Boiler type	Destinguishing features
Normal boiler	Small header tank in the loft Hot water cylinder in an airing cupboard Exposed pump and valve(s), mostly in airing cupboard
Combi boiler	No header tank in the loft No hot water cylinder Boiler fires up and produces hot water instantaneously when taps are opened
System boiler	No small header tank in the loft Hot water cylinder in an airing cupboard A small flexible hose connects heating system with the cold mains pipe