Thanks for the engineering lecture Kaptin. Shall I cut and print it to send to Boeing? I reiterate-manufacturers advice for the 744 is to leave recirc. fans on. I reckon Boeing are pretty touchy at the moment with all the litigation and problems they face with fuel pumps etc., so I suspect some thought has gone into this. So for now, as always, I will follow the specialists advice. When they cant tell me what to do I shall ask you.