Carbon Monoxide Poisoning: Finding a Qualified Heating Contractor (AEN-167)

ISU Extension Publication #: AEN-167
Author: Dr. Thomas Greiner, Dept. of Agricultural and Biosystems Engineering
Iowa State University
Date: 7/96

What is Carbon Monoxide?

Carbon monoxide (CO) is a colorless, odorless, tasteless, deadly gas. You can’t see, smell or taste it. Carbon monoxide is slightly lighter than air and quickly spreads throughout an entire house.

What causes carbon monoxide production?

Carbon monoxide gas is produced when fossil fuel burns incompletely because of insufficient oxygen. During incomplete combustion, the carbon and hydrogen combine to form carbon dioxide, water, heat, and deadly carbon monoxide. In properly installed and maintained appliances gas burns clean and produces only small amounts of carbon monoxide. Anything that disrupts the burning process or results in a shortage of oxygen can increase carbon monoxide production. Wood, coal, and charcoal fires always produce carbon monoxide, as do gasoline engines.

What would cause carbon monoxide not to vent to the outside?

Incorrectly installed venting systems and chimneys, chimneys plugged by birds’ nests or tree leaves, deteriorating chimneys, chimneys too short to vent correctly, appliances with no venting system, house air flow patterns, and downdrafting all may cause vent failure.

What signs may indicate the presence of Carbon Monoxide in a house?

Some clues for a family include:

  • Entire family is sick at the same time.
  • Flu-like symptoms decrease while away from the house.
  • Illness is present when gas appliances are in use.

Some clues for the house include:

  • Excessive amounts of soot, rust, and/or dirt around the heating appliance or vent.
  • Strange noises or odors from the heating appliance.
  • Rust or dirt on the burners,and/or orange flames.
  • Excess moisture on the interior of windows.

What are the health symptoms of carbon monoxide poisoning?

Carbon monoxide symptoms are similar to the flu: headaches, fatigue, nausea, dizziness, confusion, and irritability. Continued exposure leads to vomiting, loss of consciousness, brain damage, heart irregularity, breathing difficulties, muscle weakness, abortions and even death. Because the symptoms mimic so many illnesses, CO poisoning is often misdiagnosed.

What should I do to protect myself from the dangers of carbon monoxide poisoning?

First, purchase a carbon monoxide detector(s). Second, have all heating appliances checked every year by a qualified heating contractor. And third, replace heating units with direct-vent sealed combustion units.

If I have a carbon monoxide problem, who do I call?

If the problem is an emergency causing illness or unconsciousness, open windows and call 911 for immediate help. After obtaining medical assistance, contact the gas company, the city mechanical inspector, and a local heating contractor for inspection and repair. If they are unable to adequately diagnose and solve the problem, a person equipped and trained to perform house diagnostics should be consulted. These people will usually have the following equipment and training:

  • Micromanometers to measure very small pressure differences.
  • Blower doors to determine the air leakage characteristics of the house.
  • Smoke pencils.
  • Carbon monoxide measurement equipment.
  • Training in carbon monoxide investigations and pressure measurement.

How do I find a reliable qualified heating contractor?

Check the yellow pages, look for local advertising, and ask friends for recommendations. Many states require certification and licensing of heating contractors. Iowa does not. Check the following before hiring a contractor:

  • The Better Business Bureau.
  • Bank and business references.
  • Previous customers.
  • City building departments
  • Training and skill level.
  • Professional membership.
  • ISU Answer Line: 1-800-262-3804.

How do I insure a contractor is qualified to check for CO?

To insure that a heating contractor is competent and qualified to perform a CO investigation ask the following questions:

  1. Do you have electronic equipment to measure CO in flue gases?
  2. Do you have equipment to measure and adjust gas flow?
  3. Do you check for gas flow and CO during your inspection.
  4. Have you attended training on carbon monoxide?
  5. Do you perform a “worse case” downdrafting test as part of your inspection?
  6. Have you attended training on gas flue venting?

Carbon Monoxide can be intermittent, sporadic and unpredictable. Sometimes locating and correcting the problem is difficult. Work with your heating contractor until the problem is solved. If you are unable to locate a contractor with the training and equipment to determine the source of CO, call Iowa State University Answerline at 1-800-262-3804 for assistance.

For more information request other notes in the Carbon Monoxide series. Agricultural Engineering Notes (AEN’s) are informally published information releases on topics of current concern to Iowans.