hi i have a vaillant turbomax 824 with the green buttons. my hot water is luke warm when u run it on very low its warm but when u turn the tap high it run luke warm. it was working fine. i had the diverter valve changed 2 weeks ago. someone told me the heat ex is probably at fault. ty

kash, January 2012

clean hot water heat exchanger or better replace new one,drain system open air vent rads, shut cold feed supply to boiler,drain hot water from lover point,undo two screws take out and replace or clean with acid,shut air vent before filling system.open one by one to take air from system fill to1.2 bar

ltd, January 2012