Combi Boiler Reviews (2023)

We’ve put together these combi boiler reviews as a great way to “try before you buy”. At Boilerhut, we have a team comprising heat engineers with over 40 years of experience. Over the years, we have installed and worked on combi boilers from all of the major boiler manufacturers in the UK.

If you’re ever unsure about which boiler to go for, looking at boiler reviews such as those featured can help you to know what’s out there currently on the market.

This post looks at the best combi boilers available in 2021 and aims to give a short, useful review for each.

Want to know more about combi boilers that are best for your property? Or which models and brands suit your property best?

You can learn more about combi boilers that are best for your property, and the best models available by taking a look at any of our previous articles for more pearls of wisdom!

  • Which Boiler is Best
  • Best Combi Boilers 2021
  • Worcester Bosch vs Viessmann

As well as this, you can speak to one of our in-house heating experts to ensure you’re getting the best possible advice. Either call us directly on 029 2009 9898or get a FREE, no-obligation quote by entering your postcode in the box below, then hit the green button!

So, without further ado, let’s jump into it! The list below is random, and in no specific order:

Best Combi Boiler Reviews

In the world of boilers, it’s important to be clued up on which manufacturer brands offer the best products and services. Whether it’s Viessmann, Worcester Bosch, Baxi or Vaillant, it’s important to know who does it best! Let’s get started:

Viessmann Combi Boiler Reviews

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Combi Boiler Reviews (2)

Viessmann are the number one heating technology manufacturer in Europe, and possibly the world. They’ve obtained decades of experiences working in the commercial sector but surprisingly lesser known in the UK domestic boiler market.

Viessmann are one of the world’s premium commercial heating brands, and many of the world’s largest commercial buildings run on Viessmann central heating. Among these buildings include the Principality Stadium and Wales Millenium Centre in Cardiff, UK.

Combi Boiler Reviews and Comparisons with Rival Brands(Gas/LPG)

If you want to know about the impressive range of boilers that Viessman has on offer, feel free to take a look at any of our review posts:

  • Viessmann 050-W Review
  • Viessmann 100-W Review
  • Viessmann Vitodens 111-W Storage Combi Boiler Review
  • Viessmann vs Vaillant Review and Comparison
  • Viessmann vs Ideal
  • Viessmann vs Baxi

Combi Boiler Reviews (3)

Boiler Review – Pros:

  • Inox-Radial Stainless Steel Heat Exchanger
  • Patented Heat Exchanger manufactured in-house
  • Which? Best Buy for 2nd year running in 2018 and 2019
  • 10 Years Warranty on Parts & Labour and Heat Exchanger
  • Parts now widely available across the UK at all Plumbase branches
  • Most extensive and impressive boiler range in the UK
  • Quick and Efficient Customer Service (highly rated)
  • Some models operate at sky high energy efficiency (98%)

Boiler Review – Cons:

  • Manufactured in Germany and not in the UK
  • Service engineer fleet not as big as rivals, but growing rapidly

For a detailed breakdown on the 050-W (one of Viessmann’s most popular combi boiler products) watch our video review below:

Find out more about the Viessmann range of boilers in our Viessmann boilers range page.

Worcester Bosch Combi Boiler Reviews

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Market leader in the UK for many years, they continue to make solid boilers with a widespread network of engineers and accredited installers. Worcester Engineering was founded in Worcester, England by Cecil Duckworth in 1992. It was acquired by the German company Robert Bosch GmbH in 1992, hence the name Worcester Bosch as it is known today.

Despite their previous high reputation, Worcester Bosch has recently faced increasing criticism on combi boiler reviews sites online for alleged poor after-sales service. They’ve also not bothered to improve the quality of their internal components. They continue to use aluminium for their heat exchangers, which is a lower quality metal compared to stainless steel that is increasingly used by their rivals in the UK. This has also resulted in reliability complaints about them.

Worcester Bosch also experienced a data breach in May 2018 that revealed the home addresses of thousands of their customers. In the ongoing debate of which boiler is best as well as several boiler reviews, this ‘red flag’ is a classic sign of combi boilers to avoid.

