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Last updated: 21st May, 2024


What is Central Heating? Different Central Heating Systems UK Guide

What is Central Heating? Different Central Heating Systems UK Guide

Key takeaways

  • Combi boilers, the most popular type of boiler in the uk, removes the need for any kind of water tank.
  • System boilers may be more suited to larger homes with a higher hot water demand.
  • Regular (Heat-Only) boilers can still be useful for heating large homes.

Central heating is almost always necessary, but that does not stop it from being hard to choose a single type for your home.

Individual parts of your heating system – right down to specific radiator styles – often determine how it performs, as well as how the entire central heating system warms up your home.

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If you are looking to adjust, upgrade, or change your existing heating options, then knowing the different types of central heating systems can make a big difference. It all comes down to what you need and what you are willing to focus on the most, especially when you are comparing huge systems that could heat an entire house.

What is Central Heating? Different Central Heating Systems UK Guide

Types of Heating Systems:

  • Boilers. Including Combi Boilers.

  • Furnaces - However this is more of an American thing.

  • Heat Pumps.

  • Gas-Fired Space Heaters.

  • Electric Heaters.

  • Wood-Burning and Pellet Stoves.

  • Fireplaces.

What is Central Heating?

Overall, most central heating systems can be boiled down to one of three major types. These all function differently and some are more efficient depending on where they are placed or how they connect to the rest of the home.

Remember that heating systems have to be tailored to the building they are placed in, so there is no such thing as a one-size-fits-all system. Some will be more efficient in buildings below a certain size, while others might need more work to set up in smaller spaces.

Conventional Heating Systems

Conventional heating systems are the most common type you will find in the average home and are often built to use gravity as their main tool. This means that the water tank used to store and heat water is placed higher up, often in an attic or a cupboard on the top floor of the building. If your boiler is currently downstairs, and you are interested in relocating the unit, find out whether this is possible here. Gravity pushes the hot water further down through natural means, rather than artificial pressure.

These heating systems are starting to appear less often in newly built homes since they have two major flaws: they have pressure limits that are not easy to increase, (if your boiler is losing pressure, take a look at iHeats informative guide) and the heating of the tank can be quite wasteful in terms of the energy used. However, they are also a personal favourite of many homeowners, especially ones who grew up with a system like this.

Older homes are quite likely to have a conventional heating system installed, but you can always replace it with another type. This may mean that you have to remove the extra pipe if your new tank and/or boiler is not being installed in the same place, though.

Pressurised Systems

Pressurised systems heat mains water directly through a water cylinder, which acts as a small tank you can place almost anywhere in your home. They can be incredibly expensive and need to be checked often, but they are also very efficient, meaning that a lot of businesses prefer to use them (especially if they rely on having hot water available).

They also need high mains pressure to function properly. However, this has the added benefit of allowing the water to move with its original level of pressure, meaning that you can run multiple appliances at once and not have to worry about the pressure temporarily dropping.

Combi Boiler Systems

A combi boiler is often seen to be the main evolution of classic boiler-based central heating systems, using a combi boiler as the main feature. These combi boilers are much more efficient and do not waste energy by heating water that is not used, but can also retain the mains pressure very well.

This type of boiler also removes the need for any kind of water tank, something that can save plenty of space in a smaller property or a building without room for two big appliances. Many people consider them the standard option when it comes to installing a new central heating system.

Boiler Types

The boiler is the heart of any central heating system, and that means that it is often the first part to focus on. A good boiler can make a sub-par system much more effective, while a bad boiler can ruin even the best central heating system if you are not working around its flaws.

Remember that all boilers are essentially meant to do the same thing, which can usually mean that you will be comparing the raw stats (like how efficient they are, how much water they can heat at one time, and so on). However, there can also be some major differences that might sway these results, and not all designs are similar enough to compare properly.

Regular Boiler

A regular boiler, or a heat-only boiler, is a simple boiler design that relies on a cold water tank and hot water cylinder. This tank stores cold water until the boiler is ready to heat it up, and the hot water cylinder keeps the hot water hot. These used to be the standard type of boiler until the introduction of the combi boiler.

