Best Combi Boilers in 2023 in the UK: A Complete Guide
A lot of people are looking for the answer to the question “what is the best combi boiler to buy?” But which combi boiler is ultimately best for you will depend on your home and your budget. In this guide, we'll go in depth about what factors you need to consider before installing a new boiler, and provide you with a list of the best combi boilers, which are well reviewed by both homeowners and heating engineers.
If you already know which combi boiler you want, be sure to get boiler quotes from several heating engineers near you, to ensure that you get the best possible price. It’s critical to compare multiple quotes, since if you just go with the first quote you receive, you risk overpaying for your new combi boiler.
However, finding reliable heating engineers can be daunting and take up hours of your time. Thankfully, Boiler Guide can help you with this – you can get quotes from up to 3 local heating engineers by using our free, non-binding comparison service. To get started, simply click the button below and find the best combi boiler for your home in no time.
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How do you choose the best combi boiler?
Going by the top brands and asking friends for recommendations are good ways to choose the best combi boiler. However, while this is all well and good, knowing if a particular combi boiler is best for YOU will come down to the size of your home and your household's specific needs.
There are a few factors you need to take into consideration when choosing the best combi boiler. First of all, let's start with the factors that are always indicators of a good boiler regardless of your personal situation: efficiency and reliability.
How much does a combi boiler cost?
Economy or budget boilers can cost as little £500 up to £900, offering lower quality parts but also less extensive warranties. Mid-range systems go from £900 to £1,500 and top-of-the-line models can be from £1,500 to £3,000.
Combi Boiler Costs | |
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Combi boiler quality | Cost excluding installation |
Economy | £500 – £900 |
Mid-range | £900 – £1,500 |
Top-end | £1,500 – £3,000 |
It's important to note that these prices only include the supply cost, so installation and associated labour are not factored in.
Efficiency rating
All boilers have an efficiency rating and a band rating. The efficiency rating is a percentage which is based on how well the boiler converts fuel into heat. This efficiency rating is reflective of how much of every £1 being spent actually goes towards heating your home.
For example, if a boiler is 93% efficient, it means only 7p of every £1 being spent on heating is wasted. Thankfully, the latest gas combi boilers in the UK are now required to have an efficiency rating of 92%. Meaning you save a lot more money compared to older G-rated boilers, which often have efficiency ratings of less than 70%!
When comparing the top combi boilers look for the highest percentages in order to save as much as possible.
Another factor to take into account is the Energy-related Products (ErP) rating. This band rating - designed as a tool to help cut down greenhouse gas emissions - relates to the performance and efficiency of boilers and other water heating systems.
The rating uses the letters A to G to rank the efficiency of a boiler with A being the most efficient and G being the least. This rating takes into account which type of fuel is used as well as how effectively the boiler operates.
For example, the electric boiler efficiency ratings (band ratings) tend to be much lower compared to gas boilers, since in the UK electricity generation is usually done with fossil fuels, which emits twice as much carbon as natural gas. That is why buying a combi boiler with a high efficiency rating will help you reduce your carbon footprint in comparison.
Later in this article, we'll go through some of the most efficient combi boilers available in the UK, including models from top brands such as Ideal and Vaillant.
Reliability and warranty
How do you determine how reliable a combi boiler is? It's good to ask around and look at combi boiler reviews online to get a better idea of which brands tend to stand the test of time and which you should avoid. Another way to determine the most reliable combi boiler is by looking at its warranty.
A longer warranty period indicates a company's confidence in the reliability and longevity of their boilers. Choosing a boiler with a longer warranty period could also save you money in the future as you won't need to spend extra for any potential repairs.
Further down the article, you can find a list of the best gas boilers for sale in the UK.
Hydrogen-ready boilers
In the future, the UK government is planning to replace natural gas with hydrogen heating. This is because it's more environmentally friendly. But what does this mean for homeowners? Is buying a gas boiler a waste of time and money?
Don't worry yet! The change will happen gradually and what's more important, most modern combi boilers can already run on a mixture of hydrogen and natural gas. Some of the top boiler manufacturers are already conducting trials for 100% hydrogen-ready boilers.
