About the free boiler scheme

The free boiler grant scheme has been set up so that homes in the UK can be more energy efficient. Installing an efficient boiler will also mean savings on your heating bills. An A rated gas boiler will heat your home and hot water using less energy. This means you will also help reduce harmful CO2 emissions being released into the environment.

Domestic gas central heating boilers in the UK are rated between A & G according to energy efficiency. The criteria which determines a boiler’s grading is SEDBUK (Season Efficiency of Domestic Boilers in the UK). Boiler ratings are determined at the time when the boiler and hot water / heating system is installed, although it is possible to have it assessed at any time by a domestic energy assessor.

Common gas boiler types

There are several types of gas boilers installed for common use in homes throughout the UK. Each has its own unique way of providing hot water for your taps & radiators. The type you should have installed depends on several factors including the size of your property, storage space and the amount of hot water you need for central heating.

  1. Conventional system boilers – this type of boiler is common and is used mostly in older houses. It includes a water storage tank where hot water is stored after it is heated. This can be expensive because even if you only want to use a small amount of hot water you have to wait for the boiler to heat all of the water in your tank to a high temperature
  2. Combination boilers – A combi boiler heating system does not require a water storage tank and is often used in modern properties where storage space is at a minimum. This type of boiler heats water on an ad hoc or “as needed” basis. When your central heating or hot tap is turned on water is taken straight from the main cold water tap and heated by the boilers burner before it reaches your radiators or hot water tap.
  3. Condensing gas boilers – Gas condensing boilers preheat your cold water by transferring waste heat from flue gases to cold water before it enters the boiler. This type of boiler is more efficient because the water takes less time & power to heat up because it is already warmed before it reaches the burner inside the boiler system.

Gas Condensing Boilers

All boilers which are available via the UK Government’s Free Boiler Grant Scheme are high efficiency gas condensing boilers.

Condensing boilers are more energy efficient than conventional gas boilers. This is because they are designed to heat water more efficiently, therefore  they use less energy, which means that less harmful Carbon Dioxide emissions are released into the environment, and also that your gas bills are reduced.

Conventional central heating boilers work by heating water via a heat exchanger – fuel, or gas, is burned and the heat passes through a compartment where a percentage heat is transferred to cold water. This hot water is used to heat your radiators or for your hot water taps.  The remainder of the heat escapes from the boiler.

A condensing gas boiler uses fuel and heat in a different way. Unlike a conventional boiler condensing boilers use some of the heat which escapes out the flue to preheat the cold water which enters the boiler, meaning that the water is already at a higher temperature before the boiler heats it further to your desired temperature.

Condensing Boiler - Energy Efficiency

Condensing Boiler – Energy Efficiency


Reliability & Servicing of Condensing Boilers

There has previously been debate over the reliability and effectiveness of condensing boilers and if they are more energy-efficient than conventional gas boilers. A study by the Building Research Establishment (BRE), the UK’s building industry research authority removed any doubts when it concluded

  • Condensing boilers are  just as reliable as standard boilers
  • Condensing boilers are no more difficult to service, nor do they require more frequent servicing
  • Servicing is not expensive; the only (minor) additional task is to check the correct function of the condensate drain
  • Not difficult to install
  • More efficient than standard boilers, under all operating conditions

The results of the research was published by BRE and the Energy Saving Trust. The document can be downloaded here.

Condensing Boilers – The Benefits and the Myths’ (CE52/GIL74)

Combi Boilers

The most common type of central heating boilers in the UK. The term “Combi boiler” is short for combination boiler, which is used because of the way the boiler & hot water heating system is designed.

Combi Boiler Design

A combi gas heating system does not store hot water in a storage tank or canister like conventional gas water heaters. They are designed to provide instant hot water for both your taps and radiators /central heating system. A combi boiler heats water straight from the cold water mains.

Combi Boiler Heating System

Combi Boiler System Design

The cold water is fed into the boiler which contains a sensor, burner and heat exchanger, which detect and heat your water to the desired temperature. They are compact, fit in a small storage space including cupboards and are highly efficient, which makes them the most popular domestic water heater and central heating system with UK home owners.


Energy Performance Certificates

EPC - boiler efficiency

EPC – boiler efficiency

All boilers installed the UK  now must have an Energy Performance Certificate (EPC). They also must have a Grade A rating. If your boiler is not A rated you my be entitled to a free boiler via the boiler grant scheme. In order to qualify for a free boiler your existing boiler must not be a condensing boiler.

Boiler and central heating performance contributes to the overall energy performance of your property and is included in any Energy Performance Certificate or report. Boiler performance is measured as a percentage although the European Grading method (A-G according to energy usage performance) is also often included for consistency.

The boiler rating system is designed to be a fair and accurate method of determining boiler efficiency, regardless of manufacturer. The energy efficiency of gas boilers (the free boilers available in the UK are gas boilers) is assessed on a variety of factors including-

  • Seasonal conditions
  • Boiler / heating usage patterns
  • Housing occupancy at the time of boiler installation
  • Boiler storage conditions
  • Boiler Location
  • Boiler insulation

Gas boilers are graded on an A – E basis with  A rating being the highest. All domestic hot water boilers currently installed in the UK must be A Rated, they must have a rating of at least 90% efficiency. Any replacement boiler installed via the Government boiler scheme will be an A-Rated boiler. A rated boilers reduce energy bills because they use less power / energy to heat your heating / hot water.

They help the Carbon Footprint of the country because they lower the level of Carbon Dioxide released into the environment. You can apply for a replacement energy-efficient boiler here – free replacement boiler.

Other factors deemed to affect the energy efficiency of boilers such as climate and the age of a boiler are also taken into account when assessing a boiler’s performance.

The table below shows how much you can save by installing an A rated gas boiler via the free boiler scheme.

Free boilers - annual savings

Free Boiler Application
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The Energy Companies Obligation (ECO) is an home energy improvement scheme which is led by the UK Government and funded by the country’s largest energy providers.

ECO provides homeowners, landlords and private tenants with access to Government grant funding for free boiler replacements to improve the energy efficiency of their homes.

You can claim a full and partial grant for a new boiler or insulation if you meet the ECO grant criteria.

How can we help you?

We have helped thousands of households with free boiler grant applications.

Many people find applying for a grant a daunting experience. So we have simplified the process to make it easier for you.

You can check online in two minutes to see if you are eligible for a new boiler or insulation – without entering any personal details.

You will only be asked for any further information if you want to apply for a grant.

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