Carbon monoxide alarm rules for London landlords

Carbon monoxide is a poisonous gas you cannot see, smell or taste. A gas boiler that is not burning properly, or a flue that is leaking, can release it into a home. Alarms are a simple safety net, and for landlords in England they are now the law in many rooms.

The rule in England

The Smoke and Carbon Monoxide Alarm (Amendment) Regulations 2022 came into force on 1 October 2022. The gov.uk explanatory booklet for landlords explains them. For carbon monoxide, private and social landlords must:

• Fit a carbon monoxide alarm in any room used wholly or partly as living accommodation that contains a fixed combustion appliance, excluding gas cookers
• Repair or replace any alarm once they are told it is faulty

Landlords must also check alarms are in working order on the day a new tenancy begins, and keep a record of those checks.

What counts

Appliance	Alarm needed in that room?
Gas boiler	Yes
Gas fire	Yes
Wood burner or open fire	Yes, fixed combustion appliance
Gas cooker or hob	No, excluded

The guidance says a bathroom or lavatory counts as living accommodation, and a hall or landing counts as a room. So a boiler in a hall cupboard or bathroom means an alarm is needed in that space.

Where to put alarms in London flats

London rentals often have the boiler in an awkward place: a kitchen wall unit, a hall cupboard, a loft above the top flat, or a utility cupboard in a new build. The regulations do not fix exact positions. The government guidance suggests:

• Fit the alarm at head height, on a wall or shelf, in the same room as the appliance
• Keep it roughly one to three metres from the appliance
• Follow the alarm maker’s instructions, which usually also say to avoid enclosed spaces and spots near vents or extractor fans

If the boiler is in a cupboard, the alarm usually goes in the room the cupboard opens into, not inside the cupboard. Check the alarm instructions.

Riverside and new build flats

In newer blocks, such as riverside flats in Battersea, many boilers have flues running through ceiling voids. The HSE flues in voids guidance says these must be inspectable through hatches. An alarm is a sensible extra, but it is not a substitute for being able to inspect the flue. See our post on flues in voids and our Battersea area page.

Some new blocks have no gas boilers at all, using a communal heat network instead. If there is no fixed combustion appliance in the flat, the CO alarm rule does not apply inside it, though many landlords fit one anyway.

How this fits with the gas safety check

The yearly landlord gas safety check by a Gas Safe registered engineer checks each gas appliance and flue. The engineer may note if a carbon monoxide alarm appears to be missing where one is needed, but fitting and testing alarms is the landlord’s job. Our landlord service and CP12 page explains the check.

What the engineer measures

During a full service, the engineer runs a combustion test with a flue gas analyser that reads carbon monoxide in the flue gases. That measures what the boiler produces, not what is in the room. A room alarm and a yearly combustion test do different jobs, and both matter. Our post on what a boiler service includes explains the test.

Signs of carbon monoxide

Tell tenants about the warning signs:

• Headaches, dizziness, sickness, tiredness or breathlessness that ease when away from home
• Yellow or orange flames on gas appliances instead of blue
• Soot or staining on or around appliances
• A pilot light that keeps going out
• More condensation than usual in the room with the appliance

If an alarm sounds or anyone has symptoms, they should turn off appliances if safe, open windows and doors, leave the property, and call the National Gas Emergency Service on 0800 111 999. Anyone feeling unwell should get medical advice.

Buying alarms

Look for alarms marked to the British and European standard for CO alarms, BS EN 50291. Sealed units with long life batteries are popular with landlords, because tenants cannot easily remove the battery. Smart alarms that send alerts to a phone can help with remote checks, but are not required.

Smoke alarms too

The same 2022 regulations also require at least one smoke alarm on every storey used as living accommodation. Many landlords fit combined smoke and CO alarms, but check the position suits both, because smoke alarms usually go on ceilings and CO alarms near the appliance.

Owner occupiers

If you live in your own home, the rules do not apply to you, but an alarm near your boiler is a cheap and sensible step. Pair it with a yearly annual boiler service.

Gas work in the UK must be done by a Gas Safe registered engineer. Ask to see the ID card and check it on the Gas Safe Register.