Glow Worm Boiler

[walkman]

My central heating boiler has started making a loud noise, almost like an aircraft taking off, a new pump has been fitted today, and air let out of the system, but we still have this noise, it only comes on when the heat drops down , when the temperature is reached it is quiet ... the it goes on and on why ever the heating is being used.

Please help and advise.
Regards Walkman

[gasman]

could be the fan or the gas valve is faulty or then again is the casing and sides and front panel secured properly after the work has been carried out on it , and it is not just vibrating and rattling about is it.