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  • Best Condensing Boilers of 2024

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  • Best Condensing Boilers of 2024

    Updated: April 6, 2024

    What is a Condensing Boiler?

    A condensing boiler is a type of heating appliance that is designed to maximize energy efficiency by recovering heat from the combustion process. Unlike traditional boilers that release waste gases into the atmosphere, condensing boilers are able to extract additional heat from these gases before they are exhausted.

    What are the best condensing Boiler types?

    #1- Worcester-Bosch Combi Boilers

    #2 – Viessmann Combi Boilers

    #3 – Vaillant Combi Boilers

    #4 – Alpha Combi Boilers

    #5 – BAXI Combi Boilers

    Condensing boilers are super clever, super at saving energy and super at saving money.

    Here are the best condensing boilers of 2024, as according to the Comparison site Let’s heat recent review:

    Did you know that every year, more than 1 million new boilers are installed into UK homes?

    That’s an incredible amount of boilers, and thanks to the introduction of ‘Boiler Plus’ legislation back in 2005, all new installs are now condensing boilers that are a huge improvement on the inefficient non-condensing models of the past. But what exactly is a condensing boiler?

    Condensing boilers are water heaters fueled by gas or oil. These boilers achieve a high-efficiency level (typically greater than 90% on the higher heating value) by condensing water vapour in the exhaust gases and so recovering its latent heat of vaporisation, which would otherwise have been wasted.

    This condensed vapour leaves the system in liquid form, via a drain.

    In many countries, the use of condensing boilers is compulsory or encouraged with financial incentives.

    And how do you know which condensing boiler to choose?

    See the summary of the Let’s Haet article and guide for the best Condensing Boilers of 2021, 2023 and Beyond.

    Best Condensing Boilers of 2021, 2023 and beyond (By Brand) 

    To determine the best boilers available in 2021 and beyond, Let’s Heat considered the following factors: 

    • Warranty period offered by the brand 
    • The overall reputation of the brand based on customer reviews 
    • The brands Trustpilot reviews  
    • Awards and accolades e.g. Which? Best Buy Awards etc.
    • Customer service performance levels 
    • Price range of the boilers  
    • Boiler efficiency ratings

    Based on the results, here are the top 5 best condensing boiler brands in the UK right now (on 2021 results):

    1. Worcester Bosch Combi Boilers
    2. Viessmann Combi Boilers
    3. Vaillant Combi Boilers
    4. Alpha Combi Boilers
    5. BAXI Combi Boilers

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    Best Condensing Boilers of 2024

    Worcester Bosch Combi Boilers (Best)

    One of the UK’s most well-known and trusted boiler manufacturers, Worcester-Bosch remains a favourite among professional Boiler installers and heating engineers.

    Why did smartadapt think Worcester-Bosch deserved the number one spot? 

    • Which? Best Buy Award for 10-years running 
    • 10-year guarantee
    • Availability of parts is second to none 
    • Excellent customer reviews & aftercare
    • High efficiency A-rated combi boilers 

    Model: Worcester-Bosch Greenstar i

    The Worcester-Bosch Greenstar i is officially Worcester’s best selling combi boiler range having sold and installed more than 1 million of them in the UK alone. 

    Suitable for small to medium sized homes on a budget the Greenstar i is the brand’s entry level offering and the range includes the 30i i.e. 30kW and the less powerful Greenstar 25i at 25kW. 

    Although not the brand’s best offering, it still boasts some great features, not least of which is an A-rating for efficiency, a user-friendly digital display and a reassuring ‘Which?’ Best Buy Award.

    Model: Greenstar CDi Compact Boiler 

    The CDi Compact is Worcester Bosch’s compact boiler, designed to be the ideal size to fit into small spaces, such as kitchen cupboards. 

    Available with multiple power outputs including 28kW, 32kW and 36kW, this combi boiler can still provide heating and hot water for properties with varying demands but offers the dimensions required to save as much space as possible.

    Model: Worcester Bosch 2000

    The Worcester-Bosch 2000 is the brand’s latest entry-level offering and officially the brands quietest ever boiler.

    Its compact design makes it suitable for installation within small spaces such as kitchen cupboards and is available within 25kW or 30kW it has enough power for flats and small homes. 

    Boasting A-rating efficiency, a user-friendly digital display and a reassuring Which? Best Buy Award and a contemporary and stylish case, it’s a superb option for small property dwellers on a budget. 