Therefore, if you buy a gas combi boiler today you'll still be able to use it for its entire lifespan and get your money's worth.
More factors to consider before buying a combi boiler
The factors you need to consider that are personal to you and the type of property you have are:
- Budget: Your budget depends on your personal financial situation. Buying a boiler is an investment, but you don't need to compromise on quality to get a good deal. For example, Ideal is a brand known for its quality and affordable prices.
- Size (output rating): Boiler sizing is measured in kilowatts (kW). A higher output doesn't necessarily mean the boiler is better. What size you should buy depends on the number of bathrooms and radiators you have. If you don't get the right size you might struggle to heat up your home or you could end up wasting money on high energy bills.
For example, even if you buy the best combi boiler on the market, it won't keep you too warm if you live in a large home with over 20 radiators and it only has an output of 20kW. On the other hand, if you buy a great combi boiler with an output of 40kW but you live in a one-bedroom apartment, you can say hello to extortionate energy bills!
Therefore, always check what output size is appropriate for your home by getting advice from a heating engineer. You can receive advice and compare quotes from up to 3 local heating engineers by filling in a short form.
It’s completely free and you’re under no obligation to accept any of the quotes you receive. Click the button below to get your free quotes and choose the best combi boiler deal now.
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- Type of fuel: Boilers can be fuelled by gas, oil, LPG, biomass, or electricity. You need to check which types of fuel your boiler is compatible with. In the case of gas, you also need to check whether your home is connected to the gas grid.
- Dimensions & aesthetic: Many of us prefer to place our combi boilers out of sight in a cupboard. Even though combi boilers are known for being compact, it's still a good idea to double check the dimensions of the models you're considering to make sure it'll fit into your home. You can also research to find the best small boilers.
If your boiler isn't located in a cupboard you might think twice about how it looks. As the name implies, Worcester Bosch's Greenstar 8000 Style model is known to be one of the most aesthetically-pleasing boilers on the market. - Noise level: The quietest combi boilers have a similar noise level to modest rainfall. If peace and quiet are a priority for you then it's a good idea to look into combi boilers which are Quiet Mark approved.
- Controls & accessories: Preferences on controls and accessories vary from person to person. For example, a smart thermostat might be a must for one person and redundant for another. So consider which features will make a difference for you.
What is the most efficient combi boiler?
In 2023, the competition for being the most efficient combi boiler is definitely fierce. As mentioned above, the efficiency of a boiler is dependent on both its efficiency rating and its band rating. We've selected our top 5 combi boilers based on how efficient they are:
1. Grant VortexBlue Internal 36kW Combi Oil Boiler
We'll start off the list with a boiler for those of you who are not on the gas grid. The Grant VortexBlue Internal 36kW Combi Oil Boiler has an impressive efficiency rating of 94.5% and band rating A. However, keep in mind the ErP (Energy-related Products) rating specifically for water is grade B.
The output rating of 36kW is best suited for larger homes with more than one bathroom. This combi oil boiler is also available in sizes 21kW and 26kW, although it's important to note that the efficiency rating is slightly lower for these sizes.
Its warranty length is only 2 years. This is standard for combi oil boilers. However, it is possible to find brands that offer longer periods.
Grant VortexBlue key features:
- Award-winning Vortex condensing heat exchanger
- Market-leading Riello Blue Flame burner
- 24 litre expansion vessel
- High quality external powder coated casing
- Built in frost protection
2. Ideal Logic Max Combi Gas Boiler
The Ideal Logic Max is the first of the gas combi boilers on our list. Some of the boilers in this range are also compatible with LPG heating (liquefied petroleum gas). This model has the potential to lower your energy bills thanks to its efficiency rating of 94% and ErP A-rating for heat and hot water.
All combi boilers in the Logic Max range have a central heating output of 24.2kW which is suitable for homes with about 3 bedrooms and 10 radiators. The C35 model has a domestic hot water (DHW) output of 35.3kW, the highest in the range, which means it can meet higher demands for hot water.
Ideal have attached an extensive 10 year warranty to all of the Logic Max boilers to ensure you're well covered after the installation.
