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Last updated: 14th March, 2024

Guides

Best Combi Boilers in 2024 (UK Buying Guide)

Best Combi Boilers in 2024 (UK Buying Guide)

Key takeaways

  • Discover the best combi boilers available on the market in 2024
  • Cost and brand reputation are significant factors in the boiler purchasing process.
  • Compare the efficiency of each boiler and estimate how much money you can save.

Finding the best combi boiler for your circumstances can prove difficult. Lets discuss the best 5 boilers on the market in 2024.

Navigating the vast landscape of combi boilers can be daunting, but as 2024 unfolds, we're set to make sense of the options available to homeowners. With a variety of models vying for the title of 'best combi boiler', it's important to consider factors such as suitability for different property types, cost implications, and brand reliability.

The investment in a new boiler is not only a significant financial decision but also a move towards energy efficiency and comfort in your home.

Choosing the right combi boiler involves weighing up the functionality and features that align with your domestic needs.

Whether it's the compact nature of the Alpha boilers or the advanced technology of the Viessmann, every homeowner deserves a system that delivers consistent heating and hot water.

The market in 2024 provides a host of options, each with their unique selling points, and navigating through this spectrum is key to finding a boiler that fits seamlessly into your lifestyle.

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Essential Insights

We've conducted thorough comparisons of various combi boilers — ideal for those ready to upgrade their home heating systems in 2024. Here's what we've uncovered:

  • Top Boiler Brands: Brands like Worcester Bosch, Viessmann, and Alpha stand out for their balance of quality and value.

  • Price Range: Expect a range of pricing options to suit diverse budgets, with premium models offering additional features.

  • Efficiency: High-efficiency ratings are standard across leading models, translating into potential savings on energy bills.

  • Warranty: Longer warranties often accompany higher-priced units, offering peace of mind regarding future repairs.

  • Features and Performance: Look for boilers with user-friendly controls, robust build quality, and strong performance metrics.

  • Installation and Maintenance: Ease of installation and the clarity of maintenance guidelines can vary, so consider these factors critically.

By understanding these elements, you're equipped to choose a combi boiler that not only meets your needs but also provides reliable and cost-effective heating for your residence.

Considering a Boiler Upgrade?

As the time we spend in our homes increases, the appeal of a cosy environment with steaming beverages and reliable heating grows significantly. Consequently, we might find ourselves contemplating an enhancement to our central heating system. A combi boiler, recognised for its efficiency and space-saving benefits, might just be the solution we're pondering.

  • Quick Decisions: Secure a price estimate in merely 60 seconds, with the possibility of next-day fitting.

  • Financial Flexibility: Options for 0% APR financing can make this investment more manageable.

We have curated a selection of the most commendable combi boilers of 2024, built to cater to diverse domestic needs. It's worth noting that the difference between a perfect match and a near miss in the boiler world can come down to minute details.

When looking to upgrade, consider these pointers:

  • System Suitability: Assess boilers with features that align with your home's demands.

  • Installation Options: We cater to a vast range of boilers, including top performers from this year's selection.

Whether your focus is on reducing energy bills or ensuring a warm and inviting living space, we're here to guide you towards making an informed boiler choice.

Top Choices for Combi Boilers

Understanding Combi Boilers

We consider a combi boiler a high-efficiency multipurpose solution for both central heating and hot water in a single compact unit. With these systems, you do away with the need for separate water tanks, allowing for a significant space-saving in your property. Combi boilers are straightforward to install and are recognised for their reliability, making them a popular choice in homes across the UK.

Leading Combi Boilers on the Market:

  • Worcester Bosch 4000 - renowned for its effectiveness.

  • Viessmann Vitodens 050-W - appreciated for its advanced technology.

  • Worcester Bosch 8000 - a premium choice with superior performance.

  • Ideal Logic Plus - stands out for its value and efficiency.

  • Viessmann Vitodens 100-W - balances functionality with innovation.

Whether opting for a gas combi boiler, an electric combi boiler, or even an oil boiler, we advocate assessing your household’s requirements to find the best match.

Combi Boilers: Ideal for Various Homes

Combi boilers cater to hot water demand and central heating simultaneously, directly linking to the water mains for immediate hot water. We find them particularly adept in smaller homes due to their compact nature—no need for separate tanks or cylinders. The gas combi boiler has become a staple in UK households, providing a heating system with water pressure-dependent power output.

