please can anyone tell me why, when central heating comes on the three bedroom radiators {not pipes}make loud banging noises and the bathroom one makes a ticking type sound. i have been round all radiators and bleed air out and have had a new Baxi boiler installed within the last year along with TRV,s. These noises are waking my 3yr old up and driving us mad. Is it worth considering getting new radiators? please help.