, draws about 8W

I don't understand what this means:
"It will switch on OK but automatically switches off after a couple of seconds. The run-on works as it should so the fan keeps running for a minute."

Can we see the way the wires have been connected in your switch please?

 

[flameport]

The touch switch is switching off after a few seconds, as the SL input to the fan is a logic level only, and doesn't draw any current. No current = no way for the electronics in the switch to charge.

I guess my next step is to see if it works with a light in parallel.

Do that. It will probably work.

 

[Inchiquin]

The touch switch is switching off after a few seconds, as the SL input to the fan is a logic level only, and doesn't draw any current. No current = no way for the electronics in the switch to charge.

Ah, that sounds logical, many thanks. It makes perfect sense now that you've said it - it already has a live connection so it only needs to be switched.

Alan

 

[Inchiquin]

I don't understand what this means:
"It will switch on OK but automatically switches off after a couple of seconds. The run-on works as it should so the fan keeps running for a minute."

It should work like this: Switch it on. It stays on. Some time later switch it off. It then keeps running for the timeout period.

flameport has now posted a perfect explanation of why it's not staying on in the second phase of the above.

Alan

 

[winston1]

’
The only reason I want a touch switch is for aesthetic purposes. I'm creating a modern room.

Alan

I’m sure you could find an aesthetic rocker switch. Much more environmentally friendly than having a light on you don’t need!