  • Instantaneous hot water on demand

  • Suitable for properties with natural gas

  • Fuel type flexibility, including gas or electric models

  • Optimal for both space-saving and energy efficiency

Though robust, even these systems have a lifespan. Post a decade of service, it's prudent for us to consider an upgrade.

Reasons to Invest in a New Heating System

Enhanced Operational Effectiveness

Modern boilers embody energy-saving prowess. If you're contending with a combi boiler that's surpassed the fifteen-year mark, it's likely operating at a suboptimal level. Contrast that with the latest A-rated condensing boilers which can surpass old models by a staggering 30% in terms of energy expenditure. Not only does this reflect positively on your heating bills, but it's a stride towards lessening your home's environmental impact.

  • Up to 30% more energy efficiency compared to 10-year-old boilers

  • Condensing boilers are designed for maximum heat recovery

  • Potential savings on energy bills

  • Contributes to reduced carbon emissions

Augmented System Dependability

We seek uninterrupted comfort in our homes, and a trustworthy boiler is central to this. The advance in years comes with a dip in boiler reliability. Frequent repairs can be both bothersome and expensive. By choosing a new boiler, you substantially reduce the risk of malfunctions.

  • Lower likelihood of unexpected breakdowns

  • Boiler warranties offer peace of mind with coverage for the warranty period

  • Use of premium components like stainless steel heat exchangers enhances durability

Quieter Operating Conditions

The advent of contemporary boiler technology has ushered in a new era of serenity. Unlike their predecessors, modern boilers hum along in the background, allowing for a tranquil home environment. If your current unit is a cacophony of unsettling sounds, an upgrade promises a whisper-quiet operation.

  • Reduction in operational noise levels

  • Frost protection features to ensure silent running during colder months

  • Features designed for quiet operation

To reiterate, the benefits are multifold. An investment now not only relieves your pocket in the long run through abated energy expenses but also secures the cosiness of your living space with dependable and serene heating solutions.

Selecting Your Ideal Combi Boiler

We understand the challenge in choosing an efficient combi boiler that meets your needs, given the vast array available, each with their own merits. Prices vary too, a factor certainly not to be ignored.

  • Our Top Picks: We've considered performance and customer feedback to guide you.

    • Affordable: For budgets tight, yet quality required.

    • Efficiency Leader: Maximum heat, minimal waste.

Trust us to steer you through this landscape to a wise decision for warmth and hot water this year.

Selecting the Top Combi Boiler

Assessing Boiler Energy Efficiency

When examining combi boilers, we pay keen attention to the energy efficiency ratings. Boilers with an 'A' rating represent the pinnacle of energy conservation, which can significantly reduce heating bills in the long run.

Understanding Boiler Output

The output, measured in kilowatts (kW), is critical as it correlates with the boiler's capacity to heat your home. For most small to medium homes, a combi boiler with an output between 25kW and 30kW is often adequate, but your gas engineer will guide you to the perfect fit.

Sizing Up Your Combi Boiler

It's not just the heating capacity that matters, but also the compactness of the combi boiler. Confirming the physical dimensions is vital to ensure a smooth installation and adequate space management within your household.

Boiler Feature

Why It Matters

Energy Efficiency

'A' rating ensures top savings on bills

Output Rating (kW)

Matches boiler power to home's heating need

Boiler Physical Size

Must fit the designated installation space

We recommend always consulting a certified gas engineer who can assess your home’s flow rate and size requirements accurately. They can help you find a boiler that meets both the hot water and heating needs without unnecessary overspending on a too-powerful unit.

Cost Analysis for Combi Boiler Implementation

Variation in Pricing by Providers

We must acknowledge that the expense of acquiring a combi boiler isn't consistent across the board; it fluctuates markedly. It's not merely the model or make that swings the price tag but also where you reside and its due availability. Installing a boiler up North may prove lighter on the wallet compared to the steeper prices of the capital.

Reflect on the sort of dwelling you have—be it a terraced house or a semi-detached. The space you occupy influences not just the combi boiler suitable for you but also the installation costs. A professional will need to evaluate your living space, tallying bedrooms and water facilities, to conclude the requisite boiler size and installation complexity.

