I have a Vaillant Turbomax combination heating boiler.

When the central heating is operating & a hot tap is opened
the hot water temp is low. If the heating is off then the temp
is fine.
I have noticed that the Diverter valve is still allowing hot water to
flow around the central heating system.
Is there any way to test the Diverter valve ?
Has anyone else had the same problem?
Many Thanks

Dave Tedder, November 2007

you have tested the diverter valve yourself..that is the main test you have done...the diverter is letting by into the CH circuit..just replace the diverter valve

gedodonnell, November 2007