As the temperatures drop and heating systems roar to life, most homeowners shift their focus to warmth and comfort. But there’s a hidden danger that every household with a furnace or gas-powered heater must be aware of—carbon monoxide (CO). Known as the “silent killer,” carbon monoxide is a colorless, odorless, and tasteless gas that can be deadly in high concentrations. One of the most common sources? A faulty or poorly maintained heating system.
If your furnace, boiler, or other fuel-burning appliance is operating without proper monitoring or maintenance, you could be putting your family at serious risk. In this post, we’ll explain what carbon monoxide is, why testing is essential for your heating system, and how to protect your home from CO poisoning.
What Is Carbon Monoxide and Why Is It Dangerous?
Carbon monoxide is produced when fossil fuels like natural gas, oil, wood, or coal do not burn completely. It can be released from:
Gas furnaces
Fireplaces (gas or wood-burning)
Gas stoves or ovens
Boilers and water heaters
Generators and other gas-powered tools
Car engines (in attached garages)
When inhaled, carbon monoxide binds to the hemoglobin in your blood, preventing oxygen from being delivered to your body’s vital organs. Prolonged exposure can lead to:
Headaches
Dizziness
Nausea
Confusion
Chest pain
Loss of consciousness
Death
The real danger? You won’t see it, smell it, or taste it—which is why testing and detection are absolutely critical.
Why Your Heating System Is a Common CO Risk
Furnaces and other heating equipment that burn fuel produce a small amount of carbon monoxide as a byproduct of combustion. Under normal, well-ventilated circumstances, CO is vented safely outdoors. However, malfunctions and poor maintenance can lead to:
Cracked heat exchangers
Blocked or leaky flue pipes
Incomplete combustion
Poor airflow or ventilation
These issues may go unnoticed for months—especially during winter when doors and windows are closed. Without a working CO detector or regular testing, you could be unknowingly breathing toxic air.
Signs Your Heating System May Be Producing Carbon Monoxide
While carbon monoxide is undetectable to human senses, there are still some signs your heating system might be leaking CO:
Soot or rust around the furnace
A yellow or flickering burner flame (instead of blue)
Excess condensation on windows near the furnace
Pilot light frequently going out
Stale or stuffy air in your home
Family members experiencing flu-like symptoms at home but improving when away
If you notice any of these warning signs, shut off your system immediately, ventilate your home, and call a professional HVAC technician.
What Is Carbon Monoxide Testing?
Carbon monoxide testing involves checking for the presence of CO gas in your home, particularly near fuel-burning appliances and inside air ducts. It includes:
✅ Using Electronic Detectors
HVAC technicians use handheld CO detectors to measure CO concentration in parts per million (ppm).
A reading above 9 ppm is considered potentially unsafe for prolonged exposure.
Immediate danger exists at 70 ppm or higher.
✅ Inspecting the Furnace and Heat Exchanger
Technicians inspect the condition of your heat exchanger—a crack can allow combustion gases, including CO, to mix with indoor air.
✅ Testing Flue and Ventilation
CO testing includes ensuring your flue pipe is clear and functioning, allowing safe ventilation to the outside.
✅ Checking Burner Operation
Improper gas-to-air ratio can cause incomplete combustion. Your technician will adjust and test burner flames for proper performance.
Benefits of Regular Carbon Monoxide Testing
✅ 1. Protects Your Family’s Health
Early symptoms of CO poisoning are often mistaken for the flu or common cold. Regular testing helps you detect CO leaks before they reach dangerous levels, keeping your family safe and healthy.
✅ 2. Helps Catch Furnace Problems Early
CO leaks often result from cracks or damage within the heating system. By detecting the leak, you may also uncover a bigger mechanical issue that needs repair—before it causes total system failure.
✅ 3. Ensures Proper Ventilation
Sometimes the problem isn’t the furnace itself, but poor ventilation or backdrafting that allows CO to accumulate inside the home. Testing helps identify and resolve airflow and venting issues.
✅ 4. Maintains Manufacturer Warranties
Some heating system warranties require regular professional inspections. CO testing as part of annual maintenance can help you stay compliant and avoid losing coverage.
How Often Should Carbon Monoxide Testing Be Done?
At a minimum, your heating system should be professionally inspected and tested for carbon monoxide once a year, ideally in the fall before heating season begins.
However, additional testing is recommended if:
Your CO alarm goes off
Your heating system is over 10 years old
You recently had repairs or renovations near your HVAC system
You notice unusual odors, soot, or system behavior
Installing Carbon Monoxide Detectors Is NOT Enough
While having CO detectors in your home is essential, they are not a substitute for professional testing. Detectors:
May not catch low-level leaks
Can have dead or missing batteries
Only sound an alarm after dangerous levels are present
They’re a last line of defense—not a proactive solution. Testing gives you peace of mind by ensuring your home is safe before an alarm ever needs to sound.
How South Nashville Heating & Cooling Can Help
At South Nashville Heating & Cooling, we take indoor air safety seriously. That’s why our seasonal maintenance includes comprehensive carbon monoxide testing for gas furnaces, boilers, and heating appliances.
Our certified technicians will:
Inspect your furnace and heat exchanger
Check for flue obstructions and leaks
Test for carbon monoxide at key points in your home
Tune your system for efficient and safe operation
Provide maintenance or repairs if needed
With over 20 years of trusted service in Middle Tennessee, we’re committed to keeping your family safe, comfortable, and informed.
Don’t Take Chances This Winter—Schedule a CO Test Today
Carbon monoxide poisoning is preventable—but only if you take the right steps. Whether your system is brand new or has been running for years, regular carbon monoxide testing is one of the smartest things you can do for your home and your family.
👉 Fill out the form below to schedule your seasonal HVAC tune-up and CO safety inspection with South Nashville Heating & Cooling. Let’s make sure your home is warm, efficient, and above all—safe.
