Carbon Monoxide Alarm Requirements for London Rentals: 2022 Law, Placement and Alarm Types

The 2022 Legislative Change

The Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 came into force on 1 October 2022 and significantly extended the requirements for carbon monoxide (CO) alarms in rented properties in England. Prior to this date, CO alarms were only required in rooms with a solid fuel burning appliance. From October 2022, a CO alarm is required in any room used as living accommodation that contains a fixed combustion appliance — this now includes gas boilers, gas fires, oil boilers, and open-flued appliances, not just solid fuel burners.

For London landlords, this means that properties with a gas boiler located in a kitchen, utility room, or any other room that tenants occupy (or pass through regularly as living accommodation) now legally require a CO alarm in that room. Properties where the boiler is in a dedicated cupboard that is part of living accommodation — common in London flat conversions — are also affected.

What Does Not Trigger the Requirement

Gas cookers and gas hobs are not combustion appliances for the purposes of this regulation — they do not have a flue and are therefore excluded. CO alarms are not legally required solely because a property has a gas hob (though fitting one near a hob remains sensible practice). Electric-only properties with no combustion appliances have no CO alarm requirement under this legislation.

Types of Carbon Monoxide Alarm

CO alarms use one of two main sensor technologies: electrochemical sensors and biomimetic (gel) sensors. Electrochemical sensors are the industry standard for domestic CO detection — they are accurate, respond proportionally to CO concentration, and provide a reliable alarm at the 50 parts-per-million (ppm) threshold specified by EN 50291 (the relevant British and European standard). Biomimetic sensors are older technology and generally less suitable for primary protection.

Alarms must comply with British Standard EN 50291-1 for domestic use. Look for this marking on the packaging. Cheap alarms that do not carry this certification may not respond correctly to dangerous CO concentrations — in a rental context, using a non-compliant alarm does not satisfy the legal obligation.

Mains-powered alarms with battery backup are preferable for rental properties because battery depletion cannot be relied on to be reported by a tenant. Interconnected alarm systems — where CO detected in one room triggers all alarms — are best practice for larger properties or those with multiple combustion appliances.

Placement Requirements

The regulations require an alarm in any room containing a fixed combustion appliance used as living accommodation. This means the alarm must be in the same room as the appliance, not on the landing outside or in an adjacent room. CO is slightly lighter than air, so positioning the alarm on or near the ceiling is appropriate, though EN 50291 specifies the alarm should be placed at breathing height (0.5 to 1.5 metres from the floor) for optimal response in some installation scenarios — check the manufacturer guidance.

Keep alarms away from direct airflow from windows, doors, and fans, which can dilute CO and delay alarm response. Do not install within 1 metre of a cooking appliance.

Landlord Obligations and Enforcement

Landlords must ensure CO alarms are installed at the start of each tenancy and test them on the day the tenancy begins. If a tenant reports a faulty alarm, the landlord must repair or replace it as soon as reasonably practicable. Local authorities can issue remedial notices and levy civil penalties of up to £5,000 for non-compliance — London councils have been increasingly active in enforcement, particularly in boroughs with high concentrations of older properties with gas heating.

Document alarm testing dates and model numbers. Keep purchase receipts showing EN 50291 compliance. This documentation protects you if a compliance dispute arises.