Hot Water temperature rise from boiler

[norush]

Hi Folks
I have a Worcester Bosch 30CDI Combi Boiler of 4 Yrs old.
A few Months ago the temperature of the hot water suddenly dipped.
Shower was OK but I needed to run this on Max unlike before. Baths need topping up with kettle water.
Diverter valve is fine.
had a company come out and said it was a turbine that they replaced. This did not fix the problem. They came back and diagnosed Heat Exchanger but this has made marginal difference.
Boiler is set on full and is showing 70 deg on front panel.
I have checked Today the tap temperature and on cold it is 7.4C - On Hot reading 43C.
Is this normal as it does not apear to be as it was pre 3 Months back.
However a few Months back a new Mains supply in the area was installed as part of a big project.
Any help appreciated.
dave

 

[Nozzle]

do you have a mixer tap?

 

[norush]

Yes

 

[Dan Robinson]

A 35.6 degree temperature rise. What is the flow rate in litres per minute?

 

[shambolic]

Exactly @Dan Robinson boiler could be perfect.

 

[norush]

that is around 12 Lts

 

[Dan Robinson]

About right then.

Temperature drop is likely due to the weather reducing the incoming cos temperature. The joys of having s combi. Reduce the flow rate and get hotter water.