I'm after a little advise with a Vaillant Ecotech Plus. We had a Code 75, Pressure sensor replaced, no change. Pump was vibrating every 20 seconds or so on start up, but engineer said it was faulty, new pump fitted. OK code 75 has gone. Customer has now reported the the heating is on all the time. I have found that when there is a call for hot water or the "C" Warmstart System is active the rads get hot and the hot water is not that warm. The diverter valve is not leaking, but if i manually pull the plunger out more you get hot water. New diverter was fitted. Still the same problem, engineer said there could be a blockage in the plate. This was taken off and looked clear. I'm reluctant to pay any more money out as I've been told it could be the board. Do you have any ideas.
