Potterton Suprima 50L working intermitently

[45marathon45]

Hi all,

I have been experiencing problems with this boiler not working intermitently (it fires up for a few minutes then goes off then on and off and so on). After some research, and to see if I could get a quick win I decided to replace the PCB with a reconditioned unit. Unfortunately the problem is still there. Specifically the green LED flashes on and off which according to the manual the status of the boiler is:

EXT.Call for Heat (STNDBY switch to ON, 2 Per Sec.Temp. Control set to Max.)

I have gone through the recommended start up process and that hasn't made any difference.

I would appreciate any help you can give. Thank you

 

[ChrisR]

fires up for a few minutes then goes off then on and off and so on

That's what they're supposed to do...
Poor circulation for whatever reason, would reduce the "on " time.

 

[Agile]

The PCB should be the last thing to change only after everything else has been checked.

I would expect the pump has failed or is blocked or running slow or there is a blockage in the system.

The temperature differential across flow/return should be 10-15°C maximum. Any more and there is insufficient flow.

If you got the repaired PCB from CET then he owes me the next meal!

Tony