Thanks Stem it is thermal store and functions as the above diagram, the oventrop blending valve was sticking. I replaced it today and is now working perfectly, thanks for the help guys.
It's a new issue, we've owned the house 5 years system has been fine until this morning.
I've had different heating systems in other house but always found this layout to be confusing in its operation.
My hot water has stopped working the water is Luke warm at best with intermittent spells of warming up when tap is run for an extended period.
The boiler is running fine with the tank and pipes hot.
Would this system be described as an s plan system?
Would the blue pump on the left be a hot...