Carbon monoxide (CO) kills over 400 Americans every year, and furnaces are one of the leading sources. Colorado homeowners face greater risk because gas furnaces burn differently at high altitude, and improperly adjusted systems produce more CO. Here's what you need to know.
Why Colorado Homes Face Higher CO Risk
At Denver's 5,280-foot elevation, there's about 17% less oxygen in the air than at sea level. Gas furnaces need their gas valve orifice and burner adjusted for altitude — if this isn't done correctly (or wasn't done at all), the furnace produces excess carbon monoxide. Many furnaces installed by unlicensed contractors or DIY homeowners lack proper altitude adjustments.
Warning Signs of CO from Your Furnace
- Yellow or orange pilot light instead of blue (indicates incomplete combustion)
- Soot or scorch marks around the furnace or vents
- Excessive moisture on windows near the furnace
- Symptoms in your family: headaches, nausea, dizziness, confusion that improve when you leave the house
- Stale or stuffy air even with the furnace running
Where to Place CO Detectors
- One on every level of your home
- Within 15 feet of every bedroom
- Near (but not directly above) gas appliances including the furnace, water heater, and stove
- Replace batteries every 6 months and replace the detector itself every 5–7 years
How Annual Inspections Prevent CO Leaks
A proper furnace inspection includes combustion analysis (measuring CO levels in the flue), heat exchanger inspection for cracks, and verification that altitude adjustments are correct. A cracked heat exchanger is the most dangerous furnace problem — it allows combustion gases to mix with your home's air supply. This is why we include combustion testing on every furnace inspection.