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Gas Boiler Replacement Costs Explained in Detail

Many properties may not be large enough for a ground source heat pump or have a good enough insulation system to install an air source heat pump. For those houses, a new boiler can be the right answer. 

There are different types of gas boilers and different ways to replace them – from swaps to conversions. This article will provide information about the major types of gas boilers, the time when you need a new one, prices of gas boilers, and gas boiler replacement costs.

If you are thinking of purchasing a new gas boiler, let’s look at the options you have for your new one.

There are three main types of gas boilers: Combi boilers, regular (heat only) boilers, and system boilers.


What is a combi boiler?

With a combi boiler, or a combination boiler, you can control both heating and hot water in your place. In the UK, gas combi boilers are the most popular option and they are said to be far more efficient than immersion heaters.


Should I install a combi boiler?

Combi boilers have enough advantages to be chosen by many customers in the UK. However, to know if they are suitable for your family, you should go through all of their pros and cons:

  • A gas combi boiler doesn’t take up too much space, therefore, it is a good choice for small properties.

  • Combi boilers don’t require hot water storage cylinders. 

  • Cold-water tanks are not necessary for combi boilers.

  • This type of boiler isn’t suitable for larger places with more than one bathroom and/or a high hot water demand.

  • Places with the problem of low mains water pressure shouldn’t use a gas combi boiler.


Regular boilers and system boilers

Compared with combi boilers, both regular boilers and system boilers have a water cylinder and/or a water tank. These two types of boiler are suitable for large properties with multiple bathrooms, but they cannot provide instant hot water.

Although regular boilers and system boilers have a few things in common, they are still two different kinds of boilers with different characteristics. 


Is a regular boiler a good fit for my home?

To answer the question above, you need to know both the advantages and disadvantages of a regular boiler, or heat only boiler.

  • A regular boiler is suitable for a large home that has multiple bathrooms and demands high volume of hot water. 

  • This type of boiler can be a good fit for places suffering from low water pressure.

  • A regular boiler can be an addition to an older heating system that doesn’t work well with high pressure. 

  • Regular boilers require more space since they accompany cistern tanks.

  • An owner may have to face some problems when using a regular boiler: its cistern is likely to freeze in the winter and the boiler may get serious leakage. 


Should I choose a system boiler?

The list below shows all the characteristics of system boilers and can help you answer the question above:

  • If you have a spacious place, this type of boilers may be a good choice.

  • A system boiler doesn’t need a cistern tank in the loft.

  • The installation would be simple.

  • You need to find a place for a hot water tank if you want to swap from a combi boiler to a system one. 

  • System boilers are more expensive to install compared to combi boilers. 

  • System boilers are less efficient than combi boilers.

  • This kind of boilers may not work well at a place with the problem of low water pressure. 

  • If you have an older heating system that cannot tolerate high water pressure, a system boiler may not be the right option for you. 

What are the different types of gas boilers?

What are the benefits of new gas boiler?

Installing or replacing a gas boiler may be a big investment. However, using a high-quality gas boiler for a long term can financially benefit you since it can be more efficient than old heating systems like immersion heaters.

According to Energy Saving Trust, you can save up to £340 each year using a new A-rated boiler.

If your property has thermally efficient roofing and insulation with upgrades such as cavity wall, solid conservatory roof and good quality double glazing - you can expect even greater savings.

How long does a gas boiler last?

If you buy a new boiler in 2021, its lifespan will likely be around 10 – 15 years. However, since technology keeps developing continuously, better heating solutions are expected to come to life in the future. After 10 years of using a boiler, you can start looking for a new heating product that can work more efficiently, be more friendly to the environment, and save you more money on the bills. 

When should I replace a gas boiler?

If your gas boiler is over 10 years old and better heating inventions are being introduced on the market, you can start thinking of a gas boiler replacement. Statistics show that boilers that are more than 10 years old loose 30% of efficiency. Otherwise, a replacement should be considered when your boiler is getting on a bit and you notice it doesn’t function properly anymore. 

  • If your boiler is Beyond Economical Repair (BER), it means you would have to pay more to get it repaired than buying a new boiler. In this case, it’s a good idea to carry out a boiler replacement.

  • A gas boiler that causes too high energy bills should be replaced.

  • If you have your boiler serviced and repaired more than once a year or you face serious problems like water leaks, it’s time to do some research about a new boiler.

A boiler replacement should be considered when you want to make some changes to your property. For instance, instead of moving your current boiler to a new location in the house, you should buy a new one to avoid inconveniences and unnecessary workload. 

Furthermore, if you have a plan to sell or rent your place, do think of getting a new boiler as a way to add value to your property.  

How to prepare for a boiler replacement?

A boiler replacement requires a plan. Keep in mind the elements you need to consider before making your final decision.


The size of the boiler

The term “size” refers to the power output of the boiler which is measured in kilowatts (kW). Boilers with greater kW can provide heat for larger properties. The boiler size can be determined based on the number of radiators in your house. 

For example, in a 1-bathroom flat, when the number of bedrooms increases from 2 to 5, the boiler’s size increases from 16kW to 35kW. When the number of bathrooms is doubled, boilers with greater kW are required. 

Where should I put the boiler in the house?

Moving an existing boiler to a new position in the house is possible. However, the process would cause inconvenience, require more labour and materials, thus, costing you extra money.

Instead of relocating the current boiler, it would be better to buy a new boiler and find the best position for it. Putting the new boiler at the same place with the old one can be the most straightforward solution. Nevertheless, you can pick any other positions in your house as long as it’s comfortable for your family. 


How long does it take to install a new boiler?

The amount of time you need to spend on installing a new boiler depends on the type of boiler replacement.

If you want to swap your current combi boiler for a new one, it typically takes about a day.

