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Use our ultimate gas boiler guide to browse and compare UK gas boilers, prices, and suppliers today.

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Our guide to buying gas boilers

If you need help choosing the best gas boiler for your needs, you’ll be glad to know that there’s a model out there to suit you and your home. But how can you compare the different gas boilers available in the UK? At SpotDif, we can provide you with a gas boiler comparison in seconds


Comparison sites are a great way to compare different features and styles, leading you to the best gas boiler for your lifestyle and budget. What’s more, you’re only a few clicks away from comparing gas boiler suppliers


Ready to explore your options? Here’s everything you need to know about gas boilers in the UK.


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What type of boiler do you have?

What is a gas boiler?

A gas boiler is a heating system that uses natural gas or propane to heat water, which then circulates through your pipes to your home’s radiators, underfloor heating, or hot water taps. 

Gas boilers have fallen under scrutiny in recent years since the development of their more environmentally friendly and energy-efficient counterparts — electric boilers and heat pumps. However, gas boilers are still an option for many homes for an array of reasons:


Cheaper running costs


Natural gas is cheaper than electricity, leading to lower running costs. 


Existing infrastructure


The UK has a well-established gas supply network. After all, it’s what was used to heat homes for many years before electric boilers! With this in mind, many homes are already equipped with the infrastructure needed for gas heating.


Lower installation costs


In our experience, installing a gas boiler in a home already connected to the grid is sometimes cheaper than installing an electric boiler (especially if a new electric supply is needed), as well as many heat pump varieties, including air source heat pumps, water source heat pumps, and ground source heat pumps


Higher heat output


Compared to electric boilers, gas boilers typically have a higher heat output compared to electric boilers. This makes them particularly suitable for large homes with high heating demands.

How do gas boilers work?

Gas boilers run using natural gas or propane. The burner within the boiler mixes the gas with air to create a flame, which heats the heat exchanger. This heat exchanger then heats the cold water and circulates it through the pipes to your home’s taps. This can either be done on-demand, or some gas boilers can even store excess hot water in a tank.

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Comparing types of gas boilers

There are many different types of gas boilers available in the UK. These different types are designed to meet the ever-changing heating and hot water needs of homes across the country. 


Let’s take a look at a few comparison points to help you choose the best gas boiler for your budget and lifestyle.


Combi (combination) boilers


Combi boilers are the most popular type in the UK. They combine both central heating and hot water in one unit, providing hot water on demand without the need for a separate water tank.


Cost


Combi boilers are generally cheaper to install because they do not require a separate water cylinder or cold water tank. The initial investment is lower, making them an attractive option for budget-conscious homeowners looking to upgrade their heating systems.


You’ll be able to purchase a new combination gas boiler for around £1500 £3000


Efficiency


Combi boilers are highly efficient, as they heat water on demand and eliminate the need for hot water storage. This on-demand heating reduces energy wastage and leads to lower utility bills, making them a cost-effective choice for modern homes.


Durability


With proper maintenance, combi boilers are quite durable. They tend to have fewer components, which can reduce the risk of breakdowns. However, we always say that regular servicing is essential to maintain their performance and longevity, ensuring reliable operation over time.

Installation


Installing a combi boiler is relatively straightforward and quicker compared to other types. Since there’s no need for a separate water tank or cylinder, the installation process is simpler and less disruptive, making it ideal for homes with limited space.


System boilers


System boilers, also known as sealed system boilers, work with a hot water cylinder (but not a water tank). They have most of the major components built into the boiler itself, including the pump and expansion vessel.


Cost


System boilers are more expensive than combi boilers due to the additional hot water cylinder. However, they are generally less costly than conventional boilers because they do not require a cold water storage tank, making them a mid-range option for homeowners.


The average cost of a system gas boiler in the UK is £2000£3500


Efficiency


System boilers are efficient, providing a steady supply of hot water to multiple outlets simultaneously. They are ideal for larger households with higher hot water demands, ensuring efficient heating and hot water availability without compromising performance.


Durability


With proper maintenance, combi boilers are quite durable. They tend to have fewer components, which can reduce the risk of breakdowns. 


Installation


Installing a combi boiler is relatively straightforward and quicker compared to other types. Since there’s no need for a separate water tank or cylinder, the installation process is simpler and less disruptive, making it ideal for homes with limited space.


Conventional or heat-only boilers


These are also known as ‘regular’ or ‘traditional’ boilers, requiring both a hot water cylinder and a cold water storage tank in the loft. They are also known as heat-only boilers.


Cost


Conventional boilers tend to be more expensive to install due to the need for both a hot water cylinder and a cold water storage tank. The initial investment is higher, but they can be cost-effective for homes with existing traditional heating systems.

The average cost of a conventional/heat-only boiler in the UK is £2500£4000


Efficiency


Conventional boilers are less efficient than combi and system boilers because they heat and store hot water, leading to potential heat loss. However, they are suitable for homes with high hot water demands and older heating infrastructure.


Durability


Conventional boilers are durable and known for their reliability. With fewer built-in components, they are easier to service and maintain. Regular maintenance of both the boiler and the associated tanks is essential to ensure their longevity.


Installation


Installing a conventional boiler is more complex and time-consuming due to the need for a hot water cylinder and a cold water tank. This makes the installation process more disruptive and requires more space, suitable for larger homes with existing systems.


Condensing boilers


Condensing boilers can be combi, system, or regular boilers. They are designed to be highly efficient by capturing and reusing heat that would otherwise escape through the flue.


