What is a back boiler?
A back boiler is a gas boiler fitted inside the chimney breast, behind a gas fire. It heats the radiators and usually a hot water cylinder in an airing cupboard. Back boilers were common in houses built or modernised decades ago, and many are still working in terraced and semi-detached homes today.
You probably have one if:
- there is a gas fire in the living room, often with a control panel or switches behind a hinged front;
- there is no boiler on any wall, in the kitchen or in a cupboard;
- there is a hot water cylinder in an airing cupboard upstairs.
Is there a grant to replace a back boiler?
There is no government scheme just for back boilers. The scheme that can pay is ECO4, which runs until 31 December 2026.
The reason it can help is in the law behind ECO4, which defines an inefficient heating system as one that includes a non-condensing boiler. Most back boilers are non-condensing, and Ofgem says boiler upgrades can happen where the existing boiler is non-condensing, whether it is working or not. These upgrades are not capped.
Set by the scheme · Ofgem and GOV.UK
What has to be true
- Someone in the household receives a qualifying means-tested benefit, such as Universal Credit, Pension Credit or Housing Benefit, or the council declares the household eligible through ECO4 Flex.
- You own the home and live in it. ECO4 does not fund boiler work in rented homes.
- The home has an energy rating (EPC) of D to G.
- Loft and cavity wall insulation are installed first where the home needs them, and the whole project lifts the home’s rating by the required amount.
Our service · not a scheme rule
How Warm Home Support handles your enquiry
These describe how we look at an enquiry. They are not ECO4 requirements, and they do not change what the scheme itself allows.
- We check whether ECO4 or another scheme fits before you book anything.
- We explain what moving the boiler out of the fireplace would involve, so the survey holds no surprises.
The insulation rule matters. Under the ECO4 delivery guidance, a home rated E to G normally needs its exterior cavity walls and loft insulated before any heating is installed, and a home rated D needs at least one insulation measure first. Our guide to applying for an ECO4 boiler grant walks through each step.
Tenants
ECO4 does not replace, upgrade or repair boilers in rented homes, whether private or social. If you rent and have a back boiler, keeping the heating and hot water working is your landlord’s responsibility.
What replacing a back boiler involves
It is a bigger job than swapping one wall-hung boiler for another, because the new boiler almost never goes back in the fireplace.
| Part of the job | What usually happens |
|---|---|
| The gas fire and back boiler | Both are removed, the gas supply to the fireplace is capped, and the chimney opening is made safe. |
| The new boiler | Fitted on an outside wall, often in the kitchen or a utility area, with a new flue. |
| Hot water | A combi heats water on demand, so the cylinder can often go. A system boiler keeps a cylinder, which suits homes using a lot of hot water at once. |
| Pipework and radiators | New pipe runs to the new boiler position. The system is cleaned, and some radiators may be changed. |
| Controls | A programmer and room thermostat, and thermostatic valves on radiators. |
| The fireplace | Closed off, or left ready for a new fire. Decorating afterwards is not part of the heating work. |
Ask about asbestos in older fireplaces
Some older fire surrounds, flue parts and boiler casings contain asbestos. A good installer checks before taking anything apart and explains what happens if any is found.
Should you replace a working back boiler?
If it is serviced and working, there is no rule that says you must. But back boilers are old, and spare parts for many models are getting harder to find. If your household qualifies for ECO4, the scheme’s end date of 31 December 2026 is a good reason not to wait until the boiler fails.
Got a back boiler? Check what applies
Tell us how your home is heated and whether you own it. We will take you to our eligibility check with those answers filled in. It is free, and nothing is sent until you choose to send it.
If you do not qualify for ECO4
- Pay for the replacement. Get at least two quotes, and make sure each covers removing the fire and back boiler, the new flue, pipework and making good. Our boiler replacement page explains what to compare.
- Consider a heat pump. If you own your home in England or Wales, the Boiler Upgrade Scheme offers a grant towards a heat pump instead of a gas boiler, with no income test. Our guide to getting a heat pump grant with a gas boiler explains what changes.
- Pensioners: see free boiler grants for pensioners.
- Not on benefits: see boiler grants if you are not on benefits.
Keep your back boiler safe in the meantime
Have it serviced every year by a Gas Safe registered engineer, and fit a carbon monoxide alarm. Turn it off and get it checked if you see soot or staining around the fire, a lazy yellow flame, or the pilot light keeps going out.
