can anyone help had bolier 5 year 4 weeks ago noticed water running hot and cold heating not at full temp noticed when system clicked on everthing normal except burner only come on for 10 sec then out and like trying to get on again and eventually come on for another 10 sec does not even come on when hot water switched on took air out of system but to no effect. it seemed to rectify itself for a week but back to clicking on when it wants for periods of 10 secs.cheers