Combi or regular?
Combi (combination) boilers heat water on demand and do not require a separate hot water tank. Regular boilers store hot water until it is required. The cylinder or tank is heated at set times using a programmer.
Which is better?
Regular boilers are more efficient when it comes to heating hot water in the first place, but while the water is being stored in the tank some of that heat is lost. This means that combi boilers may be more efficient overall.
The best kind of boiler is an efficient one!
Replacing an old G-rated boiler with an A-rated system with a full set of heating controls could save you around £415 a year*. Even just installing and using a full set of heating controls can save around £140 a year.
*Assumes that you already have a programme and room thermostat