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Best Combi Boilers 2021
What is the Best Combi Boiler To Buy in 2021?
If you are searching for the best combi boiler for your needs, we are here to help you.
Like any big-ticket purchase, searching for the best combi boiler can be a challenge. With so many options available for this type of boiler and at varied price ranges, it is hard to know which boiler to choose. However, that’s where we come in at Boilerhut. As an independent boiler installation company, we’ve done the hard work for you. We’ve picked out the best combi boilers available to buy in 2021.
Already know what boiler you need?
What Makes a Good Combi Boiler?
A good combi boiler is one that ultimately meets the specific needs of your household and property. Choose the wrong size combi boiler and you will end up spending too much on your heating and hot water. Or you will end up not being delivered with the levels of hot water you require. We go on to assist you in choosing the correct size combi boiler for your property further down in this guide. Whether it’s going in a kitchen cupboard or separate room our team can help you find the right boiler for your home.
We have extensively reviewed the current combi boiler ranges available in the UK. From this, we have narrowed this down into a list of the top 5 combi boiler manufacturers. To produce this list, we have called upon the experience and expertise our team of engineers have gained over 40+ years. And we have considered the following factors:
- Price
- Warranty
- Design
- Material quality
- Flow rate
- Customer feedback
- Customer service
- Awards and accolades
Top 5 combi boiler brands
1. Viessmann
A German boiler manufacturer. Viessmann was established in 1917 and entered the UK market in 1989. However, it is only in the last decade or so that Viessmann has begun making its mark in this country. Prior to this, Viessmann’s UK operations were focused upon the industrial and commercial boiler market. We are pleased to say that they have taken this expertise and effectively translated it into the domestic market. Whilst still not a household name in the UK, Viessmann is the largest boiler manufacturer in Europe.
We are confident in saying that Viessmann offers the best combi boilers available on the UK market in 2021.
Our engineers’ thoughts on Viessmann
Easy to maintain
Our engineers love Viessmann combi boilers. Due to the components utilised and how easy the boilers are to install, service and maintain. All of which means savings for you, the customer.
In terms of components, Viessmann stands out because every component it utilises in its boilers is manufactured in-house. At the same production facility where the boiler is assembled. This is something that not many other boiler brands can say. Because each of the components is manufactured by Viessmann, they are optimised to work effectively together. Meaning that the boilers suffer from fewer breakdowns and retain efficiency for longer.
High quality
The quality of Viessmann components is something that should be celebrated. Particularly its use of its patented Inox-Radial stainless steel heat exchanger. It is this component that enables Viessmann to stand out. Due to the grade of stainless steel utilised. Only one grade below surgical steel. The stainless steel used makes these heat exchangers highly resistant to corrosion and enables the boilers to retain their efficiency across the lifetime of the appliance.
Smart technology
We also recommend Viessmann boilers highly due to the future proof smart technologies they utilise and the comprehensive warranty of up to 12 years that they offer.
Why Viessmann stands out as the best combi boiler manufacturer
Technology and components
Stainless steel Inox-Radial heat exchangers
As we discussed above, the entire Viessmann combi boiler range is equipped with stainless steel Inox-Radial heat exchangers. This is a major reason to choose Viessmann for your next combi boiler. As the quality of the component will prevent future boiler breakdowns. The reason being is that stainless steel, and particularly this grade of stainless steel, is highly resistant to corrosion and erosion. Which are the leading reasons for boilers breaking down. This resistance also ensures the boilers are able to retain their efficiency. Meaning your gas bills will remain consistent and won’t suddenly increase after a few years of having the boiler installed.
Lambda Pro Control combustion controllers
An intelligent combustion control system. The benefit of a Lambda Pro Control combustion controller is that it ensures efficient operation regardless of the gas supply. This also means that it automatically adjusts to all gas types. Meaning that Viessmann combi boilers equipped with this component can be installed into homes not connected to the mains gas grid and that instead use LPG.
Brass parts and components
Brass parts and components are a simple but very beneficial feature of the Viessmann combi boiler range. Whilst other leading boiler manufacturers use plastic and composite parts, Viessmann opts for much harder wearing brass alternatives. The benefit of this is that Viessmann combi boilers don’t fall foul of the component failures that other boiler manufacturers suffer due to components perishing.
Touchscreen LCD displays
The Viessmann Vitodens 100-W, Vitodens 111-W, and Vitodens 200-W boilers are all equipped with a touchscreen LCD display. Not only does this look good and give these boilers a really modern aesthetic, but it also allows for simple control of the heating. And provides at a glance information about your heating system. Whilst being backlit, it means that you can always see it. Even if your boiler is installed in a dark cupboard.
Compatible with smart home technology
The entire Viessmann combi boiler range is compatible with smart home technology. Including Nest, Hive, tado°, and Viessmann’s own ViCare smart thermostat. This means that Viessmann combi boilers can be controlled remotely wherever you are in the world with an internet connection. It also means that the efficiency of your heating system can be increased. Thanks to smart technology that will only provide heating and hot water when you need it.
In addition to this, this technology enables you to see detailed information about your energy consumption. And brings functionality such as weather compensation to your boiler. In the case of Viessmann’s ViCare app, this also allows a heating engineer to quickly diagnose a problem with your boiler before even visiting your property.
Compatible with solar collectors, heat pumps and hydrogen fuel
Viessmann heavily invests in future innovations and compatibility with renewable energy sources. Such as solar collectors and heat pumps is massively beneficial to its combi boiler range. Providing futureproof ability. Enabling you to reduce your energy bills and your carbon footprint by adding renewable energy sources to your heating system.
