Right, it went again with the same symptoms and it does seem that it is getting stuck in HW-mode - can't state for definite that the green HW LED was on peramanently, but i'm fairly confident it was.
When it started working again the first time, it was just after the shower had been switched-on - just seemed purely coincidental to me at the time! Anyway, following failure of the boiler this time around, I switched the shower and HW tap on in the bath and low-and-behold, the boiler fired-up again.
As far as I know the (electric) shower is not fed from the HW pipe, as one would expect, and so the only link I can think of is the CW supply - don't believe the HW tap was turned-on the first time around.
Since the boiler is now working again I don't want to play with it yet and hence I haven't tried the checks kindly forwarded to me. I just wonder though if there is a 'typical' reason for failures where the boiler is stuck in HW mode? Guess you're gonna suggest PCB, microswitches, valve actuator, etc.!
Reason I ask the above question is because it could go again at any time and I may not be able to retrieve the situation so easily. Therefore i'd like to be armed with as much info as poss.
By the way, it is an 'instant' and the part number is 02-23-056445-247903-01-00. As for the comment about seeking assistance from a Service Engineer, which is perfectly fair, I haven't for the following reasons:
1. Cost and availability at this time of year.
2. Hoped it would be quicker to sort it myself - have past (limited) experience of CH systems and am also qualified / practising Electronics Engineer.
3. Was interested to learn about the system this time around, as well as for future reference.
Thanks in anticipation of your continued assistance.
When it started working again the first time, it was just after the shower had been switched-on - just seemed purely coincidental to me at the time! Anyway, following failure of the boiler this time around, I switched the shower and HW tap on in the bath and low-and-behold, the boiler fired-up again.
As far as I know the (electric) shower is not fed from the HW pipe, as one would expect, and so the only link I can think of is the CW supply - don't believe the HW tap was turned-on the first time around.
Since the boiler is now working again I don't want to play with it yet and hence I haven't tried the checks kindly forwarded to me. I just wonder though if there is a 'typical' reason for failures where the boiler is stuck in HW mode? Guess you're gonna suggest PCB, microswitches, valve actuator, etc.!
Reason I ask the above question is because it could go again at any time and I may not be able to retrieve the situation so easily. Therefore i'd like to be armed with as much info as poss.
By the way, it is an 'instant' and the part number is 02-23-056445-247903-01-00. As for the comment about seeking assistance from a Service Engineer, which is perfectly fair, I haven't for the following reasons:
1. Cost and availability at this time of year.
2. Hoped it would be quicker to sort it myself - have past (limited) experience of CH systems and am also qualified / practising Electronics Engineer.
3. Was interested to learn about the system this time around, as well as for future reference.
Thanks in anticipation of your continued assistance.