Combi Boiler Reviews and Comparisons with Rival Brands(Gas/LPG)

After consulting with heating engineers with a combined experience of over 50 years, we’ve published factual, in-depth and unbiased boiler brand comparison and reviews. Please click the comparison/review you’re interested in, below:

  • Worcester Boiler Review
  • Worcester Bosch vs Vaillant Comparison and Review
  • Worcester Bosch vs Viessmann Comparison and Review
  • Baxi vs Worcester Bosch Comparison and Review
  • Ideal or Worcester Combi Boiler Reviews

Heating Oil Boiler Reviews and Comparison

  • Grant vs Worcester Bosch

Let’s jump into Worcester Bosch pros and cons:

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Boiler Review – Pros:

  • Market leader in the UK; great exposure and brand reputation
  • Boilers are easy to install and service
  • Good technical support for boiler breakdowns
  • Rear piping chassis on most models [helps to conceal pipe work]
  • Aesthetically pleasing boiler
  • One of the winners of the Which? UK Best Buy Boiler award
  • Expensive [Some rivals offer better boilers at a better price]
  • Aluminium heat exchanger

Boiler Review – Cons:

  • Add-on controls are overpriced
  • Spare parts and bespoke flue options are expensive
  • Not as reliable as they used to be
  • Lower quality internal components, when they can be better
  • Extended warranties only with their own branded controls and magnetic filter
  • Their magnetic filter is cumbersome and ugly
  • Poor warranty on controls
  • Some rivals offer much better value for money, reliability and energy efficiency

Find out more about the Worcester Bosch range of boilers in our Worcester Bosch boilers range page.

Baxi Combi Boiler Reviews

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One of the UK’s most beloved boiler brands, Baxi began in 1866 by Richard Baxendale, an iron founder in Preston, Lancashire. Today Baxi is part of BDR Thermea, based in Apeldoorn, Netherlands.

Once one of the UK’s premier boiler brands, their reputation has declined rapidly when it comes to combi boiler reviews.

Combi Boiler Reviews and Comparisons with Rival Brands(Gas/LPG)

  • Baxi vs Viessmann – Comparison and Review
  • Baxi vs Worcester Bosch – Comparison and Review

Let’s take a look at its pros and cons:

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Boiler Review – Pros:

  • Good flue options that run longer
  • Manufactured in the UK
  • Known as an affordable boiler brand
  • Good brand reputation because of their history in the UK

Boiler Review – Cons:

  • Lots of consumer complaints for being unreliable and faulty
  • Infamous for bad customer service
  • Confusing warranty options
  • Aluminium heat exchanger
  • Low efficiency, low reliability

Ideal Combi Boiler Reviews

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Ideal Boilers launched in 1906, and have been active for over 100 years manufacturing one of the highest-selling boilers in the UK. Ideal used to be one of the UK’s premium boiler brands years ago, but today are known more for making affordable or “cheap” boilers.

Their technology and reliability may not be the best in the market, but they’re solid boilers if you’re not particularly interested in high energy efficiency or reliability.

What’s good is Ideal have recently revamped their boiler range to address some of the concerns. Time will tell if they’ve done a good job and if they can make their way to the top of combi boiler reviews in the future.

Combi Boiler Reviews and Comparisons with Rival Brands(Gas/LPG)

  • Ideal vs Viessmann Boilers Comparison and Review
  • Ideal or Worcester Boilers

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Boiler Review – Pros:

  • Well-respected boiler brand name in the UK
  • The new range of boilers is impressive but too new to judge properly
  • 12 years warranty on the Ideal “Max” Range if installed by an Ideal Accredited Installer
  • On average up to £300 cheaper than a competing Worcester Bosch model

Boiler Review – Cons:

  • Lots of consumer complaints about reliability
  • Complaints of poor customer service
  • Complaints of Low Energy Efficiency
  • Aluminium Heat Exchanger
  • Compromise on quality to keep costs low

Vaillant Combi Boiler Reviews

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Vaillant Group is present in over 20 countries with national sales companies, and exports to more than 60 states.

A family-owned company active for more than 141 years, their core business is heating technologies, and they’re the second-largest European manufacturer behind Viessmann in this sector.

