England is 20 years behind mate to start with.What temp does most boilers start condensing ?
55 is the answer so with a 15dc difference you will condense and with the new boiler plus kit you will save more etc
As I said if you set 55 the return will be about 10kelvin different so it will use the flue gas as energy instead of wasting.
Boiler plus is for 20 years in Germany .. we only install boilers with integrated heat recovery units , weather compensation sensors etc. However, Like Atag says, they are apparently Europe’s best boiler which is wrong market leader is and will be Vaillant .. the guy from Atag is a kitchen company by the way he just started 10 years ago to do some boilers .. Lol