To distil it further, when budgeting for a new combi boiler, we're not simply allocating funds for the hardware.

Our homes are unique, and the variety of boilers and their installation ought to be tailored. It's pivotal for us to seek thorough quotes, merging both the device's price and the labour, to forestall surprises on the invoice.

Leading Combi Boiler Manufacturers

In the dynamic landscape of heating solutions, numerous brands stand out. We've observed consistent performance and customer satisfaction with these select names:

  • Viessmann, a top-notch industry leader.

  • Worcester Bosch, renowned for reliability.

  • Vaillant excels with innovative technology.

  • Ideal, trusted for home comfort.

  • Alpha Heating balances quality with affordability.

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Best Combi Boiler by Alpha Innovation Company

#5 Alpha Combi Boilers

In fifth place comes Alpha. This well-established brand has been one of the UK’s leading heating companies for over 50 years, giving them plenty of experience that combines traditional business values with a highly innovative approach to its operation.

Alpha ranks among the best combi boiler because they have amazing A-Class efficiency-rated budget combi boilers that accommodate the needs of every property type and household size.

As part of the Immergas group, which operates in 30 countries and has manufactured over 7 million boilers, Alpha benefits from some of the most advanced production facilities in the world.

This means you are guaranteed a high-quality combi boiler, despite the low prices. They offer a range of combi boiler sizes from the compact E-Tec to the larger E-Tec Plus, which deliver on every aspect.

Alpha Boilers are not quite the best combi boiler on the market but are an amazing budget option if cash is a little tight and you still want a solid boiler built to last.

Great budget boiler

Alpha Boilers is a budget option but manages to balance price with some reliable design decisions to give you a cheap but fairly consistent boiler line.

The Italian design, surprisingly useful parts, and labour warranties mean that each combi boiler will usually work fine in the long term.

A great set of sales and support staff also gives you an easy way to contact them if something goes wrong, and specific boilers have warranties of up to ten years, depending on the model you choose.

Alpha E-Tec Dimensions

Italian quality

While Alpha Boilers may be relatively cheap, they are not poor-quality, so they can become a great mid-range choice when you do not want to go too high or low.

Other than that, there is not much else to say about Alpha Boilers because they are a comfortable middle-of-the-road option that can fit into most homes and businesses without issue.

You are also covered for much longer than the price would suggest, so wear, and tear are not as much of a setback. If purchased through iHeat, you also get a massive 10-year warranty on all Alpha boilers.

Alpha Boiler Range

Alpha Model

Kilowatt (kW) Outputs

#

E-Tec

28

33

-

Get a quote

E-Tec Plus

28

33

38

Get a quote

Evoke

28

33

-

Get a quote

InTec

28

33

-

Get a quote

Alpha E-Tec Boiler

The E-Tec is ideal for small and medium-sized homes. The entire E-Tec range features brand-new stainless steel heat exchangers, making them highly robust, and they also have zinc-plated expansion vessels to prevent corrosion.

Taking these extra steps to maximise the longevity of your boiler life is what makes this range stand out. The E-Tec also has a high-efficiency pump which helps to deliver an impressive 14.1 litres of hot water per minute, and the single electrode drive charge is very easy to access, meaning your Alpha combi boiler will be easy to control and manage after installation.

Get your free fixed quote here.

Just some of the features of the E-Tec include:

  • 10 Year Warranty

  • Two available kW outputs

  • Combined condensate and pressure relief valve connection

  • Single Electrode

  • Easy-access dry-change NTCs on front of pipes

Alpha E-Tec Plus

The E-Tec Plus is similar to the E-Tec. Still, it is much larger and has a few extra benefits, such as a 10-year warranty, copper pipe tails with isolation valves, an integrated filling loop, a control panel, and a bottom cover.

This combi boiler is suitable for larger homes and offers a third higher output option than the E-Tec at 38kW

Alpha Evoke

The best combi boilers from Alpha are the smallest. Its compact size and layout are an ideal solution for small to medium-sized homes and has a stainless steel heat exchanger and many other amazing features such as:

  • 7 Year Warranty

  • Backlit LCD with push button controls and detailed operational information

  • High efficiency Grundfos pump and hydroblock assembly

  • Single electrode

  • Easy access for servicing

  • IPX4D protection

  • Low electrical consumption

  • Easy-access NTCs on front of pipes

  • One-piece cartridge diverter valve

  • Clip-on DHW temperature sensor

  • Dry-change NTCs

  • Combined condensate and pressure relief valve connection

  • Frost protection and daily pump kick

  • 14.1 litres of water per minute

Alpha InTec

The InTec combination boiler is different from the others due to its built-in GasSaver.

