System Boiler Cost and Advice 2024

Last updated: April 20, 2024

Are you ready to ditch your old boiler, and need to know the latest system boiler cost in the UK? In this guide, we explore the average prices in the UK and offer top tips on securing the best quote.

System boilers are your best bet if you have a large home with high energy demands. They provide high volumes of pressurised hot water for central heating and domestic hot water use.

But what is the current system boiler cost in the UK in 2024?

The key thing to remember is that the cost will depend on various factors. These include the boiler output and size, efficiency, whether it’s a high-end or budget model, and labour and installation costs.

It’s also important to consider the complexity of the installation. For example, a like-for-like boiler swap can save you money because it features less installation complexity since there’s no need to change tanks or do more pipework.

Below, we explore the latest system boiler costs in the UK, frequently asked questions about system boilers, and how to get the best prices.

System Boiler Cost for Worcester Bosch brand
Image by Worcester Bosch

System Boiler Cost Key Takeaways:

  • System boiler costs can range from £600 – £2,500.
  • System boiler costs for installation can range from £1,500 to £3,500.
  • Factors impacting system boiler costs include the brand, warranty length, installation complexity, and extras.
  • Start your application with Which? approved boiler installers here to get an accurate quote for a new system boiler.

How Much Does A System Boiler Cost in 2024?

The price for the system boiler will largely depend on the brand you choose, the power output, boiler size, and the warranty period included.

System boilers start from as little as £500. Remember, if you go for a lower-priced system boiler, you’ll likely forego the more generous warranty periods often found with higher-priced models.

Biasi Advance Plus System16kW5 years£500
Vokera Vision S System20kW7 years£706
Ideal Logic+ System15kW7 years£800
Glow-worm Energy System25kW7 years£830
Baxi 600 System 18kW7 years£960
Viessmann Vitodens 100-W System30kW5 years£1,100
Vaillant ecoFIT Pure System25kW2 years£1,100
Worcester Bosch Greenstar 4000 System 24kW5 years£1,120

How Much Does it Cost to Have A System Boiler Installed?

Installing a new system boiler will cost between £500 and £1,000 on average, depending on the complexity of the installation.

For example, a like-for-like swap, where you replace your current system boiler in the same location will be cheaper than replacing the system boiler and the tank in a new location.

Therefore, the average cost of a complete system boiler install, including the boiler, a cylinder, a system clean, and labour, can range from £1,500 to £7,000 (excluding VAT). 

What size system boiler do you need for your home?

Another important consideration is the size of the system boiler, e.g., its power output (measured in kilowatts).

Typically, the more heat and hot water needed for the property and household requirements, the higher the kilowatt output, or boiler size will need to be.

The table below provides an estimate of the system boiler size you will require based on the number of bathrooms and radiators you have on your property:

1-2Up to 1019kW – 18kW
3-410+2-318kW – 26kW
5+20+4+27kW – 40kW

Remember, the above table only provides an estimation. You’ll need professional assistance to know exactly what size boiler your home requires.

System Boiler Prices FAQ

What is a System Boiler and How Does it Work?

System boilers are similar to conventional boilers in that they supply hot water to the central heating system and store it in an unvented hot water cylinder.

However, they differ because they don’t need as much storage space because their water is supplied straight from the mains.

They also deliver water under high pressure, resulting in a more constant flow rate.

A system boiler has the heating components needed to provide heating and hot water built into the unit.

An unvented cylinder containing hot water is the sole component required outside.

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System boilers do not require a water tank in the loft because they get their water straight from the mains water supply (unlike a regular (heat-only boiler).

They then heat the water, which serves as hot water for the cylinder and the central heating system.

How Does A System Boiler Differ From A Combi Boiler?

Combi boilers are best known for their compact size, which is extremely helpful for smaller homes with limited space. They’re excellent for condos and small flats, where it’s a challenge to fit a header tank or a hot water tank separately.

Combi boilers can comfortably meet the needs of homes with two bathrooms or less. However, some limitations make them less useful for a larger family or a place where hot water is needed from multiple outlets simultaneously.

Combi boilers use a diverter valve to switch from providing heat to hot water. This impacts their overall performance when the demand for hot water is high.

In such scenarios, system boilers present a more significant advantage over the combi boiler. According to the Energy Savings Trust, system boilers are more efficient than combi boilers at producing hot water.

System boilers have separate hot water cylinders for holding large volumes of hot water.

The separate external cylinder allows the system boiler to simultaneously provide instant hot water access in several areas, like sinks, faucets, and showers.

This makes it the best option for a house with a high demand for hot water, like large family homes with multiple bathrooms that will likely be used simultaneously.

Should You Choose A System or A Combi Boiler?

A system boiler is typically the best option for large households or properties with multiple bathrooms that will likely be used simultaneously.

