sorry to sound a bit nieve but would common then mean the red wire?
and normally closed will mean the black wire.
Many thanks so far your a great help.
i have circuit diagram for the whole boiler but it just mentions the wiring colours for the original installation. Can you help with what C, NC and NO are in relation to red black or brown?
Many thanks
Just bought a honeywell C6065AH1020 pressure switch having been told it is a uniform replacement for the one in my Sime Friendly Format LPG boiler, BUT
the contacts on the honeywell are C, NC and NO
the contacts on the Sime are 1 2 3 with black red and brown wires respectively attached. no...