This combi boiler is perfect for anyone concerned about their environmental impact. The InTec reduces gas usage by 35% compared to other gas combi boilers and has a low electrical consumption.

Some of the useful features of the InTec are:

  • Same connections as a boiler with no additional exposed pipework

  • Isothermic stainless steel heat exchanger

  • High efficiency Grundfos pump and Hydroblock assembly

  • Backlit LCD with push button controls

  • Two available outputs

  • Easy-access NTCs on front of pipes

  • One-piece cartridge diverter valve

  • Clip-on DHW temperature sensor to prevent corrosion

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Some of The Best Boilers by Ideal

#4 Ideal Combi Boilers

In fourth place comes Ideal. This boiler brand is the best at small and affordable boilers, such as the Logic range and flashier pricier models, such as the Vogue range, catering for all their customers and their budgets.

Ideal Boilers has seen rapid growth over the last ten years, and offers a very simple warranty system that gives combi boilers either 2, 7, or 10-year warranties depending on which model you are buying.

Built to last

In terms of quality, they sit around the same level as Worcester Bosch but with a slightly lower price, which can make them more budget-friendly if you are trying to save every penny you can.

Of course, this price depends on the installer, so the cost of getting a combi boiler form Ideal Boilers can vary by location.

When compared side by side, they are a good alternative to Worcester Bosch, and many of their ranges are similar enough to stand in for WB combi boilers if you need them.

Looking for a mid-range boiler, then Ideal may be the Ideal choice 😉

Solid price

A mid-range price and a compact design ensure that these combi boilers can be used in various locations and situations, often knocking around 10% off the price compared to more expensive brands.

However, this comes at the cost of not necessarily having the same features, so that you may lose out on some unique benefits here and there.

Ideal Logic Plus Dimensions

Even still, Ideal combi boilers could offer you the best combi boiler depending on what you are looking for and how large your budget is.

They may be cheaper than other choices, but that does not make them worse or less reliable.

Ideal Boiler Range

Ideal Model

Kilowatt (kW) Outputs

Logic

24

30

35

Get a quote

Vogue Gen2

26

32

40

Get a quote

Vogue Max

26

32

40

Get a quote

Logic

Although the Logic combi boilers aren't as flashy as the rest of Ideal’s range, they’re reliable, compact and easy to use, earning The Queens Award in 2013 as well as The Good Housekeeping Award in 2013 and 2017.

Ideal offers a standard 2-year warranty that can be extended to 5 years, though with only a 3% chance of The Logic's best combi boiler breaking down, it looks like you won’t even need it.

Here are some of the features of the Logic boiler:

  • Large digital display

  • Easy to reach pressure gauge on front panel

  • Compact

  • Scratch resistant

Vogue Gen2

This is Ideal’s best combi boiler for its features and attractive design whilst remaining compact. It has a backlit 3.5” LCD full-colour display and has multi-function buttons for ease of use, built using premium components.

Endorsed by the Energy Saving Trust, you can be sure that this combi boiler is better for the environment. This boiler comes with a standard 8-year warranty.

Vogue Max

Ideal’s newest premium combi boiler has the same fantastic features and attractive appearance of the Vogue Gen2 with the addition of a high-quality Ideal System Filter, which boosts the warranty from 8 to 10 years.

Some of the other features include:

  • Easy to read pressure gauge

  • Premium components

  • Full-text support for fault modes

  • Stylish composite design with damped opening control cover and large rotary control dials

  • Service timer with telephone number/service display

A range of Combi Boilers by Vaillant

#3 Vaillant Combi Boilers

In third place is Vaillant, another Which? Best Buy Award winner. Vaillant is a premium contender and offers a 5-star boiler range for both small and large properties, though they do have premium prices which aren’t too friendly to your bank account.

However, they come with a convenient app to control your heating anytime, anywhere and have a 5-year warranty which can be upgraded to 7 or 10 years.

