Boilers

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

How do I know if I've got sludge in my central heating system?

If you notice your radiators are hot at the top but cold at the bottom, or need to bleed your radiators more often, then you may have sludge built up in your system. 

What should my boiler pressure be set at?

A safe level for your boiler pressure should be between 1.0 and 2.0 bar. Watch this video to learn how. 

Should I turn off my boiler in the summer?

In Summer, you might be tempted to switch off your boiler to save money. However, this can be inefficient and expensive. Instead, you should consider setting your boiler to only heat your water.

What is the Boiler Upgrade Scheme?

The Boiler Upgrade Scheme is a Government grant of £7,500 to support with the upfront costs of installing low carbon heating systems, such as an air source heat pump, subject to eligibility. A temporary uplift of £1,500 was also introduced in July 2026 to provide additional support for off-grid property owners.

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