potterton prima boiler

[millenniumharbour]

My boiler is not firing properly. The pilot light is fine, and when cold the jets fire fine, then after about five minutes of running, the jets go out and whilst the water is still being pumped around the system, the jets do not re-light however the pilot burner stays alight. I have tried cleaning the top of the jets but no luck. Does anyone have any bright ideas? Thanks.

 

[sifu]

It could be one of a number of things.
What model is it? The most common are Prima, Netaheat, Profile or Suprima. Does the flow pipe from the boiler get very hot? Do you have a fully pumped system i.e. can you run the heating on its own without a hot water demand?

 

[millenniumharbour]

Thanks for the reply. It's the Potterton Prima F. I have a feeling it may be a failed thermostat internally, and the boiler is cutting out as a safety mechanism. For a few months now, there has been loud clicking, as if from a bi-mettalic strip that at a certain temperature clicks on and off for about 10 seconds before settling. That isn't happening now.

 

[sifu]

Does the spark stop when the pilot is lit or can you still hear the spark. If you still have a spark then you are not getting flame rectification at the pilot, in which case either the pilot is partially blocked or you need a new pcb. If the spark stops then the gas valve solenoid GV2 (the high flame solenoid) is faulty.
From you description concerning the clicking I would hazzard a guess that the PCB is faulty.
PCB part no is 407677 - about £80 (I have one on my van )
If you need a solenoid then you also need a CORGI installer. Part no is 907716 - about £15
These part numbers are for the Prima and Profile Prima 30 to 60 series. The part numbers are different for the 80 and 100 but if you have your manual they will be in there.

Paul