Ariston boiler locks out.

[Jandap]

Hello,
I have an Ariston Micro System gas boiler. Type C G.C.N. 41-116-06 or 41-116-07.
Installed 6 years ago, no trouble in that time. Suddenly it locks out and I have to press the reset button to get it going again then only stays on for minutes. Have changed both PCB's and all three electrodes, the gap in the spark generator for the ignition is correct, have also changed the overheat detector. Pump and fan working OK diverter valve working OK. I know that there is a good electrical earth.
I am at my wits end to find a remedy. Problem is I have a wife who is disabled and as winter is approaching I must keep her warm.
Ariston techie help were not much help, all the guy says is 'Must be earth' and I know the earth is good.
If there is any kind soul who could give me any advice I would be eternally grateful.
In hope.
Jandap
In addition have also checked the air pressure switch, that is OK.

 

[Agile]

You have already done quite a few things.

I cannot guess whats causing your lockouts but if I was diagnosing the faults there are a lot of settings that would be checking.

Because many of these are gas settings I cannot give you any information for safety reasons.

The best advice that I could give is to get a competent CORGI engineer.

Tony

 

[Jandap]

Thank you Tony for you quick response. Actually I did employ a CORGI registered gas engineer in the first instance to service the boiler, all he did was to vacuum out the combustion chamber, clean the burner and electrodes and check the fan, pump and flue. All appeared in order. He has been virtually living at my house for a week The neighbours are beginning to talk! He is equally as baffled. I am still no further forward. What else could he check?
Again in hope.
Jandap

 

[Jandap]

Eureka!. The lovely CORGI man came this evening, changed the air pressure valve and the boiler has been running on DHW and CH for the past 1 1/2 hrs. so maybe (fingers etc. crossed ) the problem has been fixed, I do hope so it's cost me a bomb in teabags!!
In retrospect the CORGI man did everything right, by that I mean by testing out components one by one, the air pressure valve appeared OK but was obviously faulty.
All praise to the mans persistence.
Thanks for looking.
Jandap