Boiler Replacement Costs & Prices 2021

Boilers do not have an infinite lifespan. In fact, we’re getting to a point now where most UK homes built in the 1960s until as late as the 1990s are in dire need of new boilers – especially if those fitted are not good quality. 

Whilst a boiler is hardly a glamorous purchase, it’s an investment that is worth considering in a wide variety of situations. 

Simply waiting for an old boiler to stop working will likely also include increasing heating bills, poor heating performance and numerous other issues that can cost more than proactively replacing the boiler before it fails. 

Also, you have to factor in the decreases in energy bills that come with a modern A-rated boiler – savings can be worth £200 to £300 a year or more in some cases. 

This article will explore the cost of boiler replacements, also analysing the average costs of replacing boilers in the UK.

Average Cost of Replacing Boiler

By compiling quotes from 7 primary sources and 11 secondary sources, we found the following costs for replacing a boiler. Costs include replacing the boiler only, including labour, but not the full central heating system. 

For system and conventional boilers, costs also include the necessary hot water tank for both and the cold water storage tank for the conventional boiler. Average costs for LPG, electric and oil boilers are also included. 

Type of BoilerFlat with 6 to 8 radiators and one bathroomSmall house with 10 or fewer radiators and two bathrooms 4-bed detached house with 15+ radiators and three bathrooms
Combi Boiler£1,000 to £1,500£1,500 to £2,250N/A (too many bathrooms)
Conventional/Standard boilerN/A (no attic)£2,000 to £2,750£2,500 to £3,500
System Boiler£1,500 to £2,250£2,500 to £3,250£3,000 to £4,000
Electric Boiler£1,500 to £2,250£2,500 to £3,250N/A (not powerful enough)
LPG BoilerN/A£2,500 to £5,000+£3,500 to £6,000+
Oil BoilerN/A£3,000 to £6,000+£5,000 to £8,000+

Should I Replace My Boiler?

Replacing a boiler is not as difficult or expensive as most people think. There are many situations where a boiler replacement is well worth considering, including:

1: If Your Boiler is More Than 15 Years Old

Quality boilers can last much longer than 15 years with regular maintenance and repairs, but the question is, how much does that maintenance cost, and how does it factor in with the price of your energy bills? 

The vast majority of sources indicate that yearly boiler servicing is a good idea, but a service for a new boiler is more of just a quick health check that should take no longer than an hour. For older boilers, that service will likely yield more costly problems that need fixing. 

Moreover, old boilers are often G, F, E or D rated – you can save pretty massive sums by upgrading – more on that shortly. 

You don’t need a really old boiler to benefit from a replacement either. Modern boilers are up to 50% more efficient than boilers fitted in just the year 2000. 

2: Your Energy Bills Are Increasing

Whilst energy bills are practically always increasing, it’s worth considering whether or not these increases result from an inefficient boiler. Your gas engineer should be able to tell you when they do their yearly service, but if your bills seem to rise without any other obvious cause then this might be an indication that your system needs upgrading. 

3: You Need To Move Your Boiler

Extensions and other home modifications might require your boiler to be moved. In this scenario, it’s also worth comparing the cost of a new boiler to that of simply moving the old one. Often, there won’t be as much in it as people expect which makes a boiler upgrade an attractive proposition. 

4: Your Boiler is Incapable of Properly Servicing Your Home

If your home is fitted with a smaller boiler suitable for standard heating and a single bathroom or so and you extend, adding another bathroom and more radiators, then your old boiler may be incapable of properly heating your home.

In this situation, you may need to upgrade to a more powerful boiler. 

5: Leaking Boilers or Other Dangerous Symptoms

All homes should have carbon monoxide alarms fitted, ideally on each floor and one close to the boiler.

Old boilers will not ‘blow up’ (except under exceptionally rare circumstances), but they may start to leak carbon monoxide which is a silent killer of some 60 people in England and Wales each year

If a boiler shows any signs of carbon monoxide leakage then immediate replacement is required. Other dangerous symptoms include leakage or changes to the blue flame visible inside the boiler (e.g. it goes yellow). 

6: You Want to Modernise Your Home

Many people budget for a new boiler when they move home. Committing to a boiler replacement is not only beneficial for long-term energy bills, but it also benefits the environment, reducing the home’s carbon footprint. 

Many people are actively creating energy-efficient homes that combine modern boilers with insulation and other green technologies. This can significantly boost the value of a home. 

How Much Money Can You Save With a New Boiler?

According to Energy Saving Trust, the typical savings of upgrading to a modern A-rated boiler are as follows:

Existing Boiler RatingAnnual Savings for a Semi-Detached HouseAnnual Savings For a Detached HouseAnnual Savings For a Mid-Terraced HouseAnnual Savings For a Mid-Floor Flat
G£205£315£175£85
F£145£220£120£55
E£125£190£105£50
D£110£170£95£45

As we can see, there are savings to take into account in every example. This has to be compared to the cost of the boiler installation. 

