A combination boiler provides central heating and heats water instantaneously whenever you open a hot tap, so you don't need space for a storage cylinder and the hot water supply is endless. The temperature at the tap is dependent on the temperature of the mains supply and the flow rate. Combination boilers are ideal for smaller one bathroom properties without the frequent and simultaneous use of sinks, showers, baths, washing machines and dishwashers. Because a combination boiler heats water instantaneously as you turn on a tap, it helps save on fuel and helps save on space as you don't need a cylinder to store hot water until it's needed. Hide this answer

Combi is an abbreviation of combination boiler. A combi provides central heating and heats water instantaneously whenever you open a hot tap, so you don't need space for a storage cylinder and the hot water supply is endless. The temperature at the tap is dependent on the temperature of the mains supply and the flow rate. Combination boilers are ideal for smaller one bathroom properties without the frequent and simultaneous use of sinks, showers, baths, washing machines and dishwashers. Because a combi heats water instantaneously as you turn on a tap, it helps save on fuel and helps save on space as you don't need a cylinder to store hot water until it's needed. Hide this answer

Traditional boilers (also known as heating only boilers) are used for the central heating system. Traditional boilers can deliver hot water to several taps simultaneously via an indirect hot water storage cylinder which is required as well as the boiler. Hide this answer

A system boiler is used for the central heating system; it is factory fitted with all the components needed for use with an external indirect cylinder for the production of domestic hot water. System boilers neatly incorporate a number of components found outside of the boiler on traditional installations - the pump for example. Another is the expansion vessel, which replaces the tank in the roof-space. So installation is easier and quicker and the risk of burst pipes in winter is eliminated. Hide this answer

A high efficiency boiler is the most efficient boiler available. It converts more than 88% of the fuel it uses into heat, compared to 72% for conventional types. High efficiency boilers have either a larger or second heat exchanger which saves the heat which would normally escape up the flue in normal boilers. This reduces the temperature of the flue gases to a point where water vapour produced during combustion is 'condensed out'. High efficiency boilers are established products and can be fitted to most new and old heating systems. They are easy to install and can be bought for oil and gas-fuelled homes, even LPG (liquefied petroleum gas). These boilers are often no larger than conventional boilers. You can buy high efficiency boilers as either combination boilers, which heat up hot water on demand, or conventional system boilers, where a separate hot water cylinder is required. Hide this answer

A condensing boiler is the most efficient boiler available. It converts more than 88% of the fuel it uses into heat, compared to 72% for conventional types. Condensing boilers have either a larger or second heat exchanger which saves the heat which would normally escape up the flue in normal boilers. This reduces the temperature of the flue gases to a point where water vapour produced during combustion is 'condensed out'. Hence the name 'condensing boiler'. Condensing boilers are established products and can be fitted to most new and old heating systems. They are easy to install and can be bought for oil and gas-fuelled homes, even LPG (liquefied petroleum gas). These boilers are often no larger than conventional boilers. You can buy condensing boilers as either combination boilers, which heat up hot water on demand, or conventional system boilers, where a separate hot water cylinder is required. Hide this answer