What is the Most Energy Efficient Boiler in the UK in 2024?

25 June 2024

Are you tired of the high energy bills at your commercial property? If so, upgrading to a more energy efficient commercial boiler could be the right solution for you. Modern boilers are designed to be more efficient than older models, and can provide optimal heating output whilst also significantly reducing your fuel costs. Plus, when factoring in that the UK Government is increasingly tightening their regulations for boiler efficiency, there’s never been a better time to consider an upgrade.

However, with so many brands and models to choose from, how do you know which boiler will provide the best energy-saving properties? We’ve got you covered. In this blog, we’ll uncover which boiler is considered the most energy efficient system in the UK in 2024, weighing up the specs of several different systems to help you make an informed decision.

How is Boiler Efficiency Measured?

An efficiency rating measures how much energy a boiler converts into heat compared to the amount lost during combustion. It’s displayed as a percentage, where higher numbers indicate better efficiency.

The easiest way for you to check the energy efficiency of a boiler is to look at where it ranks on rating systems. Since 2015, a vast majority of boilers have been rated with the ErP (Energy related Products), which assigns efficiency percentages to a corresponding letter. Letters range from G (lowest efficiency) to A+++ (most efficient). ErP labels on boilers include information about heat output, water heating efficiency, noise levels and other relevant pieces of data that help customers make informed decisions when choosing their next boiler.

What Factors Affect Boiler Efficiency?

When considering the most energy efficient boiler in the UK, it’s important to understand the factors that impact efficiency ratings.

Burner Quality

The burner is responsible for igniting the fuel and generating heat in the boiler. High-quality burners allow fuel to be burned cleanly, the result of which is better combustion and higher efficiency. By contrast, a poor-quality burner can lead to incomplete combustion and wasted fuel.

When choosing a new boiler or upgrading an existing one, it’s good to factor in burner quality to improve boiler efficiency. Some of the best burners on the market include the Riello RDB series burners and the Worcester Bosch Greenstar Danesmoor burners.

Flow Rate

Flow rate refers to the amount of water that flows through the boiler at any given time. A higher flow rate means that more water passes through the system per minute. While this might seem like a good thing at first, since it increases the availability of hot water, this can negatively impact the efficiency of the boiler. This is because higher flow rates require more energy to heat up all of that water quickly, and as such, boilers with low flow rates tend to be more efficient as they use less energy overall. As such, opting for models with lower flow rates will improve efficiency while still providing enough hot water for your needs.

Output

Boilers are available in many different sizes, from small, domestic units to large, commercial ones. However, contrary to belief, bigger doesn’t always mean better. In fact, high output boilers are likely to be less efficient since they yield more power than is necessary for many businesses. Because of this, they end up using more fuel than what’s needed, which results in wasted energy and more expensive bills.

Much like flow rate, selecting a boiler with a lower output will help to improve efficiency while still providing your business premises with enough heat.

Parts Quality

Lastly, the quality of the parts that make up your boiler can massively impact how efficient it is. High-quality parts are designed to work together seamlessly, allowing the system to run smoothly and efficiently. On the other hand, low-quality parts can lead to breakdowns and other issues that reduce the boiler’s efficiency and can increase repair costs over time.

When choosing a boiler, you should opt for models made by reputable manufacturers who are known for using premium parts. As we’ll discuss below, some of the best brands on the market include Worcester Bosch, Valiant and Ideal Boilers.

Top Energy Efficient Boilers in the UK

There are two main types of boiler - combi and conventional - that we’ll be discussing when it comes to determining the most energy efficient system. Combi boilers heat water directly from the mains supply, whereas conventional boilers store hot water inside the tank. Both have their pros and cons in terms of their energy efficiency ratings.

Best Combi Boilers

Worcester Bosch Greenstar i
Vaillant ecoTEC Plus
Viessmann Vitodens 050-W

The Worcester Bosch Greenstar i is considered to be one of the most popular combi boilers available on the market due to its efficiency and reliability. It has an efficiency rating of up to 94%, making it one of the most efficient models available.

Like the Greenstar i, the Vaillant ecoTEC Plus is another highly-rated combi model that boasts an equally impressive efficiency rating of 94%. Its compact design makes it ideal for smaller commercial spaces. However, if you’re looking for a more regular boiler, this might not be the right option for you.

Finally, the Viessmann Vitodens 050-W is a fantastic choice for those in need of an energy efficient combi boiler. With an energy rating of up to 97%, it stands out as one of the most efficient systems on this list.

Best Conventional Boilers

Baxi 800 Heat
Ideal Logic+ Heat
Potterton Titanium

If you’re looking for a conventional boiler over a combi model, these three systems are some of the most energy efficient on the UK market.

