Best Combi Boiler (Review) in 2023

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Last updated: October 31, 2023
best combi boiler

Looking for the best combi boiler for your home’s central heating system? You’ve come to the right place! At Heating Wise, we cut through the marketing blurb of various boiler manufacturers and get right down to the business of what really matters, which is how reliable a boiler is, how expensive or cheap it is to run it, and whether it has a long or short warranty length. Sounds good? Let’s dive right into it!

The Best Combi Boiler Brands

With so many boiler brands and models available on the market, choosing the right one for your home can be a rather challenging process. But with the right expert advice that you’re guaranteed to get at HeatingWise, we promise you there’s nothing to worry about.

To help point you in the right direction, we’ve outlined five best combi boiler brands plus their best-selling ranges down below. These boiler manufacturers are well-reviewed by both boiler engineers and customers thanks to providing the most reliable and energy-efficient combi boilers today. All of the boilers we reviewed also come with either extensive or at least decent warranties which is also something to take notice of during your selection process.

Remember, buying from an unreliable boiler brand is likely to lead to your combi boiler breaking down early, resulting in either expensive repairs or worse yet, an entire boiler replacement. We would only recommend purchasing a combi boiler from one of these six combi boiler manufacturers as they are trustworthy and most offer long boiler warranty periods.

After months of research, which involved us delving deep into boiler specifications, customer reviews and warranty sheets, plus consulting with a number of heating engineers, we’re happy to say that we have our winners. Granted, deciding on which is the best combi boiler out of these is still up for debate, but you really can’t go wrong with any of these options.

Worcester Bosch Combi Boilers

Worcester Bosch is a prestigious name in the heating industry for a good reason. Their boilers boast excellent, award-winning design, and are some of the most reliable and energy-efficient options on the market. Worcester Bosch also offer extensive warranty periods, have excellent customer service and aftercare, plus their boiler parts and spares are always available. With over 1 million homes using a Worcester Bosch boiler, they’ve been the most popular UK boiler brand historically.

But times change and so does the market. As a customer, you want not only the best combi boiler model for your home, but also one that is budget-friendly. Is Worcester Bosch really worth it? We believe these three options are some of the best combi boilers currently on the market.

Worcester Bosch Greenstar 8000 Style

The Greenstar 8000 Style is Worcester’s most powerful wall-hung combi boiler with a modern and ultra-quiet design that comes with a host of helpful features. Capable of outputs up to 50kW, the Greenstar 8000 Style is suitable for practically any home, including bigger properties with multiple bathrooms. The Style range also has great connectivity thanks to its smart thermostat, the Bosch EasyControl, plus its full-colour display is incredibly easy to use. Best of all? It’s available with the longest ever warranty – 12 years if installed by a Worcester Accredited Installer.

greenstar 8000

Worcester Bosch Greenstar CDi Classic (8000 Life)

The Worcester Bosch Greenstar 8000 Life is a replacement for the Greenstar CDi Classic, which is one of the Worcester’s most popular combi boilers. This is a  premium combi boiler that is truly amongst the best on offer as it comes with low energy pump for reduced electrical usage and frost protection so it can be installed in a loft or garage, plus it boasts other helpful features. The Greenstar 8000 Life also connects to smart technology with its thermostat, and it’s generally very easy to use thanks to its improved display screen with push buttons. Like the Greenstar 8000 Style, the Life range is also available with a 12-year guarantee.

Greenstar i

The Greenstar i is Worcester Bosch’s most popular combi boiler and for a good reason. While reasonably priced, it’s highly reliable, energy-efficient and comes with a long warranty – up to 10 years when installed by a Worcester Accredited Installer. This range comes with simple control and clear info display yet has a wide array of controls for greater comfort and economy. The Worcester Bosch Greenstar i is also resilient to freezing temperatures – up to -15C to be precise – and has reduced electrical usage. While 25i is the most popular model, we prefer 30i as it is more powerful in terms of water flow.

Viessmann Combi Boilers

Boasting clean and efficient German engineering, Viessmann boilers are taking the heating market by storm. Founded in 1917, the company has over 100 years of experience in the industry so it’s safe to say they know what they’re doing: they understand exactly what their customers want and they deliver it, at affordable prices. They’ve even won multiple Which? Best Buy awards which help back up their already highly popular products. While durable and efficient, Viessman boilers are also budget-friendly, offering excellent value for money.

But if Viessmann is a top-quality brand, how come they’re more affordable than Worcester, you may ask? For one, they don’t have a tonne of new features and technologies like their pricier competitor does – they rely on an efficient yet simple design. They also don’t offer very long warranties, but thankfully, they’re decent enough.

