Energy Efficient Boilers – What are they and How do They Save Money?

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In the UK, the focus on energy-efficient boilers has become much more intense in recent years, driven by a heightened awareness of environmental concerns and the need to reduce energy bills. 

The energy efficiency of a boiler is critical in reducing your carbon footprint and ensuring cost-effectiveness for homeowners.

If your boiler is old, consider upgrading to a newer, more energy-efficient model. Modern condensing boilers are significantly more efficient than older models. 

You should always ensure your boiler operates in its condensing mode, which is more energy-efficient, as much as possible. 

It would be best to consider setting the hot water temperature comfortably but not excessively hot. Overheating water can waste a lot of energy.

Understanding Energy Efficiency in Boilers

Energy-efficient boilers, particularly those with high A+++ ratings, stand out for their ability to convert more fuel into usable heat, surpassing standard A-rated boilers by at least 30%. 

These ratings reflect the boiler’s overall energy performance, taking into account the fuel type and brand-specific technologies​. This guide from compare boiler quotes can help you gain more of an understanding of the most energy-efficient boilers in the UK. The A+++ rating is the highest achievable rating, with each “+” symbol indicating a 10% increase in efficiency over the basic A rating. 

Types of Boilers and Their Efficiency

Condensing Boilers

These are currently the most efficient types available. They are designed to maximize energy efficiency and reduce carbon emissions. These boilers use the heat from exhaust gasses that would otherwise be wasted in traditional non-condensing boilers.

By capturing and condensing these gasses into liquid form, they extract additional heat, making the process much more efficient. Condensing boilers are known for converting over 90% of fuel into usable heat, surpassing the efficiency levels of older boiler models.

They are commonly found in modern homes as they align with environmental regulations to reduce carbon emissions and promote energy-efficient heating solutions. 

The condensing technology contributes to lower energy bills but also helps minimize the environmental impact by conserving energy and reducing greenhouse gas emissions.

Combi Boilers

Combi boilers are all-in-one heating systems widely used in the UK. These boilers provide hot water for taps, showers, and central heating for the home, all from a single unit.

Unlike traditional boilers, combi boilers don’t require a separate hot water cylinder or cold water tank, saving significant space in homes. 

They work by heating water directly from the mains, delivering hot water almost instantly whenever a tap is turned on. Combi boilers are known for their efficiency, providing continuous hot water on demand without preheating, making them a popular choice for smaller properties or households looking to save space.

System Boilers

System boilers are a heating system commonly found in homes across the UK. Unlike combi boilers, they work alongside a separate hot water cylinder to store and supply hot water to taps and showers.

These boilers heat water from the mains, which is then stored in the cylinder, ensuring a constant hot water supply ready for use. 

System boilers are known for their efficiency and ability to meet high hot water demands, making them suitable for larger households with multiple bathrooms. They offer the advantage of not requiring a cold water tank in the loft, freeing up space compared to traditional heating systems.

System boilers are favored for their reliability and consistent performance in providing ample hot water for more significant properties without compromising efficiency.

Regular Boilers

Regular boilers, or conventional or heat-only boilers, are a traditional heating system often found in older homes in the UK. These boilers work alongside both a hot water cylinder for storing heated water and a cold water tank, usually located in the loft.

Regular boilers heat water from the cold water tank, which is then stored in the hot water cylinder until needed for taps, showers, or the central heating system. They operate on the principle of stored water, providing a consistent hot water supply for more significant properties with multiple bathrooms.

Regular boilers are known for their reliability and compatibility with existing heating systems, making them a preferred choice for households with older infrastructure accommodating separate tanks for hot and cold water storage.

Also known as conventional boilers, these require both a hot water cylinder and a cold water storage tank, making them suitable for larger homes with high hot water demands​​.

Financial and Environmental Benefits

Upgrading to an energy-efficient boiler can lead to significant savings. Replacing an older, non-condensing boiler with a modern condensing model can save up to £300 annually on energy bills. 

High-end models like the Viessmann Vitodens 200-W can achieve up to 98% efficiencies, translating into tremendous savings over time​​.

Advantages of Condensing Boilers

Energy Efficiency

By reclaiming heat that would usually be lost, condensing boilers operate more efficiently, reducing energy consumption and lowering heating bills.

Environmental Benefits

Higher efficiency means less fuel consumption, leading to lower greenhouse gas emissions. If you want less environmental impact and to reduce your carbon footprint, condensing boilers should be considered.


Despite the higher initial purchase cost than traditional boilers, the energy savings achieved by condensing boilers can lead to significant cost savings over time.

Flexibility and Compatibility

Condensing boilers can be a good match for low-temperature applications, such as radiant floor heating systems and older heating systems like cast iron radiators​​.

Selecting the Right Boiler

When choosing a boiler, consider your home’s size, hot water needs, and whether you plan to use renewable energy sources like solar panels. 

These factors will depend on the choice between a combi, system, or regular boiler. It’s also important to consider the installation and long-term running costs, as well as the warranty and customer service offered by the manufacturer​​.

Future Considerations

The UK government plans to phase out fossil fuel heating systems, with a ban on gas and oil boilers in new homes starting from 2025. 

This is part of the broader strategy to reach net-zero carbon emissions by 2050. Homeowners are encouraged to consider low or zero-carbon emission heating systems, such as heat pumps, in line with these environmental goals​​.


In summary, investing in an energy-efficient boiler is a prudent choice for UK homeowners, offering both financial savings and environmental benefits. 

Understanding the different types of boilers and their efficiency ratings, along with considering future heating trends, is very important when making an informed decision that aligns with your personal and environmental objectives.

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