By using this website, you agree to our use of cookies to enhance your experience.
Graham Awards


Expert advice to agents and landlords over carbon monoxide alarms

Letting Agent Today has been contacted by the Council of Gas Detection and Environmental Monitoring - the trade association for gas detection experts - seeking to put across a full explanation and context of how carbon monoxide issues may impact letting agents and landlords.


Given CoGDEM’s credentials, LAT is very happy to give space for its expert assessment of the reliability of domestic carbon monoxide (CO) alarms, especially over the Christmas period when occupation of some rented properties may be greater than usual.



CoGDEM says, at the outset, that the assertion that some make concerning sensors being disabled if exposed to sub-zero temperatures is untrue.


“To comply with [British Standard] EN 50291, an independent laboratory such as the British Standards Institution will perform a test of a CO alarm’s full operation at -10°C after storage at -20°C. Tests are also done at +40°C, so the alarm will have been designed and manufactured with very sophisticated atmospheric sensors and electronics to be able to achieve this large temperature range.  The EN 50291 standard also requires every alarm to test its own CO sensor automatically and identify any faults” says a statement from the council. 


CoGDEM is also keen to reassure landlords and letting agents that an October 2016 report by consumer magazine Which? showed that in independent tests, the EN 50291-compliant CO alarms from reputable manufacturers were 100 per cent reliable, whereas it was the less reliable alarms available on the internet that were not.  


“A few years ago, the Health & Safety Executive conducted tests of over 100 EN 50291-compliant alarms that were up to six years old, retrieved from homes at random by Gas Safe Register’s inspectors. When exposed to accurate concentrations of CO gas, the HSE recorded a 99 per cent pass rate - one unit had an intermittent connection fault after being shipped in a jiffy bag to the HSE laboratory” says CoGDEM. 

The National Landlords Association says it advises responsible landlords and letting agents to only install CO alarms that truly comply with the tough standard EN 50291 and that it is important to follow the alarm manufacturer’s instructions on installation and testing. 

“However, CO alarms should only be regarded as a second line of defence against CO. If all fuel-burning appliances are installed, serviced, ventilated and used correctly, there should never be a CO incident in the first place” the NLA adds. 

CO alarms from reputable manufacturers sold by reputable suppliers will comply with EN 50291 and will therefore give reliable service for their entire operating life, including over the important Christmas period when everybody expects to be safe to relax in their homes and when visiting family or friends.

* Our thanks to CoGDEM and the NLA for their guidance on this matter.

  • Kristjan Byfield

    This is a genuinely useful piece of technical info and advice that would not have readily been available or easily sourced by agents. It would be great to see more of these detailed and legislative specific articles in the future by leqading experts in their field.

  • john stones

    COGDEM are a trade body representing and financed by CO alarm and other related manufacturers. Their main objective is to "protect the commercial interests of their members" by representation in Standards bodies, trade associations and government.

    Since 2000 there have been numerous independent reports which have found an average of 45% of installed CO alarms in the USA and UK are no longer sensing gas.

    Hackney Homes had 26% of 23,000 Kitemarked CO alarms not sensing gas after just 2 years into a 7 year warranty.

    This year West Sussex Trading Standards found 80% of new CO alarms bought from high street retailers and sheds were not working to BS EN 50291. Some were Kitemarked models from CoGDEM members who have been under criminal investigation.

    A major U.K.
    Housing Association have recently tested their installed CO alarms (manufactured by a CoGDEM member and Kitemarked ) to find 53% not sensing gas. All within warrantee.

    Information acquired via the Freedom Of Information Act found that the HSE report on CO alarm reliability refered to was incorrect. HSE Laboratories and BSI are members of CoGDEM. The HSE responded that the figure quoted of 1% was due to a typographical error but have never amended the report which continues to be sited by CoGDEM who never mention the other reports. We were told that the alarms submitted were subjected to pre selection so the actual failure figure was probably higher still. Too many vested interests at play here.

    In the USA the Standard (NFPA720) for CO alarms requires all alarms to be sensor inclusively tested on installation and at least annually thereafter. This is not reflected in BS EN standards. The test button only tests the electronic circuit, NOT the sensors ability to sense gas. Why ? CoGDEM represent the CO alarm manufacturers on the BS EN Standards commiteees and block any move to sensor test CO alarms.

    Most CO alarms now carry a 10 year warrantee but most Sensors, the critical component in all CO alarms only have a 2 year warrantee. Most sensor manufacturers advise that due to the nature of CO sensors they could fail at any time and for any reason and that they should be tested with gas before use if used as a life saving device.

    CO alarm manufacturers give up to 10 Year warranties on products mass produced mostly in China for a few pounds. Why ? To give the impression of low cost of ownership to unwitting Social Landlords, utility companies and consumers.

    33 million CO alarms sold since 1996. Half are most likely no longer sensing gas.

    Just last month a CoGDEM member was forced to recall 5 million CO alarms due to sensor problems. A few years ago the same company were forced to recall 1 million CO alarms due to...sensor failure.

    The issues around CO alarm failures are well known,well documented and easily found on any Search Engine yet CoGDEM blindly support their members commercial interests whilst portraying themselves as "industry experts".

    Trade bodies financed by manufacturers look after their members interests.

    This is generally fine but not when life saving devices are being sold under false pretences putting lives at risk.

    Social Landlords have been installing CO alarms in volume since 1996. Most are now waking up to the problems, risks and liabilities with law firms lining up to sue landlords who have been mislead by an industry obsessed with profits rather than the safety of the public.

    Sensor manufacturers warn against storing sensors in low temperatures. This was highlighted by the National Caravan Council this year and probably accounts for the high number of non sensing CO alarms found in Caravans after being winterised.

    CO alarms do save lives but only when they are sensing gas. After nearly 20 years of denial by CoGDEM the cat is out of the bag and to retain some credibility CoGDEM need to re consider their stance and legal position or face the consequences.

  • icon

    We had an incident yesterday where a building contractor working next door damaged the flue to the boiler of a property we manage. Fortunately the tenant was out at the time. The neighbour told us what had happened and by the time we got to the property the Carbon Monoxide alarm was ringing and the property full of the dangerous gas.
    If the tenant was at home who knows what would have happened had the alarm not been installed. We have one very relieved Agent and Landlord. And a builder who will no doubt take much more care when working near flues in the future.
    Alarms save lives, any landlord who does not install them is one or two bricks short of a full house.


Please login to comment

MovePal MovePal MovePal
sign up