Silent Killer

Your furnace is a heating system that produces carbon monoxide (CO), a silent and harmful gas that can be fatal. You need to be diligent about regular furnace maintenance in order to keep your family safe from the dangers of carbon monoxide poisoning. Your unit needs to remain efficient and safe at all times.

Natural Gas and Propane Furnaces

Forced-air furnace models that run on natural gas or propane produce carbon monoxide due to incomplete combustion. Most of the small amount of deadly gas is carried out of the home through the ventilation system. However, older models are prone to increased carbon monoxide production, and even the modern high efficiency models can pose a threat in your home.

Regular maintenance of your natural gas or propane powered furnace involves changing the furnace filters at least twice a year, and engaging a qualified technician to service your unit annually. The ventilation system will be inspected, as well as the interior mechanisms of your furnace in order to ensure their proper function. If the furnace is not operating properly, or if a vent cracks, or if the combustion mixture is altered, a significant risk exists. CO may leak into your home and cause flu-like symptoms that signal potential carbon monoxide poisoning.

Oil and Wood Furnaces

Much like gas-powered models, oil and wood furnaces produce carbon monoxide when the combustion inside the appliance is incomplete. It is important to keep your furnace clean so that it functions well. If you find that your unit is using an excessive amount of fuel (regardless of the temperature), or if it does not stay lit, or if the surface becomes excessively hot, call in a professional and have it inspected as soon as possible.

When a furnace is dirty or running at low efficiency, CO is being produced at a higher rate and the risk of carbon monoxide poisoning is increased.

Tips on Furnace Operation

To reduce the risk of carbon monoxide poisoning resulting from the operation of your furnace, follow these important tips:


  • Schedule annual furnace maintenance visits and tackle any repairs immediately
  • Change your furnace filter regularly
  • Be aware of and alert to the signs of CO poisoning
  • Install carbon monoxide detectors on every floor of your home
  • Keep the area around your fireplace clean and tidy, allowing significant space
  • Keep your vents unobstructed and clean by removing accumulated snow, ice, leaves, etc. around the opening


  • Store solvents and other combustibles around your furnace
  • Close off or block more than 20 percent of your registers as your furnace will overheat
  • Ignore signs of distress coming from your furnace – remember that carbon monoxide is silent and can be deadly
  • Assume that your home is automatically safe because you have upgraded to a high efficiency furnace

Sometimes carbon monoxide can leak from cracks in the combustion chamber, and over time, the accumulated dirt in a furnace can create such an excess of CO that the ventilation system cannot contain it.


Headache Dizziness, Nausea Flu-like symptoms, Fatigue, Shortness of breath on exertion, Impaired judgment, Chest pain, Confusion, Depression, Hallucinations, Agitation, Vomiting, Abdominal pain, Drowsiness, Visual changes, Fainting Seizure, Memory problems and Walking problems