    Model: Worcester Bosch 8000 Style 

    The Worcester-Bosch 8000 offers the same contemporary design and feel as it’s cheaper brother, the 2000 but with cutting edge features and superior power outputs, it is ideal for larger homes with more than one bathroom. 

    It’s the most powerful and connected wall-hung boiler to date, capable of delivering up to 50kW’s, and with optional smart technology that will top up the boiler for you when low pressure is detected.

    Want a quote for a Worcester-Bosch Boiler & Installation?

    With us here at Let’s Heat you can get an online quote now to see how much we can install it for: Get Quote Now!

    And please remember that whoever you use to install your boiler, please ensure that they are gas safe registered, as we are and that they have a great review score for their workmanship see our 4.9 Trustpilot rating here!

    Read more: Worcester Bosch Greenstar 8000 Life Combi Boiler Review 

    Viessmann Combi Boilers (2nd Best Condensing boilers)

    Dominating the European boiler market, Viessmann is a relatively new entrant to the UK market, but thanks to their prestigious German engineering, reliability and superb customer support they have seen huge growth and popularity within a very short period of time. 

    Major benefits of Viessmann boilers include: 

    • Technically brilliant boilers e.g. they use stainless steel heat exchangers
    • 10-year guarantee
    • Excellent customer reviews & aftercare
    • High efficiency A-rated combi boilers 

    Model: Viessmann Vitodens 050-W Gas Combi Boiler

    The Viessmann 050-W is the brand’s entry level combi boiler, offering all of the essentials Viessmann are renowned for on a budget, including the Inox-Radial heat exchanger. 

    Available with multiple size outputs including 29kW and 35kW it is suitable for small and medium sized properties, while it’s dimensions make it quite a compact size for a wall-mounted combi boiler. 

    Model: Viessmann Vitodens 100-W Gas Combi Boiler

    The Viessmann Vitodens 100-W is the best selling combi boiler from the award winning brand and has an impeccable reputation.

    The boiler is an upgrade on the 050-W featuring superior internal parts and components with fewer plastic parts than the 050-W, as well as the signature stainless steel Inox-Radial heat exchanger. 

    The updated 2021 model also features a new and improved stylish exterior casing, hydrogen-ready technology and an upgraded backlit LCD touchscreen display. 

    The latest Vitodens 100 also includes an updated LCD touchscreen display with integrated Wi-fi, allowing you to control, diagnose the boiler and enable remote access to Viessmann support so that they can assist from afar and diagnose faults. 

    Model: Viessmann Vitodens 111-W Combi Boiler

    If your property has high hot water demands e.g. multiple bathrooms but you don’t have the space or necessary requirements to install a system boiler with a separate hot water storage tank, the 111-W may be the solution. 

    The Vitodens 111-W is a storage combi – essentially it’s like a usual combi boiler – and has its own internal hot water storage tank, allowing it to deliver a ludicrous 18 litres of hot water per minute.

    Want a quote for a Viessman Boiler & Installation?

    With us here at Let’s Heat you can get an online quote now to see how much we can install it for: Get Quote Now!

    And please remember that whoever you use to install your boiler, please ensure that they are gas safe registered, as we are and that they have a great review score for their workmanship see our 4.9 Truspilot rating here!

    Best Condensing Boilers of 2024

    Vaillant Combi Boilers (3rd Best Condensing Boilers)

    Made in the UK, Vaillant is another German owned brand that has earned a reputation for reliability & high quality engineering. 

    Among installers, they are credited with being one of the easiest boilers to repair.

    Due to their superb reputation, Vaillant is the second largest manufacturer of boilers in Europe today.

    Model: Vaillant EcoTec Pro

    The EcoTec Pro is one of Vaillant’s most popular combi boilers and previously held the Which? Best Buy Award in 2016.

    It has been awarded Quiet Mark certification, only given to the quietest models and as ‘Eco’ name suggests, one of the brands most energy efficient boilers to date. 

    Ideal for small to medium sized properties with the kW model’s coming in three different outputs to suit all, including 24kW, 28kW and 30kW along with a 2 year guarantee, with an additional 7 to 10 years available when you book a Vaillant Advance installer. 