In the case of the Viessmann Vitodens 100-W, this is one of the first boilers on the market that comes H2 ready. This means it has been developed to use a 20:80 hydrogen mix as its fuel source. This is in line with the government’s proposals for a future fuel source to replace natural gas.
The energy efficiency of up to 98%
With market-leading energy efficiencies of up to 98% across its range, with a Viessmann combi boiler, you will be able to save on your energy costs. Meaning that your know that you are doing your bit to reduce carbon emissions.
Warranty
Viessmann offers up to a 12-year warranty on its combi boiler range when installed by a Viessmann trained installer. This is very beneficial as Viessmann boiler warranties are comprehensive, and cover both parts and labour.
So that the warranty remains valid, Viessmann requires customers to register their boiler within 30 days of being installed. And ensure that it is serviced annually by a Viessmann Trained Installer or another Gas Safe Registered engineer.
Availability of parts
Viessmann has a UK parts distribution centre in Telford. All combi boiler parts are now widely available in all Plumbase stores across the UK. Plus many other plumbing merchants online and in-store.
Reputation
Out of 1,837 reviews, Viessmann UK has a Trustscore of 4.5 and an excellent rating on Trustpilot.
Viessmann combi boilers have also been the recipients of multiple Which? Best Buy awards over the past five years.
Interested in a Viessmann boiler?
2. Worcester Bosch
Worcester Bosch has been a permanent fixture in the UK boiler market since being established in 1962. Since then it has become a household name amongst UK consumers. Many consumers choosing the brand time and time again because they know the name or already have a Worcester Bosch boiler installed.
Put simply, Worcester Bosch has an enviable reputation in the UK. This is for good reason. For many years Worcester Bosch has offered high-quality combi boilers to their customers. All of which are backed up by the global reputation and engineering might it has gained since becoming part of the Bosch group in 1992.
Worcester Bosch is the UK market leader in domestic boilers. And has built up an excellent reputation over the last 50 years. Becoming a household name in the UK. During this time, they have also received a Royal Warrant for supplying boilers to Her Majesty The Queen’s Sandringham Estate.
Our engineers’ thoughts on Worcester Bosch
Worcester Bosch has earned its place in this list due to the excellent reputation it has in the UK. As well as the sheer volume of Worcester Bosch combi boilers that are installed in UK properties.
Our engineers rate the Worcester Bosch combi boiler range due to the range of options that are available. Worcester Bosch combi boilers are available in gas, oil and LPG fuel types and are available in a very wide range of outputs. This means that there is a Worcester Bosch combi boiler available for the heating and hot water demands of many properties and household sizes.
Worcester Bosch combi boilers are noted for their high efficiencies, solid build qualities and long warranties. These things make them a favourite amongst consumers. We also like them due to their compact dimensions and their ability to be able to be installed in multiple locations throughout the home.
Technology and components
Aluminium heat exchangers
Whilst not as good as stainless steel heat exchangers overall, aluminium heat exchangers do come with some benefits. The biggest benefit of an aluminium heat exchanger is its thermal conductivity. Aluminium heat exchangers have a high thermal conductivity which means Worcester Bosch boilers have the ability to get hotter more quickly.
Another benefit of aluminium heat exchangers is their low operating noise. As the waterways in aluminium heat exchangers are larger, it means a larger volume of water can pass through them with less obstruction. This means lower operating noise.
Combi boiler options available for gas, oil and LPG
The Worcester Bosch combi boiler range is vast. Meaning there is an option for many types of property and sizes of the household.
Compatible with smart home technology
The entire Worcester Bosch combi boiler range is compatible with smart home technology. Including Nest, Hive, tado°, and Bosch EasyControl. This allows Worcester Bosch combi boilers to be controlled remotely from anywhere in the world. Providing you have an internet connection.
Smart home technology will also increase the efficiency of Worcester Bosch combi boilers. By optimising your home’s heating and hot water schedule to only provide this when you need it.
If opting for Bosch EasyControl, allowing for remote control of the boiler. Providing detailed information about your heating system via the companion app. In addition to this, Bosch EasyControl also allows for your boiler to be controlled via voice commands using Amazon Alexa, Google Home, Google Assistant, and Siri Shortcuts. Allowing for control remotely using Facebook Messenger.
The energy efficiency of up to 98%
The efficiencies of Worcester Bosch combi boilers make them a great choice for consumers looking to reduce their energy bills and their carbon footprint. When installed with a smart thermostat, Worcester Bosch combi boiler models such as the Greenstar i are able to achieve impressive efficiencies of up to 98%.
Warranty
Warranty, referred to as guarantee by Worcester Bosch, is a strong point for the Worcester Bosch combi boiler range. Covering replacement parts, call out charges and labour costs. Worcester Bosch offers up to 12-year guarantees on its combi boiler ranges.
Like other manufacturers, the guarantee is subject to terms and conditions. Namely the following: the product must be purchased and installed within the UK or Ireland. It must be installed and commissioned in accordance with Worcester Bosch’s installation instructions. It should be registered within 30 days of installation and should be serviced annually. The boiler should only be used in a domestic or light commercial environment, and once installed, the boiler should not be moved.
Availability of parts
Worcester Bosch combi boiler parts are widely available in the UK from Screwfix, Plumbase and many other plumbing merchants both in-store and online.
Reputation
Out of 24,121 reviews, Worcester Bosch has a Trustscore of 4.6 and is rated Excellent on Trustpilot.
