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Last updated: 13 March 2024

Best Combi Boiler 2024 UK: Reviews & Prices

Best combi boilers

Combi boilers are space-saving options for heating your home and are considered to be some of the best boilers in the UK. They consist of a single compact unit capable of both running your radiators and providing your taps and showers with hot water. Their high functionality —alongside the modern technology they incorporate— has made them the most commonly installed type of boiler in the UK.

If you are looking for a new boiler, considering a new combi is a must. You’re probably asking yourself “but what are the best combi boilers in the UK and how do I choose one?” Given their popularity, the market is full of options so finding the best combi boiler for your house could become overwhelming. In this article, we will share with you tips, lists, and the best combi boilers reviews that will make your search easier.

Are you interested in a combi boiler? GreenMatch can help you find the best boilers on the market that best meet your needs. We will save you hours of going through countless product pages thanks to our team of experts and our nationwide network of partner installers. Ask for quotes now, and we will send you up to 3 tailor-made quotes for free. You are not obliged to accept any of them.

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What is the Best Combi Boiler?

With so many models available, there is not just one best combi boiler suiting all needs. It is more accurate to say that when it comes to the best combi boiler (and other central heating boilers), the best buy for you is the one that best meets your house requirements and your budget.

There are, however, a few things you can look at when looking for the best combi boilers. Here we share the essential ones with you. We have also covered them in our best combi boilers reviews throughout this article.

  • Brand. Try to buy your combi from a reputable boiler brand. They might be more expensive, but you will get a reliable appliance that is less likely to run into issues.
  • Fuel. Choose a combi boiler running on the type of fuel that suits your needs. All of them have advantages and disadvantages you must consider.
  • Output size. Combi boilers have 2 output sizes, one for central heating (CH) and one for domestic hot water (DHW). These values indicate how powerful the combi boiler is and how well it can meet your house’s central heating and hot water demands.
  • Efficiency. The efficiency level of a combi boiler tells you how much fuel the boiler can turn into usable energy against how much fuel is wasted in the process. It is the key to lowering your heating bills!
  • Warranty. It is the period after installation where your combi boiler is covered by the manufacturer against possible faults. The longer the warranty period, the more reliable you can expect your combi boiler to be.
  • Price. Look for a boiler that falls within your desired price range. The good thing about having so many options is that you can always find affordable combi boiler models. Check our section Best Combi Boiler Under £1000, and you will see!

Best Combi Boilers (by Boiler Manufacturer)

To help you find the best combi boilers, we’ve listed the top 5 boiler manufacturers in the UK market:

Each of these brands has been in the boiler production business for decades. Besides their products’ reliability, customer service ratings, great warranties, and excellence awards, they invest in future-proofing and increasing the efficiency of their boilers.

Best Worcester Bosch combi boiler

Worcester Bosch Greenstar 8000 Style combi

Greenstar 8000 Style combi

  • Available CH output: 30kW, 35kW
  • Available DHW output: 30kW, 35kW, 40kW, 55kW, 50kW
  • Suitable for: Smaller homes with 1 bathroom to properties with up to 20 radiators and 2 bathrooms
  • Efficiency: 94% and ErP A-rated for heat and hot water
  • Warranty: Up to 12 years when installed by a Worcester Accredited Installer
  • Estimated price (Exc. installation): £1,300 – £2,297

Best Baxi combi boiler

Baxi Platinum combi

Baxi Platinum combi

  • Baxi Platinum combi​ 25.9kW,  25.9kW, 30.3kW, 34.4kW
  • Available DHW output: 24kW, 28kW, 33kW, 40kW
  • Suitable for: Homes with up to 10 radiators and a single bathroom to larger homes with 2 bathrooms and around 20 radiators. 
  • Efficiency: 92% and ErP A-rated for heat and hot water
  • Warranty: 10-year parts and labour warranty
  • Estimated price (Exc. installation): £928 – £1,276

Best Vaillant combi boiler

Vaillant ecoTEC exclusive with Green iQ combi

ecoTEC exclusive with Green iQ combi

  • Available CH output: 26kW, 36kW
  • Available DHW output: 35kW, 43kW
  • Suitable for: Larger properties with around 20 radiators
  • Efficiency: 94% and ErP A-rated for heat and hot water
  • Warranty: Guarantee up to 10 years available when you book a Vaillant Advance installer
  • Estimated price (Exc. installation): £1,425 – £1,673

