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Find the Best Combi Boiler in the UK: A Complete 2022 Guide

Bronte McClelland
By: Bronte McClelland
Updated: 17th June 2022

best combi boiler UK
There are a lot of great options when it comes to choosing the best combi boiler for 2022. Based on certain criteria we've deemed the ATAG IC Economiser Plus to be the top-rated combi boiler for 2022, however, this doesn't necessarily mean it's the best boiler for you.

Which combi boiler is ultimately best for you will depend on your home and your budget. In this guide we'll go more in depth about what factors you need to consider before installing a new boiler, and we'll provide you with a list of the best combi boilers which are well reviewed by both homeowners and heating engineers.

If you already know which combi boiler you want, be sure to get quotes from several heating engineers near you, to ensure it gets installed for the best possible price. You can get comparison quotes from up to 3 local heating engineers by using our free comparison service. To get started, simply click below.

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How do you choose the best combi boiler?

Going by the top brands and asking friends for recommendations are good ways to choose the best combi boiler. However, while this is all well and good, knowing if a particular combi boiler is best for YOU will come down to the size of your home and your household's specific needs.

There are a few factors you need to take into consideration when choosing the best combi boiler. First of all, let's start with the factors that are always indicators of a good boiler regardless of your personal situation: efficiency and reliability.

Efficiency rating

All boilers have an efficiency rating and a band rating. The efficiency rating is a percentage which is based on how well the boiler converts fuel into heat. This efficiency rating is reflective of how much of every £1 being spent actually goes towards heating your home.

For example, if a boiler is 93% efficient, it means only 7p of every £1 being spent on heating is wasted. Thankfully, the latest gas combi boilers in the UK are now required to have an efficiency rating of 92%. Meaning you save a lot more money compared to older G-rated boilers that are often less than 70%!

Therefore, when comparing the top combi boilers look for the highest percentages in order to save as much as possible.

The band rating uses the letters A to G to rank the efficiency of a boiler. With A being the most efficient and G being the least. This rating takes into account which type of fuel is used as well as how effectively the boiler operates.

For example, electric boilers tend to have a much lower rating compared to gas boilers, since in the UK electricity generation is usually done with fossil fuels, which emits twice as much carbon as natural gas. Therefore, buying a combi boiler with a high rating will reduce your carbon footprint in comparison.

Later in the article, we'll go through some of the most efficient combi boilers available in the UK, including models from top brands such as Ideal and Vaillant.

Reliability and warranty

Now, how do you determine how reliable a combi boiler is? It's good to ask around and look at combi boiler reviews online to get a better idea of which brands tend to stand the test of time and which you should avoid. However, another way to determine the most reliable combi boiler is by looking at its warranty.

A longer warranty period indicates a company's confidence in the reliability and longevity of their boilers. Choosing a boiler with a longer warranty period could also save you money in the future as you won't need to spend extra for any potential repairs.

Further down the article, you can find a list of the most reliable gas combi boilers for sale in the UK.

Hydrogen-ready boilers

You may have heard that the UK government is planning to replace natural gas with hydrogen. This is because it's much more environmentally friendly. But what does this mean for homeowners? Is buying a gas boiler a waste of time and money?

Don't worry yet! This change will happen gradually and what's more, most modern combi boilers can already run on a mixture of hydrogen and natural gas. Some of the top boiler manufacturers are even already conducting trials for 100% hydrogen-ready boilers.

Therefore, if you buy a gas combi boiler today you'll still be able to use it for its entire lifespan and get your money's worth.