Worcester Bosch combi boilers have notably been the recipient of multiple Which? Best Buy awards over the past few years.
Interested in a Worcester Bosch boiler?
3. Navien
Navien is a very new entrant. Not just to the UK combi boiler market but the UK boiler market in general. Despite this, we see big things for this South Korean boiler manufacturer. We tip it to be the recipient of multiple prestigious UK awards in the next few years.
It should be noted that whilst Navien is a new entrant to the UK market, having only been here since 2014 and having only offered combi boilers since 2017, it is a major player internationally. They are the world’s best-selling boiler brand. Its production facility in Seotan, South Korea, is the largest boiler production facility in the world. As you would expect with such accolades, Navien is already making waves in the UK market with its use of innovative technology.
Our engineers’ thoughts on Navien
Our engineers recommend Navien for its oil combi boiler range. This range is equipped with cutting edge heating innovation. Namely its blue flame technology.
Our engineers are impressed with Navien’s blue flame technology. As it increases the efficiency of its oil boilers, whilst guaranteeing low NOx emissions. Not only that, but it also comes as standard across the Navien oil boiler range. Whilst it is a costly upgrade from other boiler manufacturers.
The fact that Navien utilises a stainless steel heat exchanger across its entire oil boiler range is another major positive for the manufacturer. Stainless steel heat exchangers have always been a component reserved for premium boiler manufacturers. This already sets Navien apart from the competition who are much more established in the UK.
Navien’s stainless steel heat exchangers will protect the boiler from breakdown. Due to their high corrosion and erosion resistance. In addition to this, they will also ensure that the efficiency of the boiler is retained throughout its service life.
Very much like Viessmann, Navien is also a major advocate of not using plastic and composite parts. Instead utilises parts made from stainless steel and brass across its oil combi boiler range. This again sets Navien apart as a premium boiler manufacturer. Preventing its boilers from suffering from the perishing of parts and breakdowns that come with this. Issues that boilers with plastic and composite parts are known for.
Beyond technology, our engineers also recommend Navien due to how easy its boilers are to install, service and maintain. Navien has invested in the development of this area heavily. It shows boilers that are much lighter than the competition and provide easy access to vital components. Whilst definitely making the engineers’ lives easy, this is also of benefit to the customer. As it means reduced labour costs as the engineer won’t have to spend as long with the boiler.
Technology and components
Stainless steel heat exchanger
The entire Navien oil combi boiler range is equipped with stainless steel heat exchangers. Which is a massive positive for Navien. A greatly reduced chance of a boiler breakdown and retained efficiency for the lifetime of the appliance. The two biggest benefits that the superior material this component is manufactured from, brings.
Blue flame technology
Navien’s use of blue flame technology, which comes as standard, really sets it apart from the competition who charge extra for this as a feature. The benefits of this technology are superior efficiency and guaranteed low NOx emissions.
Navien’s Smart Plus smart thermostat app
Navien’s Smart Plus smart thermostat app brings worldwide heating system control to its oil combi boiler range. Allowing you to control your heating wherever you are with an internet connection. In addition to this, when combined with Navien thermostatic radiator valves (TRVs), the app also enables you to set heating zones on your property. So that you can remotely and independently control the heating in different areas of your home. Further to this, the Smart Plus app also enables Navien boilers to connect to the internet. Monitor the weather via the OpenWeatherMap, and adjust the inside temperature based on the weather conditions outside.
Stainless steel and brass components
The stainless steel and brass components utilised within the Navien oil combi boiler range go a long way to stop the boiler from falling foul of the perishing and corrosion that plagues boilers that utilise plastic and copper parts.
Efficiency
The technology and components utilised within the Navien combi boiler range go a long way to increasing the boilers’ efficiency. This pays off with the Navien LCB700 offering up to 93% efficiency.
Warranty
The entire Navien boiler range comes with 10-year parts and labour warranty.
Availability of parts
Navien combi boiler parts are widely available in the UK from Plumbase and Screwfix branches across the UK.
Interested in a Navien boiler?
4. Vaillant
Vaillant is a German boiler manufacturer which has been manufacturing heating solutions for over 140 years. It is a well-established brand in the UK and has been providing combi boilers to the UK market for decades. All of the combi boilers that Vaillant supplies to the UK market are manufactured at its production facility in Belper, Derbyshire.
Our engineers’ thoughts on Vaillant
Vaillant offers a comprehensive range of combi boilers that are equipped with cutting edge technologies and future-proof functionalities.
Our engineers are impressed with the efficiencies offered across the Vaillant combi boiler range. With up to 94% efficiency offered on the Vaillant ecoFIT pure Combi. Vaillant ecoTEC exclusive with Green iQ Combi, and the Vaillant ecoTEC Pro Combi.
Technology is a winner for Vaillant. The company has invested heavily in this area. Utilising technologies that enable it to be described as a premium boiler manufacturer.
Technology and components
Stainless steel heat exchangers
Though Vaillant doesn’t utilise stainless steel heat exchangers across its entire boiler range, these can be found in most of its combi boilers. The Vaillant ecoTEC exclusive with Green iQ combi, Vaillant ecoTEC plus combi, Vaillant ecoTEC plus combination store, and Vaillant ecoTEC pro combi all utilise stainless steel heat exchangers. Whilst the Vaillant ecoFIT pure combi is the only Vaillant combi boiler in the current range to feature an aluminium heat exchanger.
