Vent-Axia install from fCU

[ROLAND Harding]

Hi all I need your help my old vent Axia went busted and i needed a new one . I bought the same model VA100 and wire it up . That where the problem begin, on the terminal block on the vent got L. N SL so I conect the blue cable to the N terminal the Brown to the L terminal and the black to the SL terminal . When I switch on the FCU the vent works But can't control it from the light switch. It's looks like the FCU totally bypassed the light switch . On the circuit diagram on the vent there are isolator switch and pull cord which I don't have . What am I doing wrong ? How can I wire it so that the FCU is ON but the Light Switch control on and on ? At the moment it's permanently on which I don't want . Please help

 

[Wilko]

Hi Roland and Welcome to the Forum .
It's possible there is no fault, so here's something to try ... With the FCU switched off, try setting the fan timer to minimum run time position. Then turn FCU on. The fan should start and run as you've said, but just let it. After say 10 minutes it should stop. Be patient, I go off for a cup of tea. If you are seeing the "initial start behaviour" the fan should now be under light switch control as per normal.

 

[Wilko]

Also - just seen they ask for a 1 Amp fuse in the FCU. They are not common but are available from electrical supplier shops (probably not Screwfix for example).
1 Amp Plug Fuse - BS1362 - https://www.tlc-direct.co.uk/Products/TLF1.html

 

[MJPD29]

You may have switch live and permanent live wrong way round try switching brown and black

 

[Pete999]

Hi all I need your help my old vent Axia went busted and i needed a new one . I bought the same model VA100 and wire it up . That where the problem begin, on the terminal block on the vent got L. N SL so I conect the blue cable to the N terminal the Brown to the L terminal and the black to the SL terminal . When I switch on the FCU the vent works But can't control it from the light switch. It's looks like the FCU totally bypassed the light switch . On the circuit diagram on the vent there are isolator switch and pull cord which I don't have . What am I doing wrong ? How can I wire it so that the FCU is ON but the Light Switch control on and on ? At the moment it's permanently on which I don't want . Please help

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Where is the light switch in this set up?

 

[ROLAND Harding]

Thanks guys will definitely will try your suggestions and see what's happening and will come back again to share with you the result.

 

[DefyG]

Did the previous fan work off the light switch?
Looks like its just controlled from the S/fcu to me, may not even be a lighting circuit supplying the fcu!
Is this in a bathroom, what zone?

 

[ROLAND Harding]

It's in the bathroom above the toilet . The pervious one hmmmnn not sure if it's worked becouse it's wasn't coming on so I changed it . Am the maintenance person in a school and its my job to put them in . It's seem the FCU control it and not the light switch .

 

[ROLAND Harding]

Thanks gent it's worked lol nothing was wrong with the wiring . It's turns out that the timer had to be put on the lowest settings and takes about 10 to 15 to go off after the switch is off .