QT100HT Extractor Fan on Lighting Circuit

[JJPP]

The Airflow QT100HT Manual states "Room lighting: When connecting the fan to the light switch (terminal 1 or 2), a double-pole switch must be used" - it doesn't clarify as the why or the how though.

The diagram indicates a SINGLE Live input, with 2 Live Outputs, when the switch is in the ON position (see image attached):

I'm not sure such a thing exists though - can anyone clarify/weigh in on if this should actually just be a DPST light switch, using a split Live input to both input terminals, with one output going to the fan and the other to the light?

Thanks

 

[Doggit]

The fan has a 2 speed function, with the 1st speed also having a delay of 2 minutes to allow a quick visit to pay a penny, but not need to fan running. The second speed runs faster, so you need an isolating swith outside the bathroom, and also a 2 position switch to determine which fan speed you want.

 

[JJPP]

Hi - thanks for the reply - much appreciated.
A little bit more info....
I'm not going to be using terminal 2 (second speed switch) as i'll only be runnng it via terminal 1 (2 min delay on switch-on, 15 min run-on after switch-off and auto-on based on relative humidity).
I will be connecting permanent live and neutral, and wish to connect a switched live to terminal 1 only. This switch will also power the bathroom light.
For this, the manual states I need a double-pole switch, so I therefore need 1 switch to activate 2 separate circuits.
As the switch outside the bathroom is currently a 2 gang, SPDT switch (operates bathroom light and landing light), I'm trying to find a 2 gang DPDT switch to allow me to operate both the fan and bathroom light off one switch on separate circuits, but also continue to operate the landing light from the second switch.
The bathroom light currently uses it's SPDT as a SPST (one terminal is not connected to anything). The landing light, because it can also be operate from downstairs, uses the SPDT as intended.

So, my question has turned into more of a 'does this product exist' i.e. a 2 gang DPDT light switch?
I will use one DPDT switch to mimic 2x SPST switches (to operate 2 separate circuits for the light and fan), and the other DPDT switch I will ignore one side and use the other as a normal SPDT.

 

[EFLImpudence]

I'm not going to be using terminal 2 (second speed switch) as i'll only be runnng it via terminal 1 (2 min delay on switch-on, 15 min run-on after switch-off and auto-on based on relative humidity).
I will be connecting permanent live and neutral, and wish to connect a switched live to terminal 1 only. This switch will also power the bathroom light.

Then why do you need more than one SPST switch?

For this, the manual states I need a double-pole switch, so I therefore need 1 switch to activate 2 separate circuits.

...but doing it the way you are, you don't need a DP switch, do you?

As the switch outside the bathroom is currently a 2 gang, SPDT switch (operates bathroom light and landing light), I'm trying to find a 2 gang DPDT switch to allow me to operate both the fan and bathroom light off one switch on separate circuits, but also continue to operate the landing light from the second switch.
The bathroom light currently uses it's SPDT as a SPST (one terminal is not connected to anything). The landing light, because it can also be operate from downstairs, uses the SPDT as intended.

We term that as 2 gang, 2 way switch which - unless I have misunderstood - is all you need; i.e. the same as now.

So, my question has turned into more of a 'does this product exist' i.e. a 2 gang DPDT light switch?

No, not in domestic type switches.[/quote]

 

[EFLImpudence]

Is this not all you require?

Note I have changed around 1 and 2 positions

 

[JJPP]

Close - more like this I think and it's the 2 gang switch I'm having trouble finding:

Reason being, the fan Live terminal 1 needs to be a separate supply than the light but on the same switch - if connected to the same supply on the same switch,
the light bulb stays dimly lit, suggesting power is being fed to the bulb via terminal 1, through the fans circuitry - weird, but true (faulty?)!
Maybe some power leaking from the L terminal to the 1 terminal through the circuit board?
Because of this seeming loop when wired this way, this also has the effect of making the fan think Terminal 1 is receiving power, and the fan stays on permanently.

 

[JJPP]

I think I will use a 3 Gang, 2 way switch, and designate the middle switch for the fan... That may be the best solution.
Thanks all, very helpful, as always

 

[Doggit]

If you're just going to use speed 2, then i'd ignore trying to set up a double pole switch, and just take 3 core cable from the ceiling light to the fan. You need a switched live and neutral from the light to operate the fan, but also need a permenant live from the ceiling rose (or somewhere else as well) to keep it running after the light gets switched off. But all of this will depend on how the bathroom light is wired up.

They've made a bad job of trying to explain the electrics in the manual, and certainly haven't put it in plain language, and you've ended up overthinking the problem, but that's their fault, not yours.

Here's the manual section that tells you how to wire it.
Terminal N/L:
A permanent supply voltage of 230v/1Ph/50-60 Hz should be connected to terminals N and L, for ALL installations.
The unit is double insulated and does not require an earth. (drawing SS-919)
You need an additional switched live to Terminal 1 OR/AND Terminal 2
to give your fan its functionality