my vokera linea28 combi boiler has a problem HELP

[smacfras]

My linea 28 combi boiler is 6 years old, and it is only heating the tap water up to 40 degrees. The central heating is working fine.
I have changed both thermistors. I have cleaned the domestic heat exchanger but to no avail. I have also checked and cleaned the none return valve, which seems ok.
I have had to reduce the input water pressure to get it to heat up to 40. Otherwise it would only get up to about 34 degrees. One thing I have noticed but am not sure if it is correct is when I have a hot tap running the central heating flow pipe also heats up so do the radiators nearest the boiler. Should this happen? or are the 2 systems mixing? Please let me know your thoughts.

 

[wiggikins]

Dodgy diverter valve!???

 

[nickso]

yeh, replace the seals on the diverter.

 

[superdupergasman]

yeh, replace the seals on the diverter.

blow off the pressure, take off div motor, 6 srews, replace internals with a service kit. rebuild, refit motor, refill. 20 mins, roberts your fathers brother!