Best Ideal combi boiler

Ideal Vogue Max combi boiler

Vogue Max combi boiler

  • Available CH output: 18kW, 26kW, 32kW
  • Available DHW output: 26kW, 32kW, 40kW
  • Suitable for: Homes with around 10 radiators and 1 bathroom to homes with 2 bathrooms and around 15 radiators
  • Efficiency: 93% and ErP A-rated for heat and hot water
  • Warranty: 10-year warranty, increased to 12 years if installed and serviced by a Max accredited installer
  • Estimated price (Exc. installation): £1,089 – £1,323

Best Viessmann combi boiler

Viessmann Vitodens 200-W combi boiler

Vitodens 200-W combi boiler

  • Available CH output: 25kW, 32kW
  • Available DHW output: 31.1kW, 34kW
  • Suitable for: Homes with up to 10 radiators and 1 bathroom to houses with around 15 radiators and up to 2 bathrooms
  • Efficiency: 98% and ErP A-rated for heat and hot water
  • Warranty: 10-year warranty option when registered through the Viessmann Installer Portal
  • Estimated price (Exc. installation): £1,550 – £1,600

What is the Best Combi Boiler Fuel?

Gas boilers are the most popular choice among UK homeowners. Figures show that approximately 85% of homes in  England, Scotland, and Wales are connected to the gas network and use a gas boiler. As combis are the most common type of boiler across the country, it doesn’t come as a surprise that there are many gas combi boilers around.

For those houses disconnected from the grid, oil or liquefied petroleum gas (LPG) are the most common options for fueling their boilers. Electric boilers are another alternative, though they are expensive to run due to the high electricity prices in the UK.

Best gas combi boiler

Gas combi boilers run on natural gas sent to homes via the national gas grid. Even though natural gas is produced from fossil fuels, it is considered cleaner than oil and coal.

Although they release CO2 into the atmosphere when running, modern gas combi boilers have inbuilt condensing technology. Because the condensing boiler efficiency is very high, they can help you keep your energy bills low and reduce your carbon footprint.

Best oil combi boiler

Oil combi boilers are a cost-effective alternative for houses disconnected from the grid. However, you will need to store the fuel in an external tank. This makes them less space-saving than gas and electric combis. The best oil combi boilers available on the market also have inbuilt condensing technology.

Best LPG combi boiler

LPG is a combined product of natural gas and oil extractions. The best gas combi boilers are usually compatible with LPG. This makes them suitable for properties connected to the grid as well as for the disconnected ones.

Best electric combi boiler

Electric combi boilers don’t waste energy or release CO2 when working. However, they can only achieve a zero-emissions performance as long as the electricity powering them comes from renewable sources. For instance, you could power them using solar panels.

The best electric combi boilers don’t waste energy at all, as they boast efficiency ratings of 100%. Nevertheless, they are very expensive to run. 

From an environmental perspective, we can draw some conclusions on the environmental impact of each type of combi boiler based on the fuel they use.

Emission Intensity by Fuel (kilograms of CO2 equivalent per kWh)
Fuel

England, Scotland and Wales

Northern Ireland

Gas

0.213

0.213

Oil

0.298

0.298

LPG

0.240

0.240

Electricity*

0.225

0.234

* Generated using fossil fuels and distributed through the national grid

Source: Fuel prices and carbon factors, Energy Saving Trust (July 2023)

At GreenMatch, we are committed to helping you navigate the transition to more sustainable ways of heating your home. Looking at the table above, we suggest switching to low-carbon systems such as solar panels in the UK, heat pumps, or biomass boilers. However, these are still rather expensive alternatives.

If you are not ready yet to switch because of either technical or financing reasons, consider installing a highly-efficient electric or gas combi boiler. Our experts can send you up to 3 free offers for these energy-efficient solutions from suppliers near you to help you find the best boiler in 2024.

We advise you then compare these offers objectively to lock in the best deal. For instance, in a gas-heated home in England, Scotland or Wales, you could save up to £840 per year on your energy bills by installing a highly-efficient condensing combi boiler. Get started by clicking the button below.

