What is the Scottish requirement?
The Tolerable Standard requires satisfactory equipment for detecting and warning of hazardous carbon monoxide. It forms part of the Repairing Standard that private landlords must meet at the start of and throughout a tenancy.
Fit a CO detector in every room used as living accommodation where there is:
- a fixed combustion appliance burning gas, oil or solid fuel; or
- a flue serving a carbon-fuelled appliance.
Examples include boilers, open fires, heaters, stoves and wood burners. A detector is not required solely for a gas cooker or hob.
What counts as a room?
The guidance applies to areas used as living accommodation. An unconverted cellar, attic or garage does not make the house fail solely because it lacks a detector. Building Standards may impose requirements when an appliance is newly installed or replaced.
What if a flue passes through another room?
That room needs a detector if it is living accommodation, even when the appliance itself is elsewhere. Map the complete flue route through bedrooms, living rooms and other occupied spaces rather than checking only the boiler location.
Which detectors comply?
- Detectors should comply with BS EN 50291.
- Battery models should use a battery designed to last for the detector’s working life.
- The unit should warn occupants when its working life is expiring.
- Hardwired Type A units may be used if fixed rather than plug-in and fitted with a sensor-failure warning.
Combined smoke/CO devices may be used only when they satisfy the relevant standards for both functions.
Where should the detector go?
| Position | Scottish guidance |
|---|---|
| Distance from appliance | Normally between 1m and 3m in the room containing it. |
| Ceiling mounted | At least 300mm from a wall. |
| Wall mounted | At least 150mm below the ceiling and higher than doors or windows. |
| Appliance in cupboard | Do not put the detector inside the small enclosure; position it at the appropriate distance outside. |
Manufacturer instructions take priority where they specify a different suitable position. Consider the room layout and competent advice.
Do CO detectors need to interlink?
No. The Tolerable Standard does not require CO detectors to interlink with one another or with smoke and heat alarms. They remain separate safety systems, even where a compatible combined or connected product is chosen.
Testing, maintenance and expiry dates
Test and maintain every detector according to its manufacturer’s instructions. At each tenancy changeover:
- confirm every appliance and flue route;
- check detector coverage and positioning;
- use the test control as instructed;
- check fault and end-of-life indicators;
- record expiry dates and replacements; and
- show the incoming tenant how to test and report a fault.
An alarm is not a substitute for servicing
A CO detector provides warning; it does not make an unsafe boiler, fire, stove or flue safe. Keep required servicing, gas-safety and maintenance arrangements separate and current.
What should tenants do if an alarm sounds?
Landlords should provide the manufacturer’s emergency instructions. Occupants should not ignore, silence or remove an alarming detector. They should move to fresh air, avoid using the suspected appliance, seek emergency advice and obtain medical help if anyone has symptoms. The appliance and flue should not return to use until an appropriately competent person confirms it is safe.
Accessible and Telecare warnings
Deaf occupants must receive an equivalent level of warning through suitable specialist alerts. Landlords have duties concerning reasonable adjustments. Where Telecare is used, compatible CO protection should form a coordinated system rather than removing existing devices.
Landlord CO checklist
- List every fixed gas, oil and solid-fuel appliance.
- Trace every flue through living accommodation.
- Exclude a cooker or hob only where it is used solely for cooking.
- Confirm BS EN 50291 compliance.
- Check positioning and manufacturer instructions.
- Record tests, faults and end-of-life dates.
- Replace failed or expired units promptly.
- Give tenants testing and emergency instructions.
Frequently asked questions
Is one CO alarm per property enough?
Only if there is just one room requiring coverage. The rule is based on every living-accommodation room containing a fixed combustion appliance or flue.
Does an electric-only property need one?
Not solely because it is rented. Check whether any carbon-fuelled appliance or flue is present and whether another requirement applies.
Can a plug-in detector be used?
The Scottish guidance permits qualifying fixed hardwired Type A units, not plug-in mains types. Suitable sealed-life battery units are also allowed.
General information only, not legal, gas-safety or medical advice. Requirements depend on the property, appliances, flues, occupants and current guidance. Obtain competent advice for the specific home.