Carbon monoxide (CO) is called the invisible killer for a reason — it’s colorless, odorless, and tasteless, yet responsible for hundreds of preventable deaths each year in the United States.
As temperatures drop and furnaces, fireplaces, and space heaters kick into gear across Pennsylvania, understanding how CO can infiltrate your home — and how to prevent it — is critical for every property owner.
Here’s what Hill Property Inspections recommends you know and check before winter is in full swing.
1. What Exactly Is Carbon Monoxide?
Carbon monoxide is a byproduct of incomplete combustion — meaning when fuels such as natural gas, propane, oil, coal, or wood don’t burn completely.
Every gas furnace, boiler, water heater, and fireplace produces some amount of CO, but in a properly vented system, those gases are safely carried outdoors. Trouble starts when vents, flues, or burners malfunction, allowing CO to leak indoors.
Pro Tip: Even small CO leaks can build up quickly in today’s tightly sealed homes with limited ventilation.
2. The Most Common Sources in Homes
Many homeowners assume CO only comes from furnaces — but there are several common culprits:
• Gas furnaces and boilers (cracked heat exchangers, blocked flues)
• Water heaters and gas dryers
• Fireplaces and wood-burning stoves
• Gas ranges or ovens (especially if used improperly for supplemental heat)
• Attached garages (vehicle exhaust seeping through door gaps or shared framing cavities)
• Portable generators or space heaters used indoors
In multi-unit or mixed-use buildings, CO can even travel between units through shared chases or return air systems.
3. Warning Signs of Potential CO Problems
Because CO itself can’t be seen or smelled, pay attention to indirect warning signs of combustion or ventilation issues:
• Yellow or flickering burner flames (instead of steady blue)
• Soot or scorch marks around furnace panels or vent connections
• Persistent condensation on windows or cold walls near heating appliances
• Unexplained headaches, dizziness, or nausea among occupants
• Smoke smell or backdrafting from fireplaces or water heaters
If these symptoms appear, leave the building immediately, call 911, and have the property evaluated before returning.
4. How to Prevent CO Buildup
Preventing carbon monoxide issues starts with proper maintenance and awareness. Follow these steps every heating season:
1. Schedule an annual furnace or boiler service — including a combustion efficiency and draft test.
2. Inspect all vent pipes for rust, gaps, or loose fittings, especially near elbows or joints.
3. Check chimney liners in older homes; deterioration or blockage can trap exhaust gases.
4. Never use ovens, stoves, or grills for heat.
5. Keep flues clear of bird nests, leaves, and snow.
6. Maintain adequate combustion air. In sealed basements or mechanical rooms, add venting or louvered doors.
Pro Tip: Negative pressure from exhaust fans or tight building envelopes can reverse flue draft — a common cause of hidden CO migration.
5. Detector Placement and Testing
Every home should have at least one carbon monoxide detector per floor, ideally near bedrooms and adjacent to mechanical rooms.
• Avoid placing detectors directly above fuel-burning appliances, which can cause false readings.
• Replace detectors every 5–7 years, or per manufacturer’s instructions.
• Test monthly and replace batteries each daylight saving change.
• Interconnected or smart detectors are best for multi-level or multi-unit properties.
6. Inspections & Professional Testing
A professional home or commercial inspection can reveal conditions that promote CO buildup — including improper vent pitch, disconnected flues, blocked chimneys, or shared ventilation paths between appliances.
At Hill Property Inspections, our team uses combustion analyzers and infrared thermography to spot exhaust leaks, confirm vent integrity, and verify proper airflow in basements and mechanical rooms.
We also check whether detectors are properly placed — something too many property owners overlook until an emergency occurs.
Final Thoughts
Carbon monoxide is silent, but the risks are very real. A few minutes of maintenance and an annual inspection can protect your family, tenants, or employees from one of the most preventable household hazards.
Ensure your home and family are safe from carbon monoxide and other unseen hazards this season by scheduling a thorough inspection or walk-through consultation:
📞 1-833-HILL-PRO
Hill Property Inspections, LLC is a full-service residential and commercial inspection firm based in the Johnstown, PA area.
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