How do I tell if my furnace is leaking gas?

Author: Ms. Jennie Schmidt  |  Last update: Thursday, January 1, 2026

4 Signs Your Furnace Has a Gas Leak
  1. Hissing Noises. Occasionally the pipes that carry natural gas into and through your home will develop tiny cracks or holes. ...
  2. Rotten Egg Smells. People often say natural gas smells like rotten eggs, but this is not quite accurate. ...
  3. Dying House Plants. ...
  4. Flu-Like Symptoms.

How to check if gas is leaking from a furnace?

Turn off your furnace, soak a cloth in soapy water, and run it along any exposed gas lines around your furnace, as well as the heat exchanger. Bubbles will appear in the soapy water at any points where gas is escaping.

Is it okay to smell a little gas from a furnace?

A gas smell around the furnace is a sign of gas leaks. You need to take immediate precautions if you smell gas around your furnace as you wait for an expert in furnace repair. The first step should be to turn off the furnace via the thermostat and ventilate the house to get rid of the gas.

What are the symptoms of gas leak exposure?

Symptoms from a natural gas leak may include:
  • headaches, sometimes severe.
  • dizziness.
  • fatigue.
  • nausea.
  • irregular breathing.
  • chest pains.
  • memory problems.
  • blurred vision.

Can a gas leak from a furnace make you sick?

Furnace gas leaks release harmful substances into the air, such as carbon monoxide, which can cause symptoms in people who are exposed. The most common short-term symptoms of carbon monoxide exposure include headaches, dizziness, nausea, sinus irritation, and difficulty breathing.

How to Check for Gas Leaks in a Furnace

Will a carbon monoxide detector detect a gas leak?

No, carbon monoxide (CO) alarms cannot detect natural gas leaks. They are designed to detect the presence of carbon monoxide, a poisonous gas formed during incomplete combustion of fuels like oil, gas, propane, and wood.

How do I know if my furnace is making me sick?

Symptoms of Heater Sickness

Here are a few common symptoms to keep an eye out for: Coughing and sneezing. Sinus infections. Allergy symptoms.

How long does it take for a gas leak to harm you?

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. Exit the property and call 911 if you suspect your home has a gas leak.

What is the most common indication of a natural gas leak?

The most common way natural gas leaks are detected is by the smell, but you may notice a hissing sound from a connection in a lab or dead vegetation near a buried gas line. React. Evacuate the area immediately.

Can you stay in a house with a gas leak?

Here's what you should DO if you smell gas: DO leave the home, building, or area of the suspected leak. Get to a safe area as quickly as possible. After leaving your home, DO call the 24-hour emergency number for Peoples at 1-800-400-4271, or call your local emergency response number.

What does a furnace leak smell like?

If you detect a sulfuric, rotten egg-like smell coming from your furnace, it is imperative that you act immediately, as you could be dealing with a gas leak.

Is a slight gas smell normal?

It's normal for a faint odor to remain after lighting a stove or if the pilot light in a hot water heater, gas fireplace or other appliance goes out. Nonetheless, any possible leak must be taken seriously, especially if the odor is strong, persistent, or accompanied by a hissing sound.

Can a small gas leak make you ill?

Can a gas leak make you ill? Sometimes, a gas leak can cause headaches, dizziness and nausea. If you have mild symptoms they should go away when you leave the home, but it's still a good idea to see a doctor. Breathing in carbon monoxide, meanwhile, can lead to poisoning, which can be fatal.

How do I check for a furnace leak?

Leak Detection Methods

One method for detecting leaks would be using smoke generators (i.e., smoke bombs). They are very effective in finding leaks that are difficult to locate. This method is performed when the furnace is cold and after all combustibles have been purged from the furnace.

How much to fix a gas leak in a furnace?

The estimated cost of getting a leaky furnace fixed can be as low as $80. But for a thorough repair or replacing a broken down part, the cost can range from $800 to $1500.

Would a gas leak smell come and go?

Natural gas leaks are particularly likely to cause smells in small, enclosed areas where gas can build up. If the leak is outside, the smell may seem to come and go as the breeze blows it away. The other big sign to look out for is a strange noise.

Does a carbon monoxide detector detect gas leaks?

Will a carbon monoxide alarm detect gas leaks? Answer: While a carbon monoxide detector is helpful to prevent carbon monoxide poisoning, you cannot rely on a carbon monoxide detector to detect a gas leak. A carbon monoxide detector will sense carbon monoxide, not raw fuel or gas fumes.

Can a small gas leak cause an explosion?

Natural gas explosions are not only devastating but often deadly. A small leak, if exposed to a spark or flame, can trigger an explosion powerful enough to cause huge fires and significant loss of life. The energy blast of the explosion can damage or even destroy houses and buildings.

What are the symptoms of gas heater poisoning?

Key points about carbon monoxide poisoning

Most CO exposures happen in the winter. 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.

What smells like natural gas but isn't?

One often not considered source of a “gas-like” smell that can come from your home is bacteria inside of your sink or sewer system. It has a similar smell to the sulfur that is added to gas to give it an odor but is obviously less dangerous.

How do I know if something is wrong with my furnace?

A gas furnace should have a vibrant or bright blue flame. When you see a weak and wavy or flickering flame, this indicates gas is not being completely burned. Pilot light color changes are another indicator that carbon monoxide is not venting away from the system safely.

How do I make sure my furnace is safe?

Gas Furnace Safety
  1. Have your furnace cleaned and checked every year by a NATE-certified technician. ...
  2. Install a carbon monoxide (CO) alarm in your home.
  3. Change your furnace filter regularly. ...
  4. Keep the area around your furnace clean and unobstructed.
  5. Keep the burner area of your furnace clean.

Can a leaky furnace make you sick?

A furnace leak can be a severe issue. Not only can it cause your furnace to stop working, but it can also release carbon monoxide into your home. This gas is deadly and can cause serious health problems, or even death, for you and your family.

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