Best System Boiler: Which are the best system boilers for 2024?

James Elston
Written by James Elston
Updated on 2nd January 2024
Posted on 1st January 2024
Topic: Boiler Guides
Best System Boiler: Which are the best system boilers for 2023

Which is the best system boiler in 2024?

worcester 400 system boiler

System boilers are common across UK households, especially for those with more than four people or more than one bathroom, here, we provide advice on the best system boilers for 2024 and beyond.

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If you’re unsure whether you need a gas system boiler or a combi boiler, take a look at our guide System vs Combi Boilers: Which Is Best. Perhaps you may even look for a combination of the two therefore you should look at storage combi boilers which include a built in tank or CLS.

If you’re ready to dive in, then let’s take a look at the best system boilers in 2024 and save you some time and money. And don’t forget to compare against other gas boiler types and compare with our guide to boiler costs too.

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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 UK system boilers for 2024

  1. Viessmann Vitodens 100-W system
  2. Worcester Bosch 4000 system boiler
  3. Worcester Bosch Greenstar i System
  4. Vaillant ecoTEC Plus System

#1 Best System Boiler Viessmann Vitodens 100-W

The Viessmann Vitodens 100-W System boiler is a fantastic and reliable wall-mounted gas condensing boiler. Now hydrogen ready and with built in Wi-Fi, this is the system boiler for the future.

vitodens 100

These best gas system boilers are available for around £1000 making them a great choice for any home that wants a top-quality but cheap system boiler.

It comes in 25kW, 30kW, and 35kW system boiler sizes and this system boiler will be perfect for larger homes with more than one bathroom that demands water to multiple taps at once.

For Vitodens 100-w quote in 20 seconds – click here

You can get 12 years boiler warranty with Boiler Central on this boiler right now.

What do we love about this system boiler?

The Viessmann Vitodens 100-W System Boiler comes with an efficient and reliable Inox-Radial heat exchanger with MatriX cylinder burner. 

The cylinder ensures the heat is distributed cleanly and efficiently and won’t corrode or fail as with most other boilers.

With a high modulation ratio of 1:10, the boiler reduces or increases its operating power for any given room environment. This reduces heating bills and wear and tear.

The LCD touchscreen makes this system boiler easy to use, and It also comes with an optional external weather detector. What does this mean? It means that the detector allows the boiler to react to outside weather conditions and increase or decrease boiler temperature accordingly.

This system boiler rates ‘A-Class in the SEDBUK energy efficiency ratings.

Main Features:

  • High modulation ratio of 1:10
  • SEDBUK A Rating
  • MatriX pre-mix cylinder burner and an integral AquaBloc hydraulic unit
  • Various Kw Heating Output -26kW, 30kW, and 35kW
  • Very Quiet Boiler
  • Optional external weather detector
  • Advanced technology – hydrogen ready boiler and built in Wi-Fi
  • Which Rating 76%
  • LCD touchscreen
  • Compact size
  • Lightweight
  • 5- year parts and labour warranty as standard (Up to 12 years with Viessmann Installer)

Overall, we would recommend this system boiler above all others due to quality, performance, lengthy warranty, and price. 

With installation, you can expect a cost between £1800-£2200 depending on the company who installs it. 


If you’d like a new system boiler quote, then click here as we can 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. 

#2 best system boiler Worcester Bosch 4000

The new Worcester Bosch Greenstar 4000 system boiler is the latest boiler from the brand. This upgrade on the os Greenstar i system boiler which is still a great boiler is taking the market by storm.

The Worcester 4000 system boiler costs around £900 to buy on its own. It’s a mid-range system boiler and is suitable for medium to large homes in the Uk that required higher hot water demand.

It comes in 12kW, 15kW, 18kW, 21kw and 24kW system boiler sizes.

worcester bosch 4000 system boiler

This wide choice of outputs in the Worcester 4000 range means that it is suitable for more homes than not and to ensure that it is as energy efficient as possible in each situation.

