I have a bathroom exhaust ventilator installed that turns on when I flip the wall switch and that continues working on a timer when I cut the power in the switch.

In terms of wiring, I see 3 cables going in (L, T, N) on one side, and two other cables going in on another side. The two cables have electricity at all times, independently of the wall switch.

Is there a way to bypass the timer? I would like to have the ventilator off when the wall switch is turned off.

Thank you in advance

  • Is the timer in the switch or in the fan? Do you know the make and model of the fan? – Comintern Apr 6 '14 at 18:18
  • The timer is in the fan, if I understand the question. The brand is Elro, no idea of the model though. Thanks for the reply! – Dante Apr 6 '14 at 18:26

If the timer is in the fan, it may not be possible to disable the timer without disabling the fan itself. Based on the labels (L,T,N), I would guess that L is the switched input for the light and T is a switched input that starts the timer for the fan. You can test this by disconnecting the T terminal (make sure you cap the bare wire before turning the breaker back on) and see if the fan still functions with the switch.

If it doesn't, you're probably looking at altering the internal wiring of the fan to bypass the timer (not something I would recommend or consider safe). If this does turn out to be the case, I would take the covers off of the fan if possible to see if there is a timer duration adjustment in the fan someplace. You may just be able to turn it down to zero (or a considerably shorter duration).

That said, it sounds like you are trying to disable a feature of the fan that is there to ensure that the fan is on long enough to remove moisture from the bathroom. The reason fans are equipped with timers is so you can leave them running long enough to work without having to go back later and turn them off (and/or having to leave the lights on while they are running). I would ask myself if the reason you are trying to disable it is worth running a risk of issues with mildew and the host of other problems that can stem from inadequate ventilation. If it's a noise issue you might think about just replacing the fan with one that is quieter.

  • I think you nailed it. The main reason I want to do this is because the fan is really noisy. I was considering getting a new one but I wanted to check if disabling the timer is a possibility. I can control how much time it stays running (3m to 20m), but anyway we leave the door of the bathroom open after showers therefore the humidity should clear without the fan. Thanks a lot for the answer. I'm going to test disconnecting the T, like you suggest, if it doesn't work I'll just get a silent one. Cheers! – Dante Apr 6 '14 at 19:33

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