Airflow icon 15L Timer

[aubrey4444]

Hi

I have a airflow icon timer unit and all is well it turns on when i put my light on but as soon as i turn the light off the fan goes off? Is this right i thought the timer bit is supposed to run the fan a bit longer after switch off?

 

[riveralt]

If it has worked before and you haven't touched the wiring then the timer unit could have gone.
Sounds like it is operating only on switch live.

 

[JohnW2]

If it has worked before and you haven't touched the wiring then the timer unit could have gone. Sounds like it is operating only on switch live.

I suppose the timer capacitor could have failed o/c. Otherwise, it would be odd, because (if it's the 'usual' sort of timer circuit) almost all of the timer circuitry would have to be functioning for a voltage on the 'trigger' input to cause the fan to come on.

Kind Regards, John

 

[ericmark]

It does seem wrong. There is I think under Part F building regulations a set run on time I think 15 minutes where a fan is required. Oddly it does not really say from when the 15 minutes is timed one assumes exit from the room, but with a pneumatic timed push switch it is clearly from the point where switch is pressed. It also states that where there is natural light you must be able to activate fan without switching on the lights. If there is an opening window then fan is not required so up to you.

Quite often fans are not wired correctly. Often the only way to switch on the fan is with the lights even when there is a window. But for the timer to work there needs to be two line supplies one switched and one permanent getting these wrong way around will often stop it running on. Also where wired either by DIY or when there are opening windows often the permanent line is missing so no timer can make it run on.

Where I live original build had opening window in bathroom but cheaper when fitting double glazing to not have an opening window so many houses in the street do not comply with Part F building regulations. However it was not the electrician at fault but the people fitting the double glazing.

I am assuming it is in a bathroom. So if the window will open then it's OK as it is. With opening windows fans are an extra. One also has to be careful with houses with open flues as the fans can cause fumes to be drawn into the house. I have what is classed as an open flue in my house although there is nothing open about it. Open flue means it draws combustion air from inside the room not that you can assess the flue. With draft proofing fans even as part of the tumble drier can be a problem.

 

[aubrey4444]

Hi this my fan....Just wondering if its wired right as it goes off when i switch the light off and does not run on must mean theres no permanent live?
Thanks

 

[EFLImpudence]

If it has worked before

Did it?

Or has it always been as you describe now.

 

[JohnW2]

Hi this my fan....Just wondering if its wired right as it goes off when i switch the light off and does not run on must mean theres no permanent live? Thanks

As you've been asked (by implication) did it ever work as expected? Without the instructions, it's impossible to tell whether it is wired correctly.

If you had got the permanent live and switched live feeds connected to the wrong terminals of the fan (i.e. 'swapped') it would function as you describe - since the feed to what is meant to be the permanent live terminal (which is what makes the fan work) would only be present when the light was switched on (since it was being supplied by a switched live conductor). If that's what you've done, then just swapping the L snd S/L wires ought to cure it.

Kind Regards, John

 

[riveralt]

The top (green) terminal block should be right to left N, L, SL - looks like it is 'possible' your L and SL are the wrong way around.
The correct way is not to guess but test the purpose of each wire and terminate correctly.

 

[JohnW2]

The top (green) terminal block should be right to left N, L, SL - looks like it is 'possible' your L and SL are the wrong way around.

Indeed - and, as I said, that would result in the functionality the OP is describing.

The correct way is not to guess but test the purpose of each wire and terminate correctly.

Agreed. However, in this case, I think a valid test of which is permanent live and which is switched live is to connect them (both ways around) (and together with a neutral) to a timer fan (any timer fan ) and determine which 'worked'. Alternatively, another valid test would be to link together the L and S/L terminals of the fan and try connecting, in turn, each of the available conductors to one of those terminals - with one (perm L) the fan would come on permanently, with the other (S/L) it would only come on when the light was switched on. 'Testing' does not necessarily requires meters or voltage indicators

Kind Regards, John

 

[EFLImpudence]

The top (green) terminal block should be right to left N, L, SL -

It IS. The markings are just visible.

looks like it is 'possible' your L and SL are the wrong way around.

I agree. It's not as I would have connected it.

 

[JohnW2]

It IS. The markings are just visible.

Better eyesight than me

looks like it is 'possible' your L and SL are the wrong way around.

I agree. It's not as I would have connected it.

I also agree. As I said a few posts back, it's about the only single fault/error that would result in what the OP is experiencing. As for not being as you would have connected it, you are presumably assuming that the sleeved conductor is the S/L. That's certainly the way that I would do it (and probably also you), but ..... !!

Kind Regards, John

 

[EFLImpudence]

Yes but more the other way round - brown would be permanent live.

 

[JohnW2]

Yes but more the other way round - brown would be permanent live.

Well, yes, that's what I meant - so (assuming that grey has been used as neutral, albeit not sleeved) the black sleeved with brown would be the "non-permanent" live

Kind Regards, John

 

[EFLImpudence]

 

[JohnW2]

View attachment 82015

Where did that murky pic come from, and what is it meant top illustrate/provve?

Kind Regards, John