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Choosing the right combi boiler can be a challenge. We’ve analysed dozens of products to arrive at the five best combi boilers for 2024.
Combi boilers are increasingly popular as more households look to heat their homes sustainably. A-rated combi boilers have become synonymous with reduced energy bills and energy consumption: studies suggest that households can save approximately 25-35% each year by replacing an inefficient boiler with a modern model.
The best combi boilers provide unlimited hot water on demand. Their smaller size, compared to traditional boilers, makes them ideal for people living in flats or small homes.
Our expert team explores the intricacies and features of combi boilers and sheds light on their benefits. They also run through our picks of the five best combi boilers available and which households they are best suited for to make your choice easier.
Find out about 0% VAT measures on energy efficiency installation.
Combi boilers are an energy efficient, money saving way to heat your home. (Image credit: Adobe)
The Ideal Vogue MAX C40 combi boiler has a slim, compact design to fit neatly into your home. (Image credit: Ideal Heating)
The Ideal Vogue MAX C40 Combi is our pick for the best combi boiler thanks to its higher-than-average output rating of 32kW. This makes the Vogue MAX C40 capable of heating up to 15 radiators, so it is suitable for a range of household sizes.
This model has a flow rate of 16.4L per minute, more than enough to supply hot water to homes with two bathrooms. Those living in smaller homes with only one bathroom could also benefit from a powerful boiler like this one, but the Vogue Max C36 model might be better suited if you are working on a tighter budget.
One of the Vogue MAX C40’s biggest benefits is its compatibility with Ideal Control. This allows for scheduled heating hours and the ability to set presets such as holiday mode to help you save money. The LPG conversion kit also means this model can be used with either traditional gas or LPG infrastructure, and the boiler’s 93% A-rated energy efficiency enables you to reduce your carbon footprint.
Ideal Heating has the highest Trustpilot rating of any brand on this list at 4.8-stars, making it one of the most reliable choices for homeowners looking to upgrade their boiler.
Considering the smart controls, high output rating and A-rated energy efficiency score, the Ideal Vogue MAX C40 Combi averages a very fair price.
| Ideal Vogue MAX C40 Combi | |
|---|---|
| Average cost (excluding installation) | £1,323 |
| Average installation cost | £700 – £2,000 |
| Average total cost | £2,023 – £3,323 |
The Vaillant EcoTEC exclusive combi boiler range is compact and Quiet Mark approved, so it’s ideal for kitchen installations. (Image credit: Vaillant)
We recommend the Vaillant ecoTEC Plus 832 as it is powerful enough to heat smaller homes or flats with a maximum heating output of 25.7kW, more than enough to heat up to 10 radiators. It’s also more compact and affordable than other models in this guide.
The 31.8kW domestic water output rating and 13L per minute flow rate make it suitable for homes with one bathroom. Homes with one bathroom usually require between six and 12L of water per minute, putting the ecoTEC Plus 832 firmly above what is required for an affordable price.
The only downside to the ecoTEC Plus 832 is the lack of smart controls and compatibility. Vaillant has released a newer version of ecoTEC Plus 832 with smart compatibility and extra features, but the jump in price makes it a lot less affordable than the original model. If smart controls are a priority for you, the new ecoTEC Plus 832 can be found for an average of £1,640.
Vaillant has a high rating of 4.4-stars on Trustpilot, with many testimonials referencing excellent customer service and the easy-to-use interface of the boilers.
The ecoTEC Plus 832 can be found for a reasonable price, making it a great option for smaller homes or flats.
| Vaillant ecoTEC Plus 832 | |
|---|---|
| Average cost (excluding installation) | £1,248 |
| Average installation cost | £700 – £2,000 |
| Average total cost | £1,948 – £3,248 |
The Viessman Vitodens 200-W B2KE 35kW comes with a high price tag but plenty of features to boot (Image credit: Viessman).
Those living in larger homes (i.e., more than two bathrooms and 10 radiators) will want to ensure they get a powerful combi boiler to accommodate more bathrooms and radiators throughout the property.
With that being said, our top pick for the best combi boiler for large homes is the Viessmann Vitodens 200-W B2KE 35kW. This combi boiler is suitable for households with four or more bedrooms thanks to its heating outlay of 32kW, which can support up to 15 radiators.
This is the most powerful combi boiler in the Viessmann Vitodens 200-W range, meaning you can scale down if you have a smaller home. This model comes with a domestic hot water output of 34.2kW and a flow rate of 14.3L per minute, which can easily supply hot water for two bathrooms.
The Vitodens 200-W B2KE 35kW is compact considering its power, and is designed for wall-mounted installation. It can also be operated remotely from the ViCare app for further control over your heating system.
