Combi Boiler Costs UK Guide

Combi boilers are popular thanks to their compact size and ability to provide heating and hot water without an additional cylinder or storage tank. But what are the average combi boiler costs in the UK? Read on to find out.

Combi boilers are the most common type of boiler in the UK, with statistics showing that over 54% of households in England had installed them by 2019.

They’re an excellent choice for small homes or flats and can help you maximise the space in your home.

If you’re struggling with an older boiler, replacing it with a new, A-rated combi boiler can save up to £475 annually on fuel bills, depending on the size of your home and its thermal performance.

Important reminder: If you have an old G rated boiler, upgrading to a modern A rated combi boiler could potentially save you up to £475 per year on heating costs.
Energy Savings Trust

In addition, combi boilers are significantly less complicated than traditional heating systems like heat-only and system boilers. Therefore, they typically cost less to install and repair.

But what are the average combi boiler costs in the UK?

This guide explores what you can expect to pay for a new combi boiler installation, including factors that impact the final price.

Installer explaining combi boiler costs — Image by Worcester Bosch

Combi Boiler Costs Quick Takeaways:

The average combi boiler installation in the UK costs between £1,500 and £4,000, but this is for a standard, uncomplicated, like-for-like swap.
A standalone combi boiler can cost anywhere from £600 to £2,000.
The final price depends on factors like the brand, boiler size, installation complexity, warranty, and associated labour costs in your area.

savings that make combi boiler costs worth it

What Is A Combi Boiler?

The most widely used form of boiler is a combi (or combination) boiler.

The compact form of a combi boiler system saves room in your home by supplying hot water straight to your taps or radiators, eliminating the need for a storage tank.

Combi boilers connect directly to the main cold water supply and provide hot water on demand, eliminating the need for a tank or cylinder.

They burn fuel like gas or oil and have an integral heat exchanger that gets hot enough to instantaneously heat the cold water from the mains supply as it flows over it.

Combi boilers consume less power and are affordable and efficient to run since you don’t have to heat and store water.

They’re very cost-effective since you only pay for what you use by providing hot water on demand.

What Are The Advantages of Combi Boilers?

Combi boilers are a popular choice due to their various benefits. These include:

Compact Size — They easily fit into bathrooms, kitchens, and airing cupboards, and you can control the entire system, including heating and hot water, from the same appliance.
Saves Money — Purchasing a single unit can be cheaper than buying multiple system components. The streamlined design also makes them affordable to install and maintain.
Highly Efficient — Modern combi boilers are A-rated with efficiencies above 90%. They waste less fuel and can help reduce your household’s energy bills.
Instant Hot Water — Combi boilers don’t have to heat a large volume of water in a storage tank, which can take time to refill and reheat. They heat water when required when you turn on the hot water tap.
Easy Installation — Swapping one combi boiler with another makes the installation easier since no complicated components and controls, like a hot water cylinder, require separate installation.

What Are The Disadvantages of Combi Boilers

Unsuitable for Large Homes — Due to their compact size, combi boilers have a limited water capacity and can only supply hot water to one tap at a time. As a result, they’re unsuitable for large homes with higher hot water demand, especially when multiple people need hot water simultaneously.
Needs Good Mains Pressure — Combi boilers depend on good mains pressure since they get water directly from the mains supply. The combi boiler may not work effectively if your home experiences a low flow rate or pressure.

What Are The Costs of A Standalone Combi Boiler?

Without including any additional cost, the boiler itself might represent a significant portion of the total cost.

Based on the system type and model range, new boilers can cost anywhere from £600 to £2,000.

In comparison, a new system boiler can cost anywhere from £600 to £900 for the most affordable model, £900 to £1,300 for a mid-range model, and £1,300 to 2,500 for a luxury model.

The cost of a heat-only boiler ranges from £500 to £2,500, depending on the boiler size and quality. Biomass boilers usually cost from £7,000 to £15,000.

These are the pricing for the standalone boiler without including Gas Safe Installation or any other optional additions.

Want to learn about all the factors that contribute to a boiler quote? Check out our boiler cost calculator to understand the latest boiler deals and what is factored into a gas boiler replacement estimate.

How old is your boiler? Should you consider repairing the boiler or start looking at the latest boiler prices? It’s no secret that boiler efficiency deteriorates over time.

What Are The Costs of A Combi Boiler with Gas Safe Installation?

