Combi boilers, sometimes also known as combination boilers, are a specific type of condensing boilers. Combi boilers create hot water on demand for your home’s taps and domestic central heating. As a result of this ‘instant hot water’ Combi boilers are the most popular type of gas boiler and sales equate to more than 50% of all new boiler sales within the UK. Having said this combi boilers have some disadvantages and are not the right boiler type for everyone and it is important to understand whether a combi boiler is the best boiler for you and your family.

Most traditional central heating systems (regular boilers) store the boiler heated water in a copper cylinder in the upstairs airing cupboard to provide domestic hot water. Combi boilers do not require this hot water storage saving you valuable space and reducing heat loss from the previously stored water. As a result combi boilers can be more energy efficient than other boiler types.

Central heating systems incorporating combi boilers have fewer overall components. Combi boilers take their cold water feed direct from your mains supply. By installing a combi boiler the cold water feed tank, often housed in the loft, is also not required this can also save storage space and reduces the number of components in the system simplifying any combi boiler system installation. As combi boilers do not store hot water they heat water direct from the cold mains supply as you use it, this gives you the equivalent of a power shower without any requirement for an electric pump.

Other components to be assessed before you install a combi boiler

One small disadvantage with a modern combi boiler is that the hot water flow rate from combi boilers is not likely to be as good as with a traditional storage cylinder, particularly in winter. The major benefit of hot water ‘on demand’ with its energy saving benefits is also a disadvantage in that there is no store of hot water to supply two baths at the same time. The power rating of the combi boiler needs to be matched to your family’s heating requirements.

Because the combi boiler relies upon the pressure in the mains cold water pipes it is important to establish that the manufacturers minimum required water pressure level is available otherwise the boiler performance will fall away. As a consequence a combi boiler is not always suitable in all areas and a site survey by a heating expert is often required to confirm the suitability of your home’s water supply.

Is a combi boiler the right type of gas boiler for you?

Combi boilers have many advantages and are popular in the UK but combi boilers do not suit all homes. Instant heated water is attractive but not so if you are waiting a long time to fill a bath and the water is being used to fill a sink in the kitchen. There are pages in this site which outline the advantages and disadvantages of each of the boiler types to help you make the right decision, installing a new gas boiler is expensive so you need to get it right.

If, having read the information, you need assistance you should find a trustworthy boiler installer to guide you. If you do not have access to a heating installer you can get help from npower. One of their Home Energy Consultants can visit your house and perform a heat loss assessment to determine which type of boiler is right for you. You will also be provided with a quotation for a new boiler – a new or replacement combi boiler if appropriate. The assessment and free boiler quotation carry no obligations, so there is really no reason to avoid the service. As you will have been helped by an expert you can be confident that you will learn which boiler and what power rating is right for your home.

The different types of combi boilers

Believe it or not there are five ‘varieties’ of combi boilers offered by boiler suppliers in the U.K.

A combi (instantaneous) gas boiler is the most commonly used form of combi boiler and as the name implies instantaneously heats incoming cold water from the mains to supply your taps, showers, baths and other hot water requirements.

A combi (instantaneous condensing) boiler operates as an ‘instantaneous’ boiler but at somewhat higher efficiencies than the standard combi boiler.

A combi (storage) boiler is a variant of the instantaneous combi boiler type referred to above and is designed to give you better hot water performance through the internal storage of heated water. The stored water also can give you better initial water supply from cold water mains on first turning on the tap. Once the stored heat has been used, this boiler will tend to operate as an ‘instantaneous’ type. Dependent upon the make and model, the improvement in heated water delivery will depend upon the size of water store, and this can vary widely.

A combi (storage condensing) boiler operates in principle as a ‘storage’ type but at higher efficiencies.

Combined Primary Storage Unit (CPSU) – This is a special category of storage combi which will incorporate a very large water store allowing a high water flow rate to taps and other draw off points and to quickly heat radiators before the water store is used.

If you are looking for the best combi boiler for your home you first need to confirm that a combi boiler is the right type of boiler for you and what power output the combi boiler will need to produce. Combi boilers heat water on demand and save on space but this will be a poor choice if you have a large family and need several taps to be operating simultaneously.

People often search for the best combi boiler. The “best one” depends upon your needs and without expert advice you could choose a boiler that does not meet your needs. As the working lifespan of a boiler is up to fifteen years selecting the wrong type of boiler or wring size / energy output could be a bad, costly decision that you need to live with for many years.

A visit from an npower or British Gas Home Energy Consultant will ensure that you do not make this mistake and help you to select the most appropriate combi boilers for your family needs. Not only will you be able to get a quote and ensure that you are getting a competitive price but also you will be able to be confident that the combi boiler (if indeed a combi boiler is the right type for your home) will provide excellent service for its lifetime.