Carbon Monoxide and Your Furnace: Safety Tips Every NJ Family Should Know

Carbon monoxide is often called the "silent killer," and for good reason: you can't see it, smell it or taste it. Every winter, fuel-burning appliances such as furnaces, boilers, water heaters, fireplaces and generators send people to the hospital with CO poisoning. The good news is that it's almost entirely preventable with working alarms, regular maintenance and a few safe habits.

What is carbon monoxide?

Carbon monoxide (CO) is a gas produced when fuels like natural gas, propane, oil, wood or gasoline burn incompletely. A properly working furnace burns fuel cleanly and vents its exhaust safely outside. Problems arise when combustion goes wrong or exhaust can't escape.

When you breathe CO, it binds to the hemoglobin in your blood and blocks oxygen from reaching your organs. Even low levels over time can make you sick; high levels can be fatal within minutes.

How a furnace can produce CO in your home

• Cracked heat exchanger: The heat exchanger separates combustion gases from the air that circulates through your home. Over years of heating and cooling, metal can crack, potentially allowing exhaust to mix with household air.
• Blocked or damaged venting: Bird nests, debris, snow drifts over high-efficiency furnace vent pipes, disconnected flue pipes or a blocked chimney can force exhaust back into the house.
• Poor combustion: Dirty burners, incorrect gas pressure or insufficient combustion air can increase CO production. A yellow or flickering flame (instead of steady blue) can be a sign.
• Back-drafting: Powerful exhaust fans, tightly sealed homes or chimney problems can pull exhaust gases back down a flue.

What to do if your CO alarm goes off

1. Get everyone outside to fresh air immediately, including pets.
2. Call 911 from outside. Firefighters can measure CO levels.
3. Don't go back inside until emergency responders say it's safe.
4. If anyone has symptoms, tell the 911 dispatcher. Seek medical attention.
5. Before using the furnace again, have it inspected by a licensed technician to find and fix the source.

Don't open windows and stay inside to "air it out," and don't silence the alarm and assume it's faulty.

Symptoms of carbon monoxide poisoning

Early symptoms often mimic the flu:

• Headache
• Dizziness or lightheadedness
• Nausea or vomiting
• Weakness and fatigue
• Shortness of breath
• Confusion

Clues that point to CO rather than a virus: several people (or pets) in the house feel sick at the same time, symptoms improve when you leave home and return when you come back, or symptoms start when the heat first comes on in fall.

Carbon monoxide alarms: placement and care

• Install CO alarms on every level of your home, including the basement.
• Place them outside each sleeping area, so they'll wake you.
• Follow the manufacturer's instructions on placement and keep them the recommended distance from fuel-burning appliances to avoid nuisance alarms.
• Test monthly using the test button.
• Replace batteries at least once a year, or choose sealed 10-year battery models.
• Replace the alarm when it reaches the end of its life, typically 5–10 years. Many alarms chirp to signal end of life.
• Combination smoke/CO alarms are convenient, but make sure you have enough of each type throughout the home.

New Jersey requires carbon monoxide alarms in homes with fuel-burning appliances or attached garages, and alarms are checked as part of the certificate required when a home is sold. Your local fire official can confirm the requirements for your property.

How annual furnace maintenance prevents CO problems

A proper heating tune-up includes safety checks that directly address CO risks:

• Inspecting the heat exchanger for cracks, holes and corrosion
• Checking burners and flame appearance
• Measuring gas pressure and checking combustion
• Inspecting the vent pipe and flue for blockages, leaks and proper slope
• Testing safety switches, including rollout and limit switches
• Checking that the furnace has adequate combustion air

This is one reason we recommend a fall heating tune-up every year, especially for furnaces over 10 years old. Our $89 tune-up and the Prime Comfort Club ($19/month, including a heating and an AC tune-up each year) make it easy to stay on schedule.

Everyday safety habits

• Never use a gas oven, grill, camp stove or generator to heat your home.
• Never run a generator in a garage, basement or near windows, even with the door open. Keep it well away from the house.
• Don't idle a car in an attached garage, even with the garage door open.
• Keep furnace vent pipes clear of snow after storms; see our furnace troubleshooting checklist.
• Keep the furnace area clear of storage, especially flammables like paint and gasoline.
• Have chimneys and flues inspected for fireplaces and other fuel-burning appliances.

When to replace an older furnace

If a technician finds a cracked heat exchanger, most furnaces aren't worth repairing. The heat exchanger is the heart of the furnace, and replacing it is costly. A furnace that's 15–20+ years old with safety concerns is usually best replaced. We'll show you what we find and explain your options with upfront pricing. See furnace and heat pump installation.

Peace of mind for your family

Many of our customers, including residents of adult communities in Manchester, Berkeley Township and Tinton Falls, and families in older homes in towns like Mount Holly, ask us for a safety check every fall. Message us on WhatsApp to schedule yours. If your CO alarm is sounding right now, get outside and call 911 first.