If you are looking for a new combi boiler, possibly following an emergency breakdown, it is likely a quick installation is required, however, the best model at a competitive price is also important.

Unfortunately, boilers do not come cheap and therefore, homeowners will often be looking to secure the best boiler deal they can find, yet other factors like the length of the boiler warranty and reliability of the combi boiler are just as important for long term peace of mind.

So which combi boiler brands are the best on offer and why?

Best Gas Combi Boiler – Quick Takeaways:

• In order to determine which boilers are the “best” on offer, we considered the following attributes:
  • Boilers that come with a long warranty period.
  • Boilers that are the most efficient.
  • Boiler’s that come with high quality components e.g. stainless steel and free of plastic.
  • Replacement parts that are easy to source.
  • 5 star customer service and aftercare.
• To get an accurate quote for a high quality boiler, you can start your application with Which? approved boiler installers Heatable here.

Based on the attributes of the best combi boilers in the above infographic, we have determined that the best combi boiler models in 2023 are as follows:

Viessmann Vitodens 100-W (Best Combi Boiler Overall)

In our view, the best combi boiler for homeowners looking to secure a reliable and award winning combi boiler is the Viessmann Vitodens.

Viessmann is an award winning brand that offer the most reliable and high quality gas combi boiler range that come with a generous 10 year warranties and superb aftercare.

The Viessmann Vitodens was recently updated and now features a user-friendly LCD display.

This boiler is also class A rating for efficiency and features a back-lit LCD display, as well as a low fan speed for quiet operation.

Why do we think Viessmann offers the best combi boilers? 

• Which? Best Buy Award winner – titled as the UK’s “most reliable boiler”.
• 10-year boiler warranty.
• State of the art German engineering – no plastic or rubber components (like some competitors).
• Patented Inox Radial Stainless Steel Heat exchanger (not aluminium found in other boiler brands).
• The only boiler with Lamda combustion control – maximising efficiency.  
• Hydrogen ready – for the next generation of fuel.
• Availability of parts is superb.
• Excellent customer reviews and aftercare.

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Alpha E Tec (Best Value Combi Boiler)

If you are looking for a combi boiler that offers maximum value for money, then the Alpha E Tec is a superb option.

Alpha Innovation offer the best value for money in terms of price point and a hefty 10 year warranty.

The Alpha E Tec also utilises a steel heat exchanger, which is unheard of amongst budget boiler brands.

Why else do we think Alpha combi boilers are a superb option? 

• Good Homes Magazine Approved (2021).
• Also offer a 10 year warranty.
• Superior parts and design at an affordable price.

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Choosing a Boiler Installer

There are many online boiler companies selling combi boilers, often they will be promoted a myriad of different boiler brands of different sizes and with different features, which can result in information overload.

In this guide, we will discuss the process of how to choose a combi boiler including the most important factors to consider, as well as reviewing the best combi boilers available on the market at present.

Wondering which boiler manufacturers performed best? Check out our best boiler brands guide for the full rundown and if you are trying to determine who the best boiler installation company is, check out our Warmzilla and Boxt reviews.

How should I Choose a Combi Boiler?

Combi boilers are very popular these days as they are compact and efficient units that provide both heating and hot water without the need for a water tank.

There are a range of factors that will need to be considered when choosing a combi boiler, including the following:

• The size of the property including the number of bathrooms.
• The number of residents.
• The water pressure available in your area.
• The amount of space available for the boiler unit itself.

Combi boilers are most suited to smaller residential properties with only 1-2 bathrooms. If the property size is bigger than this some combi boilers may struggle with water pressure issues when, for example, more than one bath or shower is being utilised at the same time.

Another factor when looking to install a combi boiler is what existing heating system is in place.

For example, if there is a back boiler or water tanks in place, these would need to be decommissioned and removed, which will increase the costs of a new boiler installation.

Also, if there are changes required to the system pipework, there would be further additional costs.

Straight forward boiler installations, for example, installing a like for like combi-boiler in a smaller residential property could be fairly easy to organise via an online boiler supplier for example.

However where there are changes required as discussed above it would be worth seeking the advice of a qualified heating engineer in order to get an accurate assessment.

Did you know the efficiency of your boiler can impact the amount of energy it uses and ultimately impact your heating bill costs? Check out our guide to the best condensing boilers if you are interested to find out more. 

You may also find our review of the best eco-friendly boilers of interest.

Which are the Best Combi Boiler Brands?

In order to shortlist our top three combi-boiler recommendations, we have compared the following factors:

• Boiler warranty length offered by the manufacturer.
• The overall brands’ reputation.
• Previous customer reviews on platforms such as Trustpilot.
• Boiler price ranges and value for money.
• Boiler specifications and performance.
• Energy efficiency ratings.
• Reliability levels, calculated from the numbers of issues raised with recently fitted boilers.
• Brands that receive the most industry awards.
• Customer aftercare service performance.

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#1 Viessmann Combi Boilers (Best)

Our second position goes to Viessmann who is a German boiler manufacturer that has been dominating the European boiler market for some time and is now growing in popularity within the UK too.

Viessmann produces high-quality boilers at competitive prices and also offer long product warranties also.

The Viessmann boiler model that we would recommend is the Vitoden 050-W gas combi-boiler.

This popular and award-winning boiler model is available in two different power output options, produces low C02 emissions while having an A-rated energy efficiency score.

• Warranty period: up to 10 years.
• Hydrogen-ready? Yes.
• Stainless steel heat exchanger? Yes.
• Plastic components or rubber? Latest 2022 models – no.

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#2 Worcester Bosch (2nd Best Combi Boilers)

Our first position goes to Worcester Bosch who are well established UK brand that produces prestigious and sought-after boilers.

The company have a great reputation within the boiler industry for producing quality boilers, and they have even won awards along the way while also provide a high level of customer service and aftercare to their customers.