Although these boilers are older than most other options, that does not necessarily make them a bad choice. They can still be fairly powerful and do not suffer issues with a limited flow of hot water, but can also be quite wasteful in terms of how they use heat (since the hot water cylinder contains the hot water, which gradually leaks heat into the area around it).

Most of the time, these tanks are installed in the loft of the building, or at least the highest floor. They can become a lot less efficient if they are installed lower down since the water needs to travel upwards to provide heat to the higher floors.

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Combi Boiler

A combi boiler is the main focus of a combi boiler heating system, but they are also one of the most common types across the UK, even without a dedicated system that uses them to their full potential. Every combi boiler is meant to be efficient and cost-effective, removing the need for a separate water talk.

A combi boiler will usually be very small, especially compared to other options. This means that you can fit one inside a cupboard or another smaller space without having to create a whole separate room just for it. On top of that, it heats water instantly as opposed to doing it with a separate part of the system, which can make it more reliable for quick uses and emergencies.

Another useful feature of most combi boilers is the fact that they are available in multiple sizes. While every boiler generally only uses one type of power, you can buy most combi boiler options in either electric, oil or gas varieties, so you do not have to completely replace your power options if you are installing a brand new combi boiler.

This has the added benefit of making them much more useful as a standard option since they can replace any other kind of boiler without taking very much work to handle. Even better, once installed, they are able to run efficiently and won't burn through your finances quickly.

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Back Boiler

A back boiler is a very rare sight since most of the systems are completely outdated. A BBU (back boiler unit) offers both heating and hot water and is placed behind a fireplace rather than in a separate cupboard. We would generally recommend to replace a back boiler if this is the current system you have installed.

There is not much else to say about them, because they are very out of date and often horribly inefficient. If you still have one, it is usually worth replacing them, since even the most basic combi boiler can provide much better heat management for a fraction of the cost that you will be paying for a day’s worth of heat.

System Boiler

A system boiler is fairly similar to a combi boiler but uses an extra tank to store and maintain the hot water. This takes up more cupboard space, but can also allow you to deliver hot water to multiple places at once, which makes it much easier to cover an entire house at once.

The average system boiler is still quite economical and efficient to run, although they can be overkill in a smaller property that does not use very much hot water at any given moment. In larger homes where multiple people may need water, they can be very useful for getting consistent hot water.

In houses with more than one bathroom, a system boiler is a great choice. However, they may also take more maintenance, and they need more room to install properly in the first place.

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Gas vs Electric

The two main different types of central heating systems are gas and electric options, both of which are still fairly common today. Most central heating units in the UK are gas-based, but more and more electric ones are turning up every year, so it is difficult to know which one will become dominant a few years down the line.

While they might look similar and provide the same basic results, gas and electric central heating systems can be very different in terms of how they function and what kind of results they can offer. Understanding the key differences between the two can be important if you are not sure which one appeals to you more, especially as a new homeowner.

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Gas Boilers

A gas heating system relies on a gas boiler, which has a constant supply of gas entering through the mains. This gas is sent to a pipe containing cold water, which allows it to heat up the water itself: this is the basis of how the boiler actually provides the heating that you would expect.

This heated water then travels around the pipe circuit, all across your home. Each appliance that needs it (such as radiators) gets this water running through it, and the water eventually returns to the boiler again once the circuit has been completed.

As you would expect, this means that the water loses heat over time until it returns to the boiler, which can make the radiators at the end of the circuit slightly colder. On the other hand, the radiator that the water hits first will be very warm, often around the same temperature as the water itself.

This water is generally moved with an electric pump. To keep the heat steady, the boiler has to operate continuously, and that requires a constant supply of hot hot gas to manage it. If the boiler is not connected to the mains, then there are sometimes alternate gases that can be used, but these become expensive over time.

Are Gas Boilers Good?

Surprisingly, gas boilers are actually relatively cheap to run compared to options like oil and coal. A high-efficient option might be able to provide around 90% of the fuel's maximum heat output and is also less polluting in terms of CO2 than you might expect.