More factors to consider before buying a combi boiler

Now, the factors you need to consider that are personal to you and the type of property you have:

    • Budget: Your budget, of course, depends on your own personal financial situation. Buying a boiler is definitely an investment, but you don't need to compromise on quality to get a good deal. For example, Ideal is a brand known for its quality and affordable prices.
    • Size (output rating): The size of a boiler is measured in kilowatts (kW). A higher output doesn't necessarily mean the boiler is better. What size you should buy depends on the number of bathrooms and radiators you have. If you don't get the right size you might struggle to heat up your home or you could end up wasting money on high energy bills.
      For example, even if you buy the best combi boiler on the market, it won't keep you too warm if you live in a large home with over 20 radiators and it only has an output of 20kW. On the other hand, if you buy a great combi boiler with an output of 40kW but you live in a one-bedroom apartment, you can say hello to extortionate energy bills!
      Therefore, always check what output size is appropriate for your home by getting advice from a heating engineer. You can receive advice and compare quotes from up to 3 local heating engineers by filling in this short form. It's completely free and you're under no obligation to accept any of the quotes you receive.
    • Type of fuel: Boilers can be fuelled by gas, oil, LPG, or electricity. So you need to check which types of fuel your boiler is compatible with. In the case of gas, you also need to check whether your home is connected to the gas grid.
    • Dimensions & aesthetic:

Many of us prefer to place our combi boilers out of sight in a cupboard. Even though combi boilers are known for being compact, it's still a good idea to double check the dimensions of the models you're considering to make sure it'll fit into your home.
Also if your boiler isn't located in a cupboard you might think twice about how it looks. As the name implies, Worcester Bosch's Greenstar 8000 Style model is known to be one of the most aesthetically-pleasing boilers on the market.

    • Noise level:

The quietest combi boilers have a similar noise level to modest rainfall. If peace and quiet is a priority for you then it's a good idea to look into combi boilers which are Quiet Mark approved.

    • Controls & accessories:

Preferences on controls and accessories vary from person to person. For example, a smart thermostat might be a must for one person and redundant for another. So consider which features will make a difference for you.
what is the best combi boiler

What is the most efficient combi boiler?

In 2022, the competition for being the most efficient combi boiler is definitely fierce. As mentioned above, the efficiency of a boiler is dependent on both its efficiency rating and its band rating. We've selected our top 5 combi boilers based on how efficient they are:

1. Grant VortexBlue Internal 36kW Combi Oil Boiler

Grant VortexBlue Oil Combi BoilerWe'll start off the list with a boiler for those of you who are not on the gas grid. The Grant VortexBlue Internal 36kW Combi Oil Boiler has an impressive efficiency rating of 94.5% and band rating A. However, keep in mind the ErP (Energy-related Products) rating specifically for water is grade B.

The output rating of 36kW is best suited to larger homes with more than one bathroom. This combi oil boiler is also available in sizes 21kW and 26kW, although it's important to note that the efficiency rating is slightly lower for these sizes.

Its warranty length is only 2 years. This is standard for combi oil boilers, however, it is possible to find brands that offer longer periods.

Grant VortexBlue key features:

  • Award-winning Vortex condensing heat exchanger
  • Market-leading Riello Blue Flame burner
  • 24 litre expansion vessel
  • High quality external powder coated casing
  • Built in frost protection

2. Ideal Logic Max Combi Gas Boiler

Ideal Logic max Combi BoilerThe Ideal Logic Max is the first of the gas combi boilers on our list. Some of the boilers in this range are also compatible with LPG (liquefied petroleum gas). This model has the potential to lower your energy bills thanks to its efficiency rating of 94% and ErP A-rating for heat and hot water.

All combi boilers in the Logic Max range have a central heating output of 24.2kW which is suitable for homes with about 3 bedrooms and 10 radiators. The C35 model has a domestic hot water (DHW) output of 35.3kW, the highest in the range, which means it can meet higher demands for hot water.

Ideal have attached an extensive 10 year warranty to all of the Logic Max boilers to ensure you're well covered after the installation.

