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Energy Efficient Boilers

Energy efficient boilers are great news for both you and the planet – they are much more energy efficient due to changes in modern technology when compared with traditional boiler systems. Our complete guide to energy efficient boilers will help you determine whether or not to upgrade your old boiler to a new energy efficient model which will not only save you money, but will also reduce your chances of a boiler breakdown.

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What is an energy efficient boiler?

Energy efficient boilers are boilers which use less fuel, therefore less energy, than a regular non-efficient boiler. As it uses less fuel, it means it will save you more money on your hot water and heating bills. 


What is a good efficiency rating for a boiler?

Boiler efficiency is used to show how well the boiler turns fuel into usable energy, such as heat and hot water. 

All boilers now must be condensing, meaning they run on either gas or oil. Because of this, most modern boilers now have very similar efficiency ratings, also known as ERP ratings, ranging from A+++ down to a G.

The higher the score, the more efficient the boiler is, and most modern boilers are highly efficient so will typically have an A+ rating

As well as the letter graded ratings, boilers have a space heating efficiency rating which comes in the form of a percentage. Modern boilers will have a rating of around 94% to 92%.

What type of boiler is cheapest to run?

Depending on the size of your home, condensing natural gas combi boilers and system boilers are the cheapest to run, which is why they are the most popular boilers across the country.

Electric boilers are on the more expensive side, but you can make your electric boiler cheaper by adding renewable energy in the form of solar panels to your home. 

The solar energy can be turned into electricity which is then used to power appliances around your home, including electric boilers. 


What is the most energy efficient boiler?

Combi boilers are compact heating systems, meaning you don’t need to fit them with a cylinder. They deliver hot water on demand. They have very quickly become the top heating choice for UK homeowners, making the market competitive. 


Viessmann Vitodens 050-W 29kW

This impressive boiler comes with an ERP rating of A and a 97% efficiency percentage. Its reliable design makes it perfect for a busy household, and the high efficiency rating will drastically cut your fuel costs (not to mention the water flow rate of 12 litres per minute).

It is incredibly quiet whilst working hard to provide your home with heating and hot water.


Worcester Bosch Greenstar 8000 style 30kW

Being a reliable household name, you can count on Worcester Bosch to provide great quality and efficient boilers. The Greenstar 8000 offers a desirable efficiency percentage of 94%, and up to 14 litres of hot water per minute.

At Lacey Plumbing & Heating, we are Worcester Bosch Boiler Accredited Installers, which means we can offer extended guarantees on these boilers. Worcester Bosch are one of the most popular boiler brands in the UK and provide excellent products and aftercare. 


Vaillant EcoTech Plus 30kW

The EcoTech Plus delivers hot water within 5 seconds and has a very impressive water flow rate of 15.9 litres per minute, plus a decent energy efficiency percentage of 90.1%

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Energy efficient boiler systems

Condensing boilers are fitted with two internal heat exchangers to ensure that less heat is lost. This means that it uses less energy, and doesn’t have to work as hard. 

This means that condensing boilers are far more efficient than non-condensing boiler units. If you have an old non-condensing boiler, upgrading to a new condensing boiler could save you up to £300 on your annual bills. 

Most new gas condensing combi boilers come with an energy percentage of 98%. This can decrease over time, but on average the efficiency rating remains higher than conventional boiler systems. 

System boilers usually achieve an efficiency of around 90% at optimum conditions. 

How energy efficient is my boiler?

As a customer, you don’t need to know all the technical details of how efficient your boiler is. We can advise on the most energy efficient boiler when we survey your current heating system. However, it is worth understanding the basics as it can have a large impact on your annual spendings. 

To calculate the boiler efficiency, we need to divide the energy output by the total energy input, multiplied by 100 to get a percentage.


How much can an energy efficient boiler save?

If you upgrade your old boiler to a new energy efficient one, you are likely to save between 20-35% on your gas bills. 

This means you could save up to £350 per year by simply changing your boiler to a higher efficiency rated model. 


Energy efficient boiler replacement

Replacing old boilers with energy efficient alternative boilers is increasingly popular with more and more of the UK population trying to cut living costs, as well as trying to be more sustainable. 

Replacing a boiler can vary in cost depending on what type of boiler you already have. At Lacey Plumbing and Heating, our expert team of Gas Safe registered engineers will be able to fit and upgrade a new energy efficient boiler for you.

It all starts with a simple survey from our expert team.

To find out more you can get a free instant boiler quote with us, or alternatively, you can contact us on 01618 841 109 or via email at

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