For the past 2 weeks I keep having to reset the pressure differential switch on my Vaillant Thermo Compact boiler model no VC GB 112 E.. after which it works for half an hour or so then shuts down, in addition to which the lights on my timeclock go off.. any clues

Laurence, April 2012

You can't reset the pressure differential switch, it's governed by he pump. If you mean the overheat stat, suspect the ntc or ch safety switch.

Carefree, April 2012