CO alarms are warning devices

How many structures do we enter that have working and properly placed carbon monoxide alarms or detectors?  Do we sell or recommend the placement of these alarms? 

Before we tell the consumer where to put CO alarms, we need to understand how air movement in buildings and duct systems impacts the safe and efficient heating and cooling operation. 

As well, we need to determine how combustion, draft, make-up/combustion air and other factors effect the building’s operation as a ‘system’.

Is there a best location for CO alarms?  Do we understand how carbon monoxide alarms work? 

Do we know the alarm standards?  Can we explain these to the consumer? 

Are we alerting the consumer to potential and foreseeable hazards associated with any of their combustion systems?  Are we educating the public as we service them or are we merely billing them?  We have opportunities to educate them as well as generate more business.

Every building we enter that has combustion system influences should have a CO alarm.

If one is not in place upon your visit, suggest their installation.  This should also include all electric homes with attached garages.

It is always suggested to recommend the installation of a home CO alarm.  It is not uncommon to find heating contractors and others, after having notified the Authority Having Jurisdiction about a cracked heat exchanger, to leave “loaner” CO alarms and the furnace in operation until repair or replacement can occur.  Often times also, the consumer purchases the CO alarm or the contractor builds that into the replacement bid as an option.  They may even give one as a ‘free’ service.

It also appears as though a CO alarm may provide additional protection in the event of a fire.  There have been many reports of CO alarms going off before the smoke alarm in the case of a home fire where apparently the fire was generating tremendous amounts of CO before sufficient levels of smoke were detected.

What type of CO alarm should be installed?

The recommendation is to install at minimum, an alarm that meets or exceeds the current listing under UL 2034.  Under this listing, CO detectors must alarm within certain times for different concentrations of carbon monoxide.  These levels of CO for those time periods allegedly equate to safe concentrations for healthy human beings.  This standard requires alarms to signal when indoor air contains CO for periods of time that would equal 10% COHb when breathed by healthy individuals. This is referred to as carboxyhemoglobin (COHb) per cent or the amount of CO found in the human blood stream. 

Some advocates and consumer groups feel changes in the standards since 1994 have jeopardized their effectiveness and recommend models specifically designed for particularly sensitive populations.  These alarms typically read out and/or detect/alarm at lower ranges of CO exposure.  They are priced, generally, in the $80 range as opposed to the $20 range for the standard models.

Do they have the same sensor capabilities as my test instrument?

The comparatively inexpensive home alarms use sensor technology not equipped to measure and display low level, short term concentrations of CO (usually less than 60 PPM or 100 PPM).  The sensors used in Bacharach instruments are highly responsive to low levels of carbon monoxide in the sampling environment.

The typical home alarm will not read out (nor alarm) at lower levels of CO that may be present and displayed by a CO test instrument.  Nor will they react as fast as an instrument.

They are not designed to do so. 

Remember, a more vulnerable human being such as an infant or someone with congestive heart problems or breathing problems may suffer chronic ill effects from these lower levels. 

When encountering households containing inhabitants other than healthy young adults, please advise using a more sensitive CO alarm system.  They may have a higher installation cost, but may prove to be more cost effective and healthy for every body involved in the long term.

It must be noted that home carbon monoxide alarms with digital displays have been reported in the field to have low CO PPM displayed on the CO alarm but 0 PPM or trace measurements inside the building with hand-held, portable instruments.  When a hand held CO detecting instrument like the Monoxor IIâ or CO Snifitâ is used, this discrepancy is often noted. 

CO alarm sensors can also be effected by or cross sensitive to a number of other factors. Temperature, humidity, calibration requirements, and sensitivity to low level, real time measurement for both types of devices are different.  Read the instructions.  The typical home alarm, even those with a somewhat more sophisticated data logging and peak measurement recorder do not protect all inhabitants from potentially harmful concentrations of CO.

Plus, there have been reports of CO alarms responding to a number of common household compounds.  The following is a list of common household chemicals and other substances that may have an effect on the sensor:

Aerosols – (hair sprays, deodorizers, Lysol, etc…)

Cleaning supplies – (Clorox, Bleaches, etc…)

Gas from charging batteries

Paints

Stripping chemicals

Varnish

Silicon glue or compounds

Alcohol

Methane

Toluene

Acetone

Nail polish

Nail polish remover

Sulfur compounds

Sewer gas

Vapors from baby diapers

Car exhaust fumes

Cigarette smoke

Incense smoke

Ammonia

Carpet cleaning solutions

Sealant

Freon from air conditioners

Hydrogen

Nitroglycerin (usually from heart medication)

It is important to check with the manufacturer of a particular alarm or detector to determine potential cross sensitivity to these or other compounds.

The only gas test instrument CO sensors are cross sensitive to is hydrogen from, for example, charging an automobile battery in the vicinity.

You may find carbon monoxide levels higher than outside levels and the alarm has not sounded.  You may not find measurable CO inside a building where an alarm has sounded. You may feel as if you are chasing ghosts when tracing CO to its source or sources.

To chase this ghost, we’ve got to know what we’re chasing and how it is being detected.  We also need to determine the listing of a particular alarm that may or may not be sounding to help evaluate the situation.