Bathroom fan wont overun?

P

plugy

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We have installed a new bathroom fan with an isolator switch.
The fan comes on when the lights are on and off when switched off. Issue being the fan wont continue to run after the lights are off. It also has a humidity sensor built in, we have tried turning the timer/humidity screws both ways but still will not stay on after the light switch has been pulled?
Could it be a faulty unit or would we have a wire back to front?
 
The fan needs both a switched live and a permanent live. The switched live will make it come on with the lights, the permanent will enable the over run and humidistat.
 
Taylortwocities said:
Two-probe voltage tester you need.
Click to expand...
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RandomGrinch said:
If your switched live and permanent live wires were transposed, you would get that effect! :)
Click to expand...

Would you?

The humidistat would not kick in just because the lights are on- the room would have to be above a certain humidity level.

The timer overrun? If that were set to, for example, 2 minutes, wouldn't it cut out after 2 mins even though the lights were still on.

Sorry but I think you might be wrong... then again, I might be wrong.
 
opps said:
Would you?

The humidistat would not kick in just because the lights are on- the room would have to be above a certain humidity level.

The timer overrun? If that were set to, for example, 2 minutes, wouldn't it cut out after 2 mins even though the lights were still on.

Sorry but I think you might be wrong... then again, I might be wrong.
Click to expand...

If the wiring were transposed, the fan would be 'seeing' the light switch as being on permanently. However, it can only operate when it's permanent live contact receives power.
Hence when the real light switch (connected to PL) is pulled, fan 'sees' light switch (the permanent live, connected to SL) is on and starts the fan running.
As soon as real light switch is turned off, the fan has no power (on PL) and dies!

The humidistat and overrun wouldn't come into it, as the usual behaviour of the fan is to come on when the light switch is pulled!

It's possible that there is a maximum runtime built in, but I daresay that threshold hasn't been met.

As you say, I may be wrong, but that's my logic! :)
 
RandomGrinch said:
If the wiring were transposed, the fan would be 'seeing' the light switch as being on permanently. However, it can only operate when it's permanent live contact receives power.
Hence when the real light switch (connected to PL) is pulled, fan 'sees' light switch (the permanent live, connected to SL) is on and starts the fan running.
As soon as real light switch is turned off, the fan has no power (on PL) and dies!

The humidistat and overrun wouldn't come into it, as the usual behaviour of the fan is to come on when the light switch is pulled!

It's possible that there is a maximum runtime built in, but I daresay that threshold hasn't been met.

As you say, I may be wrong, but that's my logic! :)
Click to expand...

Far play. Tnx
 
Thanks all, will double check wiring, but sure is fine. Fan has a PL, SW and neutral connected.
Will hvae another look
 
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