Best system boilers in 2023

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What is a system boiler?

A system boiler is one of three main types of boiler, the others being combi boilers and heat-only boilers. System boilers require a hot water cylinder, or tank, that is used to store any hot water the machine creates for later use. This means they require more space than a combi boiler, for example, but they are better suited to larger homes with high levels of hot water demand.

How did we choose the best system boilers?

When looking for the best system boiler on the market, we only took into account products from the best boiler brands. These brands have a certain level of reputation and engineering know-how that sets their boilers apart from the rest. 

Within these leading brands, we looked at a number of features that make any particular boiler worth buying. These include: 

• Customer reviews
• Value for money
• Size and output
• Ease of use
• Awards won
• Standard warranty length 

So, without further ado, let’s take a look at what the best system boilers are in 2023:

Top 5 system boilers in 2023

Viessmann Vitodens 100-W

One of the best all-round system boilers comes from German engineering specialists Viessmann. The Vitodens 100-W system boiler, which is also available as a combi boiler, is a reliable, future-proof central heating system, being hydrogen-ready and coming with in-built WiFi.

It’s a lot more compact than your average system boiler, and being wall-mounted you can be confident of storing it away neatly in a cupboard or boiler room. It’s also great value for money, starting at just £1,000, so it can be a great choice for those on a budget, without having to compromise on quality and durability.

Like its combi boiler namesake, the Vitodens 100-W system boiler is available in outputs of both 25kW and 30kW, while you can also get a more powerful model with an output of 35kW, which would more suited to larger homes with higher hot water demand.

Ideal Logic Max

This system boiler from Ideal, which is one of the leading boiler manufacturers in the UK, is a super-compact and efficient machine that’s become of the most popular central heating systems in the country.

It’s very competitively priced compared to other system boilers on the market, starting at just over £1,000 pre-installation.

What you’ll get with that is a highly reliable machine with award-winning features, including a magnetic system filter which ensures that any impurities are removed from the water before it reaches your shower or bathtub. It’s case is also scratch resistant, and both of these features go a long way to improving the longevity of the boiler.

The Logic Max is also future-proof, being hydrogen-ready should the National Grid switch to hydrogen-based fuel instead of fossil fuels. It’s available in a range of outputs - 25kW, 18kW, 24.2kW, and 30.3kW - and all of them are small enough to be placed neatly away in a storage room or boiler cupboard. They can also be placed externally or in a garage if you prefer, thanks to its in-built frost resistant technology.

Worcester Bosch Greenstar 4000 

This system boiler from market-leading brand Worcester Bosch is the latest model on its premium Greenstar range, and is fast becoming one of the most popular system boilers in the UK. 

Part of its popularity comes down to its versatility. It’s available in a choice of five power outlets - 12kW, 15kW, 18kW, 21kW, and 24kW - so, no matter the size of your house and your hot water demand, you should be able to find a model to suit your needs.

The Greenstar 4000 is hydrogen-ready, meaning it can run on up to 20% hydrogen as it is, while it’s also fairly easy to modify in order to run on 100% hydrogen in the future. It’s wireless controls mean you can manage your hot water from a smart thermostat or even your smartphone, while it’s also compatible with solar panels, if this is something you’ve thought anbout investing in.

Another reason why it’s an ideal choice for consumers is it’s price - starting at just £900 (pre-installation), it’s even cheaper than the great-value Viessmann Vitodens 100-W. In fact, you’d struggle to find such a reliable central heating system for cheaper. 

Worcester Bosch Greenstar 24i

Another system boiler from Worcester Bosch, the Greenstar 24i is another highly-efficient and great value central heating system. Although not as compact as the Greenstar 4000, it doesn’t require a feed or expansion system along with its hot water cylinder, making it super easy to install and run.

The Greenstar 24i recycles any heat that would otherwise be lost via the flue, and uses it to power the boiler’s hot water creation, ultimately resulting in less energy, and money, used in heating your home. 

Although it’s slightly more expensive than the Greenstar 4000, starting at £1,050 pre-installation and averaging around £2,000 for the full package, the extra efficiency means it’s up to 30% cheaper to run than older, inefficient gas boilers. 

Although it’s a highly reliable and durable machine, its standard warranty of 5 years is slightly disappointing compared to its rivals. That being said, it should last at least that long and then some.

Vaillant ecoTEC Plus

This highly efficient system boiler from Vaillant is a great choice for those seeking a powerful and reliable central heating and hot water system, while also looking to cut down on their energy bills.

It comes in a range of power outputs to suit all types of household - 12kw, 15kW, 18kW, 24kW, 30kW, and 37kW. If you live in a medium to large household with 2 or more bathrooms, we recommend getting the 30kW or 37kW model, while smaller properties will be better suited to those with smaller outputs.

One of the best features of the ecoTEC Plus is its smart capabilities. It monitors your energy usage in real time, and knows when your property has less demand for hot water, using just 16% of its maximum power during off-peak times in order to save on energy and money.

Its backlit display is extremely simple to use, giving you greater control over your energy usage. It’s also very well-built, thanks to high-tech German engineering from Vaillant, and its stainless steel heat exchanger makes the ecoTEC Plus stand out from other system boilers on the market.

All in all, this model is one of the best system boilers you can currently get your hands on, but it has a price point to match - costing around £500 more on average for a full installation than other boilers on this list.