Compatible with heat pumps
Vaillant recognises that there is a need for renewable heating solutions in the UK. They have developed a range of air-source heat pumps, ground-source heat pumps, and water source heat pumps to meet this growing demand. Vaillant scores highly for us as it doesn’t just produce these products independently but produces them to be fully compatible with its range of combi boilers. Giving consumers greater choice in how they heat their homes.
Premium-quality components
The components that Vaillant utilise earn it a place in this list and confirm it as a premium boiler brand. In addition to the stainless steel heat exchangers utilised across the majority of the combi boiler range, Vaillant also utilises premium quality components. Such as brass diverter valves. By opting for brass rather than plastic or composite components, Vaillant lessens the chance of a boiler breakdown due to these components perishing.
Smart integration
With the development of its own VSmart app, Vaillant was one of the first manufacturers to ensure that its entire combi boiler range is compatible with smart home technologies. Which gave the consumer greater control over their heating system than ever. This continues with Vaillant combi boilers being compatible with a range of smart controls.
Vaillant’s own VSmart smart thermostat adds self-learning capabilities to Vaillant combi boilers. Understanding your home’s heating needs and making your boiler work smarter to reduce your energy bills. Utilising the companion iOS and Android app also enables you to control your heating from afar. Enabling you to warm your home precisely to the right temperature for your arrival home.
VSmart compatibility also means that Vaillant combi boilers can be controlled using voice commands via Amazon Echo devices. Whilst integrating it with IFTTT adds further smart functionality. Such as the ability to switch your hot water on when you leave the gym.
VSmart will also monitor the local weather conditions and adjust your boiler to ensure the temperature in your home is appropriate.
The energy efficiency of up to 98%
Vaillant is noted for the energy efficiency of its combi boiler range. Using its investment into technology to its advantage. Boilers such as the Vaillant ecoTEC Pro Combi are a great example of this and offer up to 98% efficiency.
Guarantee
Whilst we consider Vaillant to be one of the UK’s best combi boiler manufacturers, it should be noted that the guarantee they offer whilst comprehensive, is much shorter in duration than the competition. Whilst the likes of Viessmann and Worcester Bosch is offering up to a 12-year guarantee or warranty on their products, Vaillant only offers a maximum of 7 years. And that’s when the boiler has been installed and registered by a Vaillant Advance installer.
This is reduced to 5 years should a Vaillant ecoTEC exclusive with Green iQ or ecoTEC plus be installed by any other installer and just 2 years if they are installing a Vaillant ecoTEC pro or ecoFIT pure.
Though it’s shorter than the competition offers, Vaillant’s guarantee is still just as comprehensive and covers boiler component failures, material and labour charges.
To qualify for Vaillant’s guarantee, your boiler must be registered within 30 days of installation. Installation and commissioning of the boiler must be carried out by a Gas Safe registered engineer. The boiler must be serviced annually by Vaillant or another Gas Safe registered engineer. And the guarantee does not cover failures caused by contaminated water, or fair wear and tear.
Availability of parts
Vaillant combi boiler parts are widely available at Screwfix, Plumbase, and other plumbing merchants both in-store and online.
Reputation
Out of 14,788 reviews, Vaillant has a Trustscore of 4.6 and is rated Excellent on Trustpilot.
Vaillant was named as the UK’s top-scoring Gas Boiler Brand in the Which? Best Buy 2020 report and has been the recipient of many Which? Best Buy awards over the past few years. In addition to this, Vaillant has been recognised for its green credentials at the Green Home Awards, and the Housebuilder Product Awards.
Whilst its level of customer service was recognised in November 202 by winning the Domestic and General Excellence and Quality award for its service department.
Interested in a Vaillant boiler?
5. Ariston
Ariston finds its place in this list due to being an affordable combi boiler brand. A brand that we recommend to customers not looking for out and out premium functionality in a combi boiler. We say out and out, as whilst Ariston is more of a mid-range combi boiler manufacturer, it’s not completely lacking in premium features across its combi boiler range. Our engineers discuss these features in detail below.
An Italian boiler manufacturer, Ariston was founded in 1930, started producing water heaters in 1960, and entered the UK market in 1986. Ariston is today part of the Ariston Thermo Group, which also owns multiple other leading boiler manufacturers including ATAG and Elco Heating Solutions.
Our engineers’ thoughts on Ariston
Mid-range boiler manufacturers have historically been associated with lower quality components and somewhat dated technology, Ariston bucks this trend and it is for this reason we were adamant they should have a place in this list.
The stand out feature of the Ariston combi boiler range is its use of a stainless steel heat exchanger. Usually only reserved for premium boiler brands, it’s refreshing to see such a component in a boiler at a lower price point.
What a stainless steel heat exchanger means to you as the consumer, is a boiler that is less likely to break down and a boiler that will retain its efficiency for longer. This all comes down to corrosion, or should we say lack of it. Stainless steel as a material is more resistant to corrosion than alternatives such as aluminium.
Corrosion is one of the biggest causes of boiler breakdowns, so with this out of the equation, there’s less chance of an Ariston combi boiler breaking down. The corrosion also impacts the efficiency of a boiler massively too, so again with no corrosion, efficiency is retained.
Another standout feature is Ariston’s 1:7 modulation ratio across its combi boiler range. What this refers to is a boiler’s ability to reduce its maximum output to its minimum output and adapt to provide the desired heating. Whilst a modulation ratio of 1:7 isn’t the highest on the market, with there being combi boilers offering 1:10, it is great for Ariston’s price point as a ‘good’ modulation ratio is described as being 1:6/1:7.