Viessmann Vitodens 200 W

The Vitodens family is Viessmann’s best-selling range of boilers: they’re economical, efficient and compact, offering exceptional reliability. The Vitodens 200-W, in particular, is a fantastic and energy-efficient gas condensing boiler that is ideal for larger houses. It comes with a stainless steel Inox-Radial heat exchanger and thick walls, so it’s extremely durable as well as quite powerful with a rated heating output of up to 35 kW. The Viessman Vitodens 200-W also has an integrated WiFI interface which connects to the internet on request for digital comfort. However, the warranty could be better – 2 years is standard, but you can get 5 years if you hire a Viessmann Trained Installer (which is exactly what we recommend you do!).

viessmann vitodens

Viessman Vitodens 100 W

The Viessmann Vitodens 100-W is a high-quality and reasonably priced option for smaller and well-insulated homes. This boiler sits right in the middle of affordable combi boilers and premium options, making it one of the most popular boilers from Viessmann. Like all Viessmann boilers, the Vitodens 100-W boasts a stainless steel Inox-Radial heat exchanger so it’s highly reliable and durable. It’s also easy to use digitally thanks to the Viessmann’s  tado° thermostat and smartphone app. The Vitodens 100 W has a standard 5-year warranty which can be extended up to 10 years if fitted by the company’s installer.

Viessmann Vitodens 050 W

If you’re looking for a top-quality boiler at an affordable price, the Viessmann Vitodens 050 W is a fantastic combi boiler model. Don’t be fooled by this range’s friendly price tag – it’s an excellent boiler with a compact and quiet design that integrates well into any living space. With an Inox-Radial heat exchanger and stainless steel cylinder burner, the boiler is durable and extremely efficient at converting energy into heat – up to 97% (Hs). Like Viessmann Vitodens 100-W, the 050-W is easy to control remotely thanks to the tado° smartphone and thermostat app. As for the warranty, the Viessmann offer a 3-year standard guarantee which you can extend up to 7 years if the boiler is fitted by a Viessmann Trained Installer.

Vaillant Combi Boilers

German manufacturer Vaillant is another highly popular player in the British boiler market. A proud winner of Which? Best Buy award, Vaillant is one of the premium brands whose products are made to rigorously high standards. Aside from making highly reliable boilers, Vaillant also focuses on the development of systems that use sustainable energy sources. This is to say that their boilers have high-efficiency ratings and low emissions.

Of course, top-quality comes at a top price. While a Vaillant boiler is bound to help save you money long-term on your energy bills, buying it is indeed an investment. Fortunately, the company offers excellent warranty options, especially for its ecoTEC range of boilers.

Vaillant EcoTec Plus

While some of the Vaillant boilers still use an aluminium heat exchanger (as do all Worcester Bosch boilers by the way!), the Vaillant EcoTec Plus combi boiler uses stainless steel. Because of this and the fact that it’s hand-built with premium components, many put Vaillant EcoTec Plus above any Worcester. Aside from being very durable and energy-efficient, the EcoTec Plus combi is also flexible and “smart” – it knows when you don’t need as much heating power and can drop to using only 16% of its max power, helping you save on bills. It also delivers hot water within 5 seconds and comes with a range of heating control options, including a self-learning smart thermostat that can be controlled via vSMART app. The warranty is also very good – 5 years as standard, with 7 to 10 years available if fitted by a Vaillant Advance installer.

valliant ecotec plus

Vaillant  ecoTEC Exclusive Green iQ

If you’re an environmentally-conscious person, the Vaillant’s ecoTec Exclusive Green iQ model may be the best combi boiler for you. With 85% of its parts being recyclable at the end of the boiler’s life, the ecoTec exclusive range is possibly the most environmentally-friendly boiler out there. Aside from being eco-friendly and highly energy-efficient, this premium boiler is also smart as it can adapt itself so it always gives you the precise level of heat you need, helping you save on your energy bills. The ecoTec Exclusive is also fully compatible with Vaillant’s vSMART app, so you can comfortably control it via your smartphone. The 5-year guarantee is standard, but you can extend it up to 7 or 10 years.

Vaillant ecoTEC Plus Combination Store

The Vaillant ecoTec Plus Combination Store range is ideal for larger homes with high hot water demands. Hand-built with premium components, including a stainless steel heat exchanger, this storage combi boiler offers unparalleled durability and high performance: hot water within 5 seconds and up to 20 litres of it per minute. It’s also “intelligent” – when it senses you don’t need as much heat, it drops up to 16% of its max power, saving on fuel and money. The warranty is as per usual – 5 years standard, with 7 to 10 years available if installed by the Vaillant Advance boiler installer.

Ideal Combi Boilers

Founded in 1906, Ideal Boilers have been in the heating industry market for over a century. As an old and popular brand, they have a loyal base of customers who appreciate having mid-range options that are both reliable and affordable. While not as popular as some of its pricier competitors, Ideal does offer real value for money. They also continuously develop their products yet retain their key principles, including quality and value, which is something to appreciate.

