potterton boiler cutouts

[bones19]

I have a Potterton Envoy Flowsure+ which intermittently cuts out after it fails to ignite after 3 attempts. It fires up on pressing the reset botton but then cuts out again a few hours to a few weeks later. potterton engineers have looked at it and replaced the hot surface ingnitor, the flame sensor, and on one occasion said it was a loose connection. They have not replaced the PCB( although I don't know what PCB stands for!) However the problem with intermittent cutout persists. Can anyone help?

 

[ChrisR]

pcb = printed circuit board. The electronics. Potterton pcb's are notoriously bad. Cracks in solder joints are a real problem for them. An experienced eye over the back of the board will sometimes spot a solder crack. Lack of ignition can also be due to lack of gas - ie gas valve sticking shut. It's very difficult to fault-find intermittent faults like this.

 

[bones19]

Thanks very much. It has now cut out 3 times over the past 3 days. I'll call them out again and ask them to check the PCB

 

[bones19]

The heating engineer has visited 5 times in the past month but says he can't find the cause of the lockouts. he has checked the hot surface ignitor, flame sensor, looked at the PCB(but not replaced it as he says it may not solve the problem) checked the gas inlet pressure and serviced the boiler. It is still locking out once or twice a day!

Does anyone else have a Potterton Envoy Flowsure+ or have any other suggestions?

Help!!!!