For Worcester 4000 system boiler quote in 20 seconds – click here

What do we love about this system boiler?

For start it’s a Worcester, so you already know that it is going to be a good reliable and hard-working boiler. It comes with a good warranty of 10 years, but this can be extended to 12 years exclusively at Boiler Central!  It also looks pretty good too with its new facelift.

It is a very quiet boiler and has been given the Quiet Mark accreditation for its low operating noise level. It is the quietest system boiler that Worcester makes.

The new 4000 system boiler is a hydrogen ready boiler which means it is futureproofed and can run on 20% hydrogen out of the box, whilst it can easily be changed to run on 100% hydrogen in the future.

Being a system boiler and using a hot water tank, it can also be used with solar panels to help cut energy costs. It also has wireless connectivity built-in so that you can control your heating with your fingertips using a smart thermostat and your mobile devices

This system boiler rates ‘A-Class in the SEDBUK energy efficiency ratings.

Main Features:

  • Great for most homes in the UK with a hot water tank
  • SEDBUK A Rating
  • Upgrade of the Greenstar i range
  • Various Kw Heating Output from 12kw to 24kw
  • Very Quiet Boiler
  • Optional external weather detector
  • Advanced Hydrogen technology
  • LCD touchscreen
  • Compact size
  • Lightweight
  • 8- year parts and labour warranty as standard (Up to 10 years with Worcester Filter)

Overall, we would recommend this system boiler as it is a reliable and easy-to-use boiler that is energy efficient at a great price.

With installation, you can expect a cost between £1900-£2400 depending on the company who installs it. 


If you’d like a new system boiler quote, then click here as we can 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. 

#3 Best system boiler – Worcester Bosch Greenstar 24i

best system boiler
greenstar i boiler system boilers 2024

The Worcester-Bosch Greenstar 24i System is one of a range of highly energy-efficient A-rated gas boilers.

They are rated very highly by SEDBUK 2009.

Being a system boiler, the Worcester-Bosch Greenstar 24i System requires a hot water storage cylinder; however, it doesn’t require a feed and expansion cistern.

This makes the Greenstar 24i a quick and easy boiler installation as well as being efficient and economical to run.

What do we love about this system boiler?

With the Worcester-Bosch Greenstar 24i, heat from exhaust gases, that would otherwise be lost through the flue, are recycled. This heat is then used as output, powering your domestic hot water and central heating with what otherwise be wasted energy.

This means that the Greenstar 24i is up to 30% cheaper to run than some older boilers.

We rate this boiler lower than the Viessmann because the Viessmann has a much better stainless steel heat exchanger with better reliability than the Worcester Bosch. 

The price comes in around £1,050 on average with an installed price being around £2000. 

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Main Features:

  • ERP rating: A HEAT
  • Efficiency Rating: 94%
  • Band Rating: A Rated
  • LPG Compatible: Yes
  • Standard Warranty: 5 Years
  • kW Options: 24.6 kW
  • Mounting: Wall-mounted

Overall, with the price and efficiency, we recommend this boiler in 2nd place to the Viessmann.

After our extensive research, going through customer reviews, looking at our own customer’s experiences, asking our Gas Safe heating engineers about fitting, reliability, etc.

You can be sure that our information is reliable and will give you a fantastic new system boiler. 

#4 Best system boiler – Vaillant ecoTEC Plus

Best system boilers
Vaillant EcoTEC System Boiler 2024

The ecoTec boiler range from Vaillant is a fantastic and low energy consumption system boiler for 2024.

It has excellent performance for hot water and central heating – and lower fuel bills for you. 

The Vaillant ecoTec 30kW is the most popular size boiler in this range, but it is also available as 12kW, 15kW, 18kW, 24kW, 30kW and 37kW.

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.

It is known by our installers to be efficient, easy to use, reliable and quiet.

With its straightforward backlit display and like the Viessmann, its a stainless-steel heat exchanger and its premium components, it’s really one of the top system boilers available on the market today.

