Hi i have a vaillant Turbo Max 282E i have a problem that when i open the hot water after 3-seconds it goes cold and when i turn the tap of and then open it on again it comes warm but same problem so i had changed the diverter valve but still same problem so then i de-scaled my Hot Water Heat Exchanger and i still have the same problem and know when i put the heating on it comes on and when i open the hot water tap and when i close it the boiler does'nt turn back to central heating till i restart the boiler by turning it off and then back on.
ALL HELP WOULD BE APPRECIATED THANK YOU.

Trainee Plumber, January 2009

Check the bypass valve for dirt and restricted flow, this is on the pipe that runs horizontal across the rear half way up.

mike h, February 2010

make sure the diverter valve accuator motor is attached to valve correctly, has to push and pull. Ball on valve pin fits sideway into motor shaft. Pull valve pin up, turn hot water on this extends accuator shaft slide it onto the ball turn hot water off. This retracts the motor shaft, check it is still attached refasten to valve body.

mike h, February 2010