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Natural Gas Furnace Hazards | Furnace Tune-Up Tips

September was National Furnace Tune-Up Month! Did you schedule your furnace maintenance appointment yet? If not, you may change your mind by the end of this article.

Home heating is our most expensive energy cost for the year (around $1000), it’s well worth the effort to reduce this number. Schedule your annual furnace tune-up in the fall and watch your heating bills go down in the winter.

In addition to increasing energy efficiency in your home, an annual furnace check-up by a professional will also reduce your risk of fire, carbon monoxide poisoning, and other dangers associated with gas furnaces. Most home fires occur during the winter months and many dangers can be attributed to the natural gas furnace or home heating system in your home.


Despite being more energy-efficient than other fuels and releasing less combustion by-products, there are some safety concerns associated with natural gas furnaces that you should be aware of.

Carbon Monoxide

All fuel-burning appliances emit dangerous by-products such as carbon monoxide (CO) and methane. In order to detect the lethal gas, you need to have CO detectors installed throughout your home. As a rule of thumb, check your CO detectors once a month, change batteries every 6 months or so, and replace the units entirely after about 5-7 years.

If your furnace is running cleanly and efficiently, there won’t be that much carbon monoxide produced and is carried away through your venting. If, on the other hand, your furnace is dirty and running inefficiently, lots of CO will be produced. Even very small amounts of CO can cause illness and even death. When you have a professional diagnose your system, make sure they check your ventilation system and CO detectors!

Signs of Carbon Monoxide

Yellow Burner Flamer – be on the lookout for a yellow, orange, or red burner flame. Your flame should be blue with a small yellow tip in the primary cone. If your flame color is any color other than blue, call a professional right away. Your furnace could be producing dangerous levels of carbon monoxide

Strange Odor – if you notice a strong, pungent odor when your furnace is running, call a professional to diagnose the situation. Make sure your CO detectors are working.

CO Symptoms – if you or anyone in your household is experiencing the common signs of CO poisoning – nausea, drowsiness, flu-like – seek medical attention immediately and do not use furnace again until it has been inspected and serviced by a professional.

Other CO Signs Include:

  • Soot and rust around your furnace
  • An absence of an upward draft in your chimney
  • Excess moisture on your windows, walls and other cold places
  • Excessive rusting on flue pipes, pipe connections, and appliance jacks
  • Water leaking from the base of the chimney, vent or flue pipe
  • Rust on the visible portion of the vent pipe

If you notice any of these signs, you may have an issue with your gas furnace or ventilation system; make sure you test your CO detectors and call a professional immediately.

Here are some tips to prevent carbon monoxide from forming in your home (via Allstate):

  • Make certain that appliances are properly installed without any gas leaks.
  • Never self-service fuel-burning appliances without the proper knowledge and tools.
  • Install an alarm in the hallway outside the bedrooms in each area of the home.
  • Never use a generator or fuel-burning camping equipment in your home or in an enclosed space.
  • Never burn charcoal in an enclosed area, even with the windows open.
  • Never idle a car in a garage, even with the garage doors open.
  • Never heat your home with gas appliances such as your oven or clothes dryer.

Electrical Shock/Fires

There are many electrical components in your heating system’s structure. If you are thinking of doing any kind of furnace inspection or repairs yourself, it’s extremely important that you shut off power at the main power source, normally your breaker box. Opening up your gas furnace without first turning off power could result in an electrical shock.

It is also important that you have a professional electrician install AFCI breakers for your home. These electrical safety devices detect dangerous electrical faults in your system and shuts off power automatically. Over 30,000 home fires are directly attributable to arcing faults every year.

Fire & Explosion

If you smell gas, you may have a gas leak. Do NOT ignite anything or turn any electrical devices, including lights, on or off! Here are the steps to follow if you smell gas:

1. Turn off your gas supply at the main valve, located near your gas meter.

How to turn off a gas valve

2. Leave immediately and call the fire department or gas company with a cell phone or from your neighbor’s house.

3. Do not reenter your home until the fire department and/or gas company has deemed it safe to do so. Leave it to the professionals to turn your gas back on and make sure everything is safe for reentry.

Accidental fires associated with gas furnaces are normally the result of flammable materials near your gas furnace. Make sure there is at least a 24-inch clearance all the way around your furnace. Never store anything flammable in your furnace room, such as paints, gasoline, solvents, insecticides, cleaning product, paper, foggers, or anything else. Some of these materials emit flammable fumes that could lead to a fire or explosion.

The best way to maintain a safe and efficient gas furnace is to have it properly maintained every year, before each heating season. In addition to scheduling professional gas furnace maintenance, there are several things that you can do as a homeowner to ensure your furnace is running properly

For more home energy efficiency tips, see the U.S. Dept. of Energy’s four-step guide to making your home more comfortable, energy efficient and healthy.

If you turn on your furnace in the fall to check it for winter, but it doesn’t turn on, check out our 5 Furnace Troubleshooting Tips to get it back up and running again. For additional DIY Gas Furnace Tips, visit this Family Handyman Furnace Repair page.

If you have any further questions on how to tell if your furnace needs replacing, talk to the licensed, trained technicians at Cassel Home Comfort. Give us a call at (217) 866-15964

We are available 24 hours a day, 7 days a week to answer any questions you might have.