Weber County
Brigham City
Salt Lake


Modern gas furnaces are exceedingly safe, but it's never a bad idea to be prepared in case something goes wrong. Understanding how furnace gas leaks occur and what to do about them will help you keep yourself and your family safe if you are ever faced with this problem. Here's everything you should know about furnace gas leaks.

What Causes a Gas Furnace to Leak?

Gas leaks can occur in the gas supply line to your furnace, but they are commonly caused by a cracked heat exchanger. Normally, gas is combusted in a chamber inside the heat exchanger, and the blower blows air over it to pick up the heat before it circulates through your ductwork. A cracked heat exchanger can allow gas to escape before it combusts, releasing harmful fumes into your home.

The number one cause of a cracked heat exchanger is overheating. Overheating can occur when there isn't enough airflow through the furnace to dissipate heat safely. Causes of restricted airflow include a dirty furnace filter, duct blockages, ductwork that is too small, or a furnace and air handler that is too large for your home.

What Are the Warning Signs of a Gas Leak?

Natural gas is odorless, so manufacturers add a chemical known as mercaptan to give it a detectable smell. Mercaptan smells sulfur-like, similar to rotten eggs. If you detect a rotten egg smell near your furnace, coming out of your ductwork, or elsewhere in your home, you may be dealing with a gas leak.

Sometimes, you can detect a gas leak by listening closely to your furnace. Gas is pressurized inside the system, so there could be a noticeable hissing sound near the leak as the gas escapes. Houseplants are particularly susceptible to