Valliant is rarely mentioned as often as other top brands. Still, they operate similarly to Worcester Bosch, combining great quality with various useful warranties and customer service options.

Warranties

Warranties generally sit between 2-5 years, depending on the model, with a price range similar to other beloved brands.

One of the main benefits of Valliant is the variety on offer: the ecoTEC combi boiler line has become a favourite for people who want lower energy consumption without losing performance, and the warranty can be upped to ten years with a Valliant Advance Installer.

The improved efficiency can help you save money, just like with Worcester Bosch combi boilers.

Customer Service

Finally, great customer service is always useful, and Valliant is keen to offer it. If something goes wrong and you need help fixing a problem or identifying a failure, then it is not hard to contact them, meaning that you will always have a way to contact the company and won't have to hunt down an obscure email address or phone number.

Vaillant Combi Boiler Range

Ideal Model

Kilowatt (kW) Outputs

ecoTEC exclusive

-

-

35

43

Get a quote

ecoTEC plus

25

32

35

38

Get a quote

ecoTEC plus store

-

-

--

38

Get a quote

ecoTEC pro

24

28

30

-

Get a quote

ecoFIT pure

-

25

30

35

Get a quote

Vaillant ecoTEC exclusive

This combi boiler is great for larger homes with higher outputs. It has the potential to generate an impressive 17.8 litres of hot water per minute and is eco-friendly and 85% recyclable. Like all Vaillant products, the ecoTEC exclusive has been approved by Quiet Mark, meaning it is one of the quietest products on the market.

Vaillant ecoTEC plus

This is the all-rounder of Vaillant’s combi boilers with the broadest range of kW outputs. It has precision heating to reduce fuel bills, delivers hot water within 5 seconds and has a 5-year standard warranty.

Vaillant ecoTEC plus store

This boiler is a powerful solution for larger homes with its high-performance control, efficiency and an integrated hot water storage device at the back of the boiler. Providing up to 20 litres of hot water per minute and hot water within 5 seconds, this combi boiler appeals to large families with a high demand for hot water and comes with a 5-year warranty.

Vaillant ecoFIT pure

The ecoFIT pure is another of Valliant’s highly efficient, smart control and high-performance combi boilers but much more compact to fit in a kitchen cupboard in a smaller home. This boiler comes with a less impressive 2-year warranty, but there is the option to increase this to 7 or 10 years for an extra cost.

#2 Viessmann Combi Boilers

In secon place comes Viessmann. Viessmann surpasses most other combi boiler brands in the market with their advanced German engineering and efficient heating systems that are a great value for money.

Built to last

One of their key selling points is the longer lifespan, which makes their combi boilers last much longer than many competing products. Because of this, they will often appear near the top of any best combi boiler list.

Efficiency

Efficiency can mean a lot when it comes to heating, which often makes Viessman a good choice for keeping costs low in the long-run.

Even in designs with a lower maximum heat output, the improved efficiency can save plenty of money and better use the power you are already consuming.

Warranty

All of their models come with ten-year warranties when bought through iHeat, and there are simple finance options available for their more expensive offerings

Even better, most are designed to be silent or near-silent, making all the difference in a crowded home where the boiler can’t easily be tucked away.

Price

In general, Viessman is a great choice for a smaller building, especially if you do not have as much room to store it.

The higher efficiency removes a lot of the hassle from setting the combi boiler up and means more power is packed into a single body.

You can fit a lot of them into existing cupboards or small alcoves, and the long-lasting design prevents them from breaking down easily.

Viessmann Boiler Range

Viessmann Model

Kilowatt (kW) Outputs

Vitodens 050-W

-

29

35

Get a quote

Vitodens 100-W

26

30

35

Get a quote

Vitodens 200-W

-

-

35

Get a quote

Vitodens 111-W

26

-

35

Get a quote

CDi Highflow

-

-

44

55

Get a quote

Viessmann Vitodens 050-W

The Vitodens 050-W 29kW, in particular, is the most reliable and has the highest quality with its stainless steel heat exchanger (which makes it extra robust), exceptionally quiet operation and an impressive water flow rate of 12 litres/min.

