How to deal with CO Detectors and False Alarms
Everyone hates it when a smoke alarm goes off for the wrong reason. We know
this as a false alarm. False alarms are a real headache for the resident, but
they are even worse for a landlord as they are costly, involving a visit to the property more often
or not by an electrician in the case of smoke alarms and a plumber in the case
of CO alarms
With the increasing use of Carbon Monoxide (CO) alarms in rented property as
a further life saving device, does the false alarm problem double? And what do
you do when a CO alarm goes into what you think is another false alarm?
Well, CO alarms are very different from smoke alarms and false alarms are very
unlikely. They do not alarm when the toast is burnt or when you've had an extra
hot steamy shower. When a CO alarm indicates the presence of CO it must not be ignored.
Ei Electronics – Europe's largest manufacturer of smoke and CO alarms – has recently
seen a few worrying incidents where complaints were made about CO alarm false
alarms, when the alarms where actually working very well indeed. The outcomes
could have been very different.
In the first instance, a woman who had purchased and fitted another manufacturer's
CO alarm was rightly concerned when it went into alarm. She called out her gas
supplier who checked the boiler, found nothing wrong and said the CO alarm must
be faulty. The woman rang the manufacturer who said that it may have come from
a faulty batch and sent her a replacement alarm. The alarm went off again, she
repeated the process with the same result. This, in fact, happened four times. Whilst waiting for another replacement alarm to arrive, the women decided it
was best to be on the safe side and purchased another manufacturer's CO alarm – Ei. The Ei CO alarm went into alarm at which point she rang Ei who sent her an Ei206DEN
CO alarm which has a built in digital read out feature. The alarm showed 80ppm
of CO in her kitchen, however, she measured 165ppm in the corridor outside her
flat. It transpired that the CO was coming from the flat below her – and no less
deadly for it.
The other incident is actually from a housing association. Ei recently received
two Ei261ENRCs CO alarms which were reported as false alarming. Ei has vigorous testing facilities and
put the returned alarms through their paces to find they were performing accurately. We immediately advised the housing association that the alarms are working and
that therefore CO must be present in the properties from which they were taken. The housing association was taken aback and started an immediate investigation
into the source of the leak.
The moral of these two stories – or should we call it a warning – is to approach
claims of "false" alarms from CO alarms carefully. Unlike smoke alarms where
dust, cooking fumes etc. can cause false alarms the same problem does not exist
with CO alarms.
That is because CO alarms work very differently from smoke alarms. When CO is
present, it enters the sensor through a gas diffusion hole. A graphite filter
prevents any external contaminants from entering. A Platinum sensing electrode
then catalyses the oxidation of the CO. Combined with the water present in the
electrolyte, this reaction causes the voltage to rise and consequently, a small
current flows between the two electrodes. This output is directly proportionate
to the amount of CO gas present. The microchip in the unit then activates the
LED/horn/display to give a warning applicable to the CO level sensed.
As you can see, it's a complicated process, which is why CO alarms are considerably
more expensive than smoke alarms and also why they very rarely go into false alarm. In fact, the only reason for them to false alarm is not from external contamination,
but if there is something wrong with the alarm itself. If you get a good quality
CO alarm from a reputable manufacturer – avoiding the cheap influx from the Far
East which have been blighted with problems and product recalls – then this should
never be a problem.
For added reassurance, install a CO alarm that provides you with more information
than simply an alarm warning. The Ei261EN, for example, features high and low
level LED indicators, with a special pre alarm LED indication for detection of
CO at 50ppm. When the levels detected reach dangerous levels, a red warning LED
combines with an integral built in sounder outputting 85Db(A) at 3 metres to provide
a full audio-visual warning. Other indicators confirm mains power supply and
fault indication. The alarm also comes with a manual Test/Hush button, Quick
CO Gas test facility and a memory feature which enables the user to tell if CO
has been detected during a period of absence.
There is no legal requirement for a landlord to fit a CO alarm in to his property
at present, although two years ago the House of Commons All Party Parliamentary
Gas Safety Group called upon mortgage providers and insurance companies to make
the installation of a 'reliable CO detector' a prerequisite for agreeing a mortgage
or providing home insurance. This indicates CO poisoning is on the political
A landlord is, of course, required by law to check all gas appliances by an approved
engineer every 12 months. But this is not nearly adequate protection as things
can and do go wrong between inspections and, what's more, CO is given off as a
by-product of virtually any combustion process; any household appliance that burns
coal, oil, bottled gas, paraffin, wood, petrol, diesel or charcoal can be a potential
source of CO. Let's not forget, CO is an extremely dangerous – lethal – gas. You can't smell it, see it and you certainly can't hear it. The only way to detect
it is by fitting a good quality CO alarm.
For landlords, if you have taken the sensible precaution to fit a CO alarm, it
is essential that you take note of your tenants when then they tell you the CO
alarm has gone into alarm. Never make the presumption that it is a false alarm
– always assume the alarm is caused by CO being present and take action. Tell
your tenants to open all the windows and get out of the property and then call
the gas company. And don't forget, as we have seen from our first incident, if
CO can't be detected in that specific property, investigate the possibility of
it coming from outside the dwelling.
CO poisoning is extremely dangerous. The first symptoms are often a slight headache,
at concentrations around 15% COHb. As poisoning progresses, your headache gets
worse and you begin to feel sick, dizzy and drowsy – a bit like flu, which makes
it difficult to diagnose. If poisoning continues undetected, the results of even
relatively low exposures over time can be permanent lung damage, heart damage,
brain damage or death. Most victims die in their sleep from a strong leak – some
in just minutes. The family pets tend to die first, then babies, small children
or the elderly. Healthy adults tend to take longer to die, but they will be killed
just the same.
Fitting a quality CO alarm is the only way to detect CO. Reacting to it when
alarming is the only way to protect the residents.
(doc:126 V1.0). Our articles are reviewed regularly. However, any changes made to standards or legislation following the review date will not have been considered. Please note that we provide abridged, easy-to-understand guidance. To make detailed decisions about your fire safety provisions, you might require further advice or need to consult the full standards and legislation.