Vaillant manufacture in the UK as well as Germany, France, Spain, Italy, Slovakia, Turkey and China.

Combi Boiler Reviews and Comparisons with Rival Brands(Gas/LPG)

  • Vaillant Boiler Review
  • Vaillant vs Worcester Bosch Comparison and Review
  • Vaillant vs Viessmann Comparison and Review

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Boiler Review – Pros:

  • Stainless Steel heat exchangers in some models, not all
  • Number 2 Market Leader in the EU and UK
  • High quality, high-efficiency boilers
  • Extended 10-Year Warranties

Boiler Review – Cons:

  • Stainless steel heat exchanger in some models, aluminium for the rest
  • Complaints of unreliable, faulty boilers
  • Consistent boiler breakdowns for many customers
  • Complaints of poor after-sales service
  • Expensive

Find out more about the Vaillant range of boilers in our Vaillant boilers range page.

Grant Oil Combi Boiler Reviews

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Grant Engineering has been designing and manufacturing heating products for four decades now.

Their range of oil-fired condensing boilers feature at the top in all oil combi boiler reviews and have received nothing but praise and positive reviews by reputed review magazines and websites in the UK.

Grant’s oil-fired condensing boilers range have a reputation for quality and reliability, on top of being easy to install and maintain.

The Grant Vortex and VortexBlue oil boiler range is trusted by engineers and householders all over the UK. In 2016, Grant sold more Vortex and VortexBlue oil condensing boilers than any other oil boiler brand in the UK (source: EUA). And for 2017 and 2018, a prominent consumer research magazine in the UK awarded the entire Grant range a “Best Buy” stamp of approval.`

Combi Boiler Reviews and Comparisons with Rival Brands

  • Grant vs Worcester Bosch Oil Boilers

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Boiler Review – Pros:

  • Stainless Steel Heat Exchanger
  • 89.5- 91.6% Gross SAP2009 annual efficiency
  • Market-leading Riello Blue Flame burner
  • 10-year guarantee when installed by a G1 accredited installer
  • 24 litres expansion vessel
  • Neon diagnostic indicators
  • Compliant with September 2018 low NOx legislation

Boiler Review – Cons:

  • If not serviced at least once annually, may develop problems
  • Oil tank may need cleaning up and draining
  • Pipework may need to be flushed through
  • Oil boilers are very expensive (£3,000 to £5,000 range)

ATAG Combi Boiler Reviews

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Not very well known in the UK at all, this Dutch manufacturer makes one of the highest efficiency boilers in the UK, alongside Viessmann of course.

Their iCon stainless steel heat exchanger is a very unique design, patented and manufactured in-house by ATAG. So, much like Viessmann, their heat exchanger cannot be copied or used by other brands.

Rival brands like Ideal, Baxi, Worcester Bosch, Vaillant, Glow Worm and Potterton all use an aluminium heat exchanger, sourced by a third party manufacturer called Giannoni, based in France.

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Boiler Review – Pros:

  • 10 Year Warranty comes as standard
  • A compact 275mm deep model is available to fit inside kitchen cupboards
  • Lifetime replacement guarantee on their heat exchanger
  • Weather compensation as standard
  • Built-in passive Flue Gas Heat Recovery Device

Boiler Review – Cons:

  • Very expensive
  • Not aesthetically pleasing
  • Not a mainstream brand, fewer plumbing merchants stock their parts
  • Overly complicated wiring and internal components
  • Very few heating engineers aware of ATAG, fewer know how to service
  • Customers complain of difficulty understanding the ATAG controller

Intergas Combi Boiler Reviews

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Another impressive Dutch manufacturer with a unique solution when it comes to heat exchangers. Unlike other combi boiler manufacturers, which use two, a primary heat exchanger for central heating, and a secondary plate heat exchanger for hot water, Intergas uses a two-in-one heat exchanger.

In their own words: “By only having one heat exchanger, it is more efficient at using less fuel to generate the required heat output than other boilers.”

Right now there’s no tangible evidence of Intergas boilers being more energy-efficient because they start at the same (if not lower) efficiency as combi boilers from other brands listed in this post, i.e. between 88.8% and 89%.

