Vaillant ecotec pro ebus temperature too high

[Eel7]

Hello,

I have a vaillant ecotec pro boiler wired with a vaillant vrt350 thermostat (modulation enabled).

When I check the ebus target temperature it is way too high, always stuck at 90 degrees.
(I check using the diagnostic code D.009)
I reduce the circuit temperature to 50 degrees, but nothing changes regarding the ebus target temperature, always stuck at 90 degrees.
Any insight on this issue ?

Also another worrying thing is that the input and output flow temperature difference is rather low below 5 degrees, which make things that it does not condense well…

Thanks

 

[CountryFan]

I don’t think D.009 is adjustable, try D.071.

 

[Eel7]

Indeed, d.009 is not adjustable, by default D.071 was at 75 degrees, I reduced it to 60 degrees, unfortunately still not change to D.009, it still stick to 90 degrees