Best System Boilers 2025
System boilers are a popular choice for UK households, especially families with more than four people or those who live in a home with multiple bathrooms.
They’re particularly effective in homes where several people might need hot water at the same time, like during busy morning routines or when running multiple showers.
If this sounds like you and you’re on the lookout for one, this guide covers the best system boilers for 2025 and beyond.
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We’ll compare top brands like Worcester Bosch, Vaillant, and Viessmann, looking at key features such as energy efficiency, warranty length, and price ranges so you can find the most reliable solution for your home. Before you make a final decision, don’t forget to compare your favourite picks against other gas boiler types and learn more about boiler costs to get the full picture.
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Video: Best Sytem Boilers – Which Are The BEST System Boilers?
If you’re seeking for the best system boilers, we hope this video is useful.The best system boilers for 2025 are:
- Viessmann Vitodens 100-W system
- Worcester Bosch 4000 system boiler
- Vaillant ecoTEC Plus System
- Alpha ProTec NX
Viessmann Vitodens 100-W
The Viessmann Vitodens 100-W is a reliable wall-mounted gas condensing boiler featuring built-in Wi-Fi and compatibility with the ViCare app.
Priced at around £1000, it’s a great choice for any home that needs a top-quality yet affordable system boiler.
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The Viessmann Vitodens 100-W boasts an efficient and reliable Inox-Radial heat exchanger with a MatriX cylinder burner. This cylinder ensures clean and efficient heat distribution, and unlike most other boilers, it won’t corrode or fail over time.
With its high modulation ratio of 1:10, the boiler adjusts its operating power to suit any room environment. This feature helps reduce heating bills and minimises wear and tear.
The user-friendly LCD touchscreen makes this Vitodens easy to operate. It also offers an optional external weather detector, allowing it to respond to outside weather conditions and adjust its boiler temperature accordingly.
Available in four different outputs, this model is ideal for larger homes with multiple bathrooms that need water supplied to multiple taps at once.
| Outputs | Typical Price |
| 11kW | £1,000 |
| 19kW | £1,025 |
| 25kW | £1,055 |
| 32kW | £1,200 |
With installation, you can expect a cost between £1800-£2500, depending on the company that installs it.
You can get a 12-year boiler warranty on this boiler right now with Boiler Central.
Main Features
- High modulation ratio of 1:10
- Up to 94% energy efficiency rating
- MatriX pre-mix cylinder burner and an integral AquaBloc hydraulic unit
- Three heating outputs – 11kW, 19kW, 25kW, and 32kW
- Very quiet operation
- Optional external weather detector
- Advanced technology – hydrogen-ready boiler and built-in Wi-Fi
- Which? rating 76%
- LCD touchscreen
- Compact size
- Lightweight
- 10-year warranty, with the option to extend it to 12 years with a Viessmann Installer
What we love about the Viessmann Vitodens 100-W
Overall, we recommend this Which? Best Buy award-winning system boiler above all others due to its exceptional quality, reliable performance, lengthy warranty, and competitive price. It achieves an “A” rating on the SEDBUK energy efficiency scale, offering homeowners the perfect balance of powerful heating capabilities and energy-conscious operation in one compact package.
Request a new system boiler quote, and we’ll provide you with a custom quote that includes installation fees for your home so you can get an idea of the total cost.
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Worcester Bosch 4000
The new Worcester Bosch Greenstar 4000 system boiler is the latest addition to the brand’s lineup, a direct upgrade of the Greenstar i system boiler with more advanced features and efficiency.
The Worcester 4000 is a mid-range system boiler priced at around £1000. It’s suitable for medium to large homes with higher hot water demand.
Because it comes in multiple outputs, it caters to a wide variety of home sizes, ensuring optimal energy efficiency in each situation.
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This is Worcester’s quietest system boiler, so it’s no surprise it has been given the Quiet Mark accreditation for its low operating noise level.
The new 4000 system boiler is hydrogen ready—it can run on 20% hydrogen out of the box and can be changed to run on 100% hydrogen in the future.
It can also be used with solar panels to help cut energy costs.
Another perk is its built-in wireless connectivity, so you can control your heating using a smart thermostat and your mobile devices from anywhere.
| Outputs | Typical Price |
| 12kW | £1,000 |
| 15kW | £1,100 |
| 18kW | £1,200 |
| 21kW | £1,300 |
| 24kW | £1,400 |
With installation, you can expect it to cost between £1900-£2400, depending on the company that installs it.
It comes with a good warranty of 10 years, but this can be extended to 12 years if you order this boiler from Boiler Central!