For you as the consumer, it means improved efficiency and longer service life for your boiler. Because it won’t be constantly switching on and off, and placing wear and tear on the boiler’s components.
We are also big fans of the Ariston Cube s Net smart thermostat supplied with the Ariston combi boiler range and the advanced level of control and efficiency this brings to the end-user.
Technology and components
XtraTech™ stainless steel heat exchanger
A premium quality component, the XtraTech™ stainless steel heat exchanger utilised across the Ariston combi boiler range is designed to be robust. Operating well in a wide range of pH levels, making it resistant to the corrosion that causes boiler breakdowns and affects efficiency in other boilers.
Supplied with Ariston Cube s Net and compatible with the Ariston NET smart app
This gives Ariston’s combi boiler range smart technology. Including weather compensation so that the boiler automatically adjusts based on the outside temperature, improved modulation technology so that the boiler isn’t outputting more power than it needs to, Wi-Fi connectivity, and a clean and clear view of information relating to your boiler.
The Ariston Cube s Net also provides compatibility with the companion Ariston Net smart app for Android and iOS devices. This app allows you to control and manage your boiler from your smartphone wherever you are with an internet connection. In addition to this, it allows you to set up a heating schedule so that your home is always at the right temperature. Allowing for voice control using Siri Shortcuts, Google Assistant, Amazon Alexa, and Apple Homekit.
Whilst in the event of system failure, Ariston Net will send you a notification in real-time that informs you of the error code and required action.
Warranty
The warranty period differs across the Ariston range, with the E-Combi ONE LPG and E-Combi ONE coming with a 2-year warranty, the Clas ONE coming with an 8-year warranty, and the Alteas ONE NET and Genus ONE NET coming with a 12-year warranty.
Despite differing warranty periods, even 8 years is still great for a mid-range boiler range. Under Ariston’s warranty, Ariston will repair or replace a faulty boiler when the issue is a direct result of materials or workmanship from the manufacturer.
Ariston’s boilers must be registered within 30 days of installation to validate the warranty, they also must be installed in accordance with the manufacturer’s instructions, be installed by a Gas Safe Registered engineer and must be serviced annually, to ensure the warranty remains valid.
Availability of parts
Ariston combi boiler parts are widely available at Direct Heating Supplies, PlumbNation, and Plumbase both in-store and online.
Reputation
Ariston combi boilers are Good Housekeeping Reader Recommended.
Interested in an Ariston boiler?
Is a combi boiler best for you and your property?
To identify whether a combi boiler is best for you and your property, your main consideration should be the size of your property and your hot water demands.
Combi boilers are great for properties with limited amounts of space, as they don’t require the hot water cylinder or cold water tanks needed with conventional and system boiler systems. However, combi boilers aren’t just for smaller properties. There are now combi boilers available for properties from a 1 bedroom flat to a 4 bedroom house.
Ideal for Larger Properties
To identify whether a combi boiler is best for you, you shouldn’t just be considering the size of your property. You should also be considering the hot water needs of your household. If you have multiple bathrooms and will be utilising multiple showers and taps simultaneously, a combi boiler probably isn’t the best choice for you.
To assist you in determining the best combi boiler for your property, we have selected the best combi boilers for specific property sizes below.
Already know what boiler you need?
Choosing the best size combi boiler for your property
The more bedrooms and bathrooms you have, the higher the output boiler you will usually require. However, to assist you further, we have detailed specific boilers currently available that are suitable for your property size.
What is the best combi boiler for a one-bedroom flat/house?
If you have a reasonably small property with one bedroom and one bathroom, you won’t need a high capacity boiler to meet your heating and hot water needs.
Our recommendation for a property of this size is an Ariston Clas ONE 24kW combi boiler.
| Our Recommend Boiler | Recommended Output (kW) | Flow Rate | Price (Installed) | ||
| Ariston Clas ONE Combi Boiler | 24 | 10.4 l/min | From £1780 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
In addition to the Ariston Clas ONE 24kW, the following combi boilers are also suitable for a one-bedroom flat/house with one bathroom and up to eight radiators:
| Suitable Boiler | Recommended Output (kW) | Flow Rate | Price (Installed) | ||
| Baxi 200 Combi Boiler | 24 | 11.5 l/min | From £1800 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Glow-worm Betacom₄ Combi Boiler | 24 | 10 l/min | From £1750 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Ideal Logic+ Combi Boiler | 24 | 9.9 l/min | From £2000 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Vaillant ecoFIT pure Combi Boiler | 25 | 10.4 l/min | From £2200 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Viessmann Vitodens 100-W Combi Boiler | 26 | 10 l/min | From £2500 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Worcester Bosch Greenstar i Combi Boiler | 25 | 9 l/min | From £2300 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
What is the best combi boiler for a two bedroom house?
If you have a two-bedroom house, you will usually have one bathroom and up to 10 radiators. Our recommendation for a property of this size is a Viessmann Vitodens 100-W 26kW combi boiler.
| Our Recommend Boiler | Recommended Output (kW) | Flow Rate | Price (Installed) | ||
| Viessmann Vitodens 100-W Combi Boiler | 26 | 10 l/min | From £2500 (inc. VAT) | Get a quote for this boiler |
In addition to the Viessmann Vitodens 100-W 26kW combi boiler, the following combi boilers are also suitable for a two-bedroom house with one bathroom and up to 10 radiators:
| Suitable Boiler | Recommended Output (kW) | Flow Rate | Price (Installed) | ||
| Vaillant ecoFIT pure Combi Boiler | 25 | 10.4 l/min | From £2200 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Worcester Bosch Greenstar i Combi Boiler | 25 | 9 l/min | From £2300 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
What is the best combi boiler for a three bedroom property?