Condensing gas boilers make this even better, cutting down CO2 further and making it harder for the water to lose heat. However, these can cost more to install, even if the running costs may be technically lower.

In most cases, gas boilers can get expensive if you overuse them, but are not horrendously expensive to run as a day-to-day option. Using a more expensive type of gas will obviously increase how much it costs to run, especially if your boiler is not connected to the mains.

The high efficiency of a gas system makes it a great replacement for existing options, especially if you use a condensing model. However, gas prices are always rising, and getting the connection to the mains installed can cost a lot of money. On top of that, they need yearly servicing.

Electric Boilers

Electric boilers are often used to replace smaller boiler models and are gradually getting better at handling larger spaces too. They are made with fewer parts than alternative options and can sometimes make heavy use of a digital interface, which often makes them accessible to somebody without any real experience.

However, the biggest reason for using them is the 100% efficient rate, as well as their relative silence and compact size. This makes them incredibly convenient for a smaller building or home, and that is not even mentioning the fact that they are much more environmentally-friendly compared to any other boiler type.

Converting your heating system can be a pain at first, but once you have an electric system set up, you will be able to get much more efficient heating at a lower cost. This also usually means that you will not need to dedicate as much time and money towards servicing. There are numerous different models on the market, so to help you find the best electric boilers we have put together our top recommendations.

How Do I Choose?

Different types of central heating systems are perfect for different roles or locations, so there is no perfect option that will suit every landlord or homeowner. There is also no way to predict how new designs will improve over time, so it is possible that electric options could become more powerful in the future.

However, your choice should always come down to what makes the most sense to you. A larger property might work best with a single gas boiler instead of two electric options (unless you specifically want an eco-friendly boiler system), while a smaller home with one bathroom does not always need a full system boiler.

Remember that boilers – and central heating systems as a whole – are designed to provide heating first and foremost. If your system can’t do that, then there is not much of a reason to keep it, since it is failing at the main task that a heating system is meant to achieve.

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For more help and advice, why not check out our other helpful blogs and boiler guides.

Best Boiler Brands: Vaillant, Viessmann, Alpha, Ideal, Worcester Bosch

Selecting the right boiler brand is pivotal for ensuring efficiency, reliability, and longevity in home heating. Among the myriad of options, brands like Vaillant, Viessmann, Alpha, Ideal, and Worcester Bosch distinguish themselves with innovative technology and customer satisfaction. Below is an in-depth comparison of these brands, focusing on their standout models and unique industry positions.

Comparative Analysis of Standout Models


Standout Model

Energy Efficiency

Unique Features

Environmental Impact


ecoTEC Plus


Eco-friendly, quiet operation

Reduced carbon emissions


Vitodens 100-W


Compact design, smart compatibility

Low emissions technology


E-Tec Plus

High efficiency

Compact, cost-effective

Energy-saving operation


Logic Plus


User-friendly, easy installation

Efficient energy use

Worcester Bosch

Greenstar i


Robust build, smart controls

Eco-conscious design


Vaillant's eco-friendly ethos shines in their ecoTEC range, particularly the ecoTEC Plus and ecoTEC Exclusive models. These boast top-tier energy efficiency and reduced carbon footprints. They're known for quiet operation and user-friendly controls, making them a harmonious blend of performance and environmental responsibility.


Viessmann's Vitodens series, especially the 100-W and 200-W, are hallmarks of high-efficiency and technology. These models feature compact designs and stainless steel Inox-Radial heat exchangers for durability. Advanced features like smart thermostat compatibility offer enhanced control and user convenience.


Alpha Heating Innovation's E-Tec range, particularly the E-Tec Plus, offers a fine balance between affordability and quality. Notable for their impressive energy efficiency and compact size, these boilers are suitable for various home types, making them an ideal choice for straightforward, efficient heating solutions.