Viessmann has a 4.3-star rating on Trustpilot with many customers mentioning high-quality customer service and the easy-to-use ViCare app.
The Viessmann Vitodens 200-W B2KE 35kW Combi Gas Boiler is one of the more expensive combi boilers on this list, but for the features, size and power, it is worth the investment.
| Viessmann Vitodens 200-W B2KE 35kW Combi Gas Boiler | |
|---|---|
| Average cost (excluding installation) | £1,600 |
| Average installation cost | £700 – £2,000 |
| Average total cost | £2,300 – £3,600 |
The Baxi 430 Combi 2 30kW is a simple combi boiler with a lower price tag, perfect for budget-conscious buyers. (Image credit: Plumbing Supplies)
If you’re on a budget and want an affordable combi boiler that will still suit your needs, we recommend the Baxi 430 Combi 2 30kW.
Due to its low output, this combi boiler is best suited for small to medium-sized houses or flats. If you are working on a budget but require a more powerful combi boiler, consider our pick for the best value combi boiler for small homes, the Vaillant ecoTEC Plus 825.
The Baxi 430 Combi 2 30kW has a central heating output of 21.8kW, meaning it can support up to 10 radiators. The domestic hot water output rating of 29.1kW is also impressive, allowing it to easily supply hot water to one or two bathrooms. This is backed up by a flow rate of 11.7l/m; while this is on the lower side, it is still enough to cover two bathrooms, although you may want to avoid running two showers simultaneously.
The small size of the Baxi 430 Combi 2 30kW makes it easy to install anywhere in the home. Unfortunately, the Baxi 430 Combi 2 30kW does not have smart compatibility or app support, which may be off-putting for tech-savvy consumers.
Finally, Baxi has a 4.6-star rating on Trustpilot, proving its reliability as a conscientious and quality combi boiler provider. Many reviews mention helpful customer service and quick solutions to any issues with the boiler.
Overall, the Baxi 430 Combi 2 30kW is a simple combi boiler that lacks the bells and whistles of other models on this list. However, this is balanced out by the reasonable central heating, hot water output, and the lower average cost, making it a great choice for budget-conscious buyers.
| Baxi 430 Combi 2 30kW | |
|---|---|
| Average cost (excluding installation) | £730 |
| Average installation cost | £700 – £2,000 |
| Average total cost | £1,430 – £2,730 |
The Worcester Bosch Combi Greenstar 8000 boiler is compact and can be wall-mounted to save space in the home. (Image credit: Worcester Bosch)
Homeowners will want to look for a powerful boiler to power a large home with over 15 radiators or to supply hot water to multiple bathrooms. Our choice for the most powerful combi boiler that doesn’t break the bank is the Worcester Bosch Greenstar 8000 Life 50kW Combi LPG.
Worcester Bosch is a trustworthy brand with many years of experience, making it a reputable provider. This boiler is one of the most powerful available from the company and can run on either gas or LPG, although we are focusing on the LPG model here.
This model boasts a heating output rating of 35kW, ideal for a property with up to 18 radiators. Where the Bosch Greenstar 8000 Life 50kW really shines is in its domestic hot water output, at 50kW, and flow rate, at 17.9l per minute. This is really powerful for a combi boiler and more than capable of supplying hot water to three bathrooms.
It also comes with Worcester Bosch’s Intelligent Filling System, which enables the system to automatically fill the heating system once the pressure becomes low. This prevents the combi boiler from over-filling and benefits both the heating and hot water systems.
Furthermore, the Greenstar 8000 Life 45kW Combi can wirelessly connect to the company’s smart thermostat and can be controlled via EasyControl. This allows for control over heating in specific rooms and will automatically turn the heating down once you are out of the house and detect when you are returning home to crank it up to the desired temperature.
The company receiving a 4.6-star rating on Trustpilot is another reason we have recommended the Worcester Bosch Greenstar 8000 Life 50kW, as customer reviews shine a light on the company’s quality products and easy installation.
The Worcester Bosch Greenstar 8000 Life 50kW Combi LPG is the most expensive combi boiler on this list, with an average price of £2,100. While this is a costly investment, it can be attributed to the high domestic water output rating, impressive smart compatibility features and suitability for large homes.
| Worcester Bosch Greenstar 8000 Life 50kW Combi LPG | |
|---|---|
| Average cost (excluding installation) | £2,100 |
| Average installation cost | £700 – £2,000 |
| Average total cost | £2,800 – £4,100 |
A-rated combi boilers come at varying price ranges, which become further inflated by installation. The price will vary depending on the size, brand and installation service chosen132.
