Back Boilers
A back boiler is a heating unit hidden behind a gas fire on a living-room chimney breast. For decades — roughly the 1960s through the 1990s — it was a hugely popular way to provide central heating and hot water without taking up cupboard or kitchen space. The fire you see is only part of the story; behind it, out of sight, sits a boiler connected to your radiators and, usually, a hot-water cylinder upstairs. Millions were installed across the UK, and a great many are still quietly working away today.
How to recognise a back boilers
Use these tell-tale signs to work out whether this is the boiler in your home:
- There is a gas fire set into the chimney breast, often a 1970s or 1980s style.
- The fire and the central heating seem to share the same appliance.
- There is a hot-water cylinder in an airing cupboard and tanks in the loft.
- You may have a basic timer or wall thermostat rather than modern controls.
- Common brands include Baxi Bermuda and similar back-boiler units.
Still not sure? Our guide on how to tell if you have an old boiler covers the universal checks, and a free survey will confirm your boiler type for certain.
Common problems with back boilers
Back boilers are among the least efficient heating systems still in regular use. Many run at little more than 55–65% efficiency, so close to half the gas can be wasted. They are non-condensing, the heat exchanger is often heavily corroded after decades of service, and spare parts for discontinued models are very difficult to source. Because the unit is sealed behind the fire, faults can be hard to diagnose, and a failing back boiler carries a real carbon-monoxide risk. They also tie up the living-room chimney breast and force you to keep the old gas fire.
For a fuller picture across all boiler types, see the problems with old boilers.
Why so many homes still have back boilers
Back boilers were fitted in enormous numbers during the post-war housing boom because they were cheap, compact and kept the boiler out of sight. The trouble is that a unit hidden behind a gas fire is easy to ignore — out of sight, out of mind — so many have simply kept running for thirty or forty years without anyone thinking to replace them. Because they are concealed, homeowners are often surprised to learn that the appliance heating their whole house is sitting behind the living-room fire. When the time comes to replace one, the gas fire and back boiler are removed together and the chimney can be swept and capped or repurposed, often giving the room a fresh, modern feel.
Why replace it — and could it be free?
Removing a back boiler and fitting a modern wall-hung boiler is a dramatic upgrade. The new boiler is typically installed in the kitchen or a utility area, freeing the chimney breast so the room can be redecorated or opened up. Efficiency leaps from around 60% to over 90%, heating becomes faster and more controllable, and the carbon-monoxide risk of the old concealed unit is removed. Because back boilers are so inefficient and so widespread in older terraced and semi-detached homes, they are a top priority for grant-funded replacement.
If you have this boiler and your household meets the income or benefits criteria, you may qualify for a fully funded replacement. Check your eligibility or call 0800 246 8135.