Ideal Logic Max key features:

  • A large digital display
  • Boiler frost protection
  • Reachable pressure gauge
  • Hard wearing and scratch resistant case
  • The Ideal System Filter - a magnetic and non-magnetic filter designed to protect domestic central heating systems from suspended black iron oxide.
  • Compact dimensions and low lift weight, meaning potentially cheaper installation costs

3. Vaillant ecoTEC Plus Combi Gas Boiler

Vaillant ecoTEC plus combi boilerThe ecoTEC Plus is Vaillant’s ‘flagship’ model and widely recommended by professional heating engineers. It is one of the most efficient combi boilers on the market with a rating of 94%. It is available in outputs of 25, 32, 35 or the largest 38kW which is a great choice for larger homes with a high demand for hot water.
This boiler includes a 5 year warranty as standard with 7 or 10 years available when installed by a Vaillant accredited installer.
The ecoTEC Plus is also one of the more stylish models on the market with back lit digital display, contoured case and stainless-steel heat exchanger. The boiler has been awarded the Quiet Mark accreditation because of how quiet it is when it is in operation.
Vaillant ecoTEC Plus key features:

  • Rapid hot water delivery in just 5 seconds
  • Wide modulation range of up to 1:6 results improves energy efficiency
  • Flame lift detection system enables quieter combustion
  • Two-stage frost protection built in
  • Compatible with aroTHERM air to water heat pump hybrid system
  • Available with a range of controls including wired, wireless and smart (vSmart by Vaillant)

4. Vokera Evolve C Combi Gas Boiler

Vokera Evolve C combi boilerThe Vokera Evolve C is another highly efficient gas combi boiler with a 94% efficiency rating. It also has a 77% efficiency rating for hot water, making it an A-rated product. Furthermore, all of the models in this range are compatible with both natural gas and LPG.

This model is available in sizes 24, 28, 32, 36, and 42kW. Therefore, making it suitable for both small and medium-sized homes. In addition, all sizes come with a 10-year warranty so you can be sure that you are getting a reliable unit that is going to last.

Vokera Evolve C key features:

  • Text driven menus
  • A built in carbon monoxide monitor
  • Rear flue option
  • A time clock
  • Compatible with a BeSmart thermostat

5. Viessmann Vitodens 200-W B2KE Combi Gas Boiler

Viessmann Vitodens 200-W combi boilerThe last boiler in our list is the Vitodens 200-W combi gas boiler from Viessmann. It's A-rated and has an impressive efficiency rating of 94%, which will help you waste less energy and less money.

This boiler is also compatible with LPG and its dimensions are 700 x 450 x 365mm (HxWxD).

It's available in two sizes. One of which has a central heating output of 25.4kW and a hot water output of 30.5kW, making it suitable for homes with about 10 radiators and a single bathroom. The other one has a central heating output of 32kW and hot water output of 34kW, meaning it's ideal for homes with around 15 radiators and up to 2 bathrooms.

This model has a standard warranty of just 3 years. However, it can be extended to 5 years when installed by a Viessmann trained installer and even up to 10 years if you register it through the Viessmann online portal.

Viessmann Vitodens 200-W B2KE key features:

  • Wi-Fi integration - control from anywhere via the ViCare App
  • A wide modulation range of 1:17 and MatriX burner reduce energy consumption and maximise efficiency
  • A stainless steel heat exchanger
  • Touchscreen display
  • All components are accessible from the front - save time and money on servicing

What is the most reliable combi boiler?

As technology advances, so does the quality of boilers. New boilers have improved in many ways, including how reliable they are. It's always good to look up reviews and ask people you know for their opinions and experiences with their boilers. However, considering how much boilers have improved in recent years, it's a good idea to purchase a more recent model.

But how can you tell how reliable a boiler is if it's new to the market? Looking at a boiler's warranty is a good indicator of how confident a brand is in the longevity of their boiler. Below are our top 5 picks of the most reliable boilers available in the UK:

1. Worcester Bosch Greenstar 8000 Style Combi Gas Boiler

Worcester Bosch Greenstar 8000 Style combi boilerThe Worcester Bosch Greenstar 8000 Style is a compact condensing combi gas boiler which is also compatible with LPG. Its dimensions are 780 x 440 x 365mm (HxWxD). If installed by a Worcester Bosch accredited installer you can receive a warranty of up to 12 years. This is one of the longest warranties available, meaning that you can have confidence in your boiler's reliability.

