Carbon Monoxide Detectors

About Carbon Monoxide Detectors

Carbon monoxide detectors are essential safety devices designed to alert you to the presence of carbon monoxide (CO), a colourless, odourless, and deadly gas produced by the incomplete combustion of fuels. These life-saving alarms continuously monitor the air quality in your home or workplace, triggering an audible warning when dangerous CO levels are detected, giving you crucial time to evacuate and seek help. Whether you're a homeowner, landlord, or tradesperson working in residential or commercial properties, having reliable carbon monoxide detection is not just good practice – it's a legal requirement in many rental properties and an absolute necessity anywhere fuel-burning appliances are present.

Modern carbon monoxide alarms come in various configurations to suit different needs and budgets. Long-life sealed battery models, such as those offering 7-year or 10-year protection, eliminate the hassle of regular battery changes and provide peace of mind with extended warranty periods. Digital display models show real-time CO concentration levels, allowing you to monitor potential issues before they become critical, whilst standard audible-only alarms provide reliable detection at an economical price point. Many professional-grade detectors meet or exceed British Standard EN 50291, ensuring they've been rigorously tested for UK conditions.

For tradespeople installing boilers, gas fires, or other fuel-burning appliances, carbon monoxide detectors are an integral part of a compliant and safe installation. Testing equipment, such as CO alarm tester sprays, allows gas engineers and heating engineers to verify that alarms are functioning correctly during servicing and commissioning work, ensuring compliance with Gas Safe regulations and providing documentation that safety systems are operational.

Jargon Buster

PPM (Parts Per Million)

The measurement unit for carbon monoxide concentration in air. Exposure to 50 PPM over 8 hours is considered the maximum safe level, whilst levels above 400 PPM become life-threatening within a few hours.

EN 50291

The European standard (adopted as a British Standard) that specifies requirements and test methods for carbon monoxide alarms in domestic premises, ensuring devices meet minimum performance and reliability criteria.

Sealed Battery Unit

Carbon monoxide detectors with non-replaceable, long-life lithium batteries that power the alarm for its entire operational lifespan, typically 7-10 years, eliminating the need for battery replacement.

End-of-Life Warning

An audible or visual signal that indicates when a carbon monoxide detector has reached the end of its operational life and needs replacing, typically after 7-10 years when the sensor becomes less reliable.

Electrochemical Sensor

The detection technology used in quality CO alarms that uses chemical reactions to accurately measure carbon monoxide levels with minimal false alarms, more reliable than cheaper semiconductor sensors.

Peak Level Memory

A feature found in digital carbon monoxide alarms that records the highest CO concentration detected since the last reset, useful for identifying intermittent problems with appliances.

Who Uses Carbon Monoxide Detectors?

• Gas Safe Registered Engineers – installing and certifying CO alarms as part of boiler and gas appliance installations
• Heating Engineers – fitting detectors near oil, solid fuel, and biomass heating systems
• Plumbers – incorporating CO detection into central heating system installations and upgrades
• Electricians – installing mains-powered or hardwired carbon monoxide alarm systems
• Landlords and Letting Agents – ensuring rental properties comply with The Smoke and Carbon Monoxide Alarm (England) Regulations 2015
• Property Maintenance Professionals – servicing and replacing CO detectors during routine property inspections
• Building Contractors – installing alarms in new-build properties and renovations
• Homeowners and DIY Enthusiasts – protecting their families by installing detectors near fuel-burning appliances
• Caravan and Motorhome Owners – fitting compact CO alarms in recreational vehicles with gas appliances
• Fire Safety Officers – ensuring commercial premises have adequate CO detection where required

How to Choose the Right Carbon Monoxide Detectors

Power Source and Battery Life: Sealed battery units with 7-year or 10-year lifespans offer the ultimate convenience, eliminating the risk of flat batteries and reducing maintenance requirements. These are ideal for rental properties and busy homeowners. Replaceable battery models cost less initially but require annual battery changes to remain compliant and effective.

Display Type: Digital carbon monoxide alarms show real-time CO levels in PPM and store peak readings, making them valuable for tradespeople diagnosing appliance issues or for homeowners who want detailed information. Standard audible-only alarms cost less but still provide essential detection and warning capabilities, meeting regulatory requirements for most applications.

Standards and Certification: Always choose detectors that comply with EN 50291 to ensure reliable performance. Look for products from established manufacturers like Kidde, who have proven track records in life-safety equipment and offer comprehensive warranties and technical support.

Installation Location: Consider where the alarm will be mounted – most should be positioned at head height, 1-3 metres from potential CO sources like boilers, gas fires, or wood burners. Some detectors are designed for ceiling mounting, whilst others perform best on walls. Check the manufacturer's guidance for optimal placement.

