Ok just spoke with the heating engineer
The problem isn't making the boiler fire up quicker it's maintaining the temperature.
From my conversation (remember I'm an end user not an engineer) I now understand how intelligent these new boilers are and if I've understood correctly my Vaillant ecotec 28 will during it's on mode work out the demand and vary the amount of gas required
Therefore I'm safe to increase the room temperature to a higher value as it's not just like my old 20 year old boiler which was merely on and off and in its on mode was pumping out 100% of gas.
I've also been comparing my Kw usage to the last quarter in 2017 and I'm using 40% less.
Have I understood the technology correctly as if so my stat is going up
I emailed Vaillant tech support and got this reply.....
In the diagnostics menu, is the heating partial load set to auto D00. If so change it to manual KW as it may be struggling with the pipe work configuration.
Is this because the system is not configured with a low loss header? The installation manual mentions a LLH; but nowhere does it say that is compulsory or that the Auto setting will only work correctly if one is used.
The boiler is connected to one side and the heating circuit to the other. Each circuit has its own pump. There is also an air separator at the top and dirt separator at the bottom. The body of the LLH is just a large empty tube.