Condensing Boilers

Heating now accounts for around 60% of the average household’s annual energy bills, so it’s worth making your heating system as efficient as possible.

Replacing your old gas or oil boiler with an efficient condensing boiler can save you around £225 a year on your bills, and if you are using electric heating, switching to an oil or gas condensing boiler can save you around £500 a year.

See how much you can save!

The Basics

Condensing boilers are a newer, more efficient type of boiler. They are very similar to standard boilers, but have an additional heat exchanger. Boilers produce hot gases that escape through your boiler’s flue. The second heat exchanger reclaims heat from these hot gases, meaning that you have to use less fuel to heat your water, saving you carbon emissions and money.

Condensing boilers are as much as 12% more efficient than standard boilers, and from 2005, all boilers fitted in UK homes must be condensing boilers apart from in exceptional circumstances. From 2010, this was narrowed to include only boilers that are ‘A’ rated or 88% efficient on the SEDBUK scale. Regulations also state that you will have to have a time and temperature control fitted as part of the installation, to maximise the efficiency of your system.

There are two main types of Condensing Boiler:

  1. Combi (Combination) -  These don’t need a water tank as they heat the water ‘on demand’ when it is needed, such as when you turn the tap on. This means that you don’t need to wait for your water to heat and you can save the space of a hot water tank. They are more efficient than system boilers, but have lower capacities, so are generally used for smaller homes.
  2. System or Open Vent – These have a tank to store hot water and are better at providing water for larger homes with multiple bathrooms or showers, particularly if you might need to run them at the same time. You will get need an airing cupboard or another place where the hot water tank will be housed.

See which boiler is best for you!

FAQs

What is a condensing boiler?
A condensing boiler works on the principle of recovering as much as possible of the waste heat which normally leaves through the flue of a conventional (non-condensing) boiler as water vapour. The best high efficiency condensing boilers convert more than 95% of their fuel into heat, compared to 78% for conventional types. Condensing boilers get their name because as they recapture the heat from the water vapour leaving through the flue, this water vapour condenses back to a liquid, or condensate as it is known.
How easy is it to install a condensing boiler?
Boilers vary in size and shape but most are designed for simplicity of installation. With space being such a premium many boilers are small enough to be fitted by one person into a kitchen cupboard, easily and with minimum disruption.
How is the Sedbuk rating calculated?
The 'seasonal efficiency of a domestic boiler in the UK' (Sedbuk) rating for boilers is calculated from the results of standard laboratory tests, together with other important factors such as boiler type and the kind of fuel used. It describes the boiler's efficiency.
Could a condensing boiler save money on my energy bill?
Which? estimates that the average efficiency of boilers in UK homes is about 70%. This means they waste up to 30% of the heat they generate in the form of hot flue gases. This suggests that installing a condensing boiler, which has an efficiency of around 88%, can reasonably achieve savings of between £50 and £200 per year depending on the size of your house - and the saving will increase as the cost of gas increases. Complete our free assessment to find out just how much you could save.
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