If you opt for a small combi condensing boiler, you should expect to pay between £1500 and £4,500, with an average total cost of £3,000, including Gas Safe installation.

This figure covers the cost of a complete combi boiler replacement, which involves purchasing a new boiler to replace an existing one of the same type.

The price you pay can increase if you need new plumbing, cabinet removal, or clearing the space around the boiler.

More work will increase the installation time and may require additional materials. This will increase the cost since you’ll pay the heating engineer on an hourly basis.

However, this isn’t always the case, and many online boiler installation companies now offer fixed-priced boilers.

This means you no longer have to worry about extra charges or hourly fees. Instead, you pay one price, and that’s final.

The table below shows how much you can expect to pay for different types of boilers in the UK, including and excluding installation:

Type of Boiler/Fuel Source	Cost Excluding Installation	Cost Including Installation	Average Cost Including Installation
Combi Swap	£600 – £2,000	£1,500 – £4,500	£3,000
System Boiler	£500 – £2,500	£1,700 – £5,000	£3,300
Conventional Boiler	£600 – £3,500	£1,700 – £4,500	£3,000
Electric Boiler	£600 – £2,500	£2,000 – £4,500	£2,500
Biomass Boiler	£7,000 – £15,000	£10,000 – £18,000	£15,000

Table data updated June 2024.

Have you considered paying for your boiler monthly? Many boiler finance deals make paying for a new boiler much more manageable.

Did you know that not all boiler models are wall-hung? Check out our complete guide on floor-standing boilers here.

How Do You Calculate Combi Boiler Costs?

Knowing how much you’ll need to spend to install a new combi boiler can help you plan your budget accordingly.

You must factor in the following to determine the total cost:

Cost of boiler + Labour cost of boiler fitter + Additional costs

Additional costs include charges for an extended warranty, additional pipework, and the removal and disposal of your old boiler.

Remember, the final price you pay will depend on the choices you make based on different factors.

What Factors Impact Combi Boiler Costs?

It is never a good idea to try to install a boiler yourself. Not only is this risky, but it also puts your home in jeopardy.

Furthermore, even if you had the boiler installed, it will need to be tested and signed off by a professional.

Once you’ve purchased a boiler, it is important to contact a professional for the installation.

The installation price that will be quoted to you might vary depending on the following factors:

Type of Combi Boiler

The installation process varies depending on the type of combi boiler you pick.

Combi boilers are generally the least expensive to install compared to traditional and system boilers.

However, they can use different fuel types, which affects the final price. These can include:

Gas combi boilers — These use natural gas and are a common choice for homes connected to the gas network.
Oil combi boilers — These are suitable options for homes without an existing gas connection and use an oil storage tanker. The installation cost can be higher, but running costs tend to be lower.
LPG combi boilers — These use liquefied petroleum gas (LPG) and are an energy-efficient way of providing hot water.
Electric combi boilers — These use electricity to heat the water supplied to your taps, cylinders, and radiators instead of burning fuel. They cost around £2,500 plus installation.

New boiler cost guides:

Combi Boiler Brand

Like any other type of home appliance, some brands are more expensive than others. Sometimes, this is justified, and sometimes, it isn’t.

For example, some boiler brands contain higher-grade and higher-quality components, such as stainless steel heat exchangers and all metal parts, instead of plastic ones.

In addition, some brands have better reviews, longer warranty periods, and a reputation for superior customer service, which can be especially important in a boiler breakdown emergency.

Boiler brands have boiler ranges that include entry-level, mid-range, and premium boiler models, which increase in price.

Combi Boiler Size

The size of the boiler is another important factor that influences the price of a combi boiler installation.

The boiler size refers to the boiler’s power output and not the dimensions of the boiler.

A boiler’s power is measured in kilowatts per hour (kWh). The greater the kW, the greater the boiler’s capacity to meet your property’s hot water and heating requirements.

Boiler manufacturers offer combi boilers in various sizes. Your boiler installer will determine what size you need based on the number of radiators in your house.

As a matter of convention, boilers with a higher output size are more expensive than smaller boilers.

Labour Costs

The cost of a combi boiler installation will depend on the amount of labour required.

Labour costs usually range from £600 to £1500 and can vary depending on your location, the installation company, the time it takes to install the boiler, and the number of engineers required.

The installation type will also affect the labour costs. For example, a like-for-like combi swap can take around a day to complete. It’s much quicker than a back boiler conversion, which takes around 2 days and may require more than one engineer.

