Carbon Monoxide and Your Furnace: Warning Signs Every Spokane Homeowner Should Know

Every winter, furnaces become the single biggest source of carbon monoxide exposure inside homes. It’s not because furnaces are inherently dangerous – it’s because a small, easily-missed malfunction can turn a normal heating system into a source of an invisible, odorless gas that’s genuinely life-threatening. Spokane’s long, cold heating season means local furnaces run harder and longer than in most parts of the country, which makes this a bigger local risk than people often realize.

This guide covers how carbon monoxide actually gets into a home from a furnace, the warning signs -both in the house and in your own body – and what a proper inspection actually checks.

How a Furnace Produces Carbon Monoxide in the First Place

Gas furnaces burn fuel to create heat, and that combustion process naturally produces carbon monoxide as a byproduct. In a properly functioning system, that gas is contained and vented safely outside through the exhaust system. The danger appears when something in that containment or venting process fails:

• A cracked or corroded heat exchanger, which allows combustion gases to mix with the air actually being blown through your ducts
• A blocked or damaged exhaust vent, which pushes combustion byproducts back into the home instead of outside
• Incomplete combustion from a dirty burner or bad air-to-fuel mixture, which produces more carbon monoxide than normal
• A failed or disconnected flue pipe, often from age, rust, or accidental damage during other work near the unit

Any one of these can turn a routine heating cycle into a carbon monoxide source, often without any obvious sign from the furnace itself.

Warning Signs in the Home

• A yellow or flickering burner flame instead of the normal steady blue
• Soot or dark staining around the furnace, vents, or nearby walls
• Excess moisture on windows near the furnace room, especially without an obvious source
• A stale, slightly metallic or “hot” smell near the unit
• Rust on flue pipes or vent connections
• A carbon monoxide detector that’s chirping, alarming, or reading elevated levels – never something to dismiss as a false alarm without checking

Warning Signs in Your Body

Because carbon monoxide has no smell or color, physical symptoms are often the first real warning:

• Headaches that appear or worsen specifically while at home, and ease up when you leave
• Dizziness, nausea, or confusion without another clear cause
• Unusual fatigue that multiple people in the household notice at the same time
• Flu-like symptoms during the heating season with no actual fever

If multiple people in the home experience these symptoms simultaneously, especially in a pattern tied to being indoors, that’s a serious signal to leave the house, get fresh air, and have the furnace professionally checked before running it again.

What a Proper Carbon Monoxide Inspection Actually Checks

A real inspection goes well beyond just placing a detector near the unit. A thorough carbon monoxide testing visit typically includes:

• Combustion analysis to measure actual CO output during operation, not just a pass/fail check
• Heat exchanger inspection for hairline cracks, which are often invisible without specialized equipment
• Venting and flue inspection to confirm exhaust gases are actually leaving the home
• Verification that carbon monoxide detection devices in the home are correctly placed and functioning – hardwired detectors specifically need to be installed on a proper dedicated circuit, which is electrical work best handled by a licensed electrician like RF Electrician Inc. rather than tied into an existing circuit as an afterthought
• A check of gas pressure and burner combustion quality, since incomplete combustion is one of the most common root causes

Why This Matters More in Spokane Specifically

Spokane’s heating season is long enough that furnaces here accumulate significantly more total run-hours per year than in milder climates – which means more wear on heat exchangers, burners, and venting systems over the same number of years compared to a furnace in a warmer region. A furnace that would show minor, harmless wear elsewhere can develop a genuine crack or venting issue faster here simply from the volume of use. This is part of why annual inspection timing matters more locally than the general “check it every year or two” advice that gets repeated nationally.

What to Do If You Suspect a Problem

1. Get everyone out of the house and into fresh air immediately if a detector is alarming or symptoms appear suddenly in multiple people.
2. Don’t attempt to inspect the furnace yourself. Heat exchanger cracks and venting problems require specialized equipment to detect reliably.
3. Call for emergency service rather than waiting for a routine appointment if you have any reason to suspect active carbon monoxide exposure.
4. Don’t run the furnace again until it’s been professionally cleared.
5. Replace CO detector batteries at the same time you change your furnace filter – an easy habit that closes one of the most common gaps in home detection.

Carbon monoxide risk from a furnace isn’t rare or exotic – it’s a routine wear-and-tear issue that becomes dangerous specifically because it’s invisible until symptoms or a detector catch it. Annual inspection, working detectors, and knowing the early warning signs above are what keep a normal heating system safe through a full Spokane winter.