What is a condensing boiler?

Condensing boilers are really efficient, making the fuel you're burning to heat your home go further. Replacing an old G-rated non-condensing boiler with a new high-efficiency condensing boiler and improving your heating controls could save you as much as £310 a year*.

Here we explain how condensing boilers work and what the key differences are between condensing boilers and non-condensing boilers.

Almost all new boilers are condensing. Read our boiler reviews to find the best one for your home.

What is a condensing boiler?

A high-efficiency condensing boiler is a good choice if you're looking for a greener and more efficient boiler. This is because condensing boilers are able to make better use of the heat they generate from burning fuels, such as gas or oil.

A condensing boiler requires less heat from the burner, so is more efficient.

How does a condensing boiler work?

With a non-condensing heat-only boiler, some heat is wasted in the form of hot gases released from the flue. A condensing boiler captures some of the heat from these gases and uses it to heat water returning from your central heating system. It therefore requires less heat from the burner and is more efficient.

All new modern boilers are condensing boilers. So if you are thinking of replacing an old boiler with a new one, you will be buying a new condensing boiler and gaining all of the efficiency savings that come with it.

Condensing boilers vs non-condensing boilers

Both combi and heat-only boilers can be either condensing or non-condensing. Building regulations now state that all new boilers installed in a domestic home should be high-efficiency condensing boilers, although exceptions do apply in rare cases.

A non-condensing boiler will typically take air in from inside the room, whereas a condensing boiler will be fully sealed and takes in air directly from the outside.

Condensing boilers are safer than non-condensing boilers. Condensing boilers are safer than non-condensing boilers, as there is a much lower risk of anything being sucked into the boiler. What's more, a condensing boiler is typically at least 25% more efficient than a non-condensing model.

Now you know about condensing boilers, make sure you buy the right model for your home by visiting how to buy the best boiler.