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Last updated: 2nd January, 2024


Best Condensing Boilers 2024

Best Condensing Boilers 2024

Key takeaways

  • Condensing boilers are extremely efficient as they recycle excess heat for reuse.
  • Many condensing boilers feature stainless steel heat exchangers integrated within the casing unit, this aids efficiency.
  • Condensing combi boilers are very convenient as they fuse the plus points of both types of system.

Condensing boilers are considered to be some of the most efficient boilers out there on the market and are effective at heating people's homes without impacting the planet or costing too much to run.

In 2005, the UK government made it law that all new gas boilers that were being installed in homes across the country must be condensing boilers.

Why Choose A Condensing Boiler?

Good news, all our best combi boiler brands available at iHeat are also condensing boilers. 🎉

This is because condensing units are considered to be more energy-efficient boilers and are safer to use in all kinds of homes. We only offer condensing boilers at iHeat for this reason.

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If you are looking to get a next day, new boiler installed in your home, then you will need to look into getting a condensing model, as this is what will be recommended to you by any boiler installation company, most new combi boilers are condensing boilers so they are readily available.

With lots of options out there for boilers, it can be quite difficult to know where to start when you need to replace your old model, finding the best combi boiler for your home can be difficult, which is why we do all the work for you with our bespoke quoting service.

This is why we have curated this list of the best condensing boilers available from manufacturers so you can do research and figure out which boiler will be the most suitable for your home. This will make it easier to act when you need to replace your heating system.

We also offer installation of all boilers by a gas safe engineer. For more on how condensing boilers can help you stay warm and safe while also saving you money, keep reading.

What is a Condensing Boiler?

A condensing boiler is considered to be the most efficient option on the market. Like all other boilers, such as combis, this system is a way to control heating within your home.

The Fuel 🛢

They run on gas or oil and are made to work to a better energy efficiency than any other model as they rely on what is known in the industry as condensing technology. Take a look out our recommendations on the best oil boilers on the market here.

In a nutshell they recycle all heat generated, with the compact size of combi boilers ensuring they are suitable for all kinds of homes.

The Technology 🔧

This condensing technology within condensing boilers ensures that the unit makes better use of the heat they generate. They work by, unlike non condensing boilers, trapping hot gases within the unit so they can be recycled back into the system through a heat exchanger.

The Heat Exchanger 🔥

Non condensing boilers do not have a heat exchanger, which means that the hot gases and heat generated when they are turned on is wasted. In non condensing boilers, this additional heat is released via a flute into the atmosphere, where it is wasted.

Energy Efficient 🌱

A condensing combi boiler works to be more energy efficient as it recycles this additional heat and uses it again within the system, making them more effective and cheaper to run.

The recycled heat within condensing boilers is then used for hot water or heating.

Difference Between Combi Boilers and Condensing Boilers?

Not The Same As A Combi Boiler

A lot of people mistakenly believe that condensing boilers are the same as combi boilers, and this can make it even harder to find the best boiler for your home as you do not know what to look for.

No Water Tank Needed

Whilst we do offer condensing combi boilers, there are some significant differences between the two types of heating systems. A combi boiler combines both a water heating system and a central heating system and gives users control of both within one unit.

With this kind of unit, the need for a separate water tank is removed, which is why a lot of combi boilers are compact in size.

Condensing Combi Boilers

A combi boiler can also be a condensing boiler, as the two systems can be combined into one unit. This means that instead of using heat only boilers with a separate water tank, the technology of condensing boilers and their heat exchangers can be paired with the convenience of a combi boiler to ensure easy installation in all kinds of homes.

Heat Exchanger

The main feature of a condensing boiler is the heat exchangers within them. Some models will use heavy materials like stainless steel for their heat exchangers, as this is the part of the boiler that recycles heat.

Recycled Heat

Instead of letting heat escape through pipes, as non condensing boilers do, heat is trapped within the unit and is recycled through the heat exchangers so it can be used again for heating or hot water.

The combination of combi boilers with condensing boilers makes for a highly efficient heating system that can reduce energy bills and your impact on the environment.

Without the need for an additional water storage tank, they can be compact in size and offer easy installation, which can also reduce the price of the boiler. The price of the boiler usually includes the price of the unit itself as well as the cost of installation.