A boiler conversion, on the other hand, would take more time. For example, replacing a combi with a system boiler can take a few more days.


Energy efficiency

A modern boiler helps make your home more energy efficient compared to an older heating system..

Before choosing a boiler to install, you should ensure it can help reduce carbon footprint, save more money on the bills and, still, keep you warm and comfortable during the winter. 

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Every home is unique and requires an individual quote. Just answer a few quick questions to find out how much a new boiler would cost for your home. It's quick and simple to get prices and compare options.

What factors affect gas boiler replacement costs?

When you calculate the price for your gas boiler replacement, keep in mind all the factors that can affect the amount of money you will spend. 


How much is a new gas boiler?

A boiler itself can cost between £400 and £1200. The price depends on the quality, model, size and brand of the boiler.


Boiler installation

  • The amount of labour you need for your installation depends on many elements:

  • The location of the installer

  • The number of engineers

  • The type of installation you require – more complex installation requires more time and, thus, increasing the installation cost

  • The average installation price is between £500 and £1,000.


Vertical flue 

A boiler flue functions as a pipe that lets condensation and gases out of your place. 

There are two types of flues:

  • Horizontal flues don’t require extra costs.

  • Vertical flue installation requires much more work, therefore, will cost you extra money that can be from £300 to £600.


Plume kit

If you live in London, a plume kit may be required by law to comply with Gas Safe regulations. This kit acts as an extension of your boiler’s flue. If the flue is too close to a window, door or your neighbour, it’s obligatory to install a plume kit.

Typically, a plum kit costs you between £90 to £130.


Main gas pipe upgrade

Old heating systems usually use pipes with 15mm width. Modern pipes, on the other hand, need to meet the requirement of 22mm width. The old pipes were also made by old materials that should be upgraded to copper. 

On average, gas pipe upgrade would cost you £250 to £400.


Boiler relocation

From the aforementioned section, you already know that relocating a boiler requires much more work and financial investment. Do reach out and talk to our expert to calculate the cost for your boiler relocation. 


Other costs

Each property will need a tailored plan of gas boiler replacement. Depending on your requirement, some other factors would put some extra costs into your bill. 

  • Heating control upgrade: £100 – £300

  • Magnetic boiler filter: £100 – £200

  • Chemical flush: £100 – £150

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Our Expert Says

"Modern gas boilers are much more efficient than older boilers and heating systems like immersion heaters. According to Energy Saving Trust, you can save up to £340 each year by upgrading to a new A-rated boiler."

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Gas boiler replacement costs

Gas boiler replacement costs include the cost of the boiler and the instalment costs. The variation of boiler types leads to different cost scenarios that will be broken down in this section. 


How much is a single gas boiler?

The price for a new boiler can be between £600 - £2,500. Let’s have a look at an example of prices of different types, models and brands of boilers.  



Combi boiler replacement cost

Depending on the installation, a combi boiler replacement would cost you between £1,500 – £3,500. 

The simplest replacement is a combi boiler swap that you replace your old combi boiler with a new one. The amount of time you need for the swap is 4 – 6 hours, and the price for this kind of swaps can be up to around £2,500. To know the costs for specific models, speak to our experienced expert. 


Regular and System boiler replacement cost

To do a straightforward swap, you will need to pay between £1,500 – £3,500 for a new regular or system boiler. Furthermore, since these kinds of boilers require a hot water cylinder, do include some extra money for that addition. Talk with us to find out the exact cost. Get a quote

However, if you want to convert from a regular boiler to a combi boiler, the job will be done within about two days of work and additional cost of £800 - £1200 compared to a boiler swap.

Gas Boiler Replacement Cost

What is the cheapest boiler replacement in the UK?

Looking for a cheap boiler replacement means that you'll buy a cheaper model, which may ease the financial costs upfront, but may come with some complications later.

The cheaper your new boiler is, the shorter the warranty will be. Moreover, a lower cost may also raise the question of quality. If you can’t use your boiler for a long period of time, your initial investment may not be paid off.

But, cheap options for gas boilers do exist on the market but we recommend always putting quality first. To pick a boiler suitable for your budget, let our expert help you. Get a quote.

What should I choose – a gas boiler or an air source heat pump?

Choosing between different types of heating systems is always a difficult decision. When you have two options at the same time – a gas boiler and an air source heat pump – the first step is to make a thorough comparison between the two.

Initial cost

On average, it costs between £9,000 to £11,000 to buy and install an air source heat pump. It costs you less to start with a gas boiler since the highest initial cost for buying and installing a gas boiler is around £3,000. 

However, it would take you more time to calculate the price for a gas boiler installation or replacement as the process requires extra costs for additional equipment.


An air source heat pump installation is simple and can be completed within two days. A gas boiler installation time, on the other hand, depends on the type of installation you require. If you need a combi boiler swap, typically it takes only 4 – 6 hours. The process will be more complicated and take up more time if you want to change the type of boilers and/or the location of your boiler.

Long-term benefits and potential issues

In terms of financial benefit, both air source heat pumps and gas boilers can help you save more money on your bill if you use them for a long time. If your family use a air-to-water heat pump, you can apply for the Renewable Heat Incentive (RHI) which financially support people who switch to green energy. After seven years of using the heat pump, you can save approximately £7,000.

The typical lifespan of air source heat pumps is longer than a gas boilers. While gas boilers can function properly over 10 – 15 years, air source heat pumps can work for 15 – 25 years.

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Can I replace a boiler with a ground source heat pump?

Yes, you can replace a boiler with a ground source heat pump. The first step must be upgrading your insulation to minimise heat loss since boilers work with high temperature and ground source heat pumps are suitable with low temperature. Furthermore, you may also need to install some new pipes for the hot water cylinder. 

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