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smitty1892
Had a call for boiler lighting with a bang( and what a bang it starts with!) , checked and cleaned spark electrodes and did a tightness test between isolating valve under boiler and gas valve, it dropped 1.2 mbar in 2 mins . I kept gas supply off for 1st ignition attempt then switched on for 2nd attempt no bang . Redone tightness test stayed solid this time . Is it possible solenoid on gas valve sticking open a little at times? Plugged gas line until get new valve to try