Simple Installation

If the installation is simple, as there is only one unit to be installed within your home, the price will be reduced. This is another reason why a condensing boiler is a better option than a traditional non condensing boiler. If you are interested in how long it takes to fit a new boiler into your home, we have you covered. Times can vary, which is why we have produced a full guide for you.

All installation of boilers needs to be completed by a gas safe registered engineer, which is something we offer at iHeat within the cost of our boilers.

Its The Law

Condensing boilers are now mandatory, which means that most of the combi boilers available for installation will also have a heat exchanger in them for better energy efficiency. When you get a new boiler, it is likely going to be a condensing combi boiler because of the government rules following heating systems.

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Why You Should Get A Condensing Boiler

Following the government's advice in 2005, all homes that are replacing an old boiler now need to get combi boilers installed. This is because they are more energy-efficient, safer to run, and also cheaper for the household.

There are some great benefits to having a condensing boiler installed in your home, as opposed to old system boilers or any other model.

As we have mentioned, condensing boilers are significantly more efficient than system boilers because they recycle the heat they generate to be used again in hot water or heating.

Some of the most modern condensing boilers that are available, which we will talk about in this review of best condensing boilers, are upwards of 90% efficient. System boilers, which are non condensing boilers, are only able to achieve around 70% to 80% for energy efficiency.

These figures make it clear to see how condensing boilers are highly cost-effective for homeowners, which is a great reason to get them installed. Some reports claim that homeowners can save on average over £300 a year simply by replacing an old system boiler with one of the best condensing boilers.

As well as helping you save money on your energy bills, condensing boilers are also much better for the environment.

Running a condensing boiler will burn less fuel because they recycle the heat they generate, and this helps to reduce the carbon emissions coming from the home.

With reduced carbon emissions, condensing boilers have less of an impact on the environment, which is another positive reason to have them installed in your home.

What Are The Best Condensing Boilers?

The best condensing boilers will be A-Rated, which is a grade given to indicate the energy efficiency of combi boilers by the Energy Saving Trust.

The benefits we have mentioned when it comes to running a condensing boiler in the home, such as the reduced energy bills and reduced impact on the environment, are the reasons why we only offer condensing boilers and combi boilers.

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The following are the best condensing boilers available for all homes. We offer a fixed price for all condensing boilers, as well as options to pay monthly so you could save a lot of money choosing to get a condensing boiler installed instead of system boilers.

#1 Viessmann Vitodens 050-W 29kw

This is a compact condensing boiler that runs on gas. It is low cost and compact enough to fit into a range of spaces, making it a great option for heating and hot water in all kinds of homes.

For this condensing boiler, Viessmann has ensured not only low energy bills but also a low weight and quiet operation to ensure it is suitable for all kinds of home.

It is suitable for both new builds and the modernisation of homes, and the compact boiler size makes it suitable for all spaces. This is an A-rated condensing combi boiler with an efficiency rating of 89.1%.

#2 Viessmann Vitodens 050-W 35kw

This is another boiler by Viessmann that is equal in its compact size. This is reviewed as the Which? Best Buy boiler because of the A grade efficiency rating, as well as the compact boiler size, which makes it suitable for a range of properties.

This is a combi boiler, which means it can be used for both central heating and hot water but also relies on a heat exchanger to reduce waste. The fuel type is gas, and it has a maximum power output of 35kW.

Worcester Bosch Greenstar i 30kW

#3 Worcester Bosch Greenstar i 30kW

This Worcester Bosch Greenstar condensing boiler is one of our best sellers, and this version has a higher output than any other from the brand. It is a versatile condensing boiler that can be used in all kinds of homes, whether large, medium, or small, as well as detached or semi-detached homes.

The compact size of this condensing boiler makes installation simple as it is small enough to be put into even a kitchen cupboard. This is also a combi boiler which means that it can be used for heating and hot water.

This is an A-rated condensing boiler with an energy efficiency rating of 93%.

#4 Alpha E-Tec 28kw

This is one of the best condensing boilers for those working with a smaller budget, and it is available at a fixed price for the installation. This condensing boiler features a brand new stainless steel heat exchanger and is the most compact size yet, ensuring it is suitable for installation in all homes.