Ideal Logic Max key features:
- A large digital display
- Boiler frost protection
- Reachable pressure gauge
- Hard wearing and scratch resistant case
- The Ideal System Filter - a magnetic and non-magnetic filter designed to protect domestic central heating systems from suspended black iron oxide.
- Compact dimensions and low lift weight, meaning potentially cheaper installation costs
3. Vaillant ecoTEC Plus Combi Gas Boiler
The ecoTEC Plus is the 'flagship' Vaillant boiler model and is widely recommended by professional heating engineers. It is one of the most efficient combi boilers on the market with a rating of 94%. It is available in outputs of 25, 32, 35 or the largest 38kW which is a great choice for larger homes with a high demand for hot water.
This boiler includes a 5 year warranty as standard with 7 or 10 years available when installed by a Vaillant accredited installer.
The ecoTEC Plus is also one of the more stylish models on the market with back lit digital display, contoured case and stainless-steel heat exchanger. The boiler has been awarded the Quiet Mark accreditation because of how quiet it is when it’s operating.
Vaillant ecoTEC Plus key features:
- Rapid hot water delivery in just 5 seconds
- Wide modulation range of up to 1:6 results improves energy efficiency
- Flame lift detection system enables quieter combustion
- Two-stage frost protection built in
- Compatible with aroTHERM air to water heat pump hybrid system
- Available with a range of controls including wired, wireless and smart (vSmart by Vaillant)
4. Vokera Evolve C Combi Gas Boiler
The Vokera Evolve C is another highly efficient gas combi boiler with a 94% efficiency rating. It has an ErP A-rating for heat and hot water. Furthermore, all of the models in this range are compatible with both natural gas and LPG.
This model is available in sizes 24, 28, 32, 36, and 42kW. Therefore, making it suitable for both small and medium-sized homes. In addition, all sizes come with a 10-year warranty so you can be sure that you are getting a reliable unit that is going to last.
Vokera Evolve C key features:
- Text driven menus
- A built in carbon monoxide monitor
- Rear flue option
- A time clock
- Compatible with a BeSmart thermostat
5. Viessmann Vitodens 200-W B2KE Combi Gas Boiler
The last boiler on our list is the Vitodens 200-W combi gas boiler from Viessmann. It's A-rated and has an impressive efficiency rating of 94%, which will help you waste less energy and less money.
This boiler is also compatible with LPG and its dimensions are 700 x 450 x 365mm (HxWxD).
It's available in two sizes. One of which has a central heating output of 25.4kW and a hot water output of 30.5kW, making it suitable for homes with about 10 radiators and a single bathroom. The other one has a central heating output of 32kW and hot water output of 34kW, meaning it's ideal for homes with around 15 radiators and up to 2 bathrooms.
This model has a standard warranty of just 3 years. However, it can be extended to 5 years when installed by a Viessmann trained installer and even up to 10 years if you register it through the Viessmann online portal.
Viessmann Vitodens 200-W B2KE key features:
- Wi-Fi integration - control from anywhere via the ViCare App
- A wide modulation range of 1:17 and MatriX burner reduce energy consumption and maximise efficiency
- A stainless steel heat exchanger
- Touchscreen display
- All components are accessible from the front - save time and money on servicing
Overview of the 5 most efficient combi boilers
Type of Combi Boiler | Efficiency Rating | Home Size | Warranty | Typical Price |
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Grant VortexBlue Internal 36kW Combi Oil Boiler | 94.5% | Large homes | 2 years | £2,500 |
Ideal Logic Max Combi Gas Boiler | 94% | Medium sized homes | 10 years | £968-£1,156 |
Vaillant ecoTEC Plus Combi Gas Boiler | 94% | Small to larger homes | 10 years | £1,152 – £1,703 |
Viessmann Vitodens 100-W Combi Gas Boiler | 94% | Medium sized homes | Up to 12 years | £1,292 |
Vokera Evolve C Combi Gas Boiler | 94% | Small to larger homes | 3 years | £845 – £1,010 |
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What is the most reliable combi boiler?
As technology advances, so does the quality of boilers. New boilers have improved in many ways, including how reliable they are. It's always good to look up reviews and ask people you know for their opinions and experiences with their boilers. However, considering how much boilers have improved in recent years, it's a good idea to purchase a more recent model.