With compact dimensions and low weight, the Vitodens 050-W will integrate into any home without compromising quality. Winner of 2019 Which? Best Buy award, this combi boiler is Class-A rated for its energy efficiency and is easy to control with an LCD.

Viessmann Vitodens 050-W Dimensions

Here are just some of the amazing features this combi boiler has to offer:

  • 10 Year Warranty when purchased through iHeat

  • Integral instantaneous water heater

  • High efficiency of up to 97%

  • Low CO2 emissions for reduced environmental impact

  • Digital user interface

Viessmann Vitodens 100-W

This combi boiler has all the great features of the 050-W as well as extra features such as the extra 26kW output option and the user-friendly backlit LCD Touchscreen for easy operation. This boiler was endorsed by Which? and up to 94% of the fuel used is converted into heat, making it more environmentally friendly and Boiler Plus ready.

Viessmann Vitodens 100-W Dimensions

Viessmann Vitodens 200-W

If you’re looking for a combi boiler for a larger home, this boiler is for you. It has greater efficiency and lower emissions, with up to 98% of the fuel used converted into heat. Despite having to operate on a larger scale, this boiler remains compact and quiet thanks to its low-speed fan.

Viessmann have made this combi boiler incredibly easy to operate by incorporating a 7” colour touchscreen with an integrated WiFi interface for internet connection. It also has a new environmentally responsible MatriX-Plus burner which automatically adapts to the properties of different gas types to keep costs down and reduce the environmental impact of the boiler.

With its 10-Year Warranty, you can be sure you’ll have a long-lasting and reliable combi boiler.

Viessmann Vitodens 111-W

Viessmann describes its Vitodens 111-W as rapid, reliable and compact- and that it is, it's one of the best combi boilers that Viessmann offer. This combi boiler is perfect for large families with high hot water demand. With this high-performance wall mounted storage boiler, you can be sure there will be no more arguments in the morning about ‘who is using all the hot water?!’.

With the capacity to fill a bath in just 8 minutes, this combi boiler will never fail to provide the means for a relaxing soak. Here are some of the features that are bound to impress even those with minimal boiler interest:

  • 10 Year Warranty

  • Cylinder loading system (CLS) and integrated stainless steel storage tank

  • User-friendly control via backlit LCD touchscreen

  • High hot water capability of >18 litres per minute

  • Large range of outputs available

  • Optional wireless remote available

#1 Worcester Bosch (Our Best Boiler Brand Choice)

In first place come the Worcester Bosch boilers, the pioneers of combi boilers. In 2019, they secured a Which? Best Buy award for the 14th time.

Worcester Bosch is a huge household name in the boiler game for a reason.. reliability! 🏆

If you ask most people what the best combi boiler is, the Worcester Bosch group will always come up. Worcester Bosch covers many boiler types and features, which means they suit many situations.

However, they are also consistent in quality, so there is no risk of a certain model being extremely poor or unreliable.

Warranty

One of the biggest draws is their warranty offers. Depending on the exact boiler model you choose and the features included in the design, you can have a warranty of anywhere between five and ten years.

This means that with Worcester Bosch, you are covered in case something goes wrong, even if the fault only becomes obvious nine years after installation.

Even better, installing more Worcester Bosch products can extend this warranty: adding their filter system to one of their combi boilers can add another year to your overall warranty time, which means that you get even more protection if you gradually upgrade your new combi boiler during the existing warranty period.

Worcester Bosch Greenstar CDi Compact Dimensions

Price

Higher quality often comes with higher prices, and Worcester Bosch used to be a major example. Over time, though, some of their models have become much more affordable, and there are monthly payment options for people who can’t afford an up-front cost.

Getting Worcester Bosch combi boilers in 2024 can also be cheaper through third-party installers.

Worcester Bosch Boiler Range

Worcester Bosch Model

Kilowatt (kW) Outputs

Greenstar 8000 Style

30

35

40

45

Get a quote

Greenstar i (discontinued)

-

-

25

30

Get a quote

Greenstar 4000

25

30

-

-

Get a quote

Greenstar 2000

25

30

-

-

Get a quote

Greenstar Si Compact

-

-

25

30

Get a quote

CDi Classic

29

34

38

42

Get a quote

CDi Compact

-

28

32

36

Get a quote

CDi Highflow

-

-

44

55

Get a quote

Worcester Greenstar i (Now the Worcester Bosch Greenstar 4000)

The Greenstar i is Worcester Bosch’s most popular boiler that is ideal for small to medium-sized homes and has simple and easy-to-use controls; Worcester's new Greenstar 4000 range has since replaced this boiler. Here are some features of the Greenstar i:

  • Condensate discharge resilient to freezing up to -15?

