What Does a Gas Safety Check Include at Home?

A boiler that still provides heating can have a gas-safety fault that is not obvious from the outside. So, what does a gas safety check include? A Gas Safe registered engineer examines the gas appliances and associated installation in your property to confirm they are safe to use, correctly ventilated and burning gas properly. For landlords, this is a legal compliance requirement. For homeowners, it is a sensible way to protect the household, particularly where a boiler, gas fire or cooker is ageing or behaving differently.

A proper check is not a quick glance at the boiler casing. It involves a series of inspections and tests, followed by clear paperwork explaining the outcome and any work that needs attention.

What does a gas safety check include?

The precise scope depends on the appliances installed at the property. A flat with a combi boiler and gas hob will need different checks from a house with a boiler, gas fire and separate hot-water cylinder. However, the engineer will normally work through the gas meter, accessible pipework and every gas appliance covered by the appointment.

Visual inspection of the appliance and installation

The engineer starts by checking the appliance is suitably located, securely fitted and in good overall condition. They look for signs of damage, corrosion, heat marks, loose parts, water leaks around the boiler, or alterations that could affect safe operation.

They will also assess accessible gas pipework for obvious damage and check that the appliance is connected appropriately. Where a boiler is in a cupboard, for example, the cupboard must not prevent safe servicing or restrict ventilation required by the manufacturer.

Gas-tightness testing

A gas-tightness test checks whether gas is escaping from the installation pipework. Using specialist equipment at the meter, the engineer measures the pressure in the system over a set period. A pressure drop can indicate a leak that must be investigated before the installation can be considered safe.

This test matters because a gas leak may not always produce a noticeable smell, especially in a large or well-ventilated home. If a leak is found, the engineer will explain the next safe step. Depending on the fault, this may mean isolating the supply or appliance and carrying out a repair.

Checking gas pressure and combustion

Gas appliances need the right gas pressure and correct air-to-gas mix to burn fuel efficiently and safely. An engineer checks that gas is reaching the appliance at the manufacturer’s required operating pressure. Low pressure can lead to poor performance, while an incorrect supply or fault within the appliance may create a more serious safety concern.

For suitable appliances, particularly boilers, a combustion analyser is used to assess the gases produced during operation. The readings help show whether the appliance is burning gas cleanly and whether carbon monoxide or other combustion products are being managed safely through the flue.

Carbon monoxide has no colour, taste or smell. That is why combustion testing is more reliable than judging safety by whether a boiler appears to be working normally.

Flue, ventilation and air-supply checks

The flue carries combustion gases safely outside. The engineer checks that it is correctly installed, in sound condition and not visibly damaged, disconnected or obstructed. They also examine whether the flue terminal is positioned appropriately and clear of blockages such as debris, vegetation or building materials.

For appliances that rely on ventilation, the engineer checks that permanent air vents are present, unobstructed and suitable for the appliance. Blocking an air vent to stop draughts can be tempting, but it can prevent an appliance from receiving the air it needs to operate safely.

Some flues run through concealed spaces, such as ceiling voids or boxed-in areas. Access may be limited, which can affect what can be inspected during a routine visit. Your engineer should explain this clearly and advise if further access or investigation is needed.

Safety-device and operating checks

The appliance is run to make sure it operates safely. This can include checking ignition, flame picture where visible, burner operation, controls and safety devices. On a boiler, the engineer may check that it fires correctly, responds to demand for heating or hot water, and shuts down as intended.

The engineer will also look for warning signs such as unusual noises, intermittent ignition, staining around an appliance, poor flame quality or persistent fault codes. A gas safety check focuses on safety, but these observations can identify developing reliability issues before they leave you without heating or hot water.

Gas fires, cookers and hobs

A landlord gas safety inspection should cover all gas appliances supplied by the landlord, not only the boiler. That may include a gas fire, cooker or hob. The engineer checks each applicable appliance individually, including its stability, ignition, flame supervision devices where fitted, ventilation requirements and safe combustion.

Tenant-owned appliances are normally not included on the landlord’s Gas Safety Record, although the landlord remains responsible for the installation pipework and flues that serve the property. Letting agents and landlords should make this distinction clear when arranging access, particularly if a tenant has installed their own cooker.

What paperwork do you receive?

When the check is completed at a rented property, the engineer issues a Landlord Gas Safety Record, often called a CP12. This records the address, appliances checked, tests completed, any defects found, the engineer’s Gas Safe registration details and the date the next check is due.

Landlords must provide existing tenants with a copy within 28 days of the check and give new tenants a copy before they move in. A new check is required at least every 12 months. Records should be retained for at least two years.

For a homeowner, the document supplied may vary depending on the work carried out, but you should still receive clear confirmation of the inspection, any readings or findings, and recommended repairs. Keep it with your boiler and servicing records. It can be useful when selling a property, dealing with an insurer or diagnosing a recurring fault.

Is a gas safety check the same as a boiler service?

Not exactly. The two visits overlap, but they have different purposes. A gas safety check establishes whether an appliance and installation are safe. A boiler service is more maintenance-focused and follows the manufacturer’s servicing schedule. It commonly includes cleaning or inspecting internal components where required, checking condensate arrangements, assessing system pressure and helping to maintain efficiency and reliability.

For landlords, an annual gas safety check is the legal minimum for supplied gas appliances. A separate annual boiler service may still be advisable, and it may be required to maintain a manufacturer warranty. For homeowners, an annual boiler service is generally the priority, with gas-safety testing incorporated where appropriate. The right arrangement depends on the appliance, its age, warranty terms and the property’s use.

What happens if the engineer finds a fault?

Not every issue means a boiler must be replaced. Some faults are straightforward, such as a deteriorated seal, a blocked condensate pipe, an incorrect pressure setting or a flue component that needs attention. The engineer should explain the problem in plain English, tell you whether the appliance can remain in use and provide a clear recommendation for repair.

Where there is an immediate danger, the appliance may need to be turned off or disconnected to protect occupants. This can be inconvenient, especially in winter, but safety comes first. A competent engineer will explain the classification of the issue, document it and discuss the quickest safe route to restoring heating or hot water.

For landlords and property managers, prompt action also helps avoid prolonged tenant disruption and prevents a failed safety record from becoming an avoidable compliance problem.

Preparing for your gas safety appointment

Make sure the engineer can reach the boiler, meter, gas fire and any other relevant appliances. Clear stored items from boiler cupboards and avoid boxing in pipework or flue inspection points. If you are a landlord or agent, arrange access with the tenant in good time and let them know that the gas supply or heating may need to be briefly switched off during testing.

It also helps to mention any concerns when booking: a boiler that cuts out, a yellow or lazy flame, black marks near an appliance, a smell of gas, headaches that seem worse at home, or a carbon-monoxide alarm that has activated. These details help the engineer investigate efficiently.

If you smell gas, do not wait for a routine appointment. Turn off the gas supply at the meter if it is safe to do so, open doors and windows, avoid switches and naked flames, leave the property, and contact the gas emergency service. For planned gas safety checks, PlumbTech365 provides Gas Safe registered support for homeowners, landlords and managing agents across Dartford, North Kent and South East London. A clear record, a properly tested appliance and early action on faults offer the reassurance that matters most when your home relies on gas every day.