But how can you tell how reliable a boiler is if it's new to the market? Looking at a boiler's warranty is a good indicator of how confident a brand is in the longevity of their boiler. Below are our top 5 picks of the most reliable boilers available in the UK:
1. Worcester Bosch Greenstar 8000 Style Combi Gas Boiler
The Worcester Bosch Greenstar 8000 Style is a compact condensing combi gas boiler which is also compatible with LPG. Its dimensions are 780 x 440 x 365mm (HxWxD). If installed by a Worcester Bosch accredited installer you can receive a warranty of up to 12 years. This is one of the longest warranties available, meaning that you can have confidence in your boiler's reliability.
All Greenstar 8000 Style combi boilers, except one, have a central heating output of 35kW. This makes them suitable for homes with up to 20 radiators. The difference between these models is their DHW output, which ranges from 34.4kW to 48.9kW. The most powerful model in the range is suitable for homes with up to 2 bathrooms.
The other model in this range has an output rating of 30kW and flow rate of 12.3 litres a minute, making it a great boiler for smaller homes with 1 bathroom. All the models in this range have a 94% efficiency rating, meaning they are ErP A-rated for both heating and hot water.
Worcester Bosch Greenstar 8000 key features:
- 2 high gloss colour options
- An increased modulation ratio of 1:10
- Robust and lightweight – saves time and money on installation
- Features the first Greenstar intelligent filling system
- Wireless connectivity with the Bosch EasyControl
2. Alpha E-TEC Plus Combi Gas Boiler
The E-TEC Plus is a combi gas boiler manufactured by Alpha. It's one of the most reliable boilers on the UK market. They have a 10-year warranty as standard, however, if installed with the Alpha PremierPack Extra this can be extended to 13 years. Furthermore, it is compact in size with measurements of 712 x 440 x 268mm, and is also compatible with LPG.
The E-TEC Plus is available in 3 different output sizes. The central heating maximum output ranges from 26.1kW to 32kW. While the hot water maximum output ranges from 28.3kW to 37.9kW. This means you can find a model that is suitable for either a medium or larger sized home. For example, the central heating output of 32kW is sufficient for a home with around 15 radiators.
This boiler model also has a good efficiency rating of 93% and ErP A-rating, which will help to save you money on your heating bills.
Alpha E-TEC Plus key features:
- A stainless steel heat exchanger
- A high efficiency Grundfos pump and hydroblock assembly
- Combined condensate and pressure relief valve connection
- A zinc plated expansion vessel helping to prevent corrosion
- Easy-access dry-change NTCs on front of pipes
3. ATAG IC Economiser Plus Combi Gas Boiler
The IC Economiser Plus from ATAG is one of the most reliable gas combi boilers available in 2023. It has a standard warranty period of 10 years, however, this can be extended up to 14 years when you install it alongside an Adey Atom filter, a ONEZone smart controller, and an ATAG water treatment pack.
This boiler model is compact with dimensions of 700 x 440 x 355mm. Furthermore, it is compatible with both natural gas and LPG.
This model is available in a range of hot water output sizes, including 42.5kW, 40.3kW, and 29.8kW. The central heating output size for the largest two models is 31.2kW, and for the smaller model it is 23.2kW. The IC27+ model is perfect for small to medium sized homes, while the IC39+ model is ideal for larger homes with a higher demand for heating and hot water.
This boiler has an efficiency rating of 94% and is A-rated for both heat and water, as it recycles the flue gases for a second time rather than letting it go to waste. On top of that, when it's used in conjunction with the ATAG One controller it can achieve an efficiency rating of A+.
ATAG IC Economiser Plus key features:
- Unique iCon heat exchanger incl. lifetime replacement guarantee
- Instant hot water with pre-heat facility
- Built in passive flue gas heat recovery device
- An outside weather compensator
- There is also a model with 275mm depth available – perfect fit for most kitchen cupboards
4. Ariston Alteas ONE NET Combi Gas Boiler
Ariston's Alteas ONE NET is a condensing and compact combi gas boiler that is also compatible with LPG. It has a standard warranty of 12 years, making it one of the longest warranty periods available amongst combi boilers.