Using our top picks for the best combi boilers, we calculated an average cost of £1,400, excluding installation. This price will still vary, with some more affordable models falling under £1,000 and more premium boilers costing more than £3,000. Overall, our research shows that, on average, new combi boilers cost between £500 and £3,000.
Installation costs are harder to estimate; the size, weight and model of the boiler have an impact on the price, but different companies will often quote different prices for the same boiler in the same house. According to our research, installing a new combi boiler will cost between £700 to £2,000 on average.
The easiest way to find the best quote for your combi boiler is to use our guide. Simply enter your postcode and details about your boiler and home infrastructure. After 24 hours, you will be contacted by several trusted installers in your area who will offer a no-obligation quote, which you can compare to find the best price.
| Average combi boiler cost | Average combi boiler installation cost | Average total cost for a combi boiler and installation |
|---|---|---|
| £500 – £3,000 | £700 – £2,000 | £1,200 – £5,000 |
The installation of a new combi boiler will also be influenced by the boiler itself and any specific features that need to be accommodated. While we cannot specify how much these additional parts may inflate the overall cost, it’s something to keep in mind if you are looking for a combi boiler on a budget.
Additional parts may include:
Installing a new combi boiler can save you a great deal of money on your energy bills, and with the ongoing cost-of-living crisis, this will be at the top of many people’s minds. It’s worth noting though that how much you can save will depend on your house size and energy rating.
Data from the Energy Saving Trust shows how much you can save each year in a gas-heated home when replacing an old gas boiler with a new A-rated combi boiler with a programmer, room thermostat and thermostatic radiator controls. This data is based on fuel prices from April 2024.
| Property type | Energy efficiency rating D (78–82%) | Energy efficiency rating E (74–78%) | Energy efficiency rating F (70–74%) | Energy efficiency rating G (<70%) |
|---|---|---|---|---|
| Flat (mid-floor) | £65 | £75 | £85 | £120 |
| Bungalow (detached) | £160 | £175 | £200 | £285 |
| Mid-terrace house | £145 | £160 | £180 | £260 |
| Semi-detached house | £175 | £195 | £215 | £310 |
| Detached house | £215 | £260 | £330 | £475 |
As you can see, those living in detached houses will save the most money when installing a new combi boiler from an older model, while those living in flats will save the least. However, every household will save the most money when upgrading from a G-rated gas boiler due to the lower energy efficiency of these older boilers.
While installing a new combi boiler with all the fixings can generate savings of up to £475 per year, the initial outlays can be expensive for some households.
Below, we’ve compiled some of the most popular schemes and grants for new combi boilers to help fund your boiler installation. We also listed the eligibility criteria for each scheme to help you find the right grant for your situation.
The Energy Company Obligation (ECO) scheme is designed to help vulnerable UK households afford energy efficient upgrades, including new heating systems. The scheme is currently in its fourth iteration, the ECO4 Order, which came into effect in July 2022 and applies to measures installation from 1 April 2022 and will run until 31 March 2026.
You may be eligible for the Energy Company Obligation if you receive one of these benefits:
Contact your local council to apply, or contact your energy supplier directly.
The Boiler Upgrade Scheme is open to residents of England and Wales and offers grants to cover part of the cost of replacing fossil fuel heating systems with a heat pump or biomass boiler.
Current grants are available for:
You may be eligible for the Boiler Upgrade Scheme if you meet these criteria:
The Home Heating Cost Reduction Obligation (HHCRO) is a part of the Energy Company Obligation (ECO) and provides eligible households with free or heavily subsidised heating and draught-proofing measures.
You may be eligible for the Home Heating Cost Reduction Obligation (HHRCO) if you are a homeowner or private renter who receives one of the following benefits:
The Warmer Homes Scotland grant offers funding to vulnerable households in Scotland. Potential improvements include replacing central heating systems, wall and loft insulation and draught proofing.
You may be eligible for the Warmer Homes Scotland grant if you meet the following criteria:
The eligibility criteria for Warmer Homes Scotland does change occasionally and is not listed in its entirety. You can check your eligibility for this grant by completing the Home Energy Scotland self-assessment form.
Combi boilers can be powered by either gas or electricity. A majority of combi boilers are powered by gas, making them more readily available and usually, cheaper.
Here are some key pros and cons of electric and gas boilers.
Pros
Cons
Pros
Cons
Since gas boilers are more common than electric models, it’s important to know the two different types of gas boilers available. LPG (liquid petroleum gas) boilers are powered from a storage tank instead of the gas mains that standard gas boilers use. Some models cater to standard gas and LPG, with some brands offering an LPG adaptor for specific models for an additional cost.
