Timed Extractor fan

[dishwaters]

Hello
I would be greatful if someone could cast their eyes over the instructions that cam with a replacement extractor fan. The wiring as specified doesn't make any sense to me: the switched live and the live are joined, so that fan will only work when the lights are switched on - there's no alternate supply for the timer function.

Untitled

• dishwaters
• 19 Nov 2014
• 1

Am I right about that or missing something obvious?

Supposing I don't need the timer function, is it ok to wire the fan up in this manner?

And if I did want the timer function, should I wire it up as below? (I have removed earths from diagram for clarity; the fan unit doesn't need an earth) Does this wiring scheme fulfil the stated requirement that "a remote switch must be connected between the live and T-terminal on the fan"?

Untitled

• dishwaters
• 19 Nov 2014
• 1

Thanks for your time!

 

[EFLImpudence]

The wiring as specified doesn't make any sense to me: the switched live and the live are joined, so that fan will only work when the lights are switched on - there's no alternate supply for the timer function.

I think you are confusing the isolator (FCU in your diagram) with your DP pull switch.

Supposing I don't need the timer function, is it ok to wire the fan up in this manner?

Terminate permanent live conductor safely.
Connect the switched live conductor to permanent live (EDIT) and switched live at the fan.

And if I did want the timer function, should I wire it up as below? (I have removed earths from diagram for clarity; the fan unit doesn't need an earth) Does this wiring scheme fulfil the stated requirement that "a remote switch must be connected between the live and T-terminal on the fan"?

Yes, all looks fine.

 

[JohnW2]

Supposing I don't need the timer function, is it ok to wire the fan up in this manner?

Terminate permanent live conductor safely. ... Connect the switched live conductor to permanent live at the fan.

I presume what you meant to write was "Connect the switched live conductor to the permanent live terminal of the fan and join together the permanent live and switched live terminals of the fan"?

Kind Regards, John

 

[EFLImpudence]

Yes, I did. Sorry.
I edited the text and it didn't come out right.
I will alter it.

 

[dishwaters]

Thanks!

The wiring as specified doesn't make any sense to me: the switched live and the live are joined, so that fan will only work when the lights are switched on - there's no alternate supply for the timer function.

I think you are confusing the isolator (FCU in your diagram) with your DP pull switch.


But I still don't understand the manufacturer's wiring diagram. There is only one Live feed into the fan. How does this provide an alternate feed when the lights are switched off?

 

[EFLImpudence]

But I still don't understand the manufacturer's wiring diagram. There is only one Live feed into the fan.

No, the supply live is permanent because the isolator (FCU) is left switched on.

How does this provide an alternate feed when the lights are switched off?

Because it is not controlled by the light switch.

It is the same as your diagram.
I think because you are using a double pole switch instead of a single pole in the instructions you are confusing the two.

 

[JohnW2]

How does this provide an alternate feed when the lights are switched off?

Because it is not controlled by the light switch. ... It is the same as your diagram. ... I think because you are using a double pole switch instead of a single pole in the instructions you are confusing the two.

Is not the confusion arising because the manufacturer's diagram does not really show ('the usual') connections to the room's light/switch - merely showing a switch which is seemingly there for manual triggering of (just) the fan?

Kind Regards, John

 

[ban-all-sheds]

Apart from the use of red sleeving - should be brown.

 

[dishwaters]

But I still don't understand the manufacturer's wiring diagram. There is only one Live feed into the fan.

No, the supply live is permanent because the isolator (FCU) is left switched on.

But doesn't that mean the fan would be running all the time? I want it to come on with the lights and then run for a period after the light has been switched off...

 

[EFLImpudence]

But doesn't that mean the fan would be running all the time?

No.

I want it to come on with the lights and then run for a period after the light has been switched off...

That's how it will work.

That's how they do work.
The permanent live is only used by the fan while the timer is running.

 

[JohnW2]

It is the same as your diagram. I think because you are using a double pole switch instead of a single pole in the instructions you are confusing the two.

As I said, I can understand the confusion. The manufacturer's diagram is only similar/equivalent to the OP's if one interprets "Remote On/Off Switch Not Included" as to room's light switch and "Lamp (if required)" as the room's light.

dishwaters: Are you sure that there is not another diagram showing how the fan should be connected to the room's lights?

Kind Regards, John

 

[dishwaters]

It is the same as your diagram. I think because you are using a double pole switch instead of a single pole in the instructions you are confusing the two.

As I said, I can understand the confusion. The manufacturer's diagram is only similar/equivalent to the OP's if one interprets "Remote On/Off Switch Not Included" as to room's light switch and "Lamp (if required)" as the room's light.

dishwaters: Are you sure that there is not another diagram showing how the fan should be connected to the room's lights?

Kind Regards, John

Ah! Right - now I get it! I think... So the switched live would connect via the "Remote On/Off Switch"?
That's the only wiring diagram there is - very poor, even misleading information. I'd be stumped without the aid of this forum!

Thanks again chaps!

 

[JohnW2]

Ah! Right - now I get it! I think... So the switched live would connect via the "Remote On/Off Switch"?

The 'Remote On/Off Switch' would be one half of your DP pull switch (the other half actually switching the light) so the output of that switch (which goes to the fan's S/L terminal) would be effectively be a 'switched live'.

That's the only wiring diagram there is - very poor, even misleading information. I'd be stumped without the aid of this forum! Thanks again chaps!

They do seem to be particularly bad instructions, since they appear to not show what must be the most common way of wiring a timer fan (to the room's lighting)!

Kind Regards, John