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Plumbing 101: Types of Central Heating Systems Simply Explained


Lee Devlin

Published on: 21/05/2018
Types of Central Heating System - Combi Boiler image

Confused about what type of central heating system operates within your home? Thinking about upgrading? Find out how your home plumbing works and why it matters.

A quick Google search for the term ‘types of central heating systems’ is going to bring up some very varied and confusing results. You’ll find information on countless different types of heating concepts, boiler types and plumbing methods, all with perplexing jargon. It can’t really be that complicated, can it?

It’s not.

Our plumbers in London are here to help simplify things and inform you of the basics behind the different types of central heating systems. No fuss, no confusion, no scary plumbing-specific lexicon. Just information anyone can understand, whether you are simply curious about plumbing basics, need to know what system is in your home or are considering options for upgrading.

Let’s start with the most simple information. How many types of central heating systems are there? Three. Well, three that you’ll find in modern British homes. They are:

  • Conventional Central Heating – Sometimes referred to as gravity fed systems
  • Combination Boiler Systems – Systems wherein 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

Looking for more information? We break down each type of central heating system in turn.

Conventional Central Heating

The conventional system used to be the most common type of central heating system in the home. Modern alternatives have resulted in a reduction of usage, especially in new builds, but you’ll still find conventional systems across many older houses and buildings.

So how does a conventional system work?

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

Once warm, water can flow down into the lower floors through your pipework, into radiators and out of taps, by the natural pull of gravity.

This type of central heating system has seen a major decline in use for two reasons:

1. Gravity fed systems have limits of pressure, as they are subject to laws of physics. In order to increase pressure, additional systems must be installed

2. Heating of a hot water tank can be wasteful, as all the water may not be used yet energy is required to heat it and keep it warm.

Combi Boiler Systems

If conventional/gravity fed systems were the benchmark in previous decades, the combi boiler is the current title holder. This type of central heating system has risen to prominence in recent years thanks to its efficiency and compact nature.

So how do they work?

Combi boilers heat water at the source.

When you turn on your hot water tap or start up your boiler, heat is created immediately by the combi boiler. All heating is output by the appliance at the point of use, meaning no hot water storage.

This has a number of advantages over conventional types of central heating systems:

  • As mentioned, combi boilers are efficient. You only heat the water you need. There is no wastage involved
  • All water is run at mains pressure, as it flows through the boiler cold and is then 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 especially useful in smaller properties, where housing a hot water tank would be difficult

Of course, there are disadvantages to combi boilers. They are more technologically advanced, with more complex inner workings, creating more potential to go wrong than the old workhouses that are conventional systems. Water pressure is also dictated by usage. Combi boilers are limited in their ability to produce hot water, which means you’ll experience poor flow rate if attempting to have two hot water taps run at once. This means it’s not suitable for large properties with multiple occupants.

Pressurised Central Heating Systems

How does a pressurised central heating system work?

A pressurised type of central heating system operates in a similar fashion to a combi boiler. Mains water is heated directly, rather than in a hot water tank, which means a reduction in wastage while saving space over conventional systems. However, the pressurised system is different to the combi boiler as water is heated via a water cylinder, rather than the boiler itself.

A small unit that can be neatly fitted into the home, a water cylinder is a tank that heats water as it passes through. The result is that hot water can be run at mains pressure from multiple taps at once, which is much more suitable for large properties.

Before we give this system too much praise, though, you must know there are two distinct disadvantages to operating this type of central heating system in your home:

1. Pressure systems are expensive to install and maintain. Due to their nature, they must be checked annually. Their complex design also means installation processes are more detailed than other methods, required highly-qualified plumbers that charge higher rates. They are a long-term cost.

2. If your local mains pressure is weak, this system will be a poor choice. Reliant on external factors beyond your control, installation of pressurised systems in a low-pressure area is not a good idea.

Looking for boiler installation in London, or more information about the types of central heating system and what is right for your property? Get in touch with the experts at Homecure Plumbers today!

We have also covered Boiler Types Explained to explain the differences between the main boiler types and the advantages and disadvantages of each one.

Lee Devlin
Publication date: 21/05/2018

Lee Devlin is the managing director of Homecure Plumbers, London's favourite local plumbing service. Since 2009, Lee's been leading a large team of gas safe plumbing and heating engineers as well as growing a successful business built on quality customer service and workmanship, in a competitive industry within the Capital. He's been in the game for a long time, so he regularly shares his knowledge and experience with the public. His expert tips have been featured in lots of well known publications such as: The Sun, Metro, Insider, Homes And Gardens, Country Living and more!

Read More About Lee Devlin.

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