Carbon Monoxide Safety: What Houston Homeowners Should Know About Their Furnace

Why your furnace makes carbon monoxide — and why that matters

Houston winters are short and mild, so it’s easy to forget about the furnace in the garage or closet until the first real cold snap hits. But here’s what many homeowners don’t realize: every gas furnace produces carbon monoxide — a colorless, odorless gas — each time it runs. Normally, it vents safely outside. When something goes wrong, like a cracked heat exchanger, a blocked flue, or dirty burners, that gas can end up in your home instead. Fall is the right time to make sure your furnace is venting the way it should, before heating season asks it to work every day.

Where carbon monoxide comes from in a furnace

Gas furnaces burn natural gas to make heat, and carbon monoxide is a normal byproduct of that combustion. In a healthy system, the heat exchanger keeps combustion gases separate from your indoor air, and the flue pipe carries them outside. Problems start when the heat exchanger cracks after years of heating and cooling cycles, when the flue gets blocked by nests, debris, or rust, or when burners get dirty and the flame burns poorly. Any of these can let CO slip into the air you breathe.

Warning signs your furnace may have a CO problem

• Soot or dark staining around the furnace or vent pipe
• A burner flame that looks yellow or flickering instead of steady blue — many furnaces have a small sight glass, so take a quick look
• Rust or water streaks on the flue pipe
• The furnace running while the house never quite warms up
• Physical symptoms when the heat runs: headache, dizziness, nausea, weakness, or confusion — CO poisoning often feels like the flu, without the fever

Remember: carbon monoxide itself has no smell. If you smell rotten eggs, that’s the odorant added to natural gas — leave the house and call your gas utility.

Three checks every Houston homeowner can do this fall

1. Put CO detectors where they belong. One on every level of the home and one outside each sleeping area. Test them monthly, and replace batteries on schedule — most detectors need a full replacement every 7–10 years (check the date stamped on the back).

2. Look at the flame and the flue. A healthy gas burner flame is mostly blue with small yellow tips. If you see a lot of yellow, visible soot, or a flue pipe that looks blocked or damaged, don’t try to fix it yourself — call a professional.

3. Keep the area clear and the filter fresh. Furnaces need combustion air, so don’t stack boxes against the unit. Change the filter on schedule, too — restricted airflow makes the system work harder and can contribute to overheating and cracks over time.

When only a professional should take over

Detectors and visual checks are homeowner tools — they don’t replace an inspection. A technician with a combustion analyzer can measure CO levels in the flue and check the heat exchanger for cracks you can’t see. Call a pro right away if a CO detector alarms (get everyone out first, then call 911 from outside), if you see soot or a yellow flame, or if anyone feels flu-like symptoms when the heat is on. And even if everything looks fine, schedule a heating tune-up each fall: a cracked heat exchanger caught early is a repair; caught late, it’s a replacement.

A few minutes now, peace of mind all winter

Your furnace only runs a few months a year in Houston, but those months matter. Test your detectors, glance at the flame, make sure the flue is clear, and get one professional tune-up a year — that’s all it takes to keep carbon monoxide where it belongs: outside. If your furnace hasn’t been serviced in over a year, or something about it just doesn’t look right, we’re here to help.

Heating Tune-Up Special: $120 for the first system, $80 for each additional. Call (346) 346-1177 or book your tune-up online.