Is Your Furnace a Carbon Monoxide Risk? A Homeowner’s Guide to HVAC Safety.

Carbon monoxide (CO) is among the most dangerous risks a homeowner faces because it cannot be seen, smelled, or tasted. This invisible gas may originate from fuel-burning furnaces that are not functioning correctly, and without proper precautions, it can build up indoors.

This guide aims to help homeowners understand how carbon monoxide can become a threat through their heating system, what steps they can take to stay safe, and how professional HVAC service plays a vital role in preventing danger.

At A. Fagundes Plumbing & Heating Inc., our team provides safe installation of HVAC systems. Contact us at (978) 350-5522 to schedule a service.

What Is Carbon Monoxide and Why Is It Dangerous?

Carbon monoxide results from incomplete combustion. When natural gas, propane, or oil do not burn thoroughly, they can release CO into the air around us. Because the gas is colorless and odorless, it can accumulate unnoticed until symptoms develop or detectors alert us.

Health risks linked to CO exposure are serious. Once inhaled, carbon monoxide binds tightly to hemoglobin in the blood, decreasing the body’s capacity to carry oxygen.

Even low concentrations can lead to symptoms such as:

• Headaches
• Dizziness
• Nausea

Higher levels of exposure can lead to confusion, loss of consciousness, and, in the most serious cases, death. That’s why carbon monoxide is often called a silent killer—it impacts the body before many people even realize it’s there.

How Your HVAC System Can Contribute to Carbon Monoxide Risks

Although your furnace is built to vent combustion gases outdoors safely, malfunctions or improper installation can cause a dangerous situation.

Common issues that can allow carbon monoxide to leak into living spaces include:

• Cracked heat exchangers
• Blocked flues
• Improperly calibrated burners

Limited airflow or faulty venting can sometimes reduce combustion efficiency, leading to higher CO levels.

Not all HVAC components produce carbon monoxide. Air conditioners, for instance, operate on electricity and don't generate combustion gases. However, if a furnace or gas-powered heating system develops a leak, the ductwork and blower connected to your AC can circulate carbon monoxide throughout your home. That’s why proper installation, regular maintenance, and attention to ventilation are essential for any fuel-burning system.

Still, even with a properly installed and maintained furnace, your last line of defense against carbon monoxide is a working CO detector. These devices continuously monitor your home's air for carbon monoxide and trigger an alarm before levels become dangerous.

Steps You Can Take for Carbon Monoxide Safety

You have a crucial role in preventing carbon monoxide incidents. Installing CO detectors is one of the most effective ways to protect your home.

While installing or replacing CO detectors is often a simple DIY task, hiring a professional to inspect and install them provides added peace of mind. Yes, your out-of-pocket cost will be higher. However, a licensed HVAC or electrical technician can detect communication issues between your furnace, venting, and detectors that most homeowners would never notice. These minor problems, such as improper placement, poor wiring on interconnected systems, or venting design flaws, can make the difference between early detection and a disaster.

For maximum safety, be sure to:

• Install detectors on every level of your home, especially near bedrooms or sleeping areas. Keep them away from fuel-burning appliances to prevent false alarms. For combination smoke and CO detectors, carefully follow the manufacturer’s height and spacing guidelines.
• Test them monthly. This simple check verifies that the battery and internal circuits are working properly. It also acts as a regular practice, helping everyone in your household become familiar with the alarm’s sound and reminding them of your family's escape plan.
• Replace batteries following the manufacturer’s instructions. Typically, change them every six months. A good habit is to check them during daylight saving time changes in spring and fall. A detector with a weak battery can fail silently, leaving your home unprotected.
• Replace the entire detector unit when it reaches the end of its service life. Most units last between 5 and 10 years, depending on the manufacturer. Each detector has a label with either a manufacturing date or an expiration date printed on the back. When it hits that date, the sensor’s ability to detect CO diminishes—even if the test button still works—so it needs to be replaced. The good news is that replacement CO detectors are quite affordable. Typically, a basic plug-in or battery-powered detector costs between $25 and $50, while smart or interconnected models that connect with mobile apps or other safety systems can cost from $75 to $150. For most households, it’s a small expense for potentially life-saving protection.

Knowing the symptoms of CO poisoning can save lives. Headaches, dizziness, nausea, shortness of breath, and confusion are early warning signs. If these symptoms occur suddenly, especially during the heating season, it’s important to leave the home immediately and call emergency services.

Ventilation is also essential. Avoid using fuel-burning appliances indoors, such as charcoal grills or portable gas heaters, unless they are designed and rated for indoor use. During winter, ensure all vents, chimneys, and flues are clear of debris, snow, or ice.

Finally, schedule regular furnace maintenance. Annual checkups can identify minor issues before they become hazards. During a professional inspection, HVAC technicians will test combustion efficiency, examine venting systems, and confirm that safety controls function correctly. This proactive step offers peace of mind that your system is operating as it should.

How Professional HVAC Service Supports Your Home's Safety

Proper installation is the most crucial factor in lowering the risk of carbon monoxide from a furnace. At A. Fagundes Plumbing & Heating Inc., installing a heating system involves more than just placing equipment in your home. Each installation is carefully done so that the system is correctly sized, venting is tightly sealed, and combustion byproducts are directed outside. This approach helps prevent conditions that could cause CO to leak indoors.

Routine service is just as important. During a tune-up, our technicians perform thorough safety inspections focused on the parts most likely to cause carbon monoxide hazards.

These checks include:

• Visually inspecting the heat exchanger for cracks
• Reviewing the flame pattern for signs of incomplete combustion
• Verifying that venting systems are free of blockages

Our HVAC technicians are NATE-certified, showcasing advanced installation skills and knowledge of system performance. We regularly update our training on safety standards and new technologies, using that knowledge to spot potential issues a homeowner might miss.

Although we don’t install or service carbon monoxide detectors ourselves, our work focuses on preventing CO problems at their source by properly installing HVAC systems so they operate safely.

Safeguard Your Home Against Carbon Monoxide Risks

Carbon monoxide safety requires vigilance, but homeowners don’t have to handle it alone. Key steps include understanding how CO is produced, recognizing symptoms, and installing detectors. Combining these precautions with professional HVAC service helps protect against this silent danger.