Ideal Boilers, especially the Logic Plus range, are lauded for their reliability and value. These boilers stand out with their efficiency, user-friendly interface, and compactness, favoured for their ease of installation and maintenance. They come with comprehensive warranties, offering peace of mind and reliability.

Worcester Bosch

A leader in the market, Worcester Bosch is synonymous with quality and reliability. The Greenstar range, including models like Greenstar i, Si, and CDi, is known for its efficiency and robust build quality. These boilers blend innovative features such as smart thermostat compatibility with user-friendly controls, making them a top choice in many homes.

Environmental Impact and Efficiency

Each brand has made strides in environmental sustainability. For instance, Vaillant's ecoTEC reduces carbon emissions, while Viessmann's Vitodens models incorporate low emissions technology. Worcester Bosch's Greenstar range features eco-conscious designs, highlighting the industry's shift towards greener heating solutions.

Smart Home Compatibility

Smart home features are increasingly important. Viessmann's Vitodens models and Worcester Bosch's Greenstar boilers offer compatibility with smart thermostats, enhancing convenience and potentially leading to further energy savings.

New Boiler Costs

Boilers can be a daunting purchase for many people as they’re an appliance with a lot of responsibility, providing heat for you and your family is something you want to get right. Boilers aren’t exactly a quickly disposable item either, potentially lasting you a decade.

Boiler costs can be split into two segments: the first is the actual boiler itself (unit price), and the second is the cost of the boiler being installed (set up) in your property by an expert engineer. 

Here at iHeat, we want to remove all of this undue stress and make the decision making process of upgrading to a new central heating system, as easy as possible.

Boiler costs can vary depending on a number of factors including their brand, model, fuel, output, warranty, labour and installation type. Typically a new boiler will cost between £1,845 and £3,500, below is a list of average boiler installations offered by iHeat (guide only).

Installation Type

Price (inc VAT)

Combi to combi swap


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System to combi conversion


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New boiler install


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Back boiler to a combi


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System to system


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Frequently Asked Questions

How Much Does a Central Heating System Cost?

The cost of installing a new central heating system varies widely based on factors like the type of system, the size of your home, and the complexity of installation. On average, installing a new central heating system in the UK can range from £3,000 to £5,000. This estimate includes the boiler, radiators, pipework, and labor.

What is the Cheapest to Run Central Heating?

Among the different types of heating systems, gas central heating is generally considered the cheapest to run in areas where gas is available. It tends to be more cost-effective than electric heating systems due to the lower cost of gas compared to electricity per unit of energy produced.

What Central Heating System?

Central heating systems can be categorized by the type of fuel they use, such as gas, oil, electric, or renewable energy sources like solar or biomass. The system typically includes a central boiler or heat pump that heats water or air, which is then distributed throughout the home via radiators or a forced-air system.

What is the Most Efficient Central Heating?

The most efficient central heating system is typically one that uses a modern condensing boiler or a heat pump. Condensing boilers can achieve efficiency levels over 90%, converting most of the fuel into usable heat. Heat pumps are even more efficient as they utilize heat from the air or ground, potentially providing equivalent heating for as little as one-third of the energy used by electric heaters.

What is the Cheapest Way to Heat a House?

The cheapest way to heat a house generally involves using natural gas if it’s available, followed by biomass boilers or heat pumps, especially when combined with a well-insulated home to minimize heat loss. Solar thermal systems can also reduce costs if integrated effectively with your heating system.

Does It Cost More to Keep Turning Heat On and Off?

It is generally more cost-effective to keep your heat set at a consistent, reasonable temperature rather than turning it off and on. Frequent adjustments can cause your system to work harder, potentially increasing your energy costs. Using a programmable thermostat can help manage these temperatures more efficiently without the need to manually turn your heating system on and off.

How Many Hours a Day Should Central Heating Be On?

The number of hours your central heating should be on depends on your personal comfort levels, the efficiency of your home, and the outside temperature. Typically, during the winter, you might expect the heating to be active for about 8-10 hours a day. Using a thermostat to control the heating as needed, and setting it to lower temperatures overnight or when the house is empty, can help reduce overall heating time and save energy.

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Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.