Carbon Monoxide – How to Test for It and What to Look For

Carbon monoxide poisoning is a serious issue in homes today. Between 2010 and 2015, more than 2,200 people died from carbon monoxide poisoning, according to the CDC (Centers for Disease Control and Prevention). Many illnesses caused by carbon monoxide poisoning go unreported, or are attributed to the flu or other causes and are not caught by medical personnel, who often don’t test for carbon monoxide poisoning. For many, by the time the fire department has been called to investigate a possible carbon monoxide leak, a family may already be desperately ill. HVAC professionals are key to guarding against this deadly gas in homes.

What is Carbon Monoxide?

Carbon monoxide (CO) is the result of imperfect combustion of fuel. It is an odorless and colorless gas that is slightly lighter than air. When combustion occurs, the normal result is carbon dioxide (CO2) and water. However, carbon monoxide is produced when only one oxygen atom, rather than two, combines with the carbon. Ordinarily, the CO should be vented outside and cause no problems. However, when there is any problem with the exhaust of this toxic gas, carbon monoxide can begin to build up in a home, causing health problems.

Carbon monoxide is dangerous when inhaled because it binds to the red blood cells in the same way oxygen normally would, displacing the oxygen the body needs. Over time, carbon monoxide can build up in the body causing serious problems. This buildup is especially a problem for those who do not leave the house often, such as those who are ill and the elderly. Doctors often misdiagnose carbon monoxide poisoning because the symptoms often mimic those of the flu. Some people may feel better just getting out of the house and breathing clean air on their trip to the doctor, so the symptoms are reduced.

Problems with Home CO Alarms

Many homes now have carbon monoxide detectors/alarms, just as they have smoke detectors. Many of these alarms are set to go off when they detect 40 to 70 ppm (parts per million) of CO in the air. That level is too high. By that point, the family is already at serious risk from CO poisoning.

Most home CO detectors are designed to operate at the height at which people normally breathe. CO is lighter than air, so if these detectors are installed too low, they may not accurately assess the amount of CO the inhabitants are breathing. More expensive models work when placed closer to the ground, but even these models are generally set to alert at 40 ppm.

While having a home CO detector is better than nothing, by the time you are alerted to a problem it is likely that your family will already be suffering the ill effects of CO inhalation.

Suitable Levels of CO

Any amount of CO in a home is abnormal and the cause should be investigated. Even low levels of CO can cause illness, because the carbon monoxide builds up in the body over time. However, there are some levels at which the CO is definitely a hazard and steps should be taken immediately to prevent illness or even death.

Here are some significant levels of CO and their affects:

  • 3 to7 ppm Results in a 14 percent increase in hospital admissions for asthma.
  • 10 ppm May result in a significant increase in deaths from heart disease.
  • 27 ppm Causes a significant increase in cardiorespiratory complaints.
  • 30 to 35 ppm May alert on some CO detectors. Can cause exercise-induced angina.
  • 70 ppm First alert by many CO detectors when sustained for 30 days. Inhabitants may experience headaches, dizziness, weakness, irregular heartbeats, and more.

As noted before, health problems can occur at significantly lower levels of CO in the air when the home’s inhabitants remain indoors for long periods. Since the elderly and ill are already more vulnerable to the effects of CO poisoning, it is common for them to experience the negative effects of CO more quickly.

Professional Testing by HVAC Technicians

HVAC professionals have three main options for the hardware used to detect CO in a home. These are ambient air testers, pump-driven analyzers, and combustion analyzers.

Ambient air testers are the most common professional CO detectors, partly because they are relatively inexpensive, with some costing less than $200. These devices feature an ambient air sensor and a digital readout of CO levels. Ambient air testers are easy to use and do not require any special training.

Ambient air testers are unable to test raw flue air streams or warm air streams in any way. It is also important for the user to calibrate the instrument properly and use the device according to specifications. An ambient air tester must first be used outside to establish a zero reading. Only then can the device be used inside to measure possible CO presence in the home.

The pump-driven analyzer can provide more information for finding the cause of a CO leak in the home. The pump-driven analyzer can test flue air products and warm air streams as well as ambient air. This can be invaluable for not only detecting a CO problem, but for locating the device or appliance causing the CO leak.

This added utility does come with a price tag, because the cost of most pump-driven analyzers is double that of an ambient air tester. Some devices feature the ability to graph CO measurements over time and can send readings to a printer to provide permanent records. These instruments also must be calibrated outside the home before testing indoors.

The most powerful CO testing device is the combustion analyzer. These can perform all the functions of a pump-driven analyzer or an ambient air tester and also measure the oxygen and carbon dioxide in the air. By doing so, they can evaluate the efficiency of the combustion process by creating a picture of the ratio of gasses in flue products. This functionality can help pinpoint the cause of the CO leak.

Combustion analyzers are the most expensive CO detection tool in the professional’s arsenal and may run anywhere from $600 to $2,000, depending on the features. Some special training may be required to understand the information provided by a combustion analyzer, including proper combustion ratios. Like the other devices, this should be calibrated regularly and zeroed outside the home before testing inside.

HVAC professionals are often the first line of defense for spotting and intervening in a situation where carbon monoxide is present in the home. As such, they have a responsibility to be on the lookout for signs that CO may be present and to take steps to protect the residents. By using the proper equipment, and being aware of the levels that may pose a danger, the HVAC technician can save lives and improve the health of those whose homes they service.