A typical three-bedroom house will have one bathroom, a downstairs toilet, possibly an en-suite to the master bedroom, and up to 12 radiators. For this reason, a slightly higher capacity boiler between 29-35kw will be sufficient for a property of this size.
For a property of this size, we recommend a Viessmann Vitodens 100-W 30kW combi boiler.
| Our Recommend Boiler | Recommended Output (kW) | Flow Rate | Price (Installed) | ||
| Viessmann Vitodens 100-W Combi Boiler | 30kW | 12 l/min | From £2700 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
In addition to the Viessmann Vitodens 100-W 30kW combi boiler, the following combi boilers are also suitable for a three-bedroom house with one bathroom, a downstairs toilet, an en-suite bathroom, and up to 12 radiators:
| Suitable Boiler | Recommended Output (kW) | Flow Rate | Price (Installed) | ||
| Ariston Clas ONE Gas Combi Boiler | 30 | 12.5 l/min | From £1900 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Baxi 600 Combi Boiler | 30 | 12.5 l/min | From £2050 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Glow-worm Betacom₄ Combi Boiler | 30 | 12.4 l/min | From £1800 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Ideal Logic Max Combi Boiler | 35 | 14.5 l/min | From £2350 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Vaillant ecoFIT pure Combi Boiler | 35 | 14.1 l/min | From £2400 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Worcester Bosch Greenstar 4000 Combi Boiler | 30 | 12.3 l/min | From £2250 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
What is the best combi boiler for a property with four bedrooms?
If you’re the owner of a larger home with four bedrooms, the demand for hot water will naturally go up along with it as typically your house will have one bathroom, a downstairs toilet, an en-suite to the master bedroom, and up to 15 radiators.
We can’t recommend a small capacity combi boiler to be installed in this kind of scenario, as it won’t be able to cope with the multiple showers, taps and appliances being used at the same time. However, combi boiler technology has come a long way since this boiler type gained popularity in the UK in the 1980s/1990s. Whilst it would have been unheard of to recommend a combi boiler for a 4 bedroom house then, today higher capacity combi boilers, and storage combi boilers are available.
For a property of this size, we recommend a storage combi boiler. This will provide all of the benefits of a combi boiler such as instant hot water, and there is no need to have a hot water storage cylinder, or a cold water tank but it will also be equipped with an integrated hot water storage tank of around 50 litres. Having this storage tank enables the boiler to be able to provide higher flow rates and provide hot water to multiple sources simultaneously.
For a property of this size, we recommend a Viessmann Vitodens 111-W storage combi boiler.
| Our Recommend Boiler | Recommended Output (kW) | Flow Rate | Price (Installed) | ||
| Viessmann Vitodens 111-W Storage Combi Boiler | 32 | Up to 20l/m | From £3400 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
In addition to the Viessmann Vitodens 111-W storage combi boiler, the following combi boilers are also suitable for a four-bedroom house with one bathroom, a downstairs toilet, an en-suite to the master bedroom, and up to 15 radiators:
| Suitable Boiler | Recommended Output (kW) | Flow Rate | Price (Installed) | ||
| Vaillant ecoTEC plus Combination Store Boiler | 38 | Up to 20l/m | From £3900 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
| Worcester Bosch Greenstar CDi Highflow Combi Gas Boiler | 30 | Up to 25l/m | From £3700 (inc. VAT) | Find out more about this boiler | Get a quote for this boiler |
The best combi boiler for a one bedroom flat/house
Ariston Clas ONE 24kW Combi Boiler
Price (Installed): From £1780 (inc. VAT)
| Manufacturer | Ariston |
| Model | Clas ONE |
| Condensing | Yes |
| Efficiency Rating | 90% |
| Energy Efficiency Class | A Rated |
| LPG Compatible | Yes |
| Warranty | 8 Year Parts and Labour Warranty, when installed by an Ariston recommended installer |
| Central Heating Max. Output | 22kW |
| Mounting | Wall Mounted |
| Weight | 29kg |
| Dimensions | 745mm (Height) x 400mm (Width) x 401mm (Depth) |
| Flow Rate | 10.4 l/min |
We recommend the Ariston Clas ONE 24kW Combi Boiler for a one-bedroom property due to it coming in at a cheaper price point. This makes it an attractive option for first-time buyers and landlords.
Cost-Effective
Whilst it comes at a cheaper price point, the Ariston Clas ONE is what we would describe as a mid-range combi boiler. With high-quality components such as Ariston’s patented Xtratech stainless steel heat exchanger, it is by no means a budget boiler. Being stainless steel, this heat exchanger will offer retained efficiency and will lessen the chances of the boiler breaking down due to issues with corrosion, whilst offering improved water flow and enhanced heating performance. It’s a component that is usually found in what is often described as premium boilers due to their price point.
High Quality
Giving you the peace of mind needed when making a significant financial outlay, the Ariston Clas ONE comes with 8-year parts and labour warranty, as standard. This is great for a boiler at its price point and provides you with that added level of protection should something go wrong.
For a one-bedroom property, we recommend the 24kW due to its flow rate of 10.4 l/min, which is more than sufficient for the hot water requirements of a property with just one bathroom.
This boiler not only comes recommended by us but is also a Good Housekeeping UK Reader Recommended product and is an Energy Saving Trust endorsed product. It is these accolades that make this boiler stand out in Ariston’s range.