    Model: Vaillant EcoFit Pure

    Similar to the Worcester-Bosch CDi Compact, the EcoFit is Vaillant’s compact offering, helping to save space and is compact enough to fit in a kitchen cupboard.

    It’s designed to be flexible, with a rear flue option allowing you more versatility on where to install it. 

    It’s also equipped with energy saving capabilities and when you don’t require so much heat, it reduces its maximum output by 20%, helping to save energy and reduce your heating bills. 

    Want a quote for a Vaillant Boiler & Installation?

    With us here at Let’s Heat you can get an online quote now to see how much we can install it for: Get Quote Now!

    And please remember that whoever you use to install your boiler, please ensure that they are gas safe registered, as we are and that they have a great review score for their workmanship see our 4.9 Trustpilot rating here!

    Read about: Best Heat Pumps, Brands & Pricing

    Best combi boilers & boiler brands

    Alpha Combi Boilers (4th Best Condensing Boilers)

    The Alpha Boilers are a recent entrant to the UK heating market, but their reputation has quickly risen to become a brand known for reliability & affordability. 

    Major benefits of Alpha boilers include: 

    • Technically brilliant boilers e.g. they use stainless steel heat exchangers
    • 10-year guarantee
    • Excellent customer reviews & aftercare
    • High-efficiency A-rated combi boilers 

    Model: Alpha E-Tec 

    The Alpha E-Tec is Alpha Innovations most popular condensing combi boiler and although it is considered a budget-friendly brand, it uses a stainless steel heat exchanger, which is usually only seen in premium brands. 

    The E-Tec is also offered with a very generous 10-year warranty, which is again typically only available with market-leading brands, such as Worcester Bosch. 

    The Alpha E-Tec is ideal for households on a budget who care about securing a combi boiler built to last. 

    Want a quote for an Alpha Boiler & Installation?

    With us here at Let’s Heat you can get an online quote now to see how much we can install it for: Get Quote Now!

    And please remember that whoever you use to install your boiler, please ensure that they are gas safe registered, as we are and that they have a great review score for their workmanship see our 4.9 Trustmark rating here!

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    Baxi Combi Boilers (5th Best Condensing Boilers) 

    Baxi is a British based boiler manufacturer with a lot of history and a reputation for offering excellent customer service and having a well-established nationwide network of Baxi gas installers and training centres.

    Even though they are not typically viewed as a premium choice brand, Baxi does have some great condensing boilers on offer, with generous warranties and award-winning customer service. 

    Major benefits of Baxi boilers include: 

    • Made in the UK
    • Excellent customer reviews and aftercare
    • High efficiency A-rated combi boilers 
    • 7 year no-quibble warranty

    Model: Baxi 600 Combi Boiler 

    The Baxi 600 was engineered based on the feedback provided by installers and similar to other smaller models on the market, it’s designed to be installed in small spaces. 

    The Baxi 600 is available in a good selection of power outputs, ranging from 24kW to 36kW, making it an ideal boiler for small and medium sized households.

    The 600 also benefits from some very innovative features including EasyFill – a spring-loaded single lever, allowing to top up the pressure easier than ever. Baxi boilers are also available with the uSense smart room thermostat, allowing you to easily control your heating via an accompanying smart phone app. 

    Want a quote for a Baxi Boiler & Installation?

    With us here at Let’s Heat you can get an online quote now to see how much we can install it for: Get Quote Now!

    And please remember that whoever you use to install your boiler, please ensure that they are gas safe registered, as we are and that they have a great review score for their workmanship see our 4.9 Trustpilot rating here!

    Read more: Vaillant Combi Boilers Reviews

    Combi boilers common faults  

    Best Condensing Boilers for 2021, 2022 and beyond (By Model) 

    1. Worcester-Bosch Greenstar 30i
    2. Viessmann Vitodens 100-W Combi
    3. Vaillant EcoTec Pro 
    4. Baxi 600 Combi 
    5. Alpha E Tec 

    The condensing boilers above are the best ranking boiler models available from each of the manufacturers in the best boiler brand rankings. 

    Based on our analysis, these are by far the best models on offer by some of the UK’s most prestigious boiler brands. They offer the ideal combination of excellent customer reviews, warranty periods, technical brilliance, efficiency, and power.

    Best Condensing Boilers – The Let’s Heat Conclusion

    The average boiler lasts around 10 years and performs the very important role of keeping your home heated and supplied with hot water.