Main Features:
- Great for most homes in the UK with a hot water tank
- SEDBUK A Rating—94% efficiency
- Upgrade of the Greenstar i range
- Five heating outputs—12kW, 15kW, 18kW, 21kW, and 24kW
- Very quiet boiler
- Optional external weather detector
- Advanced hydrogen technology
- LCD touchscreen
- Compact size
- Lightweight
- 7-year standard guarantee, 8-year guarantee if installed with any Greenstar System Filter, and up to 10 years warranty for loyal members
What we love about the Worcester 4000
Given that it’s a Worcester product, you can expect efficiency and reliability.
It’s easy for professionals to install and maintain, which could save you money on service costs. The boiler is good at adjusting its heat output, so your home stays at a comfortable temperature without wasting energy. It also looks pretty good with its new facelift.
Overall, we recommend the Worcester 4000 as it’s a reliable and easy-to-use boiler that comes at a great price.
If you’d like a new system boiler quote, we’ll provide you with a custom quote, including installation fees for your home specifically, so you can get an idea of the total cost for you.
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Vaillant ecoTEC Plus
The ecoTEC boiler range from Vaillant is a fantastic low-energy consumption system boiler for 2025, delivering excellent performance for both hot water and central heating while keeping your energy bills low. It’s known by our installers to be efficient, easy to use, reliable, and quiet.
The Vaillant ecoTEC Plus system 30kW is the most popular size boiler in this range, but it’s also available in five other outputs, making it suitable for a variety of homes.
The ecoTEC plus is smart: when it knows you don’t need as much heating power, it can drop to using 16% of its maximum power, saving on fuel and money.
With its straightforward backlit display and stainless-steel heat exchanger with its premium components, it’s really one of the top system boilers available on the market today. It is, however, a bit more expensive than the other options on our list, but this is because of the better heat exchanger, so the price is justified.
| Outputs | Typical Price |
| 10kW | £1,200 |
| 15kW | £1,300 |
| 20kW | £1,400 |
| 25kW | £1,550 |
| 30kW | £1,650 |
| 35kW | £1,900 |
Pricing for the boiler along with installation usually comes upwards of £2000.
Features:
- Stainless steel heat exchanger
- Available in 6 outputs—10kW, 15kW, 20kW, 25kW, 30kW, and 35kW
- Advanced modulation during low usage to ensure maximum efficiency
- New high-efficiency pump to reduce energy consumption
- Stylish contemporary case design to ensure a seamless fit with home decor
- ErP Compliant
- Lightweight and compact
- Natural Gas fueled
- Includes 2-stage frost thermostat
- Built-in pump and expansion vessel
- Compatible with unvented systems
Why we love the Vaillant ecoTEC Plus
Overall, this is an excellent boiler with reliable internal components, making it a suitable choice for any home.
It’s super efficient, turning up to 94% of the gas it uses into heat for your home, and it’s also very quiet, so you won’t be disturbed by any noise. The clear display makes it easy to use, and you can even control it with your phone.
Do you have a system boiler with a hot water cylinder? If you do and need a new tundish installed, then read our what is a tundish guide to learn why it plays an important part in keeping your water clean and sanitary.
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Alpha ProTec NX
If you need a high-output system boiler designed for large domestic or commercial properties, this is the best option.
The Alpha ProTec NX is compact and can be hung on a wall, making it a space-saving choice without compromising on power or performance.
With outputs ranging from 48kW to 180kW, this boiler handle large spaces and high heating demands with ease. It also supports cascading setups to over 1MW, which means multiple boilers can be linked together to provide even more heating capacity if needed. This makes it a great option for buildings with varying seasonal and load demands.
Its advanced 1:10 modulation range minimizes energy waste by adjusting the boiler output to match the exact heating requirement. Additionally, the stainless steel heat exchanger ensures durability and long-lasting performance.
The Alpha ProTec NX comes with advanced controls to manage multiple heating zones, allowing greater flexibility and efficiency in your system’s setup.
| Outputs | Typical Price |
| 48kW | £2,500 |
| 68kW | £2,900 |
| 90kW | £3,700 |
| 115kW | £4,000 |
| 150kW | £4,500 |
| 180kW | £5,200 |
Features
- Space-saving wall-hung design
- High energy efficiency (94%) with ultra-low NOx emissions
- Wide 1:10 modulation range
- Outputs ranging from 48kW to 180kW
- Supports modular cascading setups for higher heating capacity
- Durable stainless steel heat exchanger
- Compatible with natural gas, LPG, and hydrogen-blended gas
- Built-in advanced controls to manage multiple heating zones and settings
- Weather compensation to adjust heating based on outdoor temperatures
- 10-year warranty
Why we love the Alpha ProTec NX
The Alpha ProTec NX offers a combination of high performance, energy efficiency, and flexibility, making it an excellent choice for both larger homes and commercial spaces. Its ability to handle high heating demands, along with the option for modular setups, ensures that it can adapt to various requirements.
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What’s The Average Cost Of A System Boiler?
The average cost of the best UK system boilers in 2025 is around £1,500.
