boiler on wall

When Googling ‘types of central heating systems’ it brings up various and somewhat confusing results. There are numerous different types of heating concepts, boiler types and plumbing methods, all with confusing jargon making it difficult to comprehend.

Gasworks are here to help simplify things for you. The bottom line, is that there are three common types of central heating systems that you’ll find in a modern British home:-      

  • Conventional Central Heating – often referred to as ‘gravity fed’ systems
  • Combination Boiler Systems – systems where the boiler heats both gas and water at the source
  • Pressure System Central Heating – this system uses mains pressure to move water around your home

Conventional Central Heating

The conventional system was once the most popular type of central heating system in UK homes. Newer alternatives have resulted in a reduction of installs, especially in new builds, but you’ll still find them in many older houses and buildings that haven’t yet made the transition.

How does a conventional system work?

Cold water is controlled via the mains pressure and disconnected from the central heating system. For hot water used in heating and the taps, a hot water tank is located somewhere high up in the home (the loft or a cupboard on the highest floor). The boiler is then used to heat this water in the tank.

Once heated, this water can flow down to the lower floors via the water pipes, into the radiators and out of taps, using gravity (which is why you will hear it called a ‘gravity system’).

Conventional Central Heating has seen a major decline in modern times for three reasons:

1. Gravity fed systems have pressure limitations, being subject to laws of physics. People these days want ‘power showers’ and to make these work, additional equipment needs to be installed.

2. Heating up a hot water tank can be a waste of energy resources if the water in the tank isn’t all used.

3. The tank takes up valuable space.

Combi Boiler Systems

The Combination Boiler system or ‘Combi’ for short, is the primary Conventional System killer! The prominence of Combi Boiler systems in modern times is due to their huge efficiency, simplicity and compact nature.

How does a Combi Boiler system work?

The key difference when compared with a Conventional System is that a Combi Boiler heats water at source.  When your hot water tap is turned on, heat is created on demand by the Combi Boiler negating the need for that monstrosity of a water tank to store your hot water.

This has a number of advantages:

  • You only heat the water you need and there is no wastage involved
  • All water is run at mains pressure, as it comes into the house and flows through the boiler where it is heated. This ensures good pressure throughout the home
  • Heating directly through the boiler means that there is no need for a hot water tank. This is great in smaller properties such as flats.

There are some disadvantages with Combi Boilers. Being more technologically advanced, they have a higher potential to malfunction than the simplistic work horses that are conventional systems. The main issue is that water pressure is dictated by usage and Combi Boilers are limited in their ability to produce hot water.  This means you’ll experience poor flow rate if attempting to have two hot water taps run at once rendering them unsuitable for larger homes with multiple occupants.

Pressurised Central Heating Systems

A Pressurised Central Heating System operates in a similar way to the Combi Boiler and has some cross over with the Conventional System too in that hot water is stored. Mains water comes into the house and the water is heated directly, but in a water cylinder (as opposed to by the boiler).  This cylinder is smaller than the old storage tank used in conventional systems and can be fitted neatly in the home.

The result here is that you have a water cylinder that heats and stores mains water as it comes in that runs at mains pressure. As water is stored, it allows for more than one tap to be running at one time which is much more highly desirable for larger properties.

Sounds great, however there are two distinct disadvantages to operating this type of central heating system in your home:

1. Pressurised systems are expensive to install and maintain and it is vital they are checked annually. Their complex design requires highly-qualified heating engineers for the initial install.

2.  The quality of the system will all depend on how good the mains pressure is on your street. If the mains pressure is weak then this will be a bad choice as installing a pressurised system in a low pressure area will result in poor water flow. 

Different types of Central Heating systems
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