How do you know if your furnace is emitting carbon monoxide?

Author: Miss Candace Goodwin  |  Last update: Thursday, November 20, 2025

Warning Signs of a Furnace CO Leak
  • Heavy condensation on the windows (found in the room with your furnace)
  • Yellow or brown soot-like stains found around your furnace.
  • A yellow pilot light (instead of a blue flame)
  • Stuffy indoor air.
  • The smell of gas/burning.
  • The pilot light constantly blows out.
  • Rust found on the vent pipe.

What are two warning signs of carbon monoxide poisoning?

The most common symptoms of CO poisoning are headache, dizziness, weakness, upset stomach, vomiting, chest pain, and confusion. CO symptoms are often described as “flu-like.” If you breathe in a lot of CO, it can make you pass out or kill you.

How can you tell if there is carbon monoxide without a detector?

Signs of carbon monoxide:
  1. Stuffy or stale air.
  2. A pilot light keeps going out.
  3. More condensation than usual on your windows.
  4. Soot build up around a fireplace, chimney, or other fuel-burning equipment.
  5. Fuel-burning equipment has a back-draft (flame flares up when a window or door opens and adds air).

How do I stop my furnace from getting carbon monoxide?

10 Ways to Prevent Carbon Monoxide Leaks in Your Furnace
  1. Ensure Draft Inverter Is Properly Installed. ...
  2. Be Alert to Carbon Monoxide Symptoms. ...
  3. Replace Filters Frequently. ...
  4. Install CO Alarms. ...
  5. Check Your Furnace for Carbon Monoxide Leaks. ...
  6. Get an Annual Tune-Up. ...
  7. Keep Vents Clear of Debris. ...
  8. Inspect and Clean Your Chimney Annually.

What are the symptoms of carbon monoxide poisoning from a heater?

Key points about carbon monoxide poisoning

A common source is unvented space heaters. Symptoms of CO poisoning include headache, dizziness, weakness, nausea and vomiting, rapid heartbeat, shortness of breath, seizures, chest pain, disorientation, and loss of consciousness.

How Do I Know if My Furnace is Leaking Carbon Monoxide?

How do I know if my furnace is giving off carbon monoxide?

Warning Signs of a Furnace CO Leak

If you're unsure of how to identify a carbon monoxide leak, there are several signs to keep an eye out for. These warning signs include: Heavy condensation on the windows (found in the room with your furnace) Yellow or brown soot-like stains found around your furnace.

Will opening a window help with carbon monoxide?

If you experience symptoms that you think could be from CO poisoning: DO GET FRESH AIR IMMEDIATELY. Open doors and windows, turn off combustion appliances and leave the house.

How do you test a furnace for carbon monoxide?

According to the CDC, carbon monoxide is a silent killer that takes hundreds of lives per year. Unfortunately, you cannot tell just by looking at your furnace whether it is leaking carbon monoxide. You need a carbon monoxide detector or other special equipment to test the levels yourself.

How long does it take for carbon monoxide to build up in a house?

Small carbon monoxide leaks can fill every room in your house with poisonous gas within eight hours. Severe leaks can cause this problem in just five minutes. The EPA states that exposure to concentrations of nine ppm or more for eight hours is enough to produce harmful health effects for at-risk individuals.

How do you remove carbon monoxide from the air at home?

To reduce carbon monoxide in your home without air purifiers or oxygen masks, ensure proper ventilation by opening windows and doors regularly to allow fresh air in. Regularly maintain and check gas appliances, heaters, and stoves. Install and maintain carbon monoxide detectors to alert you to any dangerous levels.

How do I check my house for carbon monoxide?

Install battery-powered carbon monoxide detectors throughout your home. While not as powerful as professional equipment, they can help alert you to dangerous levels of gas in your home.

How do I use my iPhone to detect carbon monoxide?

Go to the Home app on your iPhone or iPad. , then tap Home Settings. Tap Safety & Security. Tap Sound Recognition, then turn on Smoke & CO Alarm.

Does the fire department charge to check for carbon monoxide?

In most areas, the fire department does not charge to respond to carbon monoxide alarms or to check for the presence of CO in a residence. However, policies can vary depending on the jurisdiction or specific fire department. It's always a good idea to contact your local fire department for specifics on their policies.

How do you test for carbon monoxide?

Test Overview

The test measures the amount of hemoglobin in your blood that has bonded with carbon monoxide. Carbon monoxide can come from any source that burns fuel. Common sources are cars, fireplaces, powerboats, woodstoves, kerosene space heaters, charcoal grills, and gas appliances such as water heaters and ovens.

What are at least 3 conditions that can cause carbon monoxide poisoning?

Where Found
  • Anything that burns coal, gasoline, kerosene, oil, propane, or wood.
  • Automobile engines.
  • Charcoal grills (charcoal should never be burned indoors)
  • Indoor and portable heating systems.
  • Portable propane heaters.
  • Stoves (indoor and camp stoves)
  • Water heaters that use natural gas.

How to tell carbon monoxide without a detector?

Any of the following could be a sign of a carbon monoxide leak: Floppy yellow or orange flame on your gas hob or oven, rather than a crisp blue flame. Dark, sooty staining on or around gas appliances. Pilot lights that frequently blow out.

What appliances give off carbon monoxide?

Carbon Monoxide sources in the home
  • Clothes dryers.
  • Water heaters.
  • Furnaces or boilers.
  • Fireplaces, both gas and wood burning.
  • Gas stoves and ovens.
  • Motor vehicles.
  • Grills, generators, power tools, lawn equipment.
  • Wood stoves.

What does slow carbon monoxide poisoning look like?

The symptoms of exposure to low levels of carbon monoxide can be like those of food poisoning and flu. Carbon monoxide poisoning doesn't cause a high temperature. The longer you inhale the gas, the worse your symptoms will be. You may lose balance, vision and memory and even consciousness.

How do I know if my heater is releasing carbon monoxide?

The soot stain can have a black, brown or even yellow color. Smell: While carbon monoxide doesn't emit odor, it may get accompanied by other exhaust gases that produce an odor. A yellow burner flame: The pilot flame may produce an unusual yellow flame instead of the normal blue one.

Do all furnaces give off carbon monoxide?

Any furnace that burns fuel produces carbon monoxide as a byproduct. This is the same for any appliance in your home that burns fuel, such as a gas range. Therefore, if your furnace uses natural gas, propane, or oil to make heat, your furnace creates carbon monoxide. Electric furnaces do not create carbon monoxide.

How can I test my furnace?

Check the thermostat settings.

The furnace will not come on unless the ambient temperature drops below the setpoint. To test the furnace, temporarily set the thermostat five to ten degrees higher than you normally would to see if it comes on, then return the thermostat to its normal setting when the test is complete.

How do you check your house for carbon monoxide?

The easiest way to see if there is carbon monoxide inside your home is with a carbon monoxide detector (which also includes an alarm). In fact, many building codes require a carbon monoxide gas detector.

Can dogs smell carbon monoxide?

Carbon monoxide, commonly known as CO, is an odorless, colorless, and non-irritating gas. No pet can identify the gas because CO lacks any scent whatsoever. Exposure can lead to carbon monoxide poisoning in both humans and pets.

What puts off carbon monoxide in a house?

The most common causes of carbon monoxide building up are incorrectly installed or poorly maintained or ventilated appliances – like stoves and hot water heaters. Poorly ventilated fireplaces and other gas- or wood-burning appliances can also pose danger.

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