  • Wide choice of controls

  • Low energy pump reduces electrical usage

  • Hot water instantly heated from cold mains

  • Achieves A-Rated efficiency

  • Fills a kitchen sink in 45 seconds

Worcester Greenstar Si Compact

This combi boiler has the same features as the Greenstar i but is much more compact to fit in a kitchen cupboard. It also has extra features such as frost protection and can fill a kitchen sink in 45 seconds.

Worcester CDi Classic

The Worcester CDI This is one of the more expensive combi boilers available but does guarantee reliability, fuel efficiency and a user-friendly interface. This combi boiler is suitable for many property types and sizes and is available in four heating outputs. Its modulating pump and intelligent controls also allow a 30% electrical energy reduction. It also comes with a 5-year warranty for peace of mind.

Worcester CDi Compact

This boiler is like the classic except much smaller to enable it to fit in a kitchen cupboard, making it ideal for smaller homes. It comes with frost protection, a user-friendly display and simple boiler controls to ensure you can manage your comfort and costs.

Worcester CDi Highflow

This combi boiler is an incredibly useful floor-standing combi boiler for large homes with many bathrooms. It provides high hot water flow rates of over 90 litres of draw-off. It has a wide choice of simple-to-use controls and a temperature display; however, with having such a large unit, a large space such as underneath a kitchen counter is required.

Honorable mentions

  • Glow worm

  • Baxi

  • Potterton

Glow Worm Combi Boilers

Glow Worm are the opposite of the previous two choices: they might be somewhat simple, but they are also incredibly cheap, often appearing in rental properties and budget renovation projects.

Reliability

Lower reliability can make them a risk in some cases, but they also come with warranties between two to five years, and installation is extremely straightforward.

This gives you a very unique option for situations where a full boiler may not be needed, especially if you are actively planning to replace it with another boiler in the next few years.

This niche is hard to fill with larger and more expensive options, making Glow Worm useful in the short term.

Low low prices

The very low cost can also make them a suitable choice in the long term as long as you can keep replacing or repairing them.

For example, if you save money for a full house renovation and do not want to spend thousands on a top-tier combi boiler, one or two Glow Worm models can do the same job until you are ready to renovate the entire building.

This does not make Glow Worm a bad choice; it just means they are suited to particular situations. If you need cheap, straightforward and functional combi boilers, it is a good place to start looking.

Baxi Boilers

Baxi is another high-quality option that fits somewhere between Worcester Bosch, Valiant, and Ideal Boilers.

Their boiler range includes combi boilers and other varieties, and all of them are relatively easy to install, coming in at a slightly lower price that makes them more affordable in the long term.

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Baxi combi boilers are designed primarily for homes that do not demand a lot of hot water all at once, meaning that they may not be as effective if you have two bathrooms or multiple hot taps that you are using at the same time.

However, they are very small and can easily be installed almost anywhere in the average home, which makes them a perfect choice if you are looking for a compact solution.

Efficiency

They also come with various efficiency improvements and other benefits, making them very useful if you want to keep your cost down and your heating functioning well.

This combination of compact construction and reduced costs make them a great middle-ground option for most homeowners and ranks them as one of the best combi boilers.

Potterton

Potterton gets high ratings but is not known all that well, and their recent changes to their combi boiler models have given them two distinct types of boiler.

Durability

Older Potterton models are very durable, whereas newer ones are cheaper but lose some of their durability in the process.

Even so, engineers install them purely because of their excellent support, making it much easier to resolve faults or report issues that might be covered under warranties.

They are also the cheapest of the top-tier boiler brands featured on this list, which can make them much more accessible without sacrificing too much in terms of quality.

While Potterton may not be mentioned very often, that does not make them a bad choice, and many people still swear by using them over and over again.

They fill a niche for people who do not have a high budget but still want something more than cheaper options.

Which combi boiler do I choose?

The problem with choosing the best combi boilers is that every homeowner can want different things.