All Greenstar 8000 Style combi boilers, except one, have a central heating output of 35kW. This makes them suitable for homes with up to 20 radiators. The difference between these models is their DHW output, which ranges from 34.4kW to 48.9kW. The most powerful model in the range is suitable for homes with up to 2 bathrooms.

The other model in this range has an output rating of 30kW and flow rate of 12.3 litres a minute, making it a great boiler for smaller homes with 1 bathroom. All the models in this range have a 94% efficiency rating, meaning they are ErP A-rated for both heating and hot water.

Worcester Bosch Greenstar 8000 key features:

  • 2 high gloss colour options
  • An increased modulation ratio of 1:10
  • Robust and lightweight – saves time and money on installation
  • Features the first Greenstar intelligent filling system
  • Wireless connectivity with the Bosch EasyControl

2. Alpha E-TEC Plus Combi Gas Boiler

Alpha E-TEC PLUS combi boilerThe E-Tec Plus is a combi gas boiler manufactured by Alpha. It's one of the most reliable boilers on the UK market. They have a 10-year warranty as standard, however, if installed with the Alpha PremierPack Extra this can be extended to 13 years. Furthermore, it is compact in size with measurements of 712 x 440 x 268mm, and is also compatible with LPG.

The E-Tec Plus is available in 3 different output sizes. The central heating maximum output ranges from 26.1kW to 32kW. While the hot water maximum output ranges from 28.3kW to 37.9kW. This means you can find a model that is suitable for either a medium or larger sized home. For example, the central heating output of 32kW is sufficient for a home with around 15 radiators.

This boiler model also has a good efficiency rating of 93% and ErP A-rating, which will help to save you money on your heating bills.

Alpha E-TEC PLUS key features:

  • A stainless steel heat exchanger
  • A high efficiency grundfos pump and hydroblock assembly
  • Combined condensate and pressure relief valve connection
  • A zinc plated expansion vessel helping to prevent corrosion
  • Easy-access dry-change NTCs on front of pipes

3. ATAG IC Economiser Plus Combi Gas Boiler

ATAG IC Economiser Plus combi boilerThe IC Economiser Plus from ATAG is one of the most reliable gas combi boilers available in 2022. It has a standard warranty period of 10 years, however, this can be extended up to 14 years when you install it alongside an Adey Atom filter, a ONEZone smart controller, and an ATAG water treatment pack.

This boiler model is compact with dimensions of 700 x 440 x 355mm. Furthermore, it is compatible with both natural gas and LPG.

This model is available in a range of hot water output sizes, including 42.5kW, 40.3kW, and 29.8kW. The central heating output size for the largest two models is 31.2kW, and for the smaller model it is 23.2kW. The IC27+ model is perfect for small to medium sized homes, while the IC39+ model is ideal for larger homes with a higher demand for heating and hot water.

This boiler has an efficiency rating of 94% and is A-rated for both heat and water, as it recycles the flue gases for a second time rather than letting it go to waste. On top of that, when it's used in conjunction with the ATAG One controller it can achieve an efficiency rating of A+.

ATAG IC Economiser Plus key features:

  • Unique iCon heat exchanger incl. lifetime replacement guarantee
  • Instant hot water with pre-heat facility
  • Built in passive flue gas heat recovery device
  • An outside weather compensator
  • There is also a model with 275mm depth available – perfect fit for most kitchen cupboards

4. Ariston Alteas ONE NET Combi Gas Boiler

Ariston ALTEAS ONE NET combi boilerAriston's Alteas ONE NET is a condensing and compact combi gas boiler that is also compatible with LPG. It has a standard warranty of 12 years, making it one of the longest warranty periods available amongst combi boilers.