    Therefore, you want to buy a boiler that’s going to perform well with limited to no downtime – and in the event that there are any issues, a warranty that will help you get it back to operation in next to no time. 

    That is why the condensing boilers and brands that have been mentioned within this article have been selected based on the most important metrics: reliability, customer reviews, availability of parts, price range, and efficiency ratings.

    If you are wondering whether you should repair or replace your old boiler, it usually makes financial sense to get it replaced sooner rather than trying to keep it running.

    Whatever your budget there is sure to be a condensing boiler suitable for you and your home, whether you want a premium boiler from the likes of Worcester Bosch or Viessmann, or a more budget-friendly option like the Alpha E-Tec. 

    And remember whichever brand you choose – Worcester Bosch, Viessmann or Alpha, you will secure an exclusive 10-year warranty giving you long term peace of mind.

    Read about: Best Heat Only Boilers, Boiler Brands & Prices

    What is the cost for a Condensing Boiler?

    The cost of a new condensing boiler depends on a variety of different factors, these might include the following:

    • The type of boiler you have installed e.g. combi, regular or system.
    • The boiler model you choose e.g. mid or premium range.
    • If you want to relocate your boiler e.g. from the garage to the attic.
    • If you want to convert your boiler e.g. from combi to regular.
    • Any add-ons you purchase e.g. filters, smart controls etc.
    • Check the latest prices on our combi boilers here. 

    One of the most common and straightforward types of condensing boiler installations is a straightforward combi swap i.e. replacing your old combi with a new combi. This is much simpler than replacing a combi with a system boiler.

    This is due to conversions being more complex to install, taking more time, requiring more labour and more materials. More everything.

    The condensing boiler model you choose also has an impact on the cost and at Let’s Heat we offer more value-orientated brands such as Alpha, as well as award-winning, premium brands such as Worcester Bosch and Viessmann.

    Read more: Best Brands of System Boilers & Pricing

    Best Condensing Boilers of 2024

    Other Boiler Types:

    In addition to condensing boiler installation we also fit other boiler types:

    1. The Common, Heat Only Boiler
    2. A System Boiler
    3. Combi Boiler / Condensing Boiler
    4. New Heat Pumps!

    All of our Installations follow the latest UK energy regulations…

    Over the last few years, the UK has passed several government guidelines for boiler replacement and energy efficiency, which now need to be adhered to for all boiler replacements, so please remember:

    • If you have a gas boiler, it must have at least a 92% ErP efficiency regardless of boiler type.
    • A Combi boiler installation requires one energy-saving feature
    • You must have functioning time and temperature controls

    Finance for your new boiler…

    Buying a new boiler and having a boiler installation or a heat pump, is an investment. However, it can be expensive, especially paying for it all in one hit.

    If you haven’t got the money on hand for the boiler and installation services that you require, you can get the job done on a finance package that is FCA-approved.

    We can also offer a number of split payment options for you to consider.

    Read about: Best Ground Source Heat Pumps and Prices

    Boiler Replacement Payment Options

    For new boiler installation, you can pay by card, pay zero deposit, and pay monthly over 2 to 10-years or take our a finance package.

    So why Let’s Heat for your combi boiler replacement?

    A. smartadapt Are Quality & Accredited Boiler Installers

    smartadapt professional engineers and emergency plumbers provide a professional and reliable emergency plumbing and heating service.

    Our Coverage

    This service includes Boiler Installation and Heat Pump Installation, in Cardiff and the surrounding CF postcode areas of South Wales.

    We also cover the rest of Wales and all of England (see below).

    The installation & repair team are all fully qualified to the highest standards and take pride in producing exemplary work standards which include completing all boiler installation requirements no matter what time or day this is required!

    Qualifications & Accreditations:

    Our team of high-quality professional engineers has an extremely high 4.9 out of 5, Trustpilot score given by our previous happy customers and we are fully accredited by Gas Safe and Corgi registered, as well as FCA approved for all of our financial transactions.


    All of our staff at Let’s Heat are experts in their field and have gathered many years of experience, working on a wide selection and variety of emergency plumbing and heating solutions and services throughout Cardiff, the rest of Wales & the UK.

    B. Because we care…

    Are you still a little confused about where to start or who to use?

    Our easy-to-use online questionnaire will guide you through everything that you, and we, need to know in order to ensure that you have the correct solution for your needs.

