rads getting constantly airlocked is a symptom of a fault within a central heating system, and is either ingress of air (air being sucked into the system) at bad jointing or bad pump placement etc or a chemical reaction within the system do to non treated water and new water within leeding to the formation of gas within the system, either way you need a good plumber to come diagnose the problem and remedy it as it will lead to rapid corrosion of the inside of all your rads and boiler and eventual system failure.
T, May 2008