The Need For Additional Upgrades

Any renovations or adjustments you may require when the new boiler is installed will impact the costs you are charged for boiler installation.

In some circumstances, additional pipes, valves, or electrical outlets may be required to accommodate the new boiler being installed.

You should anticipate paying more if you need renovations or alterations to the pipes or power source than someone who does not.

Boiler Conversion or Relocation

Some boiler upgrades are simple, and some are not.

A standard boiler install entails loosening a few connections, removing the old boiler, and installing the new boiler.

In this case, your boiler installer can test the boiler immediately and sign it off as gas-safe. However, not all boiler installs are that straightforward.

If your new boiler type does not match your old one, the contractor may need to drill the holes again wherever needed and even modify the plumbing to install it.

Moving the location of your boiler is also costly and will require a lot of physical labour, new fixtures and fittings, and additional pipework.

All this requires time, increasing the expense of installing your new boiler.

Want to learn about all the factors that contribute to a boiler quote? Check out our boiler cost calculator to understand the latest deals and what is factored into a gas boiler replacement estimate.

Vertical Flue Cost

A vertical flue can cost from £300 to £600.

The boiler flue is a pipe that leads from the boiler to the outside of your home. It helps ensure condensation and the boiler’s emissions are pumped out of your home.

If the flue leaves your property horizontally, you’ll incur no costs. However, if it leaves the property vertically through the roof, it will require more work, resulting in additional work and costs.

Gas Pipe Upgrade

If you have an old heating system, you’ll need to upgrade the gas piping to meet modern regulations.

Gas pipes with a width of 15mm must be upgraded to at least 22mm, attracting additional costs of around £250 to £400.

Sometimes, older pipes must be replaced entirely, especially if made of lead. Some installation companies don’t charge for upgrading pipework, so ensure you shop around.

Plume Kit Cost

If your boiler flue is too close to a door, window, or neighbouring property, a plume kit is necessary to comply with Gas Safe regulations.

The plume kit helps extend the flue and ensure a safe exit for harmful gases, costing from £90 to £130.

Upgraded Heating Controls

Almost all new boiler installations will include some upgraded controllers.

A wide range of heating controls is available to help your heating system work more efficiently and keep your bills down.

Depending on the type and brand of the controller, it will add varying amounts to the cost of your new boiler, ranging from £100 to £300.

Chemical Flush

A chemical flush will help clear any existing sludge or debris from your heating system, costing from £100 to £150.

Sludge can prevent hot water from flowing to your radiators effectively, making it difficult to heat your home comfortably.

A chemical flush is common and standard, but you can also get a power flush for up to £500. However, you should be cautious to avoid damaging an old heating system by forcing high-pressure water through it.

Radiator Costs

When fitting a new boiler, ensure you look at your overall heating system, including radiators.

Radiators experience wear and tear after years of use. Old radiator models can also be less efficient and perform poorly than modern models.

The efficiency of the radiators will directly impact the overall efficiency of the boiler and heating system.

Incorporating features like thermostatic radiator valves (TRVs) can enhance control over individual room temperatures, contributing to energy-efficient heating and cost savings.

The price of new radiators can vary depending on factors like size, design, material, and the number you require.

Check out our boiler brand price guides and comparisons:

Conventional to Combi Boiler Conversion Cost

If you have another type of boiler already installed on your property and want to replace it with a new combi boiler, this is known as a conversion.

A combi boiler conversion is generally more expensive, costing between £2,500 and £5,000.

The reason conversions are more expensive is that they take more time to complete.

Your old boiler and water storage cylinder all need to be removed and pipework adjusted as required, which is time-consuming.

All in all, a conversion adds between £1,000 to £1,500 to the cost of a new boiler installation.
– Gas Safe Engineer Patrick Garner

Combi Boiler Costs Conclusion

Trying to find out how much you will be charged to install a combi boiler in your home may be a challenge. You can get a variety of figures ranging from £1,000 to £6,000, depending on the size of your home, the type of boiler you choose, and other considerations.

To select the ideal combi boiler for your space, you should always look for a fixed quotation that includes the desired boiler, installation, and additional parts charges. You should also get at least three quotes from different installers to ensure you get the best value for money.

Sources and References

https://www.statista.com/statistics/292259/boiler-types-in-dwellings-in-england/