Fires and flues
Gas fires, flues and chimneys: what keeps them safe
A gas fire is only as safe as the flue or chimney that takes its fumes away. Many of Liverpool's older terraces and semis have chimneys and gas fires that have been there for decades. Here's what HSE says matters, and who should check them.
Short answer
Gas fires need a Gas Safe registered engineer qualified for gas fires, and the flue or chimney must be clear and working. HSE advises servicing gas appliances and flues at least annually. Landlords must have fires and flues they provide checked every year, and in England a room with a gas fire in a rented home needs a carbon monoxide alarm.
Why the flue matters
The fire and the flue are one system
An open-flued gas fire draws air from the room and sends its combustion products up a flue or chimney. If the flue is blocked by a bird's nest, debris or a collapsed liner, or if the room lacks ventilation, those fumes, including carbon monoxide, can spill back into the room.
HSE ties carbon monoxide deaths to appliances and flues that haven't been properly installed or maintained, or are poorly ventilated. That's why a gas fire service should cover the flue too: a check that the fumes are being cleared, not just that the fire lights.
Room-sealed and balanced-flue appliances work differently, drawing air from outside and venting directly outside. Ask the engineer which kind you have.
The engineer
Registered for gas fires, specifically
Gas fires are a separate category of gas work on the Gas Safe Register, shown on the back of an engineer's ID card alongside categories such as boilers and cookers. HSE advises checking that an engineer is competent in the specific area of gas work you need. An engineer registered only for boilers isn't the right person for your gas fire.
Look the engineer up on the Gas Safe Register's website, and check that gas fires appear in their categories. See checking a Gas Safe engineer.
Warning signs
Signs a fire or flue needs attention
| What you see | What to do |
|---|---|
| Soot or black staining on or around the fire | Stop using it; book a registered engineer for gas fires |
| Lazy, yellow or orange flames on a fire meant to burn blue | Stop using it; book an engineer |
| Condensation or a stuffy room when the fire is on | Check ventilation; book an engineer |
| A carbon monoxide alarm sounding | Turn appliances off, ventilate, get outside; seek medical advice if unwell |
| A smell of gas | Call 0800 111 999 |
Rented homes
Landlords and flues
A landlord's annual gas safety check covers every gas appliance and flue the landlord provides. HSE goes further and recommends including all flues, such as chimneys, connected to gas appliances in the check, even where they serve appliances the landlord didn't provide. Pipework remains the landlord's responsibility whatever appliance it supplies.
Since 1 October 2022, rooms used as living accommodation that contain a fixed combustion appliance, a gas fire included, need a carbon monoxide alarm in rented homes in England. A purely decorative, non-functioning fireplace isn't a fixed combustion appliance in the government's view.
Ventilation
Don't block the air
Many gas fires need a permanent ventilation opening to burn safely. In older Liverpool homes, vents and air bricks are sometimes blocked to stop draughts, or covered when rooms are decorated. That can starve an open-flued appliance of air and push fumes back into the room.
If you have a gas fire, find out whether it needs ventilation and keep any vents clear. If you're unsure, ask a registered engineer to check during the next service.
Old fires
Keep, replace or remove an old gas fire?
If a gas fire is old and rarely used, the choice isn't only repair or replace. You can have it disconnected and capped by a registered engineer, which removes a carbon monoxide source you don't need. If you do use it, an annual service with a flue check is the sensible routine, and it's part of what keeping the fire costs.
Other fuels
Wood-burners and coal fires
Not every fire is gas. HSE advises that appliances burning other fuels should be serviced and maintained by a competent person and the chimney regularly swept. Gas Safe registration doesn't cover solid fuel or oil appliances, which have their own competent person schemes. In a rented home, a wood-burner or coal fire is a fixed combustion appliance for the carbon monoxide alarm rules.
Before the first cold night
A short autumn routine for gas fires
If you only use a gas fire in winter, check it before you need it. Look for soot or staining, make sure vents and air bricks are clear, test the carbon monoxide alarm, and book a service with an engineer registered for gas fires if it's been more than a year. It's much easier to sort a flue problem on a mild autumn day than in the middle of a cold snap. See carbon monoxide safety and servicing.
If you've moved into a home with a gas fire you know nothing about, treat it as unchecked until a registered engineer has looked at it and its flue. Ask the previous owner or landlord for any service history; if there isn't any, that's a reason to book a check before using it.
Fire and flue questions
Who can service a gas fire?
A Gas Safe registered engineer whose registration includes gas fires. Check the back of the ID card and the register.
Does a landlord’s gas check include flues?
Yes. All gas appliances and flues the landlord provides need an annual check, and HSE recommends including all flues connected to gas appliances, even ones serving a tenant’s own appliance.
Should the chimney be swept?
HSE says appliances that burn other fuels should be serviced by a competent person and the chimney regularly swept. For a gas fire, ask the engineer whether the flue needs sweeping or checking.
Is a gas fire a fixed combustion appliance for CO alarm rules?
Yes. In rented homes in England, a room used as living accommodation with a gas fire needs a carbon monoxide alarm.
Sources used on this page
- Domestic gas: frequently asked questions · HSE (3 November 2026)
- Carbon monoxide poisoning · HSE (3 November 2026)
- Gas safety checks: what needs them · HSE (3 November 2026)
- Gas safety checks: who needs them · HSE (3 November 2026)
- Gas Safe Register and the engineer ID card · HSE (3 November 2026)
- Smoke and carbon monoxide alarm regulations: Q&A for the private rented sector · GOV.UK (3 November 2026)
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