Picking the right combi boiler for your household can be confusing; you must factor in the size of your home, number of occupants and consumption needs first and foremost. Larger and older homes may require a system boiler due to infrastructure limitations, however, many newer houses will find combi boilers to be more than suitable.
Here are some of the biggest factors to take into account when picking the best combi boiler for your home.
Combi boilers are rated by their kilowatt (kW) rating or heating output. Generally, you need at least 2kW per radiator in your home. For example, a small flat with five radiators will be able to use a 10kW combi boiler, while a large home with 10 radiators will need at least a 20kW combi boiler.
Those living in a large four-bedroom house with three bathrooms and up to 20 radiators will need to look for a powerful combi boiler with a heating output of 38kW or higher. If you live in a multi-storey home, you may need to consider a more powerful boiler – the longer the pipework between the tap and the boiler, the longer you’ll have to wait for hot water.
Ultimately, you should never underestimate your combi boiler’s heating output regardless of your home layout. It’s generally better to overestimate your needs to ensure immediate access to hot water throughout your property.
The number of occupants in your house will have a large impact on your combi boiler; larger homes put a greater demand on your central heating system, especially if you have multiple bedrooms.
If several occupants share multiple bathrooms you will need a larger combi boiler since the likelihood of simultaneous hot water demands, for activities like bathing and showering, is much higher. If you have more than one bath or shower in your home, using them simultaneously will be tough on a small combi boiler with a low heating output.
As an estimate, households with four bedrooms and four occupants will require a combi boiler with an output between 35kW and 43kW.
Most households in the UK use mains or natural gas, but a few isolated buildings aren’t connected to the gas network and use LPG bottles or oil. This may influence the type of gas boiler you can use. LPG has lower carbon emissions and is the most efficient fuel type.
Energy efficiency is paramount when looking for a new combi boiler. Inefficient boilers waste energy and will drive up the heating of your home, making them more expensive to operate in the long run and less environmentally friendly.
An A-rated boiler can save you up to £475 a year, depending on your previous model and the type of house you live in. The most savings come from combi boilers that use a heating control system, which gives control over which rooms are heated and when.
Combi boilers are more affordable than traditional boilers, but they can still be expensive. Combi boilers can cost as low as £500, with more expensive models crossing the £3,000 mark.
Installation costs can sometimes be more expensive than the boiler itself, so should always be considered when weighing up your budget. It can sometimes be more affordable to hire a third-party technician to install your boiler, although many companies do offer extended warranties on selected models when installed by a brand-verified technician.
As previously mentioned, the overall cost of purchasing and installing a combi boiler averages between £1,200 – £5,000. Consider what model and features you want your combi boiler to have to better align with your budget.
Combi boilers will last around 10 to 15 years, depending on the brand and the quality. Faulty boilers are expensive to repair and disruptions to your central heating and hot water supply are unpleasant to deal with, especially in the colder months.
Look for combi boilers which come with comprehensive and lengthy warranties when comparing models. Warranties offer peace of mind and ensure that any issues will be resolved swiftly and smoothly without dipping into your budget.
Generally speaking, companies operating for long periods will offer quality experience and expertise. Most of the companies we have reviewed have been operating for at least 20 years, showing the longevity of their proficiency in manufacturing and installing combi boilers.
Installing a combi boiler comes with a wealth of benefits that cannot be found in traditional models. Here are some of the biggest advantages of installing a combi boiler.
Compared to conventional boilers, combi boilers are more compact, making them ideal for smaller homes and flats. Although hybrid models exist, there is no need to store hot water, which saves space and decreases the risk of your pipes freezing during winter.
The average combi boiler can fit into an airing cupboard or kitchen, with some models designed to be mounted onto walls. This makes them easier to install and maintain.
Combi boilers are highly efficient machines that make heating your home more affordable. Traditional boilers heat vast quantities of water, meaning they expend a huge amount of energy, whether you are taking a shower or simply washing your hands. Combi boilers have to heat much smaller quantities of water. Most modern combi boilers come with smart temperature controls that allow you to choose which rooms to heat and when.
Moreover, the installation cost of a combi boiler is more affordable than traditional boilers, making the initial outlay overall cheaper on average.
Combi boilers heat water according to demand – there’s no need to wait for the water to be heated. The experience of using a combi boiler is more pleasant and convenient because there’s no risk of running out of hot water. Some of the more powerful combi boilers on the market can heat homes with several bathrooms and occupants, solving hot water issues for good.
