Vokera Linea Problem

[cltheob135]

I have a Vokera Linea 24
The problem I am having is that the heating side seems to be working fine.
The hot water however is luke warm, the burner seems to be working fine, when I first turn the hot tap on the temperature displays 44c, it then progressively drops to 28c, this is as hot as it gets.
The hot water temperature control dial is turned to max, when I try various settings with this dial it seems to have no impact.

 

[gas4you]

Check to see if the ch flow is getting hot when the ch is off and the hot taps turned on. If so dv is sticking and needs a recon kit fitted.

 

[cltheob135]

I'm letting it cool down as I type