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Every year, your boiler is responsible for around 55-60% of your energy costs so choosing the most efficient boiler possible is crucial for keeping your energy bills down.

What is Boiler Efficiency?

Boiler efficiency refers to the relationship between the energy input and output of a boiler system. You will find this ratio shown as a percentage. When you see an efficiency percentage, this can help you assess the boiler’s performance and have a rough idea of what the fuel costs are to run your boiler equipment.

Understanding your boiler efficiency before buying a new boiler can help you save money in the long term. By buying a more efficient boiler up front, even if it means a bigger investment, could save you ongoing fuel usage costs in the future.

Why is Boiler Efficiency Important?

A more efficient boiler has positive ramifications for your wallet and for the environment. At a personal level, a more efficient boiler burns less fuel – this translates to lower costs. In fact, data shows that an efficient boiler can save you up to £820 on your heating bills!

Not only that, but boiler efficiency is important for the future of our planet. As efficient boilers burn less fuel, it means fewer carbon emissions released into the atmosphere. This can help delay the effects of climate change.

How Do I Know if my Boiler is Efficient?

There’s a simple way to tell how efficient your boiler is. Every boiler has an ErP (Energy-related Products) efficiency rating which tells you how efficiently a boiler will perform. To find out the efficiency of your boiler, look for a small sticker which will have the energy efficiency rating. For modern boilers, you can find this on the boiler itself or inside the information pack that came with your boiler. If you know the model of your boiler, you can also go online and check the Product Characteristics Database online.

ErP ratings are ranked from A to G – A being the highest, G being the lowest – to tell the efficiency of a boiler or a heating system. The majority of modern boilers have an A rating or could even have A+, A++, A+++ to indicate a superior level of efficiency.

How Efficient is Your Boiler?

Since April 2005, the UK has followed regulation which stated that all gas boilers installed must use condensing technology. This technology allows more of the heat to be captured rather than escaping through the flue pipe – i.e. more efficient. With this technology, you use the same amount of fuel but get more heat. That means if your boiler has been installed since 2005, it is a condensing boiler and, therefore, more efficient than a non-condensing boiler.

What Makes a Boiler High Efficiency?

High efficiency boilers are “condensing” meaning that they’re specifically designed to trap escaping heat and direct it back into the heating system. These boilers have an annual fuel utilisation efficiency of 90% or more. That means that only 10% of energy escapes while the remaining 90% of energy produced by the boiler is actually used.

What’s the Difference Between a Standard Boiler and a High Efficiency Boiler?

If you have a standard efficiency boiler that is in good condition, it probably wastes around 20% of energy – 10% more than a newer, higher efficiency boiler.

why is boiler efficiency important I

High energy efficiency boilers have an efficiency level of 90% or higher

Pros of a High Efficiency Boiler

There are many benefits to having a more efficient boiler including:

Lower heating bills – as heating our homes accounts for over half of our total energy use, a more efficient boiler can help keep energy bills down.

Better for the planet – high efficiency boilers use the same amount of fuel to produce more heat meaning they release fewer carbon emissions and contribute less to climate change.

Improved home value – an energy-efficient boiler can appeal to potential buyers and offer lower energy bills for the new homeowner.

Less noise – high-efficiency boilers tend to be far quieter than standard boilers as they have to work less hard to create heat.

Follow these tips to make your boiler more efficient!

Are There any Disadvantages to a High Efficiency Boiler?

In general, it is considered that a highly energy efficient boiler is preferable to a standard efficiency boiler. However, some downsides include higher installation costs and need for more maintenance than an older boiler (annual service).

Do Boilers Lose Efficiency with Age?

The older your boiler is, the more inefficient it is likely to be; especially if it doesn’t undergo an annual check-up or isn’t maintained well. As a result, you could face higher home heating bills for older boilers than for newer boilers.

Even if it is a condensing boiler, older models are set up to run like a non-condensing boiler with the efficiency level of an old boiler. Boilers over 10 years old are likely to have an ErP rating of G signifying a less than 70% efficiency while boilers of over 25 years old are likely to only be between 60-70% efficient.


As you can see, there are many reasons why boiler efficiency is important. A more efficient boiler will help lower your heating bills, lower your carbon footprint and heat your home more reliably. Want a quote for a more efficient boiler? We at Warmable will help you compare the best priced quotes for your boiler needs.

Get a quote today! 

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