The Alteas ONE NET is available in two sizes, 30kW and 35kW. Its maximum central heating output is 28kW and 31kW, respectively. Both models are suitable for larger homes with up to 2 bathrooms.
On top of that, this boiler also has a high efficiency rating of 94% and boasts an ErP A+ rating. It is fully compliant with the Boiler Plus government legislation.
Ariston Alteas ONE NET key features:
- Lightweight: only weighs 35.3kg
- Simple to fit connections: makes installation easy
- Quiet due to latest soundproofing technology (51db)
- A large LCD display for easy control
- Full zone management kit that can manage up to 6 heating zones
5. Viessmann Vitodens 100-W Combi Gas Boiler
Viessmann is one of the most well-known brands in the UK. The Vitodens 100-W has been updated with their new and improved PlusBus range. This new model has a standard warranty of 5 years with the option to extend by a further 7 years. To be eligible for this longer warranty, it needs to be installed by a Viessmann trained heating engineer.
This boiler measures at 700 x 400 x 360mm (HxWxD), making it easy to fit into your home. It is also compatible with LPG as well as natural gas.
The Vitodens 100-W is available in outputs from 3.2 to 32kW. The 26kW model, from the PlusBus range, has a central heating output (CH) of 25kW and it can achieve a domestic hot water (DHW) output of 31.7kW. Making it suitable for homes with 10-15 radiators and 1-2 bathrooms.
All the boilers in this range are A-rated and have an efficiency rating of 94%. This means that a minimal amount of energy is being wasted and as a result reduces your heating bills.
Viessmann Vitodens 100-W key features:
- All Vitodens 100-W boilers are hydrogen-ready with a blend of 20% hydrogen and 80% natural gas.
- Includes a stainless steel Inox-Radial heat exchanger, which helps lower heating bills.
- Low fan speed means the boiler operates quietly.
- User-friendly LED Touch screen for easy operation.
Overview of the 5 most reliable combi boilers
Type of Combi Boiler | Efficiency Rating | Home Size | Warranty |
---|---|---|---|
Worcester Bosch Greenstar 8000 Style Combi Gas Boiler | 94% | Large homes | 12 years |
Alpha E-TEC Plus Combi Gas Boiler | 94% | Medium to larger homes | 10 years |
ATAG IC Economiser Plus Combi Gas Boiler | 94% | Small to larger homes | 10 years |
Ariston Alteas ONE NET Combi Gas Boiler | 94% | Large homes | 12 years |
Viessmann Vitodens 100-W Combi Gas Boiler | 94% | Small to medium-sized homes | 5 years |
Best combi boiler prices
5 Best combi boiler prices
Type of combi boiler | Typical price |
---|---|
Worcester Bosch Greenstar 8000 Style | £1,300 |
Alpha E-TEC Plus | £1,033 |
ATAG IC Economiser Plus | £1,500 |
Ariston Alteas ONE NET | £1,300 |
Viessmann Vitodens 100-W | £1,430 |
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Which is the best value combi boiler?
ATAG IC Economiser Plus is our top choice for the best value combi boiler in the UK. As you can see in the table below, you don't necessarily need to choose between having an efficient boiler or a reliable boiler - you can have both in one! The IC Economiser Plus comes out on top for being the most reliable, with a warranty of up to 14 years. It also scores high on efficiency with 94%.
Worcester Bosch Greenstar 8000 Style and Viessmann Vitodens 100-W B1KF are also great choices. They are A-rated with 94% efficiency and include warranties of up to 12 years, meaning you can save costs on your energy bills and be sure that you won't need to think about replacing your boiler again for a long time. You can see a breakdown of these boilers and more in the table below.
We've also included an indication of price in the table below. While there are a couple of affordable but still top-quality options, it's important to note that a cheap combi boiler isn't always the best value choice.
If a boiler is cheap but not efficient you'll end up spending a lot on energy bills. And if a boiler is cheap but not reliable that means you'll end up spending a fortune on frequent repairs and need to fork out for a replacement far too soon. Therefore, you should always keep these two factors in mind when considering how much a combi boiler is going to cost you.
