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1 December 2020

Best combi boiler brands

If you want to buy the best combi boiler, you'll need to make sure it's the correct size for your home, and from a reliable brand.
Teddies on radiator
Matthew Knight

A good combi boiler will deliver plenty of hot water for your showers, baths and sinks, and will keep your radiators piping hot throughout the coldest of winters. If you just want to know which are the best combi boilers, head to our best combi boiler reviews.

What makes a good combi boiler

To get the best combi boiler, it's crucial to go for a reliable brand that won't break down, and getting one that's the right size and fit for your home. 

An unreliable combi boiler will fail early and is likely to result in regular costly repairs. On average, it costs almost £200 for a boiler repair – so it pays to invest in one that will last. 

An oversized combi boiler will lead to you spending more on your heating and hot water than you need to, and an undersized one will deliver a disappointing flow of hot water to your taps and radiators.

Is a combi boiler right for you?

The first question to ask is whether a combi boiler is the right choice for your home. 

Combi boilers don't require a hot water cylinder or cold water feed tank, so they're great if space is an issue. They heat hot water on demand, so they're very efficient and minimise waste. But heating hot water on demand does mean that they're best suited to homes with only one bathroom, or where you typically only want hot water for one tap or shower at a time.

All modern boilers, including combi, heat-only/regular and system, are condensing boilers.

Read about the different types of boiler if you're unsure what's best for your home.

Which brands make combi boilers?

Brand Summary
Alpha

Alpha boilers has been gobbling up market share from its competitors over the last few years. Its range of combi boilers is called E-tec, Intec or Evoke, and they're priced between £520 and £2,500.

Read our Alpha combi boiler reviews to find out what expert heating engineers, and its own customers, make of the brand. 

Baxi

Baxi is one of the biggest combi boiler manufacturers in the UK. Its range of EcoBlue, Duo-tec, Megaflow and Platinum combi boilers come in sizes to suit almost any size and type of home, and they range in price between £650 and £1,200.

But are Baxi boilers reliable? And what do expert heating engineers make of them? Head over to our Baxi combi boiler reviews to find out if it's worth investing in a Baxi or if other boiler brands are a better bet.

Glow-worm

Glow-Worm have several ranges of combi boilers including Energy, Essential, Betacom, Easicom and Ultimate. Its combi boilers range in price between £615 and £1,250.

Read our full reviews of Glow-Worm combi boilers to find out how long they last, what its customers make of them and expert ratings from heating engineers. 

Intergas

Dutch manufacturer Intergas is the new kid on the block in the British boiler scene. It claims to have fewer moving parts in its combi boilers than its rivals, and a super reliable heat exchanger. It has two combi ranges, Rapid and Compact, which are priced between £630 and £1,040, potentially making them an attractive budget option.

But is Intergas all that reliable? And what do heating engineers and its own customers make of them? Read our Intergas combi boiler reviews to find out. 

Potterton

Potterton has a number of combi boilers to pick from that suit all size homes. Its combi boiler ranges are called Promax, Titanium, Promax Ultra, Assure and Gold, and are priced between £675 and £1,350.

Read our Potterton combi boiler reviews to find out if they'll outlast the competition and what expert heating engineers make of them.

Vaillant

German manufacturer Vaillant is a large combi boiler manufacturer whose ecoFIT and ecoTEC range of combi boilers cost between £1,100 and £1,400, which puts them at the more premium end of the market.

Are Vaillant boilers worth the cost? Read our independent Vaillant combi boiler reviews to find out if they'll last longer than the competition and what customers and expert heating engineers make of the brand.

Viessmann

Viessmann is a German boiler brand making waves in the UK boiler scene. Its Vitodens combi boilers cost between £900 and £1300 and come in a variety of sizes to suit any home. 

Read our Viessmann combi boiler reviews to find out how long they last compared to competitors, and whether it has the respect of its customers and expert heating engineers. 

Worcester Bosch

German manufacturer Worcester Bosch is one of the biggest combi boiler manufacturers in the UK. Its combi Greenstar range starts at £875 and goes up to over £2,000, depending on the size and hot water flow you need for your home.

Read our Worcester Bosch combi boiler reviews to find out how it compares to its competitors for reliability, customer satisfaction and according to the views of expert heating engineers. 

Top three combi boiler brands

We would only recommend buying a combi boiler from one of the three best combi boiler brands. 

Every year we survey almost 10,000 boiler owners so that we can tell you which boiler brands are the most reliable, and which ones leave their customers delighted. 

The least reliable boiler brands are more than twice as likely to break down in the first six years of life compared to the most reliable.

