Condensing Boilers (Re: My current pet hate)
As an aside (i.e. OT!) we don't want a more efficient boiler as it all likelihood it would require a complete rebuilding of the C/H system
It depends how exotic your system is: certainly you can get a condensing boiler that's a plumb-in replacement for a system boiler, leaving all your existing system (hot water tank, pumps, controller etc) intact.