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Best Combi Boilers (by House Size)

Best combi boiler by house size

Simple and straightforward: the best combi boiler for your house is the one that best meets your house’s needs. In this regard, it is essential that you get a combi boiler as powerful as the size of your house requires it. Otherwise, your combi will struggle or fail to cope with the heating and hot water demand.

Approximate Combi Boiler Sizes (CH Output)

House Size

Combi Boiler Size

Houses with up to 10 radiators (usually up to 4 bedrooms)

24-27kW

Houses with 10-15 radiators (usually 4 to 5 bedrooms)

28-34kW

Houses with 15-20 radiators (usually 5-7 bedrooms)

35-42kW

Naturally, a much less powerful combi boiler will be enough for a small flat with 1 bedroom.

Best combi boiler for a 3-bed house

A combi boiler is probably the best choice for a 3-bed house, as you won’t need it to be too powerful. You have several good options here, including gas and electric boilers. In addition to the models mentioned above, you can consider the Electric Heating Company Mercury combi boiler.

Best combi boiler for a 4-bedroom house

Most likely, the best combi boiler for a 4-bedroom house will have an output rating of around 25kW to 30kW, as 4-bed homes usually have between 10 and 15 radiators. You will also need to take the number of bathrooms into account as well. Check the best combi boiler models in our article on the best boilers for a 4 bedroom house.

Best combi boiler for a large house

Combi boilers are best recommended for small to medium-sized homes as, generally, they are not powerful enough to meet large houses’ demands for heating and hot water. However, there are some models that can cope with it and even do an excellent job.

You can find what is the best combi boiler for a large house in our article on the best boiler for a large house.

Best Energy Efficient Combi Boiler

Electric combi boilers easily win this division. Their 99-100% efficiency rating is no match for even the most efficient gas or oil condensing boilers. In this regard, our pick for the best energy-efficient combi boiler is the Electric Heating Company Mercury combi boiler.

Electric Heating Company Mercury combi boiler

This boiler is available in a wide range of outputs to suit different property sizes and sports some state-of-the-art features too.

  • Output ranges of 12 – 26kW (suitable for homes with 6 – 17 radiators)
  • Compatible with central heating and underfloor heating
  • Includes 5-year guarantee
  • 100% energy efficient (no energy is lost)
  • Includes summer and winter modes to help save energy

Just be aware that the models with lower outputs cannot produce a high enough flow rate of hot water to efficiently fill a hot bath. They are recommended for use with showers.

Best Small Combi Boiler

When it comes to compactness, combi boilers have no rivals. They are the most space-saving boilers because they don’t require additional components such as hot water storage cylinders or feed tanks. These are our picks for the list of best small combi boilers.

Worcester Bosch Greenstar CDi Compact

  • Dimensions: 690mm x 390mm x 280mm (height x width x depth)
  • Available CH output: 24kW
  • Available DHW output: 28kW, 32kW, 36kW
  • Suitable for: Homes with around 15 radiators and 1 to 2 bathrooms, depending on the DHW output
  • Efficiency: 94% and ErP A-rated for heat and hot water
  • Warranty: Worcester Bosch offers 10-year guarantees on the Greenstar CDi Compact range
  • Estimated price (Exc. installation): £1,000 – £1,370

Ideal Logic Max Combi

  • Dimensions: 700mm x 395mm x 278mm (height x width x depth)
  • Available CH output: 24.2kW
  • Available DHW output: 24kW, 30kW, 35kW
  • Suitable for: Homes with around 10 radiators and 1 bathroom
  • Efficiency: 94% and ErP A-rated for heat and hot water
  • Warranty: 10-year parts and labour warranty
  • Estimated price (Exc. installation): £968 – £1,156

Baxi 800 Combi

  • Dimensions: 700mm x 390mm x 285mm (height x width x depth)
  • Available CH output: 21.2kW, 26.4kW
  • Available DHW output:  25kW, 30kW, 36kW
  • Suitable for: Properties with low demand for central heating and hot water
  • Efficiency: 93% and ErP A-rated for heat and hot water
  • Warranty: Baxi offers a 10-year parts and labour warranty on this range
  • Estimated price (Exc. installation): £858 – £1,205

Best Combi Boiler Prices

Based on our research, the 5 best gas combi boilers are the Worcester Bosch Greenstar 2000, Vaillant ecoFIT Pure 825, Ideal ESP1, Baxi 200 series, and Viessmann Vitodens 050-W.

