OK I agree that the pump should be set to 3, but if i move the switch
into position 3 I can hear a sort of different noise, but when I start
the central heating from position 3, the boiler does not turn off,
just runs continuous and the pressure goes sky high. With the pump on
no. 1 the boiler does the stop-start stuff. How would i get the pump
onto no.3 but the boiler doing the usual stop-start routine.