What is interesting is that even flats benefit from significant annual savings. This is particularly relevant to those living in terraced flats that were built through the 1930s to the 1980s or so and therefore likely have old boilers, even if they were replaced at some point. 

Types of Boilers

So, what are the options for boiler replacements? 

  • Combi boilers
  • Standard/conventional/traditional boilers
  • System boilers

Firstly, whilst there are 3 main types of boilers, there are other lesser-used types of boilers such as LPG, oil and biomass boilers which are typically used for rural properties not connected to the mains gas supply. 

Furthermore, whilst the term ‘condensing boiler’ is used a lot, any of the 3 main types of boiler can use condensing technology that reuses some of the escaped heat from the flue. These are required in all new builds under Building Regulations on 1st April 2005. New boilers must also now be more than 88% efficient. 

Lastly, electric boilers do not use either oil or any type of gas to function and run off the mains electricity alone. This is another option for properties not on the gas grid, where oil or LPG is also not suitable.

Electric boilers are becoming more popular despite being largely more expensive to run than gas boilers. 

Here is a brief rundown of the 3 main types of boilers: 

Combi Boilers

Combi boilers are a type of modern boiler that features an all-in-one system for heating the radiators and the water supply. They connect directly to the mains cold water, meaning that they don’t require a separate water tank. This means that the unit is heavily reliant on the mains water pressure, which is usually excellent in cities and towns but varies considerably in more rural or suburban locations. Moreover, they’re generally not high-performing in homes with high water demands due to the lack of a tank, but modern systems can overcome this. 

  • Heating and hot water from same combi unit 
  • Rapid water heating
  • Typical units only suitable for smaller properties with one bathroom 
  • Highly energy efficient 

Standard/Traditional Boilers

Standard/conventional/traditional boiler systems are the most common type of boiler fitted to houses in the UK. 

These systems have 3 parts, the boiler, a hot water tank (typically fitted in an airing cupboard) and a cold water feed which sits in the attic, which supplies cold water to the hot water tank.

This setup provides hot water to multiple bathrooms and does not rely on the mains water pressure to function properly. If you use up all of the water in the tank, you’ll have to wait for the system to replenish it.  

  • 3 main components; more to go wrong
  • Excellent performance in homes with 2+ bathrooms
  • Classic boiler setup 
  • Good water pressure

System Boilers

System boilers have two parts; the boiler and hot water tank. These are somewhat of a hybrid between the aforementioned boiler types, as they combine direct heating of mains water with a hot water storage tank. 

The hot water tank ensures a good provision of hot water to multiple taps, but the pressure is still largely dependent on the mains. They are however excellent all-rounders when the mains water pressure is high (providing the rest of the heating system can take the high pressure). 

  • High-pressure hot water providing the mains is high pressure 
  • Doesn’t require an attic cold water tank
  • Requires a modern heating system (if the mains pressure is high)
  • Most expensive option 

What Size Boiler Do I Need?

Boiler output power is measured in kilowatts (kW). Higher power boilers are required for larger homes with more radiators. The following table shows what boiler output is required.

Property SizeBoiler Output Power
Flat with 6 to 8 radiators and one bathroom 12kW to 14kW
Small house with 10 or fewer radiators and two bathrooms 24kW to 27kW
3-bedroom house with 10 to 15 radiators and two bathrooms 28kW to 34kW
4-bed detached house with 15+ radiators and three bathrooms35kw and 42 kW

Leading Boiler Brands

There are probably 5 leading boiler brands right now; Baxi, Ideal, Valliant, Viessmann and Worcester Bosch. This is by far from a complete list of reputable boiler brands, however. 

LPG and oil boiler brands include Mistral, Firebird, Grant and Warmflow. Popular electric boiler brands include Electric Heating Company, Heatrae and Strom. 

Each manufacturer offers many different types of boilers in different sizes and power output levels. 

Things To Consider When Installing a New Boiler

Depending on the age of the home, installing a new boiler may or may not be a straightforward task. If the heating infrastructure is reasonably modern, a straight swap is often possible which will cost the minimum amount and take the minimum amount of time. 

Otherwise, it’s common to need new piping, tanks, radiators and other components, particularly if your system cannot handle a higher pressure modern system. If the entire system needs to be replaced, total costs can easily exceed the £5,000 mark. However, this would be a significant value-adding investment for any home. 

Another consideration is insulation. It’s often recommended that homeowners consider insulating their property to the max before investing in an efficient boiler as this will vastly compound any benefits. 

Choosing a Boiler Fitter

Gas central heating installers should always be registered with Gas Safe – this is a legal requirement. Electric boilers should be fitted by an appropriate electric boiler specialist who will also of course be an electrician. Oil systems should preferably be installed by a member of OFTEC (Oil Firing Technicians Association).

Get Prices on Boiler Replacements Near You

We’ve done our best to give you a good idea of what you can expect to pay for a boiler replacement.

However, our guides are not a substitute for a fixed quote specifically for you.

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