We only rated this in third place due to the initial cost.

It does have a better heat exchanger than the Worcester Bosch however its initial cost is almost £500 more than the other two system boilers. 

Pricing is around £1500 with an installed price of £2000+

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vaillant eco tech best system boilers 2022

Vaillant System Boilers Features:

  • For use with Unvented Systems.
  • Stainless steel heat exchanger
  • 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

Overall, an excellent boiler with reliable internal components means you can’t go too far wrong with the Vaillant EcoTec series system boilers.

Do you have a system boiler with a hot water cylinder? you may have come across a small device called a tundish, if so and you need a new one or think you need one installed, then read our what is a tundish guide as they can play an important part in keeping your water clean and sanitary.

What’s the average cost of a system boiler?

boiler pressure

The average cost of the best UK system boilers in 2024 is around £2,150.

At the low end, system boiler prices are around £1500, whereas the top-end boiler systems come in around the £3000+ mark.

Remember that boilers are one of the most important features of your home in terms of use and cost, so picking the right system boiler at the right price is paramount to having a warm and cosy place to live. See the latest new system boiler costs here

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Do you need a new system boiler? 

If you’re here because you are looking for a new gas system boiler or any other fuelled system boiler, then welcome to our guide as there are other options such as removing a hot water tank and converting a system boiler to a combi boiler.

However, now we’ve discussed our recommended system boilers, let’s identify whether you need a new boiler.

Is it worth getting a new system boiler?

For the eco-friendly benefits and the green nature of modern boilers, we would recommend upgrading. 

If you want to save money on your bills, go ahead and get a new system boiler! System boilers are great to be used with S-Plan heating systems in new builds too.

This is because they are now so efficient that the savings over the years on your bills will more than pay for your new system boiler. 

If you need an almost waterfall of water then you should maybe consider the Megflo unvented system boiler hot water tank. These hot water cylinders are even more hi-tech to provide lots of hot water at once, whilst being far more efficient due to the built-in immersion heater that runs on electricity

Which is the most energy efficient system boiler?

The most energy-efficient system boiler runs at 94% energy efficiency, therefore this includes the following models that all run at 94% efficiency:

  • Viessmann Vitodens 100-w
  • Worcester Bosch Greenstar 24i
  • Worcester Bosch 4000

The energy-saving trust’s guide for 2022 says that the new system boilers can save you more than £580 a year on your heating and hot water costs. You could save even more money by setting up an S-plan system in your home too which works well with system boilers.

The warranties last longer, as do the system boilers:

The modern system boiler can have warranties starting at 10 years and go higher or lower depending on the manufacturer.

Viessmann system boilers offer a 12-year warranty at Boiler Central whereas Vaillant offers up to 10 years warranty, also, the internal components are much more reliable and make sure of more advanced digital features such as automatic frost protection, weather compensation, and boiler modulation.  

Is a system boiler better than a combi boiler?

As system boiler is better than a combi boiler if your home has, 4 or more bedrooms and 2 or more bathrooms and you have space for a hot water tank. This is due to the likelihood that there is going to be much more increased hot water demand which can be met when multiple taps and showers are used at once.

What is the best gas system boiler?

The Viessmann 100-W tops the best system boilers on the market today. Do they even have Which? Best Buy boiler accreditation!

If you’ve been looking for the best system boilers in 2024, we hope that the above information has been of value to you and helps you in your search. 

If you would like a custom boiler quote calculator which gives you a specific price, then please see our website as we offer this service with no obligation. 

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Written by
James Elston
James Elston Director Of Boiler Central
Posted on: 1st January 2024
Topic: Boiler Guides

James Elston is our resident boiler replacement and heating expert here at Boiler Central. With over 20 years experience in the boiler installation industry, James ensures that he knows everything there is about our Gas Safe boiler installations, energy saving and home heating solutions. This can be from simply procuring the latest best combi boilers, to reviewing and ensuring that Boiler Central maintains the highest standards across our boiler installation company.

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