Energy Saving Features
High-end features such as a large backlit display, an energy-saving ‘Auto’ function and an easy-to-use mechanical clock makes this a really great choice of boiler. Whilst its lightweight construction makes it suitable for wall mounting, which is a must-have for properties with limited space.
Compatibility with the Ariston Net app is a real plus point for this boiler and brings with it futureproof technology that enables you to set, change and control your boiler wherever you are with an internet connection.
Ariston Clas ONE Key Features:
- Xtratech™ stainless steel heat exchanger
- High domestic hot water flow rate
- “Auto” function technology
- Comfort function
- High-efficiency pump
- 1:7 modulation ratio
- Quiet operation at 49dB
- Lightweight unit at 29kG
- 8-year warranty
- “A” ErP rated for optimum energy efficiency
- Large backlit display
- Includes LPG conversion kit
- Ariston NET compatible
Read our detailed Ariston Clas ONE combi boiler review.
Interested in the Ariston Clas ONE 24kW Combi Boiler?
The best combi boiler for two and three-bedroom houses
Viessmann Vitodens 100-W Combi Boiler
Price (Installed): From £2500 (inc. VAT)
Price (installed): From £3400 (inc. VAT)
| Manufacturer | Viessmann |
| Model | Vitodens 100-W Combi Gas Boiler |
| Condensing | Yes |
| Efficiency Rating | 94% |
| Energy Efficiency Class | A Rated |
| LPG Compatible | Yes |
| Warranty | Up to 12 year comprehensive warranty when installed by a Viessmann trained installer |
| Weight | 38kg |
| Dimensions | 700mm (Height) x 400mm (Width) x 350mm (Depth) |
| Flow Rate | 10 l/min (26kW), 12 l/min (30kW) |
The Viessmann Vitodens 100-W is Viessmann’s best-selling gas boiler and for good reason, it comes in a range of outputs suitable for a variety of properties and it’s for that reason that we are recommending it as the boiler to install in both two and three-bedroom properties.
The options we are suggesting here are the 26kW for two-bedroom houses and the 30kW for three-bedroom houses.
With a flow rate of 10 l/min, the 26kW is equipped to provide sufficient hot water and heating for a property with one bathroom and up to 10 radiators, whilst with a flow rate of 12 l/min, the 30kW is equipped to provide sufficient hot water and heating for a three-bedroom property with one bathroom, a downstairs toilet, possibly an en-suite to the master bedroom, and up to 12 radiators.
Highly Efficient
With a 94% efficiency rating, the Vitodens 100-W is one of the most efficient combi boilers available to purchase in 2021. Due to these high-efficiency levels, the Vitodens 100-W has an A ErP energy rating.
It’s a premium boiler but it’s positioned perfectly as a bridge between affordable combi boilers and top-of-the-range boiler options.
Stainless Steel Heat Exchanger
Like every other gas boiler offered by Viessmann, it is equipped with a stainless steel heat exchanger and this is one of the biggest reasons for us recommending it. Constructed from Inox-Radial stainless steel, Viessmann has chosen the highest grade of stainless steel bar surgical steel for this component and this provides a whole host of benefits. The benefits of this component include retained efficiency for the lifetime of the appliance, less downtime due to maintenance, self-cleaning abilities, and resistance to the corrosion suffered by materials such as aluminium.
Giving you peace of mind, the Vitodens 100-W comes with a comprehensive 12-year parts and labour warranty when installed by a Viessmann trained installer. This will ensure you are covered in the event of a boiler failure, which we must say is unlikely in our experience. This warranty is, however, reduced to 7 years if your boiler is installed by any other installer. If you choose Boilerhut though, we will be able to provide this warranty as we are Viessmann trained installers.
Smart Features
The Vitodens 100-W is one of the boilers that Viessmann has overhauled for 2021 and with this, it has provided it with many new features. The biggest one of this is the fact that the boiler now has integrated Wi-Fi and is compatible with Viessmann’s new ViCare thermostat without the need for third party controls. This brings with it the ability to remotely control your heating system from anywhere in the world you have an internet connection, and also brings enhanced functionality in that heating engineers can now remotely monitor your heating system and diagnose any faults ahead of actually working on the boiler.
The 2021 version of the Vitodens 100-W also brings futureproof fuel capabilities to the boiler, with it now ready for the government’s proposed 20% hydrogen mix in the gas supply. Viessmann is one of the first boiler manufacturers to offer this.
Viessmann Vitodens 100-W Key Features:
- High-quality stainless steel Inox-Radial heat exchanger
- Environmentally responsible MatriX cylinder burner
- Backlit LCD touch screen display
- Pressure release valve and condensate combined for easy installation
- Compact design and low Weight
- Quiet operation with low fan speed
- Low CO2 emissions for reduced environmental impact
- Optional room thermostats available
- Up to 12 year warranty available
Read our detailed Vitodens 100-W review
Interested in the Viessmann Vitodens 100-W Combi Boiler?
The best combi boiler for a four-bedroom house
Viessmann Vitodens 111-W 32kW Storage Combi Boiler
| Manufacturer | Viessmann |
| Model | Vitodens 111-W Storage Combi Boiler |
| Condensing | Yes |
| Efficiency Rating | 94% |
| Energy Efficiency Class | A Rated |
| LPG Compatible | Yes |
| Warranty | Up to 12 year comprehensive warranty when installed by a Viessmann trained installer |
| Weight | 64kg |
| Dimensions | 900mm (Height) x 600mm (Width) x 480mm (Depth) |
| Flow Rate | 20 l/min |
Integrated Hot Water Storage Tank
We recommend the Viessmann Vitodens 111-W 32kW Storage Combi Boiler for properties with four bedrooms due to its integrated 46 litre hot water storage tank which allows for an excellent hot water flow rate of up to 20 l/min. With these levels of hot water available on demand plus its heating capabilities, this boiler is sufficient in size to cope with the demands that a property with one bathroom, a downstairs toilet, an en-suite to the master bedroom, and up to 15 radiators will place upon it.
