vaillant vcw gb 242 eh hot water working most of the time / central heating however comes on for ten seconds and then red neon light locks out, temp rises very rapidly and pump gets very hot. Recently changed heat exchanger, diverter valve diapragm and water valve diapragm, Servo valve working correctly micro switch adjusted ,diverter working correctly both microswitchs adjusted ...water valve diapragm has 2 types 1 with a centre hole, 1 without centre hole so my questions are which diapragm is the correct 1 and would this cause symptoms i have descriped and if not has anybody got any ideas.... Thanks
