Baxi 100 HE Plus boiler problem

[MGB_Roadster]

I have a Baxi 100 HE Plus boiler that is part of a system installed in1997 in a new (refurb) property. Last summer I realised it was long overdue for a service, so had this done last June. I had never had any problems for the three years prior to the service, but since then it's been locking out at intermittent intervals.

The boiler is in the attic, so it's not easy to get at, but I've tried to make a note of what's happening.

During the summer, when I was using just hot water for a couple of hours per day, the boiler would cut out approx every two weeks, lockout light showing red, boiler and mains lights showing green. Pressure would have dropped from 1.5 bar to approx 1.0. bar. After I re-pressurised to 1.5 bar and pressed the reset button it would be ok for another couple of weeks.

During autumn, hot water for two hours, heating for five hours per day, the boiler would cut out more frequently, approx every two-three days. Same symptoms as outlined above.

In the extremely cold weather in December/January I was using the heating for approx twelve hours per day. This caused the boiler to cut out most days, sometimes twice per day.

I checked on the boiler a couple of weeks ago, when it hadn't cut out for a few days, and found that it was running quite happily at approx 0.2 bar.

Any suggestions for what might be causing this ?

 

[cjg]

lots of things sometimes, but have come across one that had me for a little while, fault presure gauge reading wrong said 1.2+ but was aprox 2.5,heat on, over presure, prv opened and hear we go again!!!!!!! or is it ev thats at fault???

 

[Blackcatgas]

Combustion chamber door seal damaged, this leats the heat out into the case and trips an overheat stat, common problem on this boiler.