At GCS we understand that the terminology our industry uses can be a tad confusing to residents and customers. In order to assist with this we have created this simple boiler type guide which we hope to shed some light on the different types of boilers available and try to outlines the main differences between each boiler type and suggests the core benefits for each system.

Combination Boiler
A Combination boiler, also known as a ‘Combi’ boiler, is a very popular boiler selection for homes across the UK. 1 of the reasons for their popularity is that they can provide both hot water and central heating from the one appliance.

Unlike regular and system boilers, which require additional appliances such as hot water cylinders, water storage cisterns or expansion cisterns, a combi boiler removes the need for this as it heats your cold water supply on on demand (i.e. from turning on a tap or shower etc) to give you an instantaneous supply of hot water .

This is an extremely efficient process as no energy is wasted in keeping the water in a hot water storage tank.

A combi boiler therefore also takes up less space in the property once it is installed, which is perfect for a lot of UK homes where space is at a premium.

The image below shows an example of a common combi boiler system set-up.

Combi boiler description

Regular Boiler
A Regular boiler or a conventional boiler as some may know it are more commonly found in older properties. Regular and System boilers are an older design of boiler but still offer great functionality and control of your homes central heating and hot water system. A regular boilers two main objectives are to provide central heating and hot water to your home. The way it heats your home is by directly heating the radiators throughout the property to your desired temperature. The way it provides hot water is by using an immersion heater that is directly fitted into the storage tank in order to heat the water. The water is fed from a cold water storage cistern and expansion cistern situated in the loft.

Below you will find an example of a Regular boiler system set-up:

Regular boiler

System Boiler
A System boiler operates in a similar fashion as to that of a regular boiler. Within its system it still operates using the principle of a stored hot water cylinder, but even though they have this same attribute a System and Regular boiler differ in some crucial aspects. A System boiler directly heats your homes central heating system and also produces hot water that is stored in your hot water storage tank. In some cases an immersion heater is still used in the storage tank to maintain the water temperature or to give it a boost. Because of the direct feed of hot water from the boiler a cold water storage cistern and expansion cistern aren’t needed in this system. This type of system is extremely beneficial as it offers you a better response time when demanding hot water and central heating.

Below you will find an example of a System boiler system set-up with an open-vented hot water cylinder:


Below you will find an example of a System boiler system set-up with a pressurised unvented hot water cylinder:

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.