Dear Agile, Many thanks for your prompt reply.
As Iexplained, the gauze filter was cleaned (with mains water) with no effect and there is little trace of corrosion on the burner. My understanding is that the valve was replaced because of the possible intermittent failure of the soft start opening facility of the valve that appears to cause excess gas at start up.
As Iexplained, the gauze filter was cleaned (with mains water) with no effect and there is little trace of corrosion on the burner. My understanding is that the valve was replaced because of the possible intermittent failure of the soft start opening facility of the valve that appears to cause excess gas at start up.