I have a 50yr old one pipe system(3/4inch pipe)which has been through phases of solid fuel, oil,and 7yrs ago an ideal maxico gas boiler which is now making lots of pops etc when getting up to temp( think its called kettling).i would go for a new condensing boiler but am told not right for a 1 pipe system,also at 76 yrs of age pay back on brand new sys would be prohibitive and totally disruptive.ive tried Sentinel ,but limited effect,also scared of stronger chemicals and power flushing on such an old system.would a new heat exchanger do the trickif they are still available advice please
if you tried inhibitor it'll do very little. did you use the system silencer?
do not put it in the tank in the loft, it'll just stay there unless you drain some of the system to get it in and circulating. best bet is to put it in a rad. system silencers do work quite well unless the noise is due to restriction or lack of water in the system due to a blocked cold feed in either case i'd recommend getting an engineer to sort it.
you can't powerflush a one pipe system, it'd have to be repiped.
a new heat exchanger is still available if it is only a 7yr old boiler. however without knowing what version your boiler is it isn't possible to tell how much it'd be. the heat exchanger would (depending on version) cost between £250-£400 then you'd have any others parts needed plus about 4-5 hours labour depending on access, system size, refilling ease etc.