The Alteas ONE NET is available in two sizes, 30kW and 35kW. Its maximum central heating output is 28kW and 31kW, respectively. Both models are suitable for larger homes with up to 2 bathrooms.

On top of that, this boiler also has a high efficiency rating of 94% and boasts an ErP A+ rating. It is fully compliant with the Boiler Plus government legislation.

Ariston Alteas ONE NET key features:

  • Lightweight: only weighs 35.3kg
  • Simple to fit connections: makes installation easy
  • Quiet due to latest soundproofing technology (51db)
  • A large LCD display for easy control
  • Full zone management kit that can manage up to 6 heating zones

5. Viessmann Vitodens 100-W Combi Gas Boiler

Viessmann Vitodens 100-W combi boilerViessmann is one of the most well-known brands in the UK. The Vitodens 100-W has been updated with their new and improved PlusBus range. This new model has a standard warranty of 5 years with the option to extend by a further 7 years. To be eligible for this longer warranty, it needs to be installed by a Viessmann trained heating engineer.

This boiler measures at 700 x 400 x 360mm (HxWxD), making it easy to fit into your home. It is also compatible with LPG as well as natural gas.

The Vitodens 100-W is available in outputs from 3.2 to 32kW. The 26kW model, from the PlusBus range, has a central heating output (CH) of 25kW and it can achieve a domestic hot water (DHW) output of 31.7kW. Making it suitable for homes with 10-15 radiators and 1-2 bathrooms.

All the boilers in this range are A-rated and have an efficiency rating of 94%. This means that a minimal amount of energy is being wasted and as a result reduces your heating bills.

Viessmann Vitodens 100-W key features:

  • All Vitodens 100-W boilers are hydrogen-ready with a blend of 20% hydrogen and 80% natural gas.
  • Includes a stainless steel Inox-Radial heat exchanger, which helps lower heating bills.
  • Low fan speed means the boiler operates quietly.
  • User-friendly LED Touch screen for easy operation.

most reliable combi boiler

Which is the best value combi boiler?

ATAG IC Economiser Plus is our top choice for the best value combi boiler in the UK. As you can see in the table below you don't necessarily need to choose between having an efficient boiler or a reliable boiler - you can have both in one! The IC Economiser Plus comes out on top for being the most reliable, with a warranty of up to 14 years. It also scores high on efficiency with 94%.

Worcester Bosch Greenstar 8000 Style and Viessmann Vitodens 100-W B1KF are also great choices. They are A-rated with 94% efficiency and include warranties of up to 12 years, meaning you can save costs on your energy bills and be sure that you won't need to think about replacing your boiler again for a long time. You can see a breakdown of these boilers and more in the table below.

We've also included an indication of price in the table below. While there are a couple of affordable but still top-quality options, it's important to note that a cheap boiler isn't always the best value choice.

If a boiler is cheap but not efficient you'll end up spending a lot on energy bills. And if a boiler is cheap but not reliable then that means you'll end up spending a fortune on frequent repairs and need to fork out for a replacement far too soon. Therefore, you should always keep these two factors in mind when considering how much a combi boiler is going to cost you.

Type of Combi Boiler Efficiency Rating Band rating Warranty Typical Price
Grant VortexBlue Internal 36kW Combi Oil Boiler 94.5% A-rated 2 years £2,500
Ideal Logic Max Combi Gas Boiler 94% A-rated 10 years £968 – £1,156
Vaillant ecoTEC Plus Combi Gas Boiler 94% A-rated 10 years £1,152 – £1,703
Viessmann Vitodens 100-W Combi Gas Boiler 94% A-rated Up to 12 years £1,292
Vokera Evolve C Combi Gas Boiler 94% A-rated 10 years £845 – £1,010
Worcester Bosch Greenstar 8000 Style Combi Gas Boiler 94% A-rated Up to 12 years £1,300 – £2,297
ATAG IC Economiser Plus Combi Gas Boiler 94% A-rated Up to 14 years £1,950 – £2,160
Alpha E-TEC PLUS Combi Gas Boiler 94% A-rated 13 years £800 – £1,033
Ariston ALTEAS ONE NET Combi Gas Boiler 94% A-rated 12 years £1,300 – £2,000
Viessmann Vitodens 200-W B2KE Combi Gas Boiler 94% A-rated Up to 10 years £1,550 – £1,600

