How it works

Properly operating combustion appliances vent CO outdoors through their flue or vent system. Problems arise when venting fails: blocked flues, backdrafting, vent disconnection, or appliance malfunction can spill CO into living spaces. Symptoms of CO poisoning mimic flu: headache, nausea, dizziness, fatigue, and at higher concentrations, loss of consciousness and death. Pets and children show symptoms first because of higher metabolic rates.

CSIA-certified sweeps measure CO concentration in flue gases and at the appliance location during service visits using calibrated electrochemical analyzers. Any reading above 100 parts per million in the appliance area warrants immediate investigation. Every DFW home with a fuel-burning appliance should have UL 2034 listed CO alarms installed on every level and outside every sleeping area.

DFW context

DFW’s combination of wood-burning fireplaces, gas-log fireplaces, gas water heaters, and gas furnaces creates multiple potential CO sources in a single home. Texas state law requires CO alarms in new construction and substantial remodels with fuel-burning appliances, but older homes are exempt. TSE installs UL 2034 alarms during service visits when homeowners request them and verifies CO levels at every appliance during annual maintenance.

Related terms

• [Backdraft](/glossary/backdraft/)
• [Negative pressure](/glossary/negative-pressure/)
• [Combustion air](/glossary/combustion-air/)
• [B-vent](/glossary/b-vent/)

Sources

• UL 2034 Standard for Carbon Monoxide Alarms
• NFPA 720
• CDC Carbon Monoxide Poisoning Prevention guidelines