At the low end, system boiler prices are around £1000, whereas the top-end boiler systems come in around the £2000+ mark.
Here’s a quick guide to the average costs of system boilers from the top 5 brands. These prices are for the boilers only, and installation costs are extra.
| Brand | Boiler Only Price Range | Boiler + Installation Price Range |
| Viessmann | £1,000 – £1,600 | £2,400 – £3,100 |
| Worcester Bosch | £1,100 – £1,900 | £2,500 – £3,400 |
| Vaillant | £1,050 – £1,750 | £2,450 – £3,250 |
| Ideal | £900 – £1,600 | £2,300 – £3,100 |
| Alpha | £800 – £1,440 | £2,200 – £2,940 |
How To Choose The Best System Boiler For Your Needs
Here’s what you need to consider when selecting the best system boiler for your home.
Efficiency
Look for boilers with an A rating for energy efficiency. High-efficiency boilers will save you money on your energy bills and reduce your carbon footprint. Modern condensing boilers are particularly efficient because they recycle waste heat, making them even more cost-effective.
Size and Output
The size and output of your boiler should match your home’s heating and hot water needs. Common outputs range from 12kW to 37kW. For a small home with fewer radiators and one bathroom, a lower output will suffice. Larger homes with several bathrooms will require a higher output. Consult a heating engineer to determine the right size for your needs.
Reliability and Warranty
Choose a boiler from a reputable brand known for reliability. A good warranty is also essential—it offers peace of mind and protects you from unexpected repair costs. Top brands like Worcester Bosch, Vaillant, and Viessmann offer warranties ranging from 7 to 10, even 12 years, provided the boiler is installed by an approved engineer.
Installation Cost
While the boiler price is important, don’t forget to factor in the cost of installation. Installation prices can vary widely based on the complexity of the job and your location. Get quotes from at least three certified installers and ensure they include all necessary components and labour in their estimate.
Controls and Smart Features
Modern system boilers come with advanced controls and smart features. Look for models that are compatible with smart thermostats like Nest or Hive. These features not only offer convenience but can also enhance the efficiency of your heating system. Some boilers come with built-in connectivity options, making remote control and monitoring easy.
Get A Quote For A New System Boiler Today
Don’t wait any longer to upgrade your home heating system. At Boiler Central, we make it easy to find the perfect system boiler for your needs. Simply provide us with a few details about your home, and we’ll give you a fixed price quote in just 20 seconds.
Click here to get your instant quote from Boiler Central and take the first step towards a warmer, more efficient home today.
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FAQs
Do you need a new system boiler?
Buying a new boiler is not always the best solution, as there are other options like removing a hot water tank and converting a system boiler to a combi boiler.
That said, for environmental benefits and the eco-friendly nature of modern boilers, we recommend upgrading.
If you want to reduce your energy bills, a new system boiler is a great choice! They’re also ideal for S-Plan heating systems in new builds.
Modern system boilers are so efficient that the long-term savings on your bills will likely outweigh the initial cost of the new boiler.
If you need a high-volume water supply, consider the Megaflo unvented system boiler hot water tank. These advanced hot water cylinders provide ample hot water on demand while being more efficient thanks to their immersion heater that runs on electricity.
Which is the most energy-efficient system boiler?
The most energy-efficient system boilers in 2025 can achieve up to 98% efficiency. Here are some top models:
- Viessmann Vitodens 100-W: Up to 98% efficiency
- Vaillant ecoTEC Plus: Up to 94% efficiency
- Ideal Logic Plus: Up to 94% efficiency
These high-efficiency boilers can significantly reduce your energy bills. According to recent data, upgrading from an old G-rated boiler to a modern A-rated system boiler could save you up to £385 per year on heating costs.
Is a system boiler better than a combi boiler?
A system boiler is generally better than a combi boiler for homes with 4 or more bedrooms and 2 or more bathrooms, provided you have space for a hot water tank. This setup excels at meeting high hot water demands, allowing multiple taps and showers to be used simultaneously without losing pressure or temperature.
If you’re unsure whether you need a gas system boiler or a combi boiler, take a look at our System vs Combi Boilers: Which Is Best guide. You might also want to explore a combination of the two, also known as storage combi boilers, which offer the best of both worlds with their built in tanks or CLS.
What is the best gas system boiler?
The Viessmann Vitodens 100-W consistently ranks among the top system boilers in 2025. It boasts high efficiency, reliability, and has received multiple industry accolades, including Which? Best Buy recognition.
Final Thoughts
We hope this guide to the best system boilers in 2025 has been helpful in your search. Remember, the ideal boiler depends on your specific home requirements and usage patterns.
For a personalised boiler recommendation and quote, we offer a quick, no-obligation online quote calculator. Simply input your details for a tailored suggestion and pricing.
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