When investing in a new combi boiler, the installation process must be as precise and professional as the technology. An improperly installed boiler can lead to inefficiencies, malfunctions, and even safety hazards. To ensure you’re hiring a reliable and skilled boiler installer, consider the following factors:
Picking a new combi boiler for your home should not be a guessing game. We’ve spent hundreds of hours and looked at over 20 different combi boiler brands to determine the best combi boilers in the UK according to consumer needs.
Every brand listed in this article has been thoroughly researched to ensure they all offer high-quality products and services and good value for money. It’s also important to consult an expert installer before making a final decision to ensure your preferred model has the right wattage, size and type for your home and infrastructure.
Overall, our pick for the best combi boiler is the Ideal Vogue MAX C40 Combi, which balances a fair price with powerful output and smart compatibility. The Vaillant ecoTEC Plus 825 is one of the best models for smaller homes and the Baxi 430 Combi 2 30kW is ideal for homeowners working on a tight budget who don’t have strenuous heating or hot water needs.
Conversely, the Viessmann Vitodens 200-W B2KE 35kW Combi Gas Boiler is ideal for larger houses due to its high heating and hot water output. Finally, the Worcester Bosch Greenstar 8000 Life 50kW Combi LPG is the best combi boiler for large households that want a lot of power and also desire smart app compatibility for more control over their heating.
Combi boilers are cheaper to run than regular boilers, particularly if you own a smaller home. Most consumers switch from conventional boilers to combi boilers due to energy savings.
Regular boilers also store large amounts of water in the tank, which cools down. As it heats all the water again when it’s in use, it wastes a lot of extra energy, even if you are just washing your hands. Combi boilers have to heat smaller amounts of water and work on demand. Installation is generally cheaper, too, and most modern boilers come with added energy-saving apps and features.
Combi boilers have a lifespan of 10 to 15 years, but they can exceed this lifespan. Even though your combi boiler may still work after 15 years, it won’t run at maximum efficiency. As new technology brings about more efficient combi boilers, some of which are more eco-friendly, it’s best to change your heating system at least once every 15 years – it should save you money on your energy bills.
Yes, for two reasons – it benefits your household and the environment. Combi boilers are energy efficient, resulting in a positive impact on household bills. This in turn is kinder to the environment too. Combi boilers also heat water on demand, meaning you don’t heat any water you don’t use, therefore only paying for what you actually use.
No, there’s no need for a cold water tank or hot water cylinder as you only heat the water you use.
The domestic hot water should be turned on at all times so the combi boiler can provide hot water to taps on demand. Conversely, your central heating should not be left on at all times. You can set your central heating to come on as and when you want using the combi boiler timer.
Whether or not you can run multiple taps and showers simultaneously with a combi boiler depends on the flow rate and wattage of your combi boiler. A smaller boiler with a 24kW output cannot run two showers simultaneously. However, a 40kW or higher unit can do so, although this will also depend on the water pressure.
If you need to run multiple showers at the same time, consider purchasing a higher-output boiler or purchasing two cheaper boilers to carry the extra load. Some larger homes on several floors may need to consider a boiler system or regular boiler instead.
The Thermostatic Mixer shower is typically the best shower to pair with your combi boiler. This type of shower is especially good at regulating pressure and temperature changes if someone else in the household is using a tap in the home.
Conventional boilers have two tanks – a cold-water supply tank and a hot-water storage tank. The cold water is heated and then stored in the hot water tank and pumped around the central heating system. This way, the entire house is constantly supplied with hot water.
On the downside, these systems are complex, harder to maintain, less energy-efficient and harder to install. The tanks require additional storage space, making them unsuitable for smaller homes or flats.
Combi boilers do not have external tanks but heat water and the home through radiators. They provide instant hot water on demand. The heat exchanger inside the combi boiler transfers the heat from the burning gas inside the boiler to the cold water and delivers it promptly. Control valves direct water through the heating system or to the hot water tap as required. Combi boilers are more compact, faster to install and perfect for small homes with limited storage space.
Combi boilers are not ideally suited to homes with significant water demands. A high-wattage combi boiler can meet the level of demand, but the water pressure may drop as the combi boiler doesn’t have the backup water tank that a conventional boiler has. A hybrid combi boiler can overcome this issue, but it depends on the size of the home and the number of bathrooms used simultaneously.
This research was conducted and then analysed using a scoring system based on the most important considerations consumers would take into account when choosing a boiler based on their needs.
Each combi boiler was rated on its ability to deliver against these factors. We also analysed hundreds of independent consumer reviews found on third-party review sites, testimonials, marketing materials and independent journals and media coverage. Each combi boiler was given a score out of 100.
Companies were rated according to: