Carbon monoxide has no color, no smell and no taste. That is the entire reason it is dangerous. Every other problem a heating system can develop announces itself somehow. This one does not.
Before the furnace runs regularly this season, this is worth twenty minutes.
Quick answer: Carbon monoxide from a furnace usually comes from a cracked heat exchanger, a blocked flue or poor combustion, and you cannot see or smell it. Put detectors outside sleeping areas and on every level, test and replace them on schedule and have the furnace inspected every year. If a carbon monoxide alarm sounds, get everyone outside and call 911.
Carbon monoxide is a byproduct of incomplete combustion. Any fuel-burning appliance can produce it: gas and propane furnaces, boilers, water heaters, ranges, dryers, fireplaces and wood stoves.
A properly operating, properly vented appliance produces very little and sends it safely outside. Problems start when combustion goes wrong or venting fails.
A cracked heat exchanger. The heat exchanger separates combustion gases from the air circulating through your home. A crack lets them mix. This is found by inspection, because it produces no symptom you would reliably notice.
A blocked or damaged flue. Bird nests, corrosion, disconnected sections or a sagging vent pipe holding condensate.
Insufficient combustion air. Combustion needs oxygen. A furnace in a sealed utility room, or a house made much tighter by new windows and insulation without ventilation being addressed, can starve the burner.
Backdrafting. A powerful range hood, bath fan or clothes dryer can depressurize a home enough to pull flue gases back down the vent. This is more common in tight homes than most people expect.
A dirty or misadjusted burner. Improper gas pressure or a fouled burner assembly produces incomplete combustion, which is why a yellow flame is one of the signs you need a new furnace worth taking seriously.
Vehicles and generators. Not a furnace issue, but a frequent cause. Never run a vehicle in an attached garage or a generator near the house.
One on every level of the home, including the basement. One outside each separate sleeping area, positioned so it will wake someone asleep. Follow the manufacturer’s height instructions, since models vary.
Where not to put them: within about fifteen feet of fuel-burning appliances, in bathrooms or humid areas, in direct sunlight, behind furniture or curtains, or right beside a ceiling fan or supply register.
Press the test button monthly. That confirms the alarm and electronics work.
Then the part almost everyone misses: CO detectors expire. The sensor degrades over roughly five to ten years depending on the model, whether or not the unit has ever alarmed. Check the manufacture date printed on the back. Past the manufacturer’s stated interval, replace the whole unit. New batteries do not restore a worn sensor.
Get everyone out. Everyone, including pets, immediately, to fresh air outside.
Call 911 from outside. Not from inside the house.
Do not go back in until emergency responders say it is safe.
Do not assume it is a false alarm. If anyone has a headache, nausea, dizziness, confusion or unusual fatigue, tell the dispatcher.
Afterward, have the combustion appliances inspected before the system is used again. An alarm that stopped on its own is not evidence that nothing happened.
A combustion safety check is the core of a furnace tune-up, and it is the reason annual service matters even on equipment that seems fine.
The technician inspects the heat exchanger for cracks and corrosion, examines the flue for blockages, secure connections and proper pitch, verifies adequate combustion air, checks burner condition and flame characteristics, tests limit and rollout switches, verifies gas pressure and performs a combustion analysis with a CO reading.
That is a routine visit. It catches the conditions that produce carbon monoxide before they produce carbon monoxide.
For over 50 years J&J has performed combustion safety inspections across Southwest Michigan. Our maintenance plan is free to join and includes two seasonal tune-ups at $79 each with a reminder postcard, so the inspection does not get forgotten.
CO poisoning is regularly mistaken for the flu, which is part of what makes it dangerous in winter. Headache, dizziness, weakness, nausea, shortness of breath, confusion, blurred vision.
What distinguishes it is the pattern: symptoms that improve when you leave the house and return when you come back, or several people and pets in the household feeling unwell at once. If you notice that, get out and call for help.
No. It has no odor at all. The rotten-egg smell people associate with gas is an additive in natural gas itself, not carbon monoxide. A CO hazard can exist with no smell whatsoever, which is why furnace smells and CO are two separate checks.
Generally every five to ten years depending on the model. Check the manufacture date on the unit and follow the manufacturer’s stated interval. Replacing the battery does not reset an aged sensor.
Not reliably. There is no consistent smell, sound or symptom that identifies one. It is found by visual and instrument inspection, and it is one of the findings that stops a tune-up and starts a furnace replacement conversation.
Schedule service online or get in touch at (269) 965-1627 today! Prefer to pick a time yourself? Book your visit online.
9000 M-66 South • East Leroy, MI 49051
(269) 965-1627
Monday - Friday: 8:00am - 5:00pm
