Boiler Type Guide


Here at Swale Heating we understand that selecting a new boiler can be a confusing and daunting task - for most people buying a new boiler is not an everyday occurence so the terminology can be a tad confusing!

There are a few different types of boiler available and if you want a direct replacement then the type of boilers required will be specific to your property and the way the central heating system is setup.

With our boiler type guide we hope to shed some light on the different types of boilers available and try to outline the main differences between each boiler type and suggests the core benefits for each system.


 Combi Boiler type

Combi Boiler

A Combi boiler, full name Combination boiler, is the most popular choice of boiler across the nation.  They are cost effective and energy efficient as water gets heated when it is needed and it does not require a separate hot water store.  A combi boiler is a water heater and central heating boiler in one, which is an efficient choice for flats and small to medium size houses, where there is not high hot water demand i.e. multiple users at the same time.  Combi boilers have a secondary heat exchanger, which heats the domestic hot water directly from the mains water supply on demand.  It means that hot water is continuous and will not run out, furthermore, assuming the cold mains supply to the property is sufficient, it’s possible to have a powerful shower without the need for a pump.

You can fit a combi boiler in a smaller home as it can fit into tight spaces and does not require a feed and expansion tank, hot water cylinder or cold water storage tank; possibly freeing up loft space.  Combi boilers rely on the mains water pressure to distribute domestic water around your home and so the hot water flow rate will reduce if multiple hot water outlets are utilised at the same time.  As a result of the compact design, it’s possible to free up space within a property if you install one as a replacement for a conventional/regular boiler setup.

The image to the right hand side shows an example of a common combi boiler system set-up.  Please be aware, combination boilers require a powerful mains flow rate to work effectively and this should be checked prior to installing one.



Regular Boiler

A Regular boiler, also known as a conventional or heat only boiler, is used in a typical ‘classic’ heating system setup, where there is also a cold water storage tank (feeding the hot water cylinder), hot water cylinder and feed and expansion tank (which maintains the appropriate water level in the central heating system).  By creating a hot water store, the system is able to deal with higher hot water demand and is often used in conjunction with a domestic hot and cold water pump, which rapidly distribute domestic water around the property.  They’re often designed to be able to cope with multiple hot water outlets being used at the same time.

Conventional boilers are suited to homes with an older radiator system, which may not cope with the higher pressures, which combi and system boilers work at.  They’re a good option where water pressure is low, as other means can be utilised to increase the domestic water performance in the property e.g. a pump.  They can also be used in conjunction with solar water heating panels.

The image to the right hand side shows an example of a Regular boiler system set-up:


System Boiler

A System boiler is very similar to a conventional boiler as they both require a hot water cylinder.  However, a system boiler has all the major components for the heating system built in to it (an expansion vessel and a pump).  This can make the installation easier and faster.  If you use one with an unvented cylinder (details below), there is no need to have a cold water storage tank, which means space in lofts can be freed up to allow for a future conversion if required.  They are ideal in homes with high hot water usage and the installation can be neater as a result of the boiler’s inbuilt components.


The above image on the left shows an example of a System boiler system set-up with an open-vented hot water cylinder, the image on the right shows an example of a System boiler system set-up with a pressurised unvented hot water cylinder.


If you have any other questions or queries then feel free to give us a call and we will point you in the right direction.


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