Which combination boiler?

There are five types of combi boiler. These are instantaneous condensing, instantaneous, storage condensing, storage and Combined Primary Storage Units. Instantaneous are the most common types as they allow instant access to hot water. The instantaneous condensing type is a little more efficient. Combined Primary Storage Unit types are a special category of combi, which incorporates a very large water store allowing for higher water pressure, faster water flow, and for your radiators to heat more quickly.

In smaller dwellings, the installation of a compact combination boiler can be a great way to conserve space. With a combi boiler, a balanced flue, some pipes, and a few radiators, you have all the necessary components of a fully-fledged central heating system. With a combi boiler, there is no need for an additional water pump, feed and expansion cistern, or water tank.

For a long time, combination gas boilers have been more popular in mainland Europe than in the UK, but this has changed in recent years, to the extent that it is now the most commonly installed type. Combi boilers use essentially the same technology as standard boiler, but there are a number of functional differences between the two.

All the water used in a heating system which uses a combination boiler is sealed in, negating the requirement for a feed and expansion cylinder. Combination boilers have their own internal hot water tank, which cannot store as much as a separate tank, but that should prove sufficient for smaller homes.

A combination boiler is able to provide instant hot water by using the heat from the central heating system to heat freshly drawn water.

Due to the fact that the boiler has to switch over to supply hot water to the taps, the central heating is turned off while the hot water is flowing. By turning off the hot tap, you are turning back on the central heating.

Although a combi boiler has some disadvantages over a regular boiler, in that the central heating is not constant, and you cannot draw hot water from more than one source at a time, the space saving advantages far outweigh these disadvantages in smaller homes. Furthermore, combination boilers tend to be a good deal cheaper than their component counterparts, so you could up saving money as well as space with one of these flexible units.


British Gas can help you to save money on a central heating installation. By replacing your old boiler with one of our central heating boilers such as the energy efficient range of Worcester boilers, you could save up to 40% on your bills.

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