Thanks for that, what I'm really looking for is information about the fan
motor, since it's got 3 leads going to it, a red, blue and a white, and
as I
said before the white lead is terminated with an insulated crimp
connector
which is not connected to anything. I suspect the manufacturers (Silavent
SVC6) use an universal 2 speed motor which can be used in one speed or 2
speed mode. I'm guessing that if I connect the white and blue across the
mains and disconnect the red it will run at a lower speed but I 'm loath
to
try it.

On the back of the installation leaflet it has the following info :-

230V- AC. 50Hz
High speed /Single speed 35W
Low Speed 25W

Don

why not check it with a multimeter, and if it fits what you suspect,
try running it in series with a lightbulb. At your own risk.


Good idea, I'll try that when I'm a bit more awake.
Cheers
Don