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Boiler Efficiency: How Efficient are Modern Gas Boilers?

Everything you need to know about gas boiler efficiency

Today we are looking at the factors which make an efficient boiler. Overall, modern boilers are far more efficient than even 10 years ago.

Today, the most modern best combi boiler options are condensing systems and so we’ll be looking at these systems today and explaining this further for you.

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So What is an Energy Efficient Gas Boiler?

boiler efficiencyIf you’re looking into and trying to decide on the best boiler type for your home, you may be getting slightly confused with all the options out there. 

We like to explain things for you so that you can make the best choice so let’s look into these types of boiler systems.

In gas boiler systems,  the heated gases pass through the boiler’s heat exchange surface, transferring the generated energy to the radiators. Once it’s all heated, the extra combustion gases are released into the atmosphere through the boiler’s flue.

The issue with this is that a certain amount of heat is lost here because the gases as well as a large amount of steam gets forced out of the flue. This leads to a lot of lost heat and energy just being released out of the flue. But why can’t we use this excess heat?

Well, this is where a condensing boiler becomes the smart, ecological, and cost-effective choice. This is because they recirculate this wasted heat back into the system, therefore requiring less energy to heat your home as a percentage is recycled.


The boiler efficiency of gas combi boilers

The modern condensing boilers are far more efficient than even 5-year-old boilers. A brand-new condensing combi boiler made by or recommended manufacturers is going to be significantly more efficient than a 2015 boiler.

In measurable terms, a high-efficiency A-rated boiler replacement will convert up to 94% of consumed energy into usable heat.

That means only 6% of the energy is wasted. If, however, you have an old inefficient boiler, you will be wasting 20% to 35% of energy and that makes a huge difference in bills. 

This also answers the age-old question of whether your should turn your hot water off or not

The reason this is so important is that depending on your energy consumption behaviour, your gas central heating system probably accounts for at least 50% of your yearly energy bill. 

If you are looking for a new boiler cost then use our free online quote below and get a price online in 20 seconds:

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Main Types of Efficient Gas Boilers

alteas one boiler systemThere are two main types of condensing boilers: system boilers and combi boilers. The system boiler is a good choice for larger houses or for houses that have low water pressure. The combi boiler is the ideal choice for houses that require heating on demand.

There are various types of combi and system boilers but below is a simple example of the various types:

  • Wall-mounted boilers: Sometimes also referred to as mounted boilers, this type of condensing boiler is very convenient because of their smaller size and because they can fit alongside a modular boiler arrangement.
  • Floor boilers: Also called a floor standing boiler or a floor mounted boiler, this type of boiler is larger than wall boilers and can produce a greater volume of hot water.
  • Single circuit boilers: The pipe system is a single closed circuit which means that there is a single main feed through which the water enters and exits the boiler. The risk with this type of heating installation is that if it is not properly balanced, then it will heat the house unevenly depending on the circuit the hot water makes.
  • Double circuit boilers: This type of boiler system has two separate pipelines, one that takes the heated water away from the boiler and heats the house and the second that moves the water toward the boiler to be reheated. This type of boiler is properly balanced and can heat the entire house to a similar degree.

Efficient boiler systems: Examples

Below is a list of some of the efficient systems available.

There are so many systems on the market that it is probably best to look through our website and see if there are any other efficient systems that would be suitable for your home.

Model Efficiency Heating output
Ideal Logic Heat + 89.5% 15kW
Vaillant ecoTEC Plus 15 93% 15kW
Worcester Greenstar Ri 15i 92% 15kW
Viessmann Vitodens 100-W 94% 30kW

How efficient is my boiler likely to be?

vokera combi boiler review

Boilers have efficiency ratings of A-G much like other appliance ratings. Nowadays, modern boilers have to be A-rated in order to be allowed on the UK market.

Although it is hard to review older boilers, in general, the below information should be accurate enough to discern the advances in boiler efficiency.

Efficiency ratings for system boilers

  • A – 90% and above
  • B – 86-90%
  • C – 82-86%
  • D – 78-82%
  • E – 74-78%
  • F – 70-74%
  • G – below 70%

Older boiler inefficiencies:

  • Over 25 years old: 60% efficient
  • 20 years old: 70% efficient
  • 15 years old 80% efficient
  • 10+ years old 85% efficient

As you can see, modern boilers are far more efficient and with up to 40% efficiency giants over the past quarter-century, your bills will be significantly lower with a new system.

Modern Boiler efficiency: Conclusion

As with most things, modern technology has allowed us to create more advances in heat recuperation and energy efficiency.

With the world moving closer and closer to a more green alternative, boiler companies either have to adapt to the times and build better systems or lose out to newer alternatives.

With up to 96% efficient systems, however, they’re on the right track and the companies today have nothing to worry about from these alternatives in the near future. 

Thanks again for reading and check back often for more articles.

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