Get the best boiler in 4 simple steps

Now that you know which combi boilers have the best value on the market, you need to figure out which ones are best suited for your home and budget. Boiler installation costs can vary enormously depending on factors like how much work is required and even where you live. We've simplified the process so that you can find the best and most cost-effective combi boiler for you in just a few quick steps:

  1. Answer a few simple questions

    To start you just need to answer a few straight-forward questions using this form. These questions are simply relating to your home, the type of boiler you have and what you’re looking for. You'll also be asked for your postcode so that we can find heating engineers available in your area.

  2. Confirm your details

    After you’ve submitted your enquiry, someone from our team will contact you to check we have the correct contact information and to make sure we understand exactly what you need. This means we can get the best boiler quotes for you, and you can sit back and relax.

  3. Receive quotes and compare prices

    You’ll then be contacted by up to 3 Gas Safe registered heating engineers in your area. Sometimes it's possible for the heating engineer to give you an estimate over the phone, however, usually they'll need to arrange a home visit so that they can see what they'll be working with. This way they can assess the price more accurately, and then you can compare the quotes from each heating engineer.

  4. Book your boiler installation

    Now that you've received all the quotes, you can choose the one that works best for you. You can then arrange a convenient date and time for the work to be carried out by the heating engineer, and get the best combi boiler installed at the best price.

Remember there is absolutely no fee for using our service to find boiler quotes, and at no point are you under any obligation to accept any of the quotes you receive. This way you can find out what the best deals for boilers in your area are without any extra expenses or pressure. If you're curious about how much you could save on a new boiler, simply click the button below to get started.

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What are the best combi boilers on the market?
The best combi boilers on the market in the UK are the ATAG IC Economiser Plus, Worcester Bosch Greenstar 8000 Style, and Viessmann Vitodens 100-W. All of these boilers are known for their superb efficiency and reliability.

Which boiler brand is the most reliable?
The most reliable boiler is the ATAG IC Economiser Plus Combi Gas Boiler. It has a warranty period of up to 14 years, giving you peace of mind that it will keep your home cosy and warm for many years to come.

What is the most efficient gas combi boiler?
There are a few top gas combi boilers available on the market with a high efficiency rating of 94%. These include the Ideal Logic Max, Worcester Bosch Greenstar 8000 Style, and Viessmann Vitodens 100-W.

Which is the best combi boiler for a large house?
The Worcester Bosch Greenstar 8000 Style and Vokera Evolve C are two of the best combi boilers for larger houses, as they are available in sizes which have an output rating of 40-50kW. However, if you have more than 2 bathrooms in your home then you should consider getting a system boiler.

Which is the best combi boiler under £1000?
The Ideal Logic Max, Vokera Evolve C, and Alpha E-TEC PLUS are some of the best combi boilers available for under £1000. It's important to keep in mind when considering the cost of a combi boiler you should also consider its efficiency and reliability. As this will have an effect on the cost of your energy bills and how soon you'll need to replace it.

It's important to note that this price doesn't include the installation costs. We have a gas boiler installation calculator you can use to get an accurate price.

Bronte McClelland

About the author

Bronte McClelland

Brontë is one of our resident home heating experts. She has expertise in writing about renewable energy and heating systems, and continues to stay up to date with the latest trends and technology.

approved by engineer This article has been checked and approved by a Gas Safe registered engineer.

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