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Boiler Review – Pros:

  • The unique 2-in-1 heat exchanger may save energy
  • Fewer parts, more reliability
  • Built-in digital time clock
  • Built-in expansion vessel
  • Central flue

Boiler Review – Cons:

  • Same issues as ATAG, not well known etc.
  • Complaints of boiler losing pressure
  • Frozen condensate pipe
  • Complaints of clicking sound when requesting for hot water or heating

Alpha Combi Boiler Reviews

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Alpha, part of the Immergas Group from Italy, is firmly placed in the affordable or cheap combi boiler category. The boiler-only cost is around £500 to £600, and you could probably get them installed for less than £1,500 inc. VAT. Good if you want to slap a cheap boiler on the wall, sell your house and leave the country.

But if you’re planning on living in your home for the next decade, probably not the wisest choice. Or in the age of online reviews and transparency, any potential buyers may not be enthralled

While you may save a small amount of money on the initial cost of installation, you will lose money in lost energy efficiency (i.e. paying more on your energy bills) and repair costs over the years.

Alpha Heating Innovation has been inspired by Viessmann for their latest range of combi boilers. Whether that makes Alpha a reliable boiler brand remains to be seen.

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Boiler Review – Pros:

  • Low cost, “cheap” combi boiler
  • Stainless Steel Heat Exchanger
  • 10 Year Warranty
  • Combined Condensate and Pressure Relief Valve

Boiler Review – Cons:

  • Historically one of the worst boiler brands in the UK
  • Lots of complaints of unreliability and low energy efficiency
  • Frequent low boiler pressure problems
  • No hot water issues

Other Manufacturers in the “Cheap Boiler” Category

  • Vokera
  • Ferroli
  • Biasi
  • Ravenheat
  • Main
  • Potterton
  • Glow Worm

Glow Worm is now owned by Vaillant, and serve as their “affordable” brand. Combi boiler reviews for any of the cheap brands listed above are not amazing, to say the least. We would give any of the brands listed above 3 stars out of 5. Simply because they are great if you want to slap a cheap boiler on the wall, but not great for anything else.

The good news is a lot of these traditionally cheap, low-quality brands are waking up and improving their boilers, case in point Alpha and Ideal being inspired by Viessmann and offering stainless steel heat exchangers in their boilers along with extended warranties of 10-12 years.

Quality of Internal Components

What’s surprising is that some prominent consumer research magazines in the UK give “Best Buy” awards to certain market-leading boiler brands in their combi boiler reviews. Then sing endless praises about after-sales service, parts availability etc. But completely ignore or fail to talk about the quality of internal components, which is the most important aspect when it comes to boiler reliability and durability!

Aluminium vs Stainless Steel Heat Exchangers

We’ve done detailed guides explaining What is a Combi Boiler and How a Combi Boiler Works on our website previously.

In short, a combi boiler has two heat exchangers; the primary heat exchanger for central heating, and a secondary plate heat exchanger for hot water. With a furnace-like environment inside a boiler, its internal components have to go through ridiculous thermal stresses on a daily basis. More so during winter. This is where the quality of internal components determines how long your boiler will last.

It’s amazing so many websites ignore this completely in their combi boiler reviews.

I think you know where this is going. Unless you are completely clueless, it’s common knowledge that stainless steel is a superior metal and extremely resistant to corrosion compared to aluminium. Stainless steel also works with a wide range of pH levels. Whereas for aluminium, if the special manufacturer-recommended heat transfer fluids and inhibitors are not used to produce and maintain a narrow pH range, it will corrode much faster and get damaged.

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As you can see in the diagram above, while aluminium starts off great initially due to higher thermal conductivity, it drops off massively after the first 1000 operating hours. Whereas stainless steel maintains its efficiency and output for far longer, roughly translating into a much reliable boiler for your hard-earned money.

This is why we’ve ranked boiler brands with stainless steel heat exchangers higher than the ones with aluminium.

Many people in the UK still ignore facts and go by brand reputation or word of mouth advertising and stick “what they know” on their wall. Only to lose money in lost energy efficiency or boiler repairs down the line.

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