I hope someone might be able to help. I guess the title sums up the problem pretty well.
The boiler fires up fine for both CH and HW but usually cuts out either before the rads or HW are warm enough or sometimes it will get the rads hot but then not fire again once they have cooled and allowed the room temp to fall below the thermostat temp.
It also sometimes fails to get the HW warm enough.
The timer control is telling the system be on and the room therm is at about 21 so it should be firing.
THE HEAT EXCHANGER IS LOCATED ABOVE THE BURNER.
YOU COULD HAVE THE BOILER SYSTEM FLUSHED BUT IT IS MORE LIKELY THAT A REPLACEMENT HEAT EXCHANGER WOULD BE REQUIRED.
IT COULD BE SCALE BUILD UP.
DO YOU LIVE IN AN AREA NOTED FOR SCALING UP PROBLEMS DUE TO HARD WATER?
THIS WOULD REQUIRE A REPLACEMENT.
DOES BOILER EVER OVERHEAT TO SUCH AN EXTENT THAT THE OVERHEAT STAT LOCKSOUT AND HAS TO BE RE-SET?
I THINK IT IS UNLIKELY THAT THE CH & DHW SENSORS WOULD BOTH FAIL, BUT IT HAS BEEN KNOWEN! THIS COULD ALSO GIVE EARLY SHUT DOWN SYMTOMS YOU DESCRIBE.
I THINK YOU SHOULD GET A "GOOD" CORGI GUY IN TO RESOLVE PROBLEM/S.
HOPE THIS HAS BEEN OF SOME HELP TO YOU.
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