Photograph of a 120Vold carbon monoxide detector deviceCarbon Monoxide Gas Alarm Causes
Why does the CO alarm keep going off?

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Carbon monoxide CO alarm sound-off troubleshooting:

this document discusses the causes of CO alarms going off - when a carbon monoxide alarm sounds you should assume there is dangerous carbon monoxide gas (CO) present. But other things might set off some alarm and not all of them are CO hazards.

Beware that the production of dangerous carbon monoxide gas in a building is usually not constant - it can start and stop. So even if someone tests and does not find CO gas present, especially if your CO alarm has been sounding, you can NOT assume that conditions are safe in the building, and further expert visual inspection of heating equipment, chimneys, etc. are in order.

For example, simply closing the door to a boiler room where gas fired equipment is operating can cause sudden production of CO gas if there is insufficient combustion air when the door is closed. Yet when someone opens the door to inspect the area, more combustion air is provided. CO production may stop.

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What Makes a CO Detector Alarm Go Off

IF YOU SUSPECT CARBON MONOXIDE POISONING GO INTO FRESH AIR IMMEDIATELY and get others out of the building, then call your fire department or emergency services for help.

Seek prompt advice from your doctor or health/safety experts if you have any reason to be concerned about exposure to toxic gases. Carbon monoxide poisoning can be fatal but exposure at lower limits can produce flu-like symptoms and headaches that are often mistaken for ordinary illness.

Carbon monoxide detector alarms may sound for a variety of reasons, but until you have diagnosed for sure why a particular alarm has sounded, you should assume that it has detected dangerous carbon monoxide indoors and you should follow our safety advice above.

Here are some causes of Carbon Monoxide Detector alarms sounding:

  • The CO alarm has detected carbon monoxide in the building at a dangerous level. The alarm may sound if there is a sudden surge of high concentrations of CO or it may sound if lower levels of CO have been present for a longer period.
  • Heating system malfunctions or malfunction in other gas or oil burning equipment (such as a space heater or a water heater) can produce dangerous levels of carbon monoxide indoors
  • A blocked chimney flue can cause dangerous backup of carbon monoxide gas indoors
  • Inadequate combustion air can cause production of dangerous levels of CO indoors

All of these conditions are dangerous. Follow our safety advice above

  • Other indoor contaminants, including smoke, other particles, chemicals, and gases might cause some models of smoke alarms or carbon monoxide detector alarms to sound.
  • Beeping or chirping from a CO carbon monoxide detector alarm, a sound that is not continuous but sounds every few minutes, may indicate a dead or dying battery - replace the battery; if the alarm is in doubtful condition replace it.

Safety Suggestions: Install Carbon Monoxide Detectors in addition to Smoke Detectors

Carbon monoxide detectors are inexpensive and readily available, both as a battery-operated unit and as a unit that plugs into an electrical outlet in the home.

No home should be without this safety protection, and homes with gas-fired equipment (natural gas or LP propane), space heaters, or other sources of risk should be extra cautious. Smoke detectors do not protect against carbon monoxide poisoning, and the opposite is also true. Carbon monoxide detectors do not warn of smoke or fire.


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CO ALARM CAUSES at - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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