Condensing boilers

Condensing boilers

by Matthew Knight

Find out how condensing boilers work and how they differ from non-condensing models, then take a look at our boiler reviews and pick the best model.

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

Read our full expert boiler reviews and find a Best Buy condensing boiler that's right for your home. 

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

How condensing boilers work

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. 

With a 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.

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, 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.