The Baxi 800 Heat has an efficiency rating of up to 93%, making it one of the most energy efficient conventional boilers you can find right now. Like the Vaillant ecoTEC Plus, it has a similarly compact design, allowing it to be easily installed in smaller spaces.

The Ideal Logic+ Heat is one of the top-rated regular gas boilers in the UK, with an impressive efficiency rating of up to 94%. It’s best known for its reliability and ease of use, as well as its excellent boiler features. With Ideal being one of the nation’s leading boiler brands, this gas boiler is a popular choice for home and business owners looking for an effective yet efficient heating solution.

Last but not least, the Potterton Titanium is another fantastic choice of efficient conventional boiler. It also has an efficiency rating of up to 94%, and comes complete with a range of features, such as frost protection and a built-in filling loop.

Count On Our Industrial Heating Engineers

Once you’ve decided on the perfect energy efficient boiler for your business, you’ll need help installing it to make sure it functions properly. Fortunately, if you’re based in Edinburgh, Dundee or the surrounding areas, Caledonian Heating and Plumbing can help. Our expert industrial heating engineers provide a comprehensive range of reliable, cost-effective commercial heating and plumbing services, including the installation, servicing and repairs of many different types of combi and conventional boiler systems.

Every single member of our team is Gas Safe registered, with countless years of experience beneath their belts, meaning you can rely on us to deliver a high-quality service each and every time. No matter what your commercial heating needs might be, we’re here to help you find the best possible solution for your business. No job is too big or too small for our skilled engineers!

For more information about our services, please get in touch with us today.

< Older Post

Newer Post >

How Often Should Water Tanks Be Cleaned?

27 January 2026

Learn how often commercial water tanks should be cleaned to maintain water quality, manage legionella risk and stay compliant with UK regulations.

Why Planned Maintenance Beats Emergency Repairs Every Time

27 January 2026

Planned maintenance for commercial heating in Scotland reduces costly breakdowns, downtime, and ensures efficiency, safety, and compliance.

Why Water Risk Assessments Are Vital in Healthcare Settings

18 December 2025

Ensure patient safety and compliance with expert water risk assessments in healthcare. Prevent Legionella and protect your facility’s reputation.

Emergency vs Routine Plumbing Repairs: When to Call the Experts

19 November 2025

When it comes to plumbing issues, timing is everything. A small leak can quickly turn into a major problem if left unchecked, while some situations demand immediate attention to prevent costly damage or business disruption. Understanding the difference between emergency and routine plumbing repairs can save you time, stress, and money, and help you know when it’s time to call in the experts. What Counts as a Plumbing Emergency? A plumbing emergency is any issue that poses an immediate risk to safety, property, or business operations. In commercial environments, even a short period of downtime can have serious consequences, so swift action is essential. Common plumbing issues include: Burst or leaking pipes – Sudden water leaks can cause flooding and damage walls, floors, and electrical systems. Blocked or overflowing drains - Particularly in high-traffic areas, this can create health hazards and disrupt operations. No hot water or heating - Especially critical in settings like schools, hospitals, or care facilities. In these situations, it’s vital to contact a qualified plumbing engineer right away. Our team at Caledonian Heating & Plumbing provides rapid-response emergency support to restore safety and minimise downtime for commercial clients. When Is It a Routine Repair? Routine plumbing repairs cover non-urgent maintenance tasks or issues that develop gradually. While they might not cause immediate disruption, they still need attention to prevent bigger problems later on. Examples of routine repairs include: Slow-draining sinks or toilets Minor leaks under basins or radiators Reduced water pressure Regular maintenance of heating systems or water tanks Scheduling routine repairs ensures your systems continue running efficiently and helps you plan maintenance at a time that suits your business, avoiding the cost and chaos of unexpected emergencies. The Benefits of Preventative Maintenance Many plumbing emergencies are avoidable with regular inspections and servicing. Planned maintenance helps identify potential issues before they escalate, ensuring your systems remain compliant, efficient, and reliable. At Caledonian Heating & Plumbing, we tailor maintenance schedules for each client, from small businesses to large facilities, to keep everything flowing smoothly year-round. Proactive maintenance also supports compliance with health and safety regulations, such as ACOP L8 for water systems and Gas Safe standards for heating installations. When in Doubt, Call the Experts If you’re unsure whether an issue is urgent, it’s always best to speak with a professional. Attempting DIY fixes or delaying repairs can lead to greater damage, increased costs, and potential safety risks. At Caledonian Heating & Plumbing, our engineers are on hand to assess the situation and provide the right solution, whether that means an emergency call-out or scheduling routine maintenance at your convenience. Need urgent help or want to arrange a maintenance visit? Contact Caledonian Heating & Plumbing today for expert, reliable service across Scotland.