We have provided a breakdown of their prices below:

5 Best combi boiler prices
Combi boiler modelPrice (excl. installation)
Worcester Bosch Greenstar 2000£730 – £850
Vaillant ecoFIT Pure 825£907
Ideal ESP1£714 – £770
Baxi 200 series£549 – £572
Viessmann Vitodens 050-W£800

These combi boiler costs above are well-suited if you’re looking to buy a combi boiler on a budget. It’s important to keep in mind that these prices are guidelines and there are a lot of factors that can determine the price, such as the manufacturer, model, fuel type, and output rating.

Best combi boiler under £1000

If you are on a limited budget but want to get the best possible option, we recommend you check the models below. They are the best combi boiler under £1000 we’ve found after analysing dozens of options. These boilers are manufactured by top brands and will provide the best value for their price.

Worcester Bosch Greenstar 2000

  • Available CH output: 20kW
  • Available DHW output: 25kW, 30kW
  • Suitable for: Properties with fewer than 10 radiators and 1 bathroom
  • Efficiency: 93% and ErP A-rated for heat and hot water
  • Warranty: 5 years. This can be extended to 6 years when fitted with a Greenstar System Filter
  • Estimated price (Exc. installation): £730 – £850

Vaillant ecoFIT Pure 825

  • Available CH output: 19.1kW
  • Available DHW output: 25kW
  • Suitable for: Smaller homes with 10-15 radiators and 1 bathroom
  • Efficiency: 94% and ErP A-rated for heat and hot water
  • Warranty: 2 years as standard. It can be extended to 7-10 years when installed by a Vaillant Advance installer.
  • Estimated price (Exc. installation): £907

Ideal ESP1

  • Available CH output: 24kW, 25kW, 25.6kW
  • Available DHW output: 24kW, 30kW, 35.3kW
  • Suitable for: Smaller properties that do not have a high demand for hot water to large homes with 2 bathrooms
  • Efficiency: 94% and ErP A-rated for heat and hot water
  • Warranty: 2 years for parts and labour
  • Estimated price (Exc. installation): £714 – £770

Baxi 200 series

  • Available CH output: 21.8kW
  • Available DHW output: 24kW, 28kW
  • Suitable for: Homes with up to 10 radiators and 1 bathroom
  • Efficiency: 93% and ErP A-rated for heat and hot water
  • Warranty: 3-year parts and labour warranty as standard
  • Estimated price (Exc. installation): £549 – £572

Viessmann Vitodens 050-W

  • Available CH output: 19kW, 25kW
  • Available DHW output: 25.4kW, 29.6kW
  • Suitable for: Flats or small homes with 1-2 bedrooms and 1 bathroom to houses with 3-4 bedrooms and 1-2 bathrooms
  • Efficiency: 92% and ErP A-rated for heat and hot water
  • Warranty: 3 years as standard. It can be extended by a further 7 years if fitted by a Viessmann Trained Installer
  • Estimated price (Exc. installation): £800

Combi boiler installation cost

In addition to the upfront cost of a combi boiler, you have to consider installation costs. On average, boiler installation costs in the UK range from £1,600 to £3,500. The two main factors affecting the cost are:

  • Varying labour costs in different areas (usually higher in large cities)
  • The specific combi boiler replacement situation

Best deals on combi boilers

So, how do you find the best boilers in 2024? Probably the most practical way to get the best deals on combi boilers is trying to reduce installation costs as much as possible. You can easily do this by finding and comparing quotes from different heating engineers in your local area.

Once you get those, you can compare them, check prices and special offers, and see which is the best combi boiler meeting your requirements and budget.

Whilst efficient, this method has a downside: researching and sorting options among dozens of suppliers will take you several hours of your time. You will also have to go through hundreds of customer reviews and verify installers’ credentials in order to find the best boiler in the UK.

However, this is something we are ready to help you with. At GreenMatch, we work with a network of accredited heating engineers across the UK. Fill out our simple form, and we will send you up to 3 free quotes from installers in your area. You are not obliged to accept any quote you receive.

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FAQ

Luis Antonio Gómez Pérez

Luis Antonio is a seasoned Content Writer with international journalism experience. His writing style, enriched by a Master’s in Journalism, contributes informative content to GreenMatch on topics including low-carbon heating systems.

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