We ask expert heating engineers which brands they think are the best, too. In our comprehensive boiler reviews, our Which? Trusted Traders rate each brand for build quality, how easy the boilers are to repair, the availability of parts and spares, and ultimately how likely they are to recommend it.

Best combi boiler brand overall

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80%
Best Buy
£2,051.00
Reviewed

This brand of boilers is the best you can buy. Engineers adore them, its customers are delighted and it's reliable too.

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Most reliable combi boiler brand

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79%
Best Buy
£1,377.00
Reviewed

This brand of boilers has a peerless reliability record. It's also loved by its customers and heating engineers think its build quality is top notch.

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Engineers' favourite

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80%
Best Buy
£1,860.00
Reviewed

This brand is completely adored by expert heating engineers. They rave about its build quality and award it 5 stars on every measure in our Which? Trusted Trader heating experts survey.

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Combi boiler brands compared

We've compared the four biggest boiler brands in the UK, by market share, below. 

But you'll need to read our boiler reviews or visit our best boiler brands page to see how they compare on reliability, customer satisfaction and what expert Which? Trusted Traders make of each brand.

Worcester Bosch

Fuel types: Gas and oil

Types of boiler: Combi, heat-only, system

Price range: £760 - £2,600

Warranty length: Warranty lengths are typically between two and five years.

Worcester Bosch is the biggest boiler brand in the UK, by market share. It makes a range of boilers that would suit any type of home. Its boilers tend to be at the more expensive end of the market. 

You can use our Worcester Bosch boiler reviews to find out how reliable they are and what their customers and heating engineers make of them.

Vaillant

Fuel types: Gas

Types of boiler: Combi, heat-only, system

Price range: £665 - £1,490

Warranty length: Warranty lengths are typically between five and seven years.

Vaillant is another big player in the UK boilers market. Its boilers are similarly priced to Worcester Bosch, but it tends to offer slightly longer warranty periods. As with Worcester Bosch, it makes a range of boilers that would suit any type of home as long as it's connected to the gas mains, or has an LPG tank. 

You can use our Vaillant boiler reviews to find out how reliable its boilers are and what its customers and heating engineers make of the brand.

Baxi

Fuel types: Gas

Types of boiler: Combi, heat-only, system

Price range: £650 - £1,440

Warranty length: Baxi warranties can be up to ten years, depending on the type of boiler and who installs it for you.

Baxi sells a lot of boilers in the UK. It tends to be a cheaper option than Vaillant or Worcester Bosch boilers, and has a market-leading manufacturer's warranty. 

You can use our Baxi boiler reviews to find out if a Baxi boiler is worth investing in. In our reviews we tell you how reliable Baxi is compared to other brands, and how satisfied its customers are, as well as the views of expert heating engineers.

Ideal

Fuel types: Gas

Types of boiler: Combi, heat-only, system

Price range: £565 - £2,450

Warranty length: Ideal's warranties can be up to ten years, depending on the type of boiler and who installs it for you.

Ideal has been making huge inroads in the UK market in recent years and is now one of the biggest-selling UK brands. Like Baxi, its boilers tend to be a cheaper option over Vaillant or Worcester Bosch.

You can use our Ideal boiler reviews to find out if it's up to the standards of the best in the business. 

Best combi boiler for your home

Once you've picked the brand of boiler you want from the three above, the next thing you'll need to decide is what size boiler is right for your home. 

The size of the combi boiler refers to its heat output, which is measured in kW (kilowatts). Put simply, this tells you how much water the boiler can heat up and send whizzing around the pipes in your home. A larger home with more radiators and pipes to navigate will require a larger combi boiler. 

The simplest way to estimate the size of boiler you might need is to count the number of radiators you have. Use the table below for a rough guide. 

What size boiler do I need?

How many radiators are in your home Boiler size in kW
<10 <27kW
10-15 28-34 kW
>15 >34kW

Table notes

This table provides a rough guide. A fully trained heating engineer will be able to more accurately size your boiler after a full heat loss survey of your home. Never buy a boiler before a trained heating engineer conducts a full heat loss survey of your property.

Best combi boiler installer

Proper installation is key to the ongoing health and efficiency of your combi boiler. 

Poor installation can lead to early failure, as well as money wasted on repairs and through having a heating system that isn't as efficient as it should be. 

Read our guide on how to get the best boiler installation before you buy a new combi boiler and cross reference the quotes you receive with our guide to boiler prices: how much does a new boiler cost?

We'd recommend using a Which? Trusted Trader, too. They have all been vetted by a trading standards officer, and the satisfaction of their customers is regularly monitored to ensure they are the best of the best in their trade. 

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