The compact size of this Alpha condensing boiler makes it suitable to be installed into standard kitchen cupboards. It has an output of 28kW, making it suitable for smaller properties, and it is a combi boiler which means it can control heating and hot water throughout the entire home.

Alpha E-Tec 33kw

#5 Alpha E-Tec 33kw

This is another condensing boiler from the Alpha E-tec range, but this one has a higher output which makes it suitable for larger homes. It also works likes combi boilers, so it can be used to control the hot water and heating throughout the home while being energy efficient.

Like the other condensing boiler in this range, this boiler also has a new stainless steel heat exchanger, which makes it highly effective. It too is a compact boiler size making installation simple and suitable for even kitchen cupboards.

#6 Viessmann Vitodens 100-W 30kw

For this boiler, Viessmann has used their latest technology to provide the best gas boiler for all kinds of homes. This is a condensing boiler that was released in 2024, ensuring it relies on some of the best boiler features from this year.

This next-generation boiler is one of the best combi boilers out there because not only is it energy efficient, but it is also compact and quiet. This is one of the best boilers out there because it is also affordable, with installation at a fixed price along with options for monthly payments.

This new boiler features innovative technology and systems along with reliability and longevity, making it a great option for most homes. The compact size offers simple installation, and this boiler is optimised for heating your entire home to help you save money on energy bills.

Viessmann Vitodens 100-W 35kw

#7 Viessmann Vitodens 100-W 35kw

This is yet another boiler from the new generation of Viessmann condensing boilers. This new condensing boiler offers a higher output making it a more effective heating system for larger homes.

Even though it has a higher output, this Viessmann Vitodens 100 w boiler still works with a smaller carbon footprint than non condensing boilers because of its high efficiency. This is yet another A-rated condensing boiler with an efficiency rating of 89.5%.

This boiler was voted as the Which Best Buy for condensing boilers in 2019, and it continues to be a popular product.

#8 Worcester Bosch 8000 Style 30kW

These new boilers are the latest design from Worcester. They are sleek and stylish with a modern new design and are full of innovative new features. This boiler works like other combi boilers as it can control both hot water and heating throughout the entire home with a reduced carbon footprint.

This is an A-rated boiler that has an energy efficiency rating of 94%, making it a great option for those who want to reduce their impact on the environment and also save money on their energy bills.

Worcester Bosch 8000 Style 35kW

#9 Worcester Bosch 8000 Style 35kW

This is yet another of the new boilers from Worcester that is best known for its sleek, modern design.

It is an attractive boiler that can be installed in various areas around the home, and it is full of innovative system features to make it highly effective.

This new boiler relies on some of the latest technology from the industry to ensure a high energy rating and makes it one of the best condensing boilers out there.

The difference between this Worcester condensing boiler and the previous entry on this list is the higher output rating, which makes it a better option for larger homes.

#10 Worcester Bosch 8000 Style 40kW

Worcester has come out with a whole range of new boilers that have the same stylish design and modern features. This boiler has one of the highest outputs within this range, making it excellent value for the price, and it also comes with a fixed installation price to help you save money from the very start.

This is a sleek, compact boiler that offers simple installation in a range of homes. This is a combi boiler that can control both hot water and heating within your home at a reduced carbon footprint.

#11 Worcester Bosch 8000 Style 45kW

This is the final condensing boiler from the new range by Worcester Bosch and offers the highest output for the heating of the home and water.

With such a high output, this version of the new boilers can be used across multiple bathrooms to provide hot water and is suitable for a range of homes, including semi-detached or larger properties. It is a combi boiler and has a heat exchanger, so it also works like a condensing boiler with high efficiency.

These boiler models are the latest from Worcester and have such a modern design that will work well in all kinds of homes.

Viessmann Vitodens 111-W 35kw

#12 Viessmann Vitodens 111-W 35kw

This condensing boiler is one of the latest to be released, and it features all of the innovative features to ensure high efficiency. This is a high-performance storage boiler that has a heat exchanger, which is why it is a condensing boiler, as well as working with both heating and hot water, so it is also a combi boiler.

