When you turn on your heat for the first time and notice a smell coming from the vents, it is easy to worry that something is wrong. Many Central Iowa homeowners ask the same question each winter: “Is this smell normal, or could it be something dangerous?”
Carbon monoxide is one of the most serious safety concerns connected to gas heating systems. This colorless, odorless gas is created when fuel burns inside a furnace. Normally those combustion gases leave your home safely through the venting system. When something disrupts that process, carbon monoxide can leak into indoor air.
Understanding the signs of carbon monoxide from a furnace can help you catch problems early and protect your household. In this guide, we explain what warning signs to look for, how to perform a basic HVAC safety check, and when it is time to schedule a professional furnace inspection.
Quick Answer: How Do You Check Your Furnace for Carbon Monoxide?
You can check your furnace for signs of carbon monoxide from a furnace by looking for several warning indicators.
Common warning signs include:
- A yellow pilot light instead of a blue burner flame
- Soot around the furnace or visible furnace rust
- A pilot light flickering or unstable burner flame
- Blocked or damaged furnace exhaust or flue pipes
- Physical symptoms such as headache at home, nausea, or feeling dizzy from furnace operation
A working carbon monoxide detector or CO alarm is essential for safety. If warning signs appear, schedule a professional furnace inspection right away.
Why Carbon Monoxide Issues Can Occur in Central Iowa
Homes across Des Moines, West Des Moines, Ankeny, Urbandale, Altoona, Clive, and Waukee rely heavily on gas furnaces through long winter seasons. When outdoor temperatures drop well below freezing, heating systems often run for extended periods each day.
This heavy use can increase wear on burners, heat exchangers, and venting systems. Iowa homes are also tightly sealed during winter to retain heat, which means indoor air quality problems can develop faster if combustion gases leak.
Because furnaces operate for months at a time, identifying signs of carbon monoxide from a furnace early is critical for protecting your home.
1. Check the Furnace Flame Color
One of the easiest safety checks is observing the burner flame.
A healthy furnace should produce a steady blue burner flame. Blue flames indicate proper combustion.
Warning signs include:
- A yellow pilot light
- Orange or flickering flames
- Pilot light flickering repeatedly
- Flames that appear unstable or irregular
A yellow flame may indicate incomplete combustion, which increases the risk of carbon monoxide production.
2. Look for Soot or Rust Around the Furnace
Visible buildup around your furnace often signals combustion issues.
During a basic furnace inspection, look for:
- Soot around furnace burners
- Black residue near burner openings
- Furnace rust or corrosion
- Discoloration around the vent pipe
Soot buildup is often linked to airflow restrictions or burner problems and can be one of the early gas leak signs associated with carbon monoxide risk.
3. Inspect the Furnace Venting System
Your furnace depends on proper airflow to remove combustion gases safely.
A quick flue pipe inspection should include checking for:
- Loose or disconnected vent pipes
- Rust or corrosion on venting components
- Visible cracks in the vent pipe
- Debris or animal nests causing venting pipe blockage
Blocked vents can cause combustion gases to backdraft into the home instead of exiting through the chimney draft.
4. Watch for Signs of a Cracked Heat Exchanger
A cracked heat exchanger is one of the most serious furnace safety issues.
The heat exchanger separates combustion gases from the air circulating through your forced air system. If it cracks, dangerous gases can enter your home.
Possible warning signs include:
- Unusual furnace odors
- Increased soot buildup
- Pilot light flickering or unstable flames
- Excessive furnace rust
- Frequent system shutdowns
In severe cases, structural damage such as a cracked firebox or heat exchanger leak may allow combustion gases to escape into indoor air.
These problems require inspection by an experienced HVAC professional.
5. Pay Attention to Physical Symptoms
Sometimes the first signs of carbon monoxide from a furnace appear through physical symptoms rather than visible furnace problems.
Common carbon monoxide symptoms include:
- Headache at home
- Feeling dizzy from furnace operation
- Nausea or fatigue
- Shortness of breath
- Confusion or dizziness
If multiple people in the home experience symptoms at the same time, it may indicate carbon monoxide poisoning.
Leave the home immediately and contact emergency services.
6. Test Your Carbon Monoxide Detector
Every home with gas appliances should have a working carbon monoxide detector or CO alarm.
Install detectors:
- Near bedrooms
- On every floor of the home
- Close to furnace or boiler equipment
Modern air quality monitors can also detect dangerous gases and alert homeowners early.
Test your detectors monthly and replace batteries regularly.
For additional safety information, the CDC provides guidance on carbon monoxide exposure and prevention.
Why Furnace Maintenance Helps Prevent Carbon Monoxide
Many furnace safety issues develop gradually due to neglected equipment.
Routine furnace maintenance helps identify problems such as:
- Cracked heat exchangers
- Worn burner components
- Blocked heating system vents
- Airflow restrictions
- Improper combustion
A professional HVAC safety check includes inspecting burner performance, checking exhaust systems, and testing combustion gases.
Annual maintenance is one of the most effective ways to prevent carbon monoxide problems.
Frequently Asked Questions About Furnace Carbon Monoxide
Can a furnace produce carbon monoxide even if it is still running?
Yes. A furnace can continue heating your home while releasing carbon monoxide if there is a cracked heat exchanger or venting issue.
What does carbon monoxide from a furnace smell like?
Carbon monoxide has no smell, color, or taste. That is why carbon monoxide detectors and CO alarms are essential.
How often should a furnace be inspected for safety?
Homeowners should visually check their furnace at the beginning of each heating season. A professional furnace inspection should be performed once per year.
Can blocked heating vents cause carbon monoxide problems?
Yes. Restricted heating system vents or flue pipes can prevent combustion gases from exiting the home properly.
Are boilers also at risk for carbon monoxide issues?
Yes. Boiler safety inspections are important because boilers also produce combustion gases that must vent safely outside.
Stay Safe With Regular Furnace Inspections
Carbon monoxide is one of the most serious safety risks related to heating systems. Because the gas cannot be seen or smelled, early detection is critical.
Learning to recognize the signs of carbon monoxide from a furnace can help you respond quickly and protect your family.
Checking burner flame color, inspecting the venting system, and maintaining working carbon monoxide detectors are simple but important safety steps. Annual furnace inspections remain the most reliable way to keep your heating system operating safely.
Schedule a Furnace Safety Inspection in Des Moines
If you notice warning signs such as a yellow pilot light, soot around the furnace, or symptoms like headaches or dizziness at home, it is best to have your system inspected.
Lenz Heating & Cooling helps homeowners across Des Moines, West Des Moines, Ankeny, Urbandale, Altoona, Clive, and Waukee keep their heating systems operating safely and efficiently.
Call (515) 225-6446 or schedule a furnace inspection with Lenz Heating & Cooling today to keep your home warm, comfortable, and safe.
