What is a Back Boiler?

Back Boilers (also known as back boiler units or BBUs) became popular in 1966 with the launch of the original Baxi Bermuda.


A back boiler is a small, compact boiler fitted at the back of an open fireplace hearth. It sits behind a gas fire and provides hot water and central heating to the property.


Back boilers were popular until the Building Regulations changed in 2005, when it became a requirement to install high efficiency condensing boilers. Although many have been replaced with wall-hung condensing boilers, there are still a large number of back boilers still installed in UK homes.


An old standard efficiency back boiler is less than 70% efficient – so for every £1 of gas burned, on 70p worth of useable heat is generated and the other 30p worth is lost up the chimney. By replacing it with a new boiler at over 90% efficient, fuel bills can be reduced by up to £305, according to the Energy Saving Trust.

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Related FAQs

Can I run a bath and shower at the same time?

Depending on whether you have a hot water cylinder, you can normally run a bath and a shower at the same time. A system boiler and storage cylinder may be more suitable for properties that have a higher demand.

What are the different types of boilers?

The main types of boiler are combi, system, heat only, and electric boilers. The one that you choose for your property will depend on your specific needs and aspects of your home.

What temperature should my boiler be set at?

Typically, your boiler should be set to at least 65 degrees Celsius to prevent bacteria growing in the water and maintaining comfort.

Why is my boiler leaking?

Checking for damp surfaces on or around your boiler, pipe corrosion, and water dripping beneath it can help identify if there is a leak.

What are the benefits of a boiler service?

Regular servicing can keep you and your family safe, save you money and keep your warranty valid. Find out more...

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