Carbon monoxide and propane

Propane is a safe source of energy if simple precautions are followed when handling and storing it. Part of this comes from ensuring your propane appliances are functioning properly.

Propane ideal burn


Propane appliances should have what is called an “ideal burn”. Basically, an ideal burn requires that, for each part of propane, there should be 24 parts of air (1:24 propane/air ratio). In other words, an ideal burn requires 4% propane and 96% air.

Carbon monoxide detection


Sometimes, propane appliances produce a “lean burn” when the part of propane in the propane/air mix is lower than 4% propane. Similarly, a “rich burn” happens when the part of propane in the propane/air mix is above 4% propane. This is also called incomplete combustion. When it comes to residential propane use, incomplete combustion can be very dangerous as it produces carbon monoxide.


When propane appliances do not operate properly because fuel is burning incompletely or appliance venting systems are entirely or blocked, you may see sooting on appliances, on vents or on warm air registers. You may also smell a burning odor or notice moisture on the inside of the room windows. Lastly, plants can wilt or die. All these can be signs of the presence of carbon monoxide and should be acted on immediately.


Similarly, appliances that function properly produce a blue burning flame. However, a lean burn leads to flames lifting away from the burner and eventually going out. A rich burn produces yellow flames that are much larger than those of an ideal burn. Once more, if you notice either of the last two situations, act immediately.

Carbon monoxide symptoms


It is impossible to taste or smell carbon monoxide. Yet carbon monoxide replaces oxygen in human blood. Initially, the intake of carbon monoxide might give you a headache and can make you nauseous, dizzy, short of breath, confused, tired. Ultimately, carbon monoxide intoxication can make you lose consciousness and can lead to a coma, cardiovascular collapse, brain damage and even death. Carbon monoxide intoxication accounts for just under a quarter of all propane-related fatalities.

Carbon monoxide safety


If you know carbon monoxide is present:

  • LEAVE the building immediately.
  • CALL your propane company, fire department or 911.
  • IF SAFE, open windows.
  • IF SAFE, turn off appliances you suspect are faulty.


If you suspect carbon monoxide is present but experience no carbon monoxide symptoms, call your propane company’s customer care number or a qualified service technician to have carbon monoxide levels checked and propane appliances inspected.


However, never should you attempt to repair your own propane appliances or light pilot lights – this can increase the risk of carbon monoxide intoxication rather than reduce it.

Carbon monoxide prevention


The best way to avoid carbon monoxide intoxication is to have your propane appliances maintained properly and inspected regularly (before the heating season) by a qualified propane technician. Some companies offer maintenance services and this could be a selection criterion as you compare offers from different propane dealers.


Although this should not stop you from looking out for the symptoms of carbon monoxide, it is possible and recommended to have carbon monoxide detectors installed on every level of your home. Such detectors should be selected among the Underwriters Laboratories’ list of carbon monoxide detectors and manufacturer instructions on installation, location and maintenance should be followed rigorously.


Also, proper appliance venting is required by the National Fire Protection Association (NFPA 54). Therefore, make sure you use exhaust venting materials that are approved by the NFPA. If you have any doubts, contact your local city code compliance department, your propane company, a building inspector or a HVAC company.


Simple precautions can also reduce the risks associated to the presence of carbon monoxide:

  • Do not use outdoor heaters indoors, use a propane oven for heat, use an outdoor grill inside.
  • Ensure chimneys, flues and vents are free of debris, snow and ice.