My Potterton performa 28 fires up for approx 15 seconds then stops. After maybe 30 seconds it will fire up again and then cut out. This is for both HW & CH
does the boiler keep making an ignite sound through out the process then its the flame sensing electrode may need cleaning with sand paper or it will need replacing. could be a faulty ch sensor which is the most likey when its faulty it gives a faulty reading causing hot water and heating to turn of the cools an restarts over and over
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