New boiler fitted two years ago. Problems with air causing sudden burst of hot water overflowing back into header tank and out through overflow pipe. Eventual converted to sealed system. Now still getting air in system causing boiler to cut out and go into blue flashing mode. Sometimes resetting can fix it but can hear air gurgling through boiler. Don’t understand why I never get air trapped in any radiator. Any bleeding done via pump. Now fitted auto air valve but it made no difference. Pressure can go from 1.00 up to 2.2 when fully operating.
