Combi Boilers


What is a Combi Boiler

A Combi Boiler, also known as a combination boiler, is a single compact, high efficiency unit that heats your central heating water to your radiators and also the hot water coming from your taps. There is no airing cupboard for a hot water store as it is heated instantaneously through the boiler itself.

There are no water storage tanks in the loft or a hot water cylinder in an airing cupboard. With the water being heated instantaneously it is both convenient and energy efficient and is the choice for most standard homes.

With hot water being delivered at mains pressure you can often get a powerful shower without the addition of a pump.

The Combi Boilers we install are listed below, visit each page to see the range in more detail. If you’re still not sure which model would be best, click here to answer a few simple questions and find out.


Worcester Combi Boiler Range

Ideal Combi Boiler range

Vokera Combi Boiler Range


Combi Boiler Models, Outputs and Explanations!!

The greatest confusion arises around the outputs of a combi boiler – should I get a 24w or a 34kw? What will be the most efficient for me? –  Are two possible questions fizzing round your head when looking through the apparently endless models available.

Combi Boilers have 2 different outputs, one for the central heating and one for the hot water. The number that you see preceding the model number almost always refers to the output of the hot water, lets look at the examples below.

Worcester Greenstar 25i – Central Heating Output 24Kw, Hot Water Output 25Kw

Worcester Greenstar 30i – Central Heating Output 24Kw, Hot Water Output 30Kw

As you can see the boilers are IDENTICAL on the central heating side, the 25 and 30 on the boiler model simply refer to the hot water output. Unfortunately 90% of the time Combi Boilers are sized incorrectly, even installers misunderstanding the 2 different outputs that a combi boiler produces.

If you’re living in a standard three or four bedroom house with an electric shower and little hot water demand then you would probably be suited to the Greenstar 25i or equivalent boiler but the belief still exists that the Greenstar 30i will deliver more power to the radiators when this is not true. This occurs every day by under qualified surveyors and engineers that will lead to the customer being at least £100 out of pocket.