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Are new boilers more efficient?

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Written by  Joe Minihane
Updated: 21 Jul 2023

If you’re confused about boiler efficiency, what it means and whether your existing boiler is efficient enough, then our guide is here to explain everything you need to know. This includes details on whether new boilers are more efficient, as well tips on making your current boiler more efficient, saving you money in the process.

What is boiler efficiency?

Boiler efficiency is a percentage calculation based on how much energy it uses to deliver heating around the home. This is calculated by dividing the total energy output by the total energy input and multiplying it by 100. For consumers, the number they need to concern themselves with is this percentage. The higher it is, the less energy is escaping from your boiler.

Percentages are then used to give ratings between A to G. These are as follows:

  • A - 90% and higher

  • B - 82-86%

  • C - 82%-86%

  • D - 78-82%

  • E - 74-78%

  • F - 70-74%

  • G - below 70%

Similar ratings are applied to all white goods, such as fridges, freezers, dishwashers and washing machines. This helps consumers buy products that are efficient and cost effective. You can read more about energy efficiency in our guide to energy efficient white goods.

Older boilers tend to be less energy efficient, with those dating back over 25 years between 60 and 70%. This rises to 75% efficient for 20 year old models, 80-85% efficient for 15 years old and 80-85% efficient for those over 10 years.

Since 2018, all new boilers have to be fitted with an advanced heating measure, with a rating of 92% or more, thanks to Boiler Plus legislation.

Adjusting a boiler

Why are new boilers more efficient?

Since 2005, all new boilers have had to be condensing boilers. The technology of such boilers has developed rapidly in the ensuing two decades, ensuring that less energy is wasted and costs are kept down. Modern boilers are far smaller and take up less space than traditional models too.

Condensing boilers include the common and popular ‘combi’ boiler, which provides both heating and hot water and is found in many homes. Such boilers capture excess gases that would have previously escaped via the flue and harmed the environment, and recycle them to create more heat. They are also a lot smaller and do not require as much energy in order to give the same results.

It’s important that condensing boilers are installed properly, as they tend not to be set up to maximum efficiency right out of the box. They need to run at a lower temperature in order to get an A rating, which will save you energy and money in the process.

How do I know how efficient my existing boiler is?

Checking out how efficient your boiler is is surprisingly straightforward. Newer models should feature a prominent sticker which shows its rating from A to G.

For older models, look for the model number, which can often be found under the flap at the front or underneath on a sticker where the pipes come out. You can then use the product characteristics database (PCDB) to find your exact boiler and its rating.

How do I make my boiler more efficient?

You don’t need to spend thousands on a new boiler in order to make it more efficient. In fact, there are some simple measures that will ensure it stays more efficient for longer.

The most important thing is to have an annual boiler service. If you have boiler cover, a service should come as standard with your policy. If you don’t, expect to pay around £100. This is well worth it, as your boiler will run better after a tune up and an internal clean from a qualified engineer.

There are other, free ways to boost efficiency. It may sound simple, but dust the exterior of your boiler whenever you clean, to ensure none manages to get into the pipes and clog them up. Bleed your radiators if they feel cold to the touch when you turn the heating on.

And, as counterintuitive as it may seem, fire up your boiler in summer so that you can find any issues before the colder months arrive. Insulating pipes means that your boiler won’t need to go into overdrive to heat your home, while ensuring the pressure is around 1.5Bar will mean that it will run properly.

Will a new boiler save me money on bills?

If you have a boiler more than 15 years old, chances are its efficiency rating may be as low as 80%, meaning you could be spending more on bills than you need to. While a new boiler is expensive initially, all the latest models must have an A rating and take up much less room, which can often free up space for storage. The fact they run better and see less energy escape means you should see a reduction in your bills quite quickly.

It’s also worth remembering that older boilers are usually more environmentally unfriendly, while newer ones ensure that almost all energy output is kept within the home.