Worcester WM 12 Installation And Servicing Instructions page 15

(iii) Honeywell "S" plan. (See Fig. 20, 21, 22)
Only the burner will fire. This will allow approximately
3 minutes test time if the boiler is cold and the boiler
thermostat is set to maximum.
After servicing the appliance the Service engineer must leave the
appliance in the run mode. (See Fig. 29)
Fig. 15. Wiring diagram (standard).
Mains supply 230V 50Hz
white
brown
green/yellow
orange
violet
brown
brown
white
green/yellow
grey
black
red
blue
15
white
green/yellow
grey
black
red
red
black
grey
green/yellow
white