Below is a table showing the property type/size and the suggested type of boiler you should install:

Property TypeIdeal Boiler Type 
Small Home
1 Bathroom
Combi Boiler
Small Home
2 Bathrooms
Combi Boiler
Average Size Home
1 Bathroom
Combi Boiler
Average Size Home
2 Bathroom
Combi Boiler
Average Size Home
3+ Bathroom
Regular/System Boiler
Large Home
1 Bathroom
Combi Boiler
Large Home
2 Bathrooms
Regular/System Boiler
Large Home
3+ Bathrooms
Regular/System Boiler

What Factors Impact the Cost of System Boilers?

The total cost you should expect while installing a new system boiler depends on the following factors:

System Boiler Brand

The brand of the system boiler will impact its price. Premium brands usually cost more but offer longer warranties and better quality.

Ensure you consider the advantages and disadvantages of each brand when choosing a system boiler and consider things like reliability, efficiency, performance, warranty, aftercare, and servicing.

System Boiler Size and Output

The size and output of the boiler will impact the cost, with larger system boilers generally costing more.

Choosing a system boiler with the proper size and power output for your house is crucial to ensure it meets your needs.

To choose a system boiler that is the correct size for your home, consider the following rules as a general guide:

  • 12 to 15 kW is ideal for smaller apartments with one to three bedrooms and one bathroom.
  • 18 to 24 kW is enough for 3 or 4 bedrooms and 1-2 bathrooms.
  • 30 kW or more is sufficient for at least two baths and four bedrooms.

System Boiler Efficiency

Efficiency refers to how well a boiler converts fuel to usable energy. The amount of fuel that gets converted is usually reflected in the efficiency rating.

A more efficient system boiler will generally cost more upfront since the higher the efficiency, the less energy is wasted.

However, a more efficient system boiler will save you more on energy bills over time, and the savings can quickly offset the initial investment.

To make an informed decision, ensure you compare the possible long-term energy savings with the initial cost.

System Boiler Warranty

Higher warranties usually attract premium prices. A system boiler with an extended warranty will feature a higher initial cost, but you’ll have more protection and peace of mind.

Most boilers will have a warranty of at least two years from the boiler manufacturer, while others can have a coverage of 5-10 years.

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Some manufacturers also offer extended service plans or warranties for an additional cost to give you comprehensive coverage.

System Boiler Fuel Type

System boilers can feature different fuel types. The fuel you choose will impact the upfront boiler cost and running costs. These can include:

  • Gas – Gas is a popular fuel option in UK homes thanks to its affordability and easy connection to the gas grid network. Gas boilers are usually more affordable to install and run than other fuel types like oil. It’s worth noting that despite its popularity, the UK government is phasing out gas to help reduce carbon emissions.
  • Oil— Oil boilers are usually installed in homes not connected to the gas grid. Getting an oil system boiler isn’t recommended because installing it is more difficult and costly. You’ll also incur additional costs for installing an external oil storage tank.
  • LPG – Liquid petroleum gas can be a great choice for homes not connected to the grid. However, they require an external tank that can increase the upfront costs. LPG can also be expensive to obtain and refill.
  • Electric –  Electric boilers can help you lower your carbon footprint, and their upfront and installation costs are similar to those of gas boilers. However, electric boilers usually have higher running costs because electricity is more expensive than gas in most areas.

Labour and Installation

According to Gas Safe engineer Patrick Garner, installation costs for system boilers can range from  £1,500 to £3,500.

Factors like ventilation requirements, the existing heating system, and whether or not additional electrical work or pipework is needed will impact the installation costs.

If you upgrade your heating system or replace an old boiler, the installation complexity will vary depending on the new boiler’s compatibility with the existing system.

The amount of labour required will also impact the cost of the installation. Rates can vary based on where you live, how long it takes to install the boiler, and the number of engineers required to complete the job.

Boiler Location

The location where the boiler will be installed can also impact the overall costs.

If the location is easily accessible and there are no obstacles, the installation process will be relatively straightforward. This will reduce the time and effort required and lower labor costs.

However, it will be challenging for the installation team if the boiler is installed in a confined space or an area that’s difficult to reach, like a basement or loft.

They may need to remove obstacles like other installations, navigate tight spaces, or create access points, increasing labor costs.

Additionally, the boiler’s location can affect whether it’s close to the existing gas supply or plumbing system and impact complexity and costs.

It may require additional materials, such as fittings and pipes, extensive pipework, and labour for proper connection and routing, increasing the installation cost.

Moving the location of the boiler can also be costly as it requires additional pipework, labour, and new fittings and fixtures.

Additional Materials

Additional materials may be required to install the system and get it up and running. Depending on your property’s requirements, they can contribute to the installation’s overall cost.