The 111-W offers hot water performance that is equivalent to a separately installed 150L cylinder, this is thanks to the CLS (Cylinder Loading System) technology that it utilises.
As an example of its capabilities, the 111-W has the capacity to fill a standard bath in just 8 minutes, whilst also supplying a sink and a washbasin at the same time.
Stainless Steel Heat Exchanger
One of the biggest reasons for us choosing this boiler is because of its stainless steel heat exchanger. Like every other gas boiler from Viessmann, this is constructed from Inox-Radial stainless steel. Viessmann has chosen the highest grade of stainless steel bar surgical steel for this component and this provides a whole host of benefits. The benefits of this component include retained efficiency for the lifetime of the appliance, less downtime due to maintenance, self-cleaning abilities, and resistance to the corrosion suffered by materials such as aluminium.
Long Lifetime
The Viessmann Vitodens 111-W is another of Viessmann’s boilers that have been updated for 2021, these updates bring integrated Wi-Fi to the boiler and compatibility with Viessmann’s new ViCare Thermostat. This brings with it the ability to remotely control your heating system from anywhere in the world you have an internet connection, and also brings enhanced functionality in that heating engineers can now remotely monitor your heating system and diagnose any faults ahead of actually working on the boiler.
Remotely Controlled
With compact dimensions, the 111-W is suitable for installation in a number of different locations around the home, be it a utility room, a kitchen, or an airing cupboard. Another of the updates Viessmann has given this boiler is its operating noise, operating at just 49 decibels, this further increases the options for where this boiler can be installed.
It’s not just us who recommend the Viessmann Vitodens 111-W, this boiler has also been awarded Which? Best Buy status multiple times and has been noted for being easy to service, having a wide availability of parts, excellent build quality, and for its reliability.
Read our detailed Vitodens 111-W review
Interested in the Viessmann Vitodens 111-W 32kW Storage Combi Boiler?
The best oil combi boiler
Navien LCB700 Blue Flame Oil Boiler
Price (Installed): From £3800 (inc. VAT)
| Manufacturer | Navien |
| Model | LCB700 Blue Flame Oil Boiler |
| Condensing | Yes |
| Efficiency Rating | 93% |
| Energy Efficiency Class | A-Rated |
| LPG Compatible | No |
| Warranty | 10-year warranty |
| Mounting | Floor standing |
| Weight | 58 – 62 kgs |
| Dimensions | 860 mm (Height) x 600mm (Width) x 470 mm (Depth) |
| kW Size | Flow Rate |
| 21kW | 14 l/min |
| 28kW | 18 l/min |
| 36kW | 20 l/min |
Whilst relatively unknown in the UK, Navien is recognised globally for its boiler ranges and is a market leader in the US and its home market of South Korea, as a result. At Boilerhut, we are big fans of the LCB700 Blue Flame oil boiler range from this manufacturer and believe Navien is going to shake up the UK market in the next few years with a number of awards almost certainly on the horizon.
Blue Flame Technology
There are multiple reasons why we recommend the Navien LCB700 Blue Flame Oil Boiler and it’s our oil boiler of choice. Firstly, because it utilises blue flame technology. This comes as standard from Navien, whilst this is not the case with most of its competitors. A principle based on knowledge taken from the space industry, blue flame technology ensures cleaner burning, meaning a reduction in NOx emissions, and a reduction in oil consumption. With both of these benefits increasing efficiency.
We also recommend the LCB700 Blue Flame Oil Boiler range due to every model in the range being equipped with a stainless steel heat exchanger. This prevents corrosion and erosion and ensures an extended lifespan, as well as robust performance compared to aluminium equivalents.
Stainless Steel Heat Exchanger
Making it stand out as a premium boiler, the LCB700 Blue Flame Oil Boiler range is not just equipped with a stainless steel heat exchanger, it is also equipped with premium brass components as opposed to the plastic and composite parts found in the oil boilers offered at a similar price point from competitors.
Available in three different outputs (21kW, 28kW, and 36kW), there is an option in the LCB700 Blue Flame Oil Boiler range for properties of a range of sizes. With the 21kW option offering hot water flow rates of 14 l/min, the 28kW offering 18 l/min, and the 36kW option offering 20 l/min, there is a LCB700 for everything from a one-bedroom house with one bathroom, up to a four-bedroom house with multiple bathrooms.
Cheap Installation Costs
We also like the LCB700 for its ease of installation due to being lightweight and having very useful features such as integrated grab handles to the sides. Whilst very beneficial for the engineer, reduced installation time means cheaper installation costs for you, the customer.
As it’s what we would describe as a premium boiler range, the LCB700 is also equipped with innovative technology including a user-friendly digital control panel to the front and compatibility with Navien’s Smart Plus smart thermostat app which enables it to monitor the weather via the OpenWeatherMap and use the data to maintain a comfortable temperature inside based on the conditions outside.
Read our detailed Navien LCB700 Blue Flame Oil Boiler review.
Interested in the Navien LCB700 Blue Flame Oil Boiler?
Looking for a new combi boiler?
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