    We will also ensure that you are completely satisfied with the solution offered prior to completing any works.

    Why else?

    • Cover Cardiff and surrounding areas of South Wales
    • Reliable, professional, and trustworthy
    • High Trustpilot score of 4.9 out of 5.
    • Gas Safe Accredited (corgi registered),
    • Our prices are very competitive
    • Our Finance is FCA accredited
    • We ensure that your house is kept clean and tidy during any work
    • All workmen use floor protection on each job
    • We always make sure your rubbish is correctly disposed of
    • The Service comes with a 12-month snag guarantee
    • We travel anywhere throughout the UK

    You can research your boiler replacement requirements and choose your new boiler and the boiler installation online, without leaving the house…

    If you need a new combi boiler or heat pump and installation, please do not hesitate to reach out to our award-winning heating engineers team because they have more information.

    When you’re ready for a new boiler or heat pump then you can get everything, including the full boiler replacement from us here at Let’s Heat.

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    Can I get Next Day boiler Service?

    We replace & install boilers and heat pumps nationwide and include next-day installation (on orders placed before 12/2 pm in Spring/Summer or Autumn/Winter.

    All staff are experienced and knowledgeable in all aspects of heating installation services and repair and maintenance, so if you have any further questions please feel free to contact us.

    Full range of heating & plumbing services provided by Let’s Heat:

    • Boiler Repairs & Installations
    • Boiler Supply & Fit
    • Financing Your Boiler
    • Emergency Boiler Repairs & Installations
    • Emergency Boiler Supply & Fit
    • Plumbing Repairs
    • Bathroom Plumbing
    • Kitchen Plumbing
    • Emergency Plumbing Repairs
    • Bathroom Plumbing in Emergencies
    • Emergency Kitchen Plumbing
    • General Plumbing Services
    • Emergency Plumbing Services
    • Emergency Gas & Heating Engineer

    Read more: Ferroli Boiler Error Codes / Fault codes List

    Areas covered by our Boiler Replacement Services:

    The Let’s Heat engineers cover all of Wales & England


    Let’s Heat provide Heat Pump installations throughout Wales, including areas like; South East Wales, South Wales, South West Wales, Mid Wales, East Wales, West Wales, and North Wales.

    Welsh Cities:

    This includes all of the Welsh cities like; Cardiff, Newport, Swansea, and all other towns and cities in Wales.


    Let’s Heat provide Heat Pump installations throughout England, including areas like; South West England, South East England, East Midlands, West Midlands, North West England, and North East England.

    English Cities:

    This includes all of the English cities like; London, Reading, Southampton, Portsmouth, Bristol, Exeter, Plymouth, Gloucester, Swindon, Oxford, Leicester, Nottingham, Derby, Birmingham, Worcester, Wolverhampton, Walsall, Liverpool, Manchester, Leeds, York, Sheffield, Newcastle, Sunderland and Middlesbrough, etc.

    Any more questions?

    If you have any further questions about Combi boilers, other Boilers, or anything else, please see our FAQ Page because you might find the answers there or on our News Blog.

    Check out our Gas Safe Registration or want to see our near 5 star Trustpilot rating please click the relevant link!


    Is a condensing boiler the same as a combi boiler?

    Ultimately, they are the same thing. In fact, all modern boilers are condensing boilers, including combi, system or regular boilers.

    Is a condensing boiler worth it?

    The main reason why condensing boilers are much better than non-condensing boilers is that they are at least 25% more efficient.

    What is the difference between a condensing boiler and a non condensing boiler?

    Condensing boilers are vented with fan-powered plastic (PVC) pipes. These pipes can be terminated through a side wall. The combustion air for condensing burners is taken directly from outdoors, unlike non condensing systems that take air from the room itself.

    How do I know if my boiler is condensing?

    Mainly there are two ways to tell: If you have a white plastic pipe coming out of the bottom of your boiler, then you have a condensing boiler. Another way to tell is by checkng if your flue (exhaust) is plastic. if it is, then it’s a condensing high efficiency boiler, if it’s all metal, then it’s a non condensing boiler.

    Does a condensing boiler have a water tank?

    A condensing combi boiler does not require a hot water tank and is available in a wide range of compact sizes. Thus it is more suitable and convenient to fit in a kitchen cupboard than conventional boiler models.