Carbon Monoxide Safety for Gas Furnaces in Comal County Homes

Carbon monoxide (CO) is an odorless, colorless gas produced when fuel burns incompletely. A properly operating gas furnace produces some CO in normal combustion and vents it safely outdoors through the flue — that's the design working as intended. The safety risk appears when something interrupts that design: a cracked heat exchanger, a blocked flue, or a venting failure that lets combustion gases enter the air your family breathes. This briefing covers where the risk actually comes from, the warning signs, and the two layers of protection every gas-heated home in Comal County should have.

Where does furnace CO risk actually come from?

• A cracked heat exchanger — the heat exchanger is the sealed metal barrier that keeps combustion gases separate from the household air blowing across it. Years of heating-and-cooling stress can crack it — a process accelerated by problems like short-cycling, which multiplies the thermal stress cycles the metal endures.

• Blocked or corroded flue pipes — bird and squirrel nests, wasp activity, debris, or rust that keeps exhaust from leaving the house the way it's supposed to.

• Backdrafting — a furnace closet starved of combustion air can pull exhaust back down the flue, especially in tightly sealed homes or when large exhaust fans are running.

• Aging, dirty burners — burners that fire dirty burn incomplete, producing more CO in the first place, before venting even enters the picture.

What are the warning signs?

CO exposure symptoms look like the flu without the fever: headaches, dizziness, nausea, and fatigue — classically improving when you leave the house and returning when you're back. If multiple family members feel off at the same time during heating season, treat that pattern seriously. Physical clues around the furnace itself include heavy soot or rust streaking, a burner flame that's yellow and wavering instead of steady blue, excessive moisture on windows near the unit, and a pilot light that won't stay lit. Any of these during heating season deserves a same-day professional look — not a wait-and-see.

What should every gas-heated home have?

CO alarms on every level of the home and outside each sleeping area — that's the standard national fire-safety guidance (NFPA 720-style placement), and detectors are cheap insurance against an invisible problem. Test them when the clocks change, replace batteries on the same schedule, and replace the units themselves by their stamped expiration date — CO sensors wear out even if the test button still beeps. If an alarm ever sounds, get everyone (pets included) outside into fresh air first, then call for help from there. Don't re-enter to hunt for the source; that's what professionals with calibrated meters are for.

How does maintenance fit into CO safety?

Detectors are the last line of defense. The first line is the annual heating inspection, because you can't see a heat exchanger crack from the hallway — it takes opening the unit and inspecting the exchanger, burners, and venting directly. That's why our fall heating tune-ups include carbon monoxide hazard checks as a standard line item: burner condition, heat exchanger inspection, flue draft verification, and safety-control testing. Schedule furnace maintenance in New Braunfels before the first cold front, or let the Team HomeFront Club handle the calendar for you — the pre-winter heating visit is built into membership from $15.75/month, alongside priority service and 15% off repairs.

What if your furnace is the problem?

A cracked heat exchanger on an aging furnace usually means a replacement conversation, not a patch — the part is the core of the furnace, and on a 15-to-20-year-old unit the repair math rarely works. If the diagnosis lands there, our repair-or-replace decision framework for Texas HVAC walks you through the decision with no pressure, and our heating replacement team in New Braunfels quotes upfront and in writing. We give straight answers either way — protecting your family's safety is the mission, and it outranks the invoice.