Ideal offer a variety of boilers, ranging from simple and budget-friendly options to pricey premium models. Still, they are known for offering quality products at friendly prices, which allows them to maintain a reasonable share in the British market. Oh, and their warranties are very good too – typically around 7 to 10 years.

Ideal Logic+ Combi

Looking to replace your old boiler with something more efficient? Ideal Logic + Combi is a solid choice. With built-in frost protection, this unit provides excellent energy saving, plus performs very quietly – always a nice plus. Because it’s compact, it can be fitted in a typical kitchen cupboard, making it a fine choice for smaller flats. The Logic + Combi is also super simple to use thanks to its fully backlit LCD display. The warranty is also pretty great – 7 years standard and 10 years on the heat exchanger.

logic plus combi

Ideal Vogue Combi

The Vogue is Ideal’s premium combi boiler range that utilizes modern technology to bring its users the next step in domestic heating intelligence. Featuring a backlit 3.5″ LCD full-colour display and multi-functional buttons, Ideal Vogue offers a wide range of options for control and is very easy to use. There are three different outputs to choose from in this range (26, 32 and 40kW), and all three have great water heating energy efficiency class (A), as well as frost protection. The standard warranty is 8 years but you can claim 10 on parts and labour if the boiler is fitted with an Ideal System Filter.

Ideal Vogue Max Combi

As the name suggests, Ideal Vogue Max is the regular Vogue Ideal boiler – only maxed out. This improved range boasts an added Ideal-approved water filter which helps increase its already great warranty up to a whopping 12 years if installed and serviced by a Max accredited installer and if serviced annually (if not, the standard warranty is 10 years). Part of the Ideal’s premium range, the Vogue Max is constructed with top-quality components and parts, so it’s highly reliable and long-lasting. As usual, the unit comes with frost protection, 3.5-inch backlit LCD display, and an easy-to-read pressure gauge.

BAXI Combi Boilers

As one of the biggest and oldest combi boiler manufacturers in the UK, Baxi has a great reputation amongst both boiler installers and homeowners. While not considered a premium brand in general, Baxi does offer a wide range of boilers to their customers, including the affordable and simple models, as well as the more expensive and indeed premium ones.

Baxi boilers typically come with extensive warranties – between 7 and 10 years, which in terms of guarantees puts them in the same category as Vaillant and Worcester Bosch. If you’re looking for a reliable and efficient boiler at a friendly price, these three Baxi ranges are definitely worth checking out.

Baxi 600 Combi

The Baxi 600 is a compact yet powerful boiler range that is best suited to smaller homes and flats as it can fit in a standard kitchen cupboard. As well as being compact and lightweight, this boiler is compatible with a smartphone and tablet heating control app so you easily can use it remotely. Another thing we really like about the Baxi 600 is that it comes with an EasyFill permanent filling link which makes it easy to top up the central heating system pressure without having to call a heating engineer. The warranty is also very good – 7-year on parts and labour as standard.

Baxi 600 Combi

Baxi 200 Combi

If you’re looking for a budget-friendly combi boiler, the Baxi 200 range is a solid choice. Available in 24 and 28kW, these combi boilers are compact and efficient, perfect for smaller properties as they fit nicely in typical kitchen cupboards. If you’re replacing an old unit, the Baxi 200 will help you save money on energy bills as it has 89% efficiency. You can also use it with an optional uSense smart control app to monitor your energy use and control heating on/off times from your smartphone. The only thing we don’t like about Baxi 200 is its rather short 3-year warranty.

Baxi 400 Combi

The Baxi 400 is another compact and lightweight boiler that can be installed practically anywhere, including inside a standard kitchen cupboard. Basically, this is an improved version of the Baxi 200 – equally efficient but quieter and with a better warranty period of 5 years, the Baxi 400 is a great choice if you have a slightly bigger budget. Like the previous range, the 400 Combi is also compatible with uSense smart control, so you can monitor your energy usage and control it via your smartphone. While the 200 combi range is a solid choice if you’re on a tight budget, we prefer the 400 range because of the warranty length.

How Does a Combi Boiler Work?

A combination or combi boiler works by taking water directly from the mains water supply. When you turn on your hot water tap, the gas burner starts producing heat, which is then transferred from the combustion chamber to the water thanks to the heat exchanger.

In brief, a combi boiler provides a combination of effective central heating and instantaneous hot water (hence the name). This is, in fact, one of its main benefits – while compact and efficient, a combi boiler is capable of controlling the entire central heating system in a single unit.