Combi boilers are meant to heat water and provide heating, so they will need to do those basic things, but other features can vary depending on what you are looking for.

For example, some people are desperate for high-efficiency models that cost less to run, especially if they are already on a tight budget and do not want high heating bills that can eat into their savings.

Other people have more than enough money to cover the bills and want higher heating speeds or temperatures instead.

On top of that, some people want the lowest install price and do not care about the actual effectiveness of the boiler, especially in rental properties or homes they are renovating. A cheap boiler can be a good holdover until you are ready to replace it with something more expensive.

Price of a new combi boiler

If the price is all you care about, then the best combi boilers are the ones that do not cost much to install and even less to run. We do also have an in-depth blog on combi boiler costs to help you better decide when purchasing a new boiler.

A cheap but inefficient boiler will add up over time, so something efficient and low-priced can be the best choice in terms of affordability.

If you can get the boiler on a finance plan rather than with an upfront payment, this becomes even better.

Remember that installation fees are sometimes a thing, so you’ll want to keep that in mind if you will not install the combi-boiler yourself.

The more complex the process, the more it can cost, especially if you need new pipes and systems installed so the boiler can connect properly.

Size of the boiler

A bigger gas combi boiler can often be more powerful, but it also takes up more room and will generally make more noise.

If a boiler is too bulky, then you will need space to keep it somewhere, and that can often mean that you will have to do more work opening up space in a wall or building something to cover it.

Conversely, a compact boiler can easily be fitted into existing spaces with minimal effort and usually sounds quieter.

On the other hand, this might also reduce the power it uses and the level of heating that it can offer: improving efficiency but reducing overall strength.

Neither is necessarily better; it comes down to personal preference and the number of items in your home that will need hot water or higher water pressure to operate.

Quality of the boiler

Many best combi's will be built to a high-quality standard. There are rarely any times when a low-quality boiler is better unless it is far cheaper. A single high-quality combi boiler can cost less than replacing a low-quality option multiple times.

If you have the option, always go for the better-quality models if they are available, and be sure to look up any common issues with the boiler before you decide to purchase it.

Warranties can matter a lot, too, since they will sometimes make up for a drop in quality by allowing you to get a replacement or repair job done.


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Frequently Asked Questions

What are the top 6 combi boiler brands in the UK for 2024?

In 2024, the top 6 combi boiler brands in the UK are likely to be:

  • Worcester Bosch
  • Viessmann
  • Vaillant
  • Ideal
  • Baxi
  • Glow-worm
These brands are known for their reliability, efficiency, and excellent after-sales service.

Which combi boilers are best for 3-bedroom houses?

For 3-bedroom houses, you should consider combi boilers with a higher output to ensure adequate hot water supply and heating. Some good options include:

  • Worcester Bosch Greenstar 30i
  • Viessmann Vitodens 050-W 29kW
  • Vaillant ecoTEC Plus 30kW
  • Ideal Logic+ 30kW
  • Baxi 630 Combi 30kW

What are the most reliable gas boilers in the UK for 2024?

Reliable gas boilers in 2024 will likely include models from Worcester Bosch, Viessmann, and Vaillant, as they consistently receive high ratings for customer satisfaction and reliability in surveys and reviews.

Which boiler brands do plumbers highly recommend?

Plumbers often recommend well-established boiler brands such as Worcester Bosch, Viessmann, Vaillant, Ideal, Baxi, and Glow-worm. These brands have a reputation for producing reliable, high-quality products and offer excellent customer support.

How can I choose the right combi boiler for my home?

To choose the right combi boiler for your home, consider factors like:

  • The size and type of your property
  • Number of bedrooms and bathrooms
  • Hot water usage and flow rate requirements
  • Space available for installation
  • Your budget and preferred brands
It is always good to consult a Gas Safe registered engineer for personalized advice and recommendations.

Are there any boiler brands to steer clear of in 2024?

While specific brands to avoid might not be outlined, it's crucial to research and read customer reviews. Avoid lesser-known or budget brands with consistently negative reviews, as they may be more prone to reliability issues or lack robust after-sales support. Stick with reputable brands with a proven track record for best results.

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Article by
Stephen Day | Co-founder
Gas Safe registered and FGAS certified engineer with over 20 years experience in the heating and cooling industry.