Cost


Condensing boilers can be more expensive initially due to their advanced technology, but they offer long-term savings through higher efficiency. They are available in combi, system, and conventional types, providing various options for different budgets.


A condensing gas boiler costs around £1500£4000


Efficiency


Condensing boilers are highly efficient, capturing and reusing heat from exhaust gases that would otherwise be lost. This increased efficiency leads to significant energy savings and reduced carbon emissions, making them an eco-friendly choice.


Durability


Condensing boilers are durable and designed to withstand high-efficiency operation. Regular maintenance is necessary to ensure optimal performance and longevity. Their advanced components may require more attention but contribute to long-term reliability.


Installation


Installation of condensing boilers is straightforward, similar to their non-condensing counterparts. However, they require a condensate drain to remove the condensed water, adding a slight complexity. Their high efficiency and compliance with regulations make them a popular choice.


Back boilers


Back boilers are installed behind a fireplace or a stove and provide heating and hot water. However, they are much less common now due to their lower efficiency compared to modern boilers.


Cost


Back boilers are typically more expensive to install and maintain due to their integration with a fireplace or stove. They are less common and may require specialised installation, increasing the overall cost compared to other boiler types.


The average cost of a back gas boiler is £3000£5000


Efficiency


Back boilers are less efficient than modern condensing boilers, as they are based on older technology. Their efficiency is lower, leading to higher running costs. They are gradually being replaced by more efficient systems in modern homes.


Durability


Back boilers are durable, with a solid build that can last many years. However, their older technology and integration with a fireplace or stove require regular maintenance to ensure safe and reliable operation, which can add to upkeep costs.


Installation


Installing a back boiler is complex and often requires specialised skills due to its integration with a fireplace or stove. This makes the process more time-consuming and costly. For this reason, we recommend an experienced installer. They are less common in new installations, favouring modern, more efficient systems.


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What type of boiler do you have?

How to maintain a gas boiler for maximum efficiency

You won’t be able to skip the maintenance of your gas boiler — especially if you want to ensure its efficiency, safety, and longevity. Here are some gas boiler maintenance tips to get you started:


1. Get a professional to conduct an annual service


We recommend that a trusted professional thoroughly checks and cleans the boiler, ensuring it operates safely and efficiently. They can identify and fix potential issues before they become serious problems.


2. Regularly check your boiler’s pressure


Monitor the boiler’s pressure gauge and ensure it stays within the recommended range (usually 1-1.5 bar when cold). Low or high pressure can affect the boiler’s performance. If the pressure is incorrect, refer to the manual or call a professional to adjust it.


3. Bleed your radiators


We advise that you regularly release any trapped air from the radiators by using a radiator key to bleed them. Trapped air can cause radiators to heat unevenly, reducing the efficiency of the heating system. Bleeding the radiators also ensures they heat up properly.


4. Check for any leaks and drips


Regularly inspect the boiler and surrounding pipes for any signs of water leaks or drips. Leaks can lead to water damage and reduce boiler efficiency. Addressing leaks promptly prevents more serious issues and hefty repair costs.


5. Clean the exterior of your boiler


Keep the exterior of the boiler clean and free from dust and debris. A clean boiler can operate more efficiently and reduce the risk of overheating. Always ensure that the vents and air intakes of your gas boiler are unobstructed.

Which gas boiler is best for you?

When you’re tasked with pricing up and comparing the many different gas boilers on offer, we understand that it can be hard to know where to start. We’ve done the hard work for you and matched a specific gas boiler type to different scenarios below.

Best gas boiler for smaller homes or flats

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Combi boilers are best for smaller homes or flats with limited space and lower hot water demands. They provide hot water on demand without the need for a separate cylinder or tank, making them ideal for properties with fewer bathrooms and moderate heating requirements. Their compact design and efficiency also make them a popular choice for modern homes.

Best gas boiler for large homes with multiple bathrooms

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System boilers are ideal for larger homes with higher hot water demands and multiple bathrooms. They work well in households where hot water is needed simultaneously at several tap locations. The integrated components and separate hot water cylinders make them efficient and reliable, ensuring a consistent supply of hot water and heating for bigger families and larger properties.

Best gas boiler for homes with an existing gas system

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Conventional or heat-only boilers are suited for homes with existing traditional heating systems, especially those with older radiators and higher hot water usage. They are ideal for larger properties with multiple bathrooms and where a hot water cylinder and cold water storage tank are already in place. They also offer reliable heating for homes with significant hot water needs.

Best gas boiler for energy efficiency and a lower carbon footprint

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Condensing boilers are suitable for any home looking to maximise energy efficiency and reduce carbon emissions. Available in combi, system, or conventional types, they capture and reuse heat from exhaust gases, making them highly efficient. They are a versatile choice for environmentally conscious homeowners seeking to lower their energy bills and carbon footprint.

Best gas boiler for properties with fireplaces or stoves

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Back boilers are best for older properties with existing fireplaces or stoves where space for a modern boiler system is limited. This is due to their design compatibility and localised heating abilities. They are less common in new installations due to lower efficiency but can be a practical solution for homes retaining traditional heating methods. Regular maintenance is crucial to ensure safe and effective operation.

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Anna Dearden
Home Sector Specialist
Combining in-depth research with an interest in all things home improvement, I aim to keep SpotDif readers up to date with interior design trends, renewable energy options, and more.
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