Things to Consider When Choosing

To determine which are the best combi boilers available this year, we paid particular attention to the following factors:

  • Design and material quality
  • Overall brand reputation based on their history and customer reviews
  • Warranty length offered by the manufacturer
  • The price range of their combi boilers
  • The efficiency ratings of each combi boiler
  • Finally, awards such as Which? Best Buy Awards

While you don’t have to consider all of these factors during your selection process, we highly encourage you to at least consider these three: brand reputation, warranty period, and efficiency ratings.

How Much Does Combi Boiler Installation Cost?

The cost of installing a new combi boiler is dependant on a number of factors, but these three are the most important ones:

  • The boiler model you choose
  • Whether you’re relocating your combi boiler
  • Whether you’re converting your boiler from one type to another
  • Any add-ons you purchase

The simplest and cheapest combi boiler installation is a like-for-like replacement, e.g. when you’re replacing an old combi boiler for a new combi boiler in the same location. This type of installation can cost anywhere between £500 and £800. More complex installations, such as converting your old system boiler to a new combi boiler and installing it in a new location, will cost much more. In some cases, the total cost of a new boiler installation can be as high as £2,500. To get the best deal, we highly recommend comparing multiple boiler quotes.

gas boiler for heating

Which is the Best Combi Boiler Size for Your Home?

Combi boilers come in a wide range of outputs to accommodate homes of most sizes, starting from small 1 bedroom flats to bigger 4 bedroom houses. To get the best combi boiler for your home, it’s essential to purchase a unit with the right output for your requirements. A combi boiler that is too small for your house won’t be able to meet your hot water demands, while a boiler that is too big and powerful will end up increasing your energy bills.

Before you purchase and install a new boiler, it’s important to talk to your heating engineer about your needs and future plans. For instance, if you plan on expanding your house or adding more residents, you may want a more powerful boiler. Here are some basic guidelines that can help you choose the best combi boiler for your home.

1-21Up to 1024kW-28kW
2-32-3Up to 1528kW-35kW
4+3+Up to 2035kW-42kW

Are Combi Boilers Suitable for Larger Homes?

While most combi boilers are recommended for small and medium-sized houses, there are plenty of high capacity storage combi boilers nowadays that are suitable for larger homes. Still, it’s good to keep in mind that the bigger your house is, the bigger your hot water needs are and so the higher the output of your boiler should be. Generally speaking though, we don’t recommend installing a small or even medium-capacity combi boiler if you have more than three bathrooms.

Combi Boiler Prices

As you can probably tell by now, the prices of combi boilers (and indeed any other type of boiler) vary based on the brand, range, and model you choose. While we cannot give you any guarantees about how much a new combi boiler is going to cost you, we can give you some approximations based on our research. Bear in mind that brands sometimes change their prices based on season and year.

Combi Boiler ModelApprox. Price Excluding Installation

Benefits of a Combi Boiler

As mentioned, a combination boiler owes its name to the fact that it’s capable of providing a combination of hot water and heating. But unlike system and regular boilers that require separate tanks in order to function, a combi boiler is a single unit that provides hot water on demand directly from the mains. Because of this and many other factors, this type of boiler comes with a host of benefits.

Space-Saving Due to its Compact Size

Because a combi boiler doesn’t need a hot water tank or a cylinder in order to heat your home and provide hot water, it doesn’t take up much space. Being a single and compact unit that can be easily placed in a kitchen or airing cupboard, means it’s perfect for flats and small to medium-sized homes.

Highly Efficient

Compared to older boiler models such as conventional boilers, combi boilers are highly efficient. In fact, many new combi boilers start at around 90% efficiency and can climb up to a whopping 97% efficiency. Heating your home with a combi boiler is therefore not only better for the environment as it helps reduce your carbon footprint, but also for your wallet as it can help lower your heating bills. For example, a combination boiler that is 93% efficient loses only 7% energy to run itself, so for every £1 you spend on your bills, only 7p is lost.

Fast Access to Hot water

Taking water straight from the mains water supply and heating it on demand (or when you turn on your hot water tap), a combi boiler wastes no time on heating a water tank, making access to hot water as fast as it can get. As a bonus, a combi boiler can provide an unlimited supply of hot water on demand and stronger water pressure.

Safer and Cleaner Water

The cold water from a combination boiler is practically always safe to drink as the boiler doesn’t have a tank where water can sit for days at a time; instead, cold water comes straight from the mains. Because of this, a central heating system with a combi boiler is also cleaner, with less sludge buildup, typically requiring less servicing.

Easy to Install and Service

Speaking of service and maintenance, the popularity of combi boilers means that most boiler engineers know how to service them. This means that finding a good engineer should be pretty easy regardless of where you live. Combi boilers are also easier and therefore cheaper to install than traditional models as everything is packed in a single unit. This is especially true if you’re swapping a combi for a combi boiler.


  1. What is a combi boiler? – Viessmann
  2. Combi Boilers – Baxi
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