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

Author: Shania Schulist  |  Last update: Sunday, February 8, 2026

Strange Odors: While carbon monoxide itself is odorless, other combustion byproducts may emit unusual smells. If you detect a faint odor of gas or burning within your home, it could be a warning sign of a potential carbon monoxide leak. Never ignore strange odors, as they could indicate a serious safety hazard.

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

Signs That Carbon Monoxide Could Be Accumulating
  • Pilot light frequently blows out.
  • Brown or yellow stains appear around the appliance.
  • Smell of gas or exhaust.
  • Fallen soot accumulating in the fireplace.
  • Stale or stuffy air.
  • Smell of something burning.
  • Excessive condensation on windows around the furnace.

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).

Does my heater release carbon monoxide?

Any heater that burns fuel, such as your furnace, gas water heater or a portable butane or gas heater, produces carbon monoxide that can leak into the air. Mild exposure to carbon monoxide can cause symptoms such as nausea, dizziness or headaches. Severe poisoning can result in brain or heart damage or even death.

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.

Carbon Monoxide Poisoning: Everything You Need to Know

How to detect carbon monoxide with iPhone?

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.

How do you check your house for carbon monoxide poisoning?

The main tool used in these tests is an electronic portable toxic multi-gas monitor. This device differs from the consumer-level carbon monoxide detectors in that it can be calibrated to detect trace carbon monoxide gas from nearly zero parts per million (ppm) and at increments as small as 1 ppm.

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.

Does turning off the furnace stop carbon monoxide?

Your furnace needs to be on to burn fuel that releases CO. However, carbon monoxide can travel throughout your home via your HVAC system, so it can still create a dangerous situation even when your furnace is off.

Can space heaters give off carbon monoxide?

Overusing the heater or using an oversized heater can result in elevated levels of carbon monoxide or nitrogen dioxide fumes in the air. These fumes can cause cold or flu-like symptoms, headaches, and eye, nose and throat irritation. Don't use these heaters as your main heat source, even during power failures.

What is the easiest way to detect carbon monoxide?

A portable CO detector can be useful for detecting carbon monoxide levels near all gas-powered appliances. It's a handy way to check every room of the house. These units can be hardwired with battery backup, or you can choose a battery powered model.

Should I call 911 if my carbon monoxide alarm goes off?

My carbon monoxide alarm is sounding. What should I do? Call 911 and report what is happening. Immediately leave your residence and wait for the fire department to arrive.

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.

What causes a furnace to put out carbon monoxide?

Problems with pilot lights, cracked heat exchangers, blocked vents, and damaged fuel lines are the most common reasons for carbon monoxide poisoning. While most cases of carbon monoxide poisoning occur during the fall and winter, leaks can occur throughout the year when the unit is in its heaviest use.

How do you know if your heater is leaking gas?

Hissing sound: The release of gas from the intake line or valve may create a very small hissing sound. Or, in the case of a large leak, it may be very audible. While there can be other causes of a hissing sound, you should take the possibility of a gas leak seriously because it is a large safety issue.

Where do carbon monoxide leaks start?

How can carbon monoxide build up in a home? 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.

How do you tell if your furnace is giving off carbon monoxide?

Signs of a Furnace Carbon Monoxide Leak

These signs may include frequent pilot light blow-outs, soot accumulation in the fireplaces, smears of yellow/brown stains near appliances, duller than normal flames from their fires as well as noticeable smells like stale air and burning.

Can you vent out carbon monoxide?

Many devices in the home also produce carbon monoxide gas, but it's filtered outside the home through ventilation or exhaust pipes.

Should I put a carbon monoxide detector next to the furnace?

Yes, it's recommended to place a carbon monoxide detector at least 15 feet away from furnaces to avoid nuisance alarms. Furnaces can be a common source of carbon monoxide leaks.

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 I know if my house is filling with carbon monoxide?

It is also a good idea to know the signs of a potential CO problem: Streaks of soot around fuel-burning appliances, or fallen soot in a fireplace. Absence of an upward draft in your chimney. Excess moisture and condensation on windows, walls and cold surfaces.

What appliances give off carbon monoxide?

CO is primarily produced by the improper operation or ventilation of appliances such as furnaces, water heaters, ovens, fireplaces, fuel space heaters, generators, and charcoal grills that are fueled by oil, propane, natural gas, wood, kerosene, gasoline, and diesel.

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.

Can my phone detect carbon monoxide?

Co Checker is a free Android app developed by Meter App, falling under the category of Utilities & Tools. It is a simple and handy tool that helps detect the presence of carbon monoxide in the air.

What is the fastest way to test for carbon monoxide?

To confirm the diagnosis, the health care team might test a blood sample for carbon monoxide. This test should be done as soon as possible after removing the person from the suspected exposure environment.

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