I am not a gas service engineer but do have some experience of complex control systems in industry so these comments are a bit theoretical. It seems to me that the problem with this boiler appears to be in the relationship between the DHW differential pressure operated 3W diverter valve and it's...
Yes, I saw that post earlier but was left a little confused. Does this imply that the boiler is working with NO DHW sensor or that a non-working sensor has been replaced?
Noticed today that when boiler is "stuck" in DHW mode with no flame any increase in the pre-heat temperature knob setting...
I have an identical example of this problem occurring in my 3 year old 105E instant. DHW and CH appear to work OK for most of the time but the boiler often "Sticks" in DHW mode , no flame, pump running continuously with DHW LED solid ON. Temperature LEDS are fullscale indicating 80 Degrees +...