Type of Combi Boiler | Efficiency Rating | Band rating | Warranty | Typical Price |
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Grant VortexBlue Internal 36kW Combi Oil Boiler | 94.5% | A-rated | 2 years | £2,500 |
Ideal Logic Max Combi Gas Boiler | 94% | A-rated | 10 years | £968 – £1,156 |
Vaillant ecoTEC Plus Combi Gas Boiler | 94% | A-rated | 10 years | £1,152 – £1,703 |
Viessmann Vitodens 100-W Combi Gas Boiler | 94% | A-rated | Up to 12 years | £1,292 |
Vokera Evolve C Combi Gas Boiler | 94% | A-rated | 10 years | £845 – £1,010 |
Worcester Bosch Greenstar 8000 Style Combi Gas Boiler | 94% | A-rated | Up to 12 years | £1,300 – £2,297 |
ATAG IC Economiser Plus Combi Gas Boiler | 94% | A-rated | Up to 14 years | £1,950 – £2,160 |
Alpha E-TEC PLUS Combi Gas Boiler | 94% | A-rated | 13 years | £800 – £1,033 |
Ariston ALTEAS ONE NET Combi Gas Boiler | 94% | A-rated | 12 years | £1,300 – £2,000 |
Viessmann Vitodens 200-W B2KE Combi Gas Boiler | 94% | A-rated | Up to 10 years | £1,550 – £1,600 |
Best combi boiler boiler deals in 4 steps
Now that you know which combi boilers have the best value on the market, you need to figure out which ones are best suited for your home and budget. Boiler installation costs can vary enormously depending on factors like how much work is required and even where you live. We've simplified the process so that you can find the best and most cost-effective combi boiler for you in just a few quick steps:
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Answer a few simple questions
To start you just need to answer a few straight-forward questions using this boiler quotes form. These questions are simply relating to your home, the type of boiler you have and what you’re looking for. You'll also be asked for your postcode so that we can find heating engineers available near you.
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Confirm your details
After you’ve submitted your enquiry, someone from our team will contact you to check we have the correct contact information and to make sure we understand exactly what you need. This means we can get the best boiler quotes for you, and you can sit back and relax.
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Receive quotes and compare prices
You’ll then be contacted by up to 3 Gas Safe registered heating engineers in your area. Sometimes it's possible for the heating engineer to give you an estimate over the phone, however, usually they'll need to arrange a home visit so that they can see what they'll be working with. This way they can assess the price more accurately, and then you can compare the quotes from each heating engineer.
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Book your boiler installation
Now that you've received all the quotes, you can choose the one that works best for you. You can then arrange a convenient date and time for the work to be carried out by the heating engineer, and get the best combi boiler installed at the best price.
Remember there is absolutely no fee for using our service to find boiler quotes, and at no point are you under any obligation to accept any of the quotes you receive. This way you can find out what the best deals for boilers in your area are without any extra expenses or pressure. If you're curious about how much you could save on a new boiler, simply click the button below to get started.
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FAQ
What is the best combi boiler to buy?
After reviewing multiple boilers, we can conclude that the Worcester Bosch Greenstar 8000 Style is the best combi boiler to buy in the UK for 2023. This is based on overall quality, value for money and output capacity of the combi boiler.
What is the most reliable boiler brand?
ATAG is the most reliable boiler brand. The ATAG IC Economiser Plus Combi Gas Boiler has a warranty period of up to 14 years, giving you peace of mind that it will keep your home cosy and warm for many years to come.
What is the most efficient combi boiler in the UK?
The Ideal Logic Max, Worcester Bosch Greenstar 8000 Style, and Viessmann Vitodens 100-W combi boilers all have an efficiency rating of 94%, making them the most efficient combi boilers on the market.
What is the most economical combi boiler in the UK?
The best value combi boilers under £1,000 in terms of efficiency and reliability are the Ideal Logic Max, Vokera Evolve C, and Alpha E-TEC PLUS.
Which is the best combi boiler for a large house?
One of the best reliable combi boilers for a large house is the Worcester Bosch Greenstar 8000. It is available in sizes which have an output rating of 40-50kW.
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