Furnace Carbon Monoxide Warning Signs for DFW Homes

Someone in your house has had a headache all week, and now a second person is dizzy and queasy. It started about when the furnace began running for the season, and it feels like a bug going around. Carbon monoxide, or CO, causes symptoms that look like the flu, and the gas gives no smell or color to warn you.

This post covers the warning signs in your body, the clues on your furnace, how to place and care for CO alarms, and exactly what to do if one goes off. Safety guidance below comes from the CDC, the CPSC, the EPA and the Minnesota Department of Health.

What Are the Furnace Carbon Monoxide Symptoms in DFW Homes?

The CDC lists headache, dizziness, weakness, upset stomach, vomiting, chest pain and confusion as the most common symptoms of CO poisoning. Heavy exposure can cause loss of consciousness and death. The CPSC describes the same pattern: low to moderate exposure feels like the flu, and severe exposure brings confusion, loss of coordination and passing out.

The EPA adds a detail that matters on a cold night. A small amount of CO can bring on breathlessness, a queasy stomach and a dull headache, and may affect your health over the long run. Moderate amounts can mean pounding headaches, dizziness, confusion and fainting.

Some people are hit harder. The CDC names infants, older adults, and people with chronic heart disease, anemia or breathing problems. The EPA also lists unborn babies. If a toddler or a grandparent in your house is unusually sleepy or sick, take that seriously.

How common is this? The CDC reports that more than 400 Americans die every year from unintentional CO poisoning not linked to fires, and more than 100,000 visit an emergency department. These are preventable cases.

CO Poisoning or the Flu? Clues You Can Check Tonight

Because the early symptoms match a cold or the flu, people explain them away. The Minnesota Department of Health offers a useful set of clues that point to CO instead of a virus:

• You feel better when you leave the house, and worse when you come home.
• Everyone in the home gets sick around the same time. Flu usually passes from person to person, one at a time.
• The people who spend the most hours at home are the sickest.
• Your pets seem ill too.
• You have no fever, no body aches and no swollen glands.
• Symptoms start or worsen when fuel-burning equipment is running.

If three or four of these fit, treat it as a possible CO problem. Get fresh air, and if anyone feels bad, go to an emergency room. The EPA says to tell the doctor you suspect CO, because a blood test taken soon after exposure can often confirm it.

Warning Signs on Your Furnace and Around the House

Your body is one clue. The furnace and its vent pipe are another. The Minnesota Department of Health lists the first four signs below as possible CO problems. The last row is general advice:

What you see	What it may mean	What to do
Streaks of soot around the furnace or vent	Fuel is not burning cleanly	Stop using the furnace and call a heating technician
Orange or yellow burner flame (it should be blue)	Incomplete combustion	Call a technician. Do not adjust anything yourself
Rust on the flue pipe	Moisture or a damaged vent	Have the vent checked before the next cold night
Heavy moisture on windows, walls or cold surfaces	Combustion gases may be staying inside	Get the system inspected
A burning smell when the heat runs	Something is overheating or burning	Switch the furnace off at its power switch or its breaker, not just the thermostat, and call a pro. If you see smoke or sparks, get out and call 911 from outside

None of these proves there is CO in the air, and the absence of all of them proves nothing either. They are reasons to bring in a professional. They are not a substitute for an alarm.

One safety rule: do not take off furnace panels or poke around the burner area to investigate. Look from the outside, and leave the inside to a technician.

A rotten-egg smell is a different emergency. That is the odor added to natural gas, not CO, which has no smell at all. Do not flip switches or touch the furnace. Get everyone out, then call the gas company or 911 from outside.

Why Furnaces Leak Carbon Monoxide

Any gas furnace makes CO as part of burning fuel. In a healthy system, a sealed combustion path and a vent pipe carry it outside. Trouble starts when that path is damaged or blocked.

The usual suspects are a cracked heat exchanger and a flue or vent pipe that is rusted, disconnected or blocked. The heat exchanger is the metal chamber that keeps burner gases separate from the air you breathe. A dirty, overheating furnace can stress the exchanger over time, which is one more reason to change the filter on schedule. The EPA wants every flue and chimney attached, sound and clear of blockage, and wants a trained professional to inspect fuel-burning appliances before each heating season begins.

That timing fits North Texas. A furnace may sit unused through a long, hot summer, then run hard for the first time on a cold November night. Many DFW homes went up during the area’s fast growth years, so plenty of furnaces here have been working a long while. If yours has never had a close inspection, fall is the time to schedule one.

Where to Put CO Alarms in Your Home

A working alarm is your only dependable warning, and where you put it matters.

• The CPSC advises installing battery-operated alarms, or plug-in alarms with battery backup, on every level of the home and outside sleeping areas.
• It says to avoid kitchens and the space right above fuel-burning appliances, where fumes from normal use could cause false alarms.
• Follow the maker’s instructions on exact placement and testing.

Two care details are easy to miss. The CPSC notes that pressing the test button checks the alarm’s circuitry, not the accuracy of its sensor. And alarms expire: the CDC advises replacing detectors every 5 years, and the Minnesota Department of Health says a typical alarm lasts 5 to 7 years depending on the brand. Check the date on the back of yours. The CDC also suggests checking batteries when the clocks change.

When you buy one, look for UL certification. The EPA warns that alarms vary in quality and that an alarm is a backup to proper furnace care, not a replacement for it.

What to Do When a CO Alarm Sounds

The CPSC puts it plainly: never ignore a CO alarm. Follow these steps in order:

1. Make sure it is the CO alarm and not the smoke alarm, if you have both.
2. Get everyone out into fresh air, including pets. Do not stop to open the furnace or hunt for the cause.
3. Call 911 from outside, or from a neighbor’s home.
4. Stay out until emergency responders say it is safe to go back in.
5. If anyone has symptoms such as headache, dizziness or nausea, get medical care and say you suspect CO.
6. After the all-clear, have a qualified technician inspect the furnace and every other fuel-burning appliance before you run them again.

The Minnesota Department of Health also notes that your gas utility company or a qualified technician can help find the cause once everyone is safe.

Can CO Show Up When the Furnace Is Off?

Yes. The furnace is only one source. The Minnesota Department of Health lists dryers, water heaters, fireplaces, gas stoves and ovens, vehicles, grills and generators too. The EPA says never to use a gas oven to heat your home and never to idle a car in a garage, even with the garage door open.

Texas winters bring another risk. When the power goes out in a freeze, people reach for generators and grills. The CDC says never to run a generator inside the home or garage, even with doors and windows open, and to run it outdoors more than 20 feet from windows, doors and vents. The CPSC reports that more than 200 people a year in the United States die from accidental CO poisoning linked to consumer products, not counting fires.

So keep alarms on all year, and treat every fuel-burning device as a possible source.

Getting a Furnace Safety Check in DFW

Flower Mound is home base for Lantern Home Services, and our Flower Mound HVAC page covers the heating and cooling work we handle in town. If you have seen soot, a yellow flame, rust on the vent, or you simply do not know the last time anyone looked at your furnace, ask us about an inspection on our HVAC service page.

We do not list a price for furnace work online, so ask for a written quote before anything starts. Our guide on why HVAC repair quotes vary shows what to compare. If you are still choosing a company, our guide to choosing an HVAC contractor in DFW lists what to look for. Work is performed by licensed pros.

Talk to Someone at Lantern

If anyone in your home feels sick or an alarm is sounding, leave and call 911 first. For everything else, tell us what is happening in the form below and a Lantern team member will reach out within 24 hours, or call or text (817) 518-4004. You can also reach us from our contact page.