whoops sorry about this misleading information...
I don't believe you.
If you were sorry you wouldn't be regurgitating it for the 2,579th time.
This has turned into Alec's vanity publishing site where he promotes the particular deviants of boilers and systems he likes to flog.
By his own admission that's to establish a market niche, as he cares about how much money he makes,
not about how well his customers do.
at my place the flow temp from my boiler is 42c... thats all it needs
Which means little except that it's on for longer than one with a higher flow temperature and for less time than one that's lower.
Alec claims it means more than that? But can't point to point to validated external references.
NOT boiler manufacturers' flagrantly puffy, figure-shy promo's, NOT his own (though he hasn't produced any, he's not up to that).
Otherwise it would be best if Alec stopped trolling the site.
This is where compensation controls score hands down...
More meaningless, sweeping assertions.
Original Poster:
More modern boilers always save over older ones. Clever control systems often give unexpected problems/issues. Concensus seems to be that it's usually more trouble than it's worth, to go very "clever". I've explained how I get to that conclusion, many times - I have feedback from a lot of others' installations. NB I'm not promoting any particular system.
"Usually" is heavily weighted by the large porportion which is coming from unsophisticated users with poor understanding - you may do better than those.
There have been improvements along the boiler-development way which give incremental percentages in efficiency. The biggest one was when we all had to go to condensing boilers, but they all had other efficiencies built in, and nobody's tried to separate them out. Boilers now control
themselves to keep operating efficiently much better than they used to.
There's always some snake-oil salesman asserting that some squiddly feature is god's gift, because it's the thing HE pushes. Beware snake-oil salesmen and their unsubstantiated claims.
How much there is to save, depends where you start. If you compare modern best-controlled with ancient (worse than band D), you might win 30 - 40%, but the chances are that the house is better insulated etc as well, so numbers are unreliable.
Replacing middle aged non condensing combis with the best, wins you about 10% -15%, judging from a small number of my customers who have gone that route and measured reasonably carefully, and comparing seasonal use with my own system which hasn't changed, though they admit watching their energy use more carefully.