It is a reliable heating system that offers versatile installation as it is made to be wall mounted. It comes with a fixed price for installation, helping you save even more money.

This condensing boiler features a cylinder loading system (CLS) as well as a stainless steel water tank which has a capacity of 46 litres. This integrated stainless steel water storage tank makes this boiler one of the fastest to heat your home, and it can fill a standard bath with hot water in under 8 minutes.

Even with an integrated water storage tank, this new condensing boiler is sleek and compact. It can be mounted on the wall and has a modern design with innovative controls for ease of use.

How Much Do Condensing Boilers Cost?

Getting a new heating system installed in your home is going to be an investment, but it is something that will benefit your home in the long run.

Getting a new boiler installed, such as those by the boiler manufacturers mentioned in this article, is an investment, but according to the Energy Saving Trust, you could save upwards of £300 per year with a new condensing boiler rather than relying on your old system boiler.

Get A Fixed Price

At iHeat, we offer a fixed price for the installation of all of our boilers. The installation will be performed by a gas safe engineer, and we can also offer next day installation for the same price.

Several costs go into total boiler prices, and installation is one of them.


Boiler prices can vary greatly based on the kind of unit you choose and what kind of model it is. Various factors are considered when it comes to the price of the boiler unit, including the brand behind it as well as the fuel type. Condensing boiler prices will be higher than those of a non condensing boiler because of their higher energy efficiency.

Condensing boilers are modern units that rely on innovative technology to provide heating and/or hot water to your home. With this in mind, boiler prices can start at £1,000 or over.

Consider Finance

We understand that boiler installation is a large cost for many households, which is why at iHeat we also offer 0% finance for all our boilers along with price match to ensure you are getting the best deal every time. All of our boilers come with a 10 year warranty.

This warranty applies to both parts of the boiler and the labour included for repairs or installation. As a company registered in England, we can also offer 0% finance to our customers when it comes to buying boilers.

We have a variety of finance options for our customers, which are authorised and regulated by the Financial Conduct Authority in England and Wales, ensuring that everyone can afford to get a new boiler installed.

What About Installation?

The price that is shown for any boiler on our website also includes a fixed price for the installation.

We work with gas safe registered engineers who can offer boiler installation even on the next day following your purchase. Working with registered engineers ensures the highest quality and safest processes when it comes to getting a new boiler installed.

Within the 10 year warranty offered for all of our boilers, coverage is also provided for any repairs that need to be done by the boiler manufacturers.

Boiler installation is included for all of the products in this article, and the cost is included in the total price of our boilers.


We have some of the best condensing boilers available for our customers from top boiler manufacturers. Condensing boilers are now mandatory for homes across the United Kingdom because of their energy efficiency rating, and this is why now when you ask for a new boiler, you will be offered a condensing model.

The Price

Condensing boilers can be much cheaper to run than traditional gas or non condensing boilers because they recycle the heat they generate. Using a heat exchanger, a condensing boiler is cheaper to run as it makes use out of everything it generates, allowing you to run heating or hot water more without ranking up high energy bills.

Think About The Environment

These kinds of boilers are also better for the environment for this reason, as they do not burn as much fuel whenever they are in use.

At iHeat, we offer some of the best condensing boilers to suit every home and budget. The price of our boilers is guaranteed to be the lowest, as we price match with other companies. We also offer installation of our condensing boilers from registered engineers to ensure that your home is safe and warm as soon as you need it to be.

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Next Day Installation

Our engineers can also offer next day installation of your boiler if requested.

There are lots of benefits to having a condensing boiler installed in your home, which we have highlighted in this article. These kinds of boilers allow you to control both the heating of water and the heating of your home in one unit, as well as to help to reduce energy costs as they are more efficient. If your boiler has stopped working, get in touch with us today for the best prices on the market, with us offering price match for any like-for-like quote.

Repair Vs Replace

All boilers need to be replaced every ten to 15 years, so it might be time for you to consider getting a new heating system at home. You will need to have a condensing boiler installed, and we are the best place to look at when it comes to these units.

Financing Options

We can offer 0% finance on all condensing boilers, as well as a 10 year warranty for parts to ensure that you get the best deal every time.

Condensing boilers are a great way to cut back on your energy bills as well as reduce your impact on the environment.

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