Testing Capability: For professional installers and heating engineers, having access to CO alarm tester spray is essential for commissioning work and annual servicing. These testing products allow you to verify the alarm responds correctly without exposing it to dangerous levels of actual carbon monoxide.

Warranty and Lifespan: Quality carbon monoxide detectors typically come with warranties matching their operational life – often 7-10 years. The sensor itself degrades over time, so replacing units at the end of their rated life is crucial for maintaining protection, even if the alarm still appears to function.

Popular Accessories

• CO Alarm Tester Spray – essential for Gas Safe engineers and heating professionals to verify alarm functionality during installation and servicing
• Smoke Alarms – complementary safety devices often required alongside CO detectors in residential properties
• Heat Alarms – additional fire detection for kitchens and areas where smoke alarms may cause false activations
• Alarm Mounting Brackets – supplied with most detectors but available separately for replacement installations
• Flue Gas Analysers – professional diagnostic equipment for heating engineers to measure combustion efficiency and CO production
• Warning Labels and Safety Signage – to identify CO alarm locations in commercial properties and rental accommodation

Safety Information

Regular Testing: Test your carbon monoxide detector weekly using the built-in test button to ensure the alarm sounder and electronics are functioning. Never use actual CO gas for testing – use approved tester spray or the test button only.

Understand the Warning: If your CO alarm sounds, it's not a drill. Immediately evacuate all occupants, open windows and doors if safe to do so, turn off fuel-burning appliances, and call the Gas Emergency Services on 0800 111 999 (for gas appliances) or seek appropriate help for other fuel types. Do not re-enter until the property has been declared safe by a qualified professional.

Replacement is Mandatory: Carbon monoxide detectors have a finite lifespan, typically 7-10 years. The electrochemical sensor degrades over time, making older units unreliable even if they appear to work. Always replace detectors when the end-of-life warning activates or when the manufacturer's expiry date is reached.

Not a Substitute for Maintenance: CO alarms protect against detector failures but don't replace proper servicing of fuel-burning appliances. Gas appliances should be serviced annually by Gas Safe registered engineers, and other fuel-burning equipment should receive regular professional maintenance to prevent CO production.

Installation Requirements: For landlords, The Smoke and Carbon Monoxide Alarm (England) Regulations 2015 require a CO alarm in any room containing a solid fuel burning appliance. Similar regulations apply across Scotland, Wales, and Northern Ireland. Professional tradespeople should always follow current Building Regulations and manufacturer installation guidelines to ensure compliant and effective protection.

Frequently Asked Questions

Where should I install a carbon monoxide detector in my home?

Install CO alarms in rooms containing fuel-burning appliances such as boilers, gas fires, wood burners, or oil heaters. Position the detector at head height (approximately 1-2 metres from the floor) and 1-3 metres away from the appliance itself. Avoid locations near windows, doors, or extractor fans where air currents might affect readings. In properties with multiple fuel-burning appliances, fit a detector in each room containing such equipment, plus one in any bedroom above an appliance.

How long do carbon monoxide detectors last?

Most carbon monoxide alarms have an operational lifespan of 7-10 years, after which the electrochemical sensor becomes unreliable and the unit must be replaced. Sealed battery models are designed to last their entire rated life without battery replacement, whilst units with replaceable batteries still need complete replacement after 7-10 years regardless of battery condition. Always check the expiry date marked on your detector and replace it promptly when the end-of-life warning sounds.

Do I legally need a carbon monoxide alarm?

Legal requirements vary depending on property type and location. In England, landlords must install CO alarms in any room containing a solid fuel burning appliance (such as a wood burner or coal fire). Scotland has more comprehensive requirements under recent legislation. New-build properties and those undergoing significant renovation may have CO alarm requirements under Building Regulations. Even where not legally required, CO detectors are strongly recommended wherever any fuel-burning appliance is present, as carbon monoxide poisoning kills around 50 people annually in the UK.

What's the difference between a 7-year and 10-year carbon monoxide alarm?

The primary difference is the operational lifespan and warranty period. A 10-year alarm offers three additional years of protection before replacement is required, which can be more economical over time and reduces the frequency of replacements – particularly beneficial for landlords managing multiple properties. Both types use sealed lithium batteries and reliable electrochemical sensors, meeting the same EN 50291 standard. The choice often comes down to budget and how frequently you want to manage replacements.

Can I test my carbon monoxide alarm myself?

Yes, you should test your CO alarm weekly using the test button, which verifies the electronics, sounder, and battery are functioning. For professional installations, heating engineers use CO alarm tester spray to verify the sensor responds correctly to carbon monoxide. Never use actual CO gas or sources like car exhaust for testing, as this is extremely dangerous. If your alarm fails the test button check, replace it immediately regardless of its age.