Just replaced pcb on this model boiler (as per MI fault finding chart) still having problems. I read a previous post from here that "it was best to change sensor" at the same time as pcb? Is this a known fault? it is not identified in the fault finding chart.
Baxi 51/5 BBU
- Thread starter anjme
- Start date
Most MI fault finding charts always revert to change pcb in the end 
PCB on these have been very reliable I have found, and usually faults are very minor and easy to fix.
What is your fault? What sensor do you mean?
PCB on these have been very reliable I have found, and usually faults are very minor and easy to fix.
What is your fault? What sensor do you mean?
Fault was boiler switched itself off. Red neon light on all time. Switch boiler stat (potentiometer) off to reset boiler, fired up and went off within 5 mins. Defo all external controls working ok , flow pipe from boiler freezing cold so not overheated etc, MI parts list shows a "thermostat sensor" what I would call the boiler stat phial in old money ! but this links into pcb (as does everything else! ) With new pcb installed boiler has run overnight ok but now same fault reported again, I was wondering if the sensor ( thermostat phial) could be at fault. As I said I read an old post that said if pcb is changed then good idea to change this sensor as well ?
N
namsag
Did you check the basic , that pilot is clean and not lifting off after being on for a few mins , common fault
Yes . Pilot perfect, tc lead sensor probe has strong pilot contact, not lifting off, no blockage from poc sensing tube. After new pcb installed boiler fired ok and has run for 24 hours. Now customer has indicated that it has gone to lock out, boiler off red neon on permanently. My experience is pushing me to a faulty thermostat sensor. tried Baxi technical for over half hour today..
line engaged ! constantly..
Will try them again tomorrow.... Any ideas on warranty on these boilers ? Heard a rumour they had 3 years warranty?
line engaged ! constantly..
Will try them again tomorrow.... Any ideas on warranty on these boilers ? Heard a rumour they had 3 years warranty?
N
namsag
That rings a bell 3 years warranty pretty certain they do
Ive changed a few thermostat sensors on these model baxi's. Often after previous engineer has changed board and had the same issue.
Boiler will run for a bit then lockout and wont reset for ages or not reset at all
Boiler will run for a bit then lockout and wont reset for ages or not reset at all
Thank you Petit_Pablo, just the answer I was looking for.. Shame the MI is not more helpful, new pcb diagnosed from MI fault finding chart, no mention of sensor related problem. more expense.
Never had this problem with the "nasty old" standard boilers no pcb, no sensors, no flame rectification, no oxy pilots, no fans not much to go wrong therefore no costly parts replacement ...
The HRPC (boiler spares) of this world are literally coining it in, there must be factories in China mass producing all this gear to go into so called modern boilers at great expense to the end user .. And what for ?
to get an extra 10-15% efficiency .. all a big con if you ask me.
Rant over thanks again to all who posted, will try fitting a new sensor.
Never had this problem with the "nasty old" standard boilers no pcb, no sensors, no flame rectification, no oxy pilots, no fans not much to go wrong therefore no costly parts replacement ...
The HRPC (boiler spares) of this world are literally coining it in, there must be factories in China mass producing all this gear to go into so called modern boilers at great expense to the end user .. And what for ?
to get an extra 10-15% efficiency .. all a big con if you ask me.
Rant over thanks again to all who posted, will try fitting a new sensor.
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