System filter that can increase system boiler cost
Image by Worcester Bosch

Such materials can include:

  • The Flue – The flue is essential in boiler installations because it allows the safe expulsion of exhaust gases. Flue costs can vary depending on the type and installation requirements. Flues can be vertical or horizontal, with vertical flues through your roof attracting higher costs because of the additional work required to ensure proper weatherproofing and sealing. Average vertical flue costs can range from £300 – £600.
  • Filters— Installing a central heating filter can help increase your system’s longevity and efficiency. Filter costs can vary depending on the type and brand, with a magnetic boiler filter costing from £100 – £200. Some installers don’t charge for installation, and some manufacturers provide longer warranties if you install a filter.

What Are The Pros and Cons of System Boilers?

Reviewing the pros and cons of system boilers can help you determine whether they’re worth the cost.

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Pros of System Boilers

  • Easy to Install and Operate

System boilers are easier to install and operate than regular boilers because the heating and hot water components are built into one unit.

  • Excellent for High Hot Water Demand

The cylinder of the system boiler allows you to store a large amount of hot water that stays hot for hours, allowing several users to use water at the same time.

  • Compatible with Solar Panel Heating Systems

A system boiler is an excellent choice if you want to generate hot water through solar panels. A system boiler’s unvented hot water storage cylinder can be altered to allow it to heat water using solar power.

  • Improved Water Pressure

System boilers get water directly from the mains supply when delivering hot water to your outlets like showers or taps. This ensures improved water pressure compared to a regular boiler that uses water from a tank in your attic and relies on gravity for pressure.

  • Space Saving

System boilers use less space than regular boilers, which require a tank in the loft. You won’t need to install additional tanks apart from the hot water storage cylinder, which you can tuck away inconspicuously.

  • Fast and Economical

System boilers feature a water pump, which enables quick delivery and distribution of hot water around the system, saving you time and energy. The insulated water storage tank also offers an economical way to provide hot water to multiple outlets and users.

Cons of System Boilers

  • Hot Water Isn’t Instant

If the boiler is left off for a significant amount of time, you’ll need to wait for the water to heat when you switch it on again. This can take a while because boilers heat a large amount of water relatively slowly.

  • Requires More Space than A Combi Boiler

Combi boilers are generally more compact than system boilers, which need a larger space for the hot water storage cylinder.

  • Cylinder Size Determines Hot Water Use

The size of the cylinder will dictate the amount of hot water your household can use and how long you have to wait for water to get heated.

If you choose a small cylinder you may have an inadequate hot water supply, while an oversized cylinder will mean you wait longer for water to get heated.

How to Get the Best Deals on System Boiler Costs

Here are some tips to help you find the best deals on system boilers:

Research and Compare Quotes

Gathering and comparing multiple quotes from reputable companies specialising in boiler installation is crucial.

It allows you to compare prices and services so you can get a better understanding of the average cost and ensure you’re not overpaying.

Remember to be wary of extremely low prices, as they can indicate poor work quality or the use of inferior materials.

Consider Energy Efficiency

Consider the product’s energy efficiency to ensure long-term savings on energy bills. Although a high-efficiency boiler may have a higher upfront cost, it can provide significant savings over its lifespan.

Look for system boilers with an A-rated energy-efficiency label. These boilers are designed to maximise energy use and minimise heat loss, resulting in lower running costs.

Utilise Local Services

Consider using local companies that specialise in boiler installations or replacements. They can provide quick response times, personalised services, and competitive pricing.

They usually better understand the locality and can provide tailored solutions based on your needs and property requirements.

Seek Recommendations

Recommendations through word of mouth can be invaluable in finding the best deals on system boiler costs.

Ask friends, family members, or neighbours who have recently installed a similar system for recommendations. They can offer invaluable insight into the quality of the service, reliability, and overall satisfaction with an installer.

You can also check online for reviews, feedback, and testimonials from previous customers to ensure you’re choosing a reputable installer.

Final Thoughts on System Boiler Cost

System boilers are excellent if you’re looking for an efficient and reliable way to heat your home while providing hot water to multiple bathrooms or users with high hot water demand.

Installing a new system boiler is a significant investment, so look for a competent installer to ensure the installation meets the highest standards. The law requires a Gas Safe registered engineer to install a gas-fired system boiler. You must find a fully qualified OFTEC engineer if your system boiler uses oil.

Consult a qualified heating engineer if you’re unsure whether a system boiler is right for you or want to learn about your alternatives. They can assess your needs, respond to your queries, and help determine which boiler or model best suits your household’s requirements.

You should also ensure your boiler gets serviced and maintained at least once a year to keep it operating at its peak longer. Finding a deal that includes some annual servicing can be a holy grail.

Sources and References