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Home & garden.

Updated: 25 Feb 2022

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.
Sam Morris
heating engineer fixing boiler

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

Read on to discover which brands make the most reliable combi boilers, and which our Which? Trusted Trader Heating Engineers think you should get.  

If you just want to know which are the best combi boilers, head to our combi boiler reviews.

The best combi boiler brands rated

Combi boilers are the most common type of boiler (Uswitch, 2021), with all the main boiler brands offering ones for you to install in your home. 

Compare how the most popular combi boiler brands, from Ideal to Vaillant, stack up against each other according to the results of our 2021 boiler survey

Which? members should log in now to unlock the scores in the table. If you're not already a member, try Which? to unlock our boiler research and all our online reviews.  

BrandOverall scoreReliability scoreBrand customer scoreBrand engineer overall scoreTypical price for a 30kW combi
Baxi£880 - £1,000
Glow Worm£700 - £990
Ideal£590 - £1,270
Potterton£650 - £1,350
Vaillant£1,160 - £1,410
Viessmann£780 - £1,280
Worcester Bosch£800 - £2,460

Read our best gas and oil boiler brands guide for the results of all boiler brands from our boiler survey.

Which brands make combi boilers?

Our 2021 boiler survey of 8,001 members of the public, found 17 gas and oil boiler brands - all produce combi boilers. 

Below you can find out a bit more about some of the most popular boiler brands* and their combi boilers.

Baxi boilers

Baxi is one of the biggest combi boiler manufacturers in the UK. Its range of Assure, Duo-tec, Megaflow and Platinum combi boilers come in sizes to suit almost any size and type of home.

They range in price typically costing between £880 - £1,000 for a 30kW mediumm-sized combi boiler, although it has models starting from around £550.

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.


Glow-Worm has several ranges of combi boilers including Energy, Essential, Betacom, Easicom and Ultimate.

Its combi boilers range in price, starting from around £560, with a medium-sized combi boiler usually being between £700 - £990.

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. 

Ideal boilers

Originally called the National Radiator Company, Hull-based Ideal has been around for 100 years. It has several ranges of combi boilers including Exclusive, Instinct, Esprit Eco and Logic+ ranges. 

Its combi boilers come at a variety of prices, you can get a 30kW medium-sized boiler from around £590, going up to £1,270. 

Our Ideal combi boiler reviews reveal how reliable Ideal boilers are, as well as what customers and engineers think of them

​Potterton boilers

Potterton is part of Baxi, which is in turn part of the BDR Therma Group. As such, several of Potteron's ranges - such as its Assure range - have been absorbed under the Baxi name. It still owns the Titanium Combi, which costs around £800 for the 28kW size.

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

​Vaillant boilers

German manufacturer Vaillant is a large combi boiler manufacturer which has the ecoFIT and ecoTEC range of combi boilers.

They typically cost between £1,160 - £1,410 for a medium-sized boiler of 30kW.

Are Vaillant boilers worth the cost? Read our independent Vaillant combi boiler reviews to find out.

​Viessmann boilers

Viessmann is a German boiler brand making waves in the UK boiler scene. Its Vitodens combi boiler lines have been updated in 2021.

They cost between £780 -  £1,280 for a mid-sized 30kW boiler, and come in a large range of sizes to suit almost 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 boilers

German manufacturer Worcester Bosch is one of the biggest combi boiler manufacturers in the UK. 

Its combi Greenstar range starts at around £800 and goes up to around £2,500, 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 competitors for reliability, customer satisfaction and according to the views of expert heating engineers. 

Combi boilers are less suited for homes with multiple bathrooms. Read your guide to different types of boiler to see which type will best suit your home.

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 to get 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 (Which? survey, 2021). So it pays to invest in one that will last. 

An oversized combi boiler will also 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. The simplest way to estimate the size of boiler you might need is to count the number of radiators you have

  • Fewer than 10 radiators - under 27kW
  • 10-15 radiators - between 28kW and 34kW
  • More than 15 radiators - over 34kW

This is 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.

Best boilers - our expert guide on choosing the best type and brand of boiler for your home.

Which? Trusted Trader boiler installers

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.

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.  

You can use our search tool below to find accredited Which? Trusted Traders in your area.

* Brand popularity based on search volume from SEMRush in September 2021.