Hot Water problems with Baxi Combi Instant 105e

[StewartI]

Hi my name is Stewart and I am new to this site.
I am having constant problems with the DHW on my Baxi Combi which is 9 years old and last serviced 2 years ago.
The hot water is sometimes hot but mostly only warm.
I had a leak on the expansion vessel which was just a case of tightening up the union nut.
Would this have affected the DHW?
I have changed the DHW Diaphragm and Temp sensor.
After ringing Baxi Tech help they advised me to change the Plate Heat Exchanger,which I have not done yet.
Can anyone give advise please before I keep on replacing parts.
Regards
Stewart

 

[rojaca]

Usual suspect on these is diverter and pressure diff' preheat diverter. If your runnin your tap for v long and only luke warm, turn heating off run taps and see if htg pipework is getting warm.
Cost of these you may wish to go for fixed price repair.
If your system water is at all dirty i'd get this sorted and maybe a filter (magnatech/spirovent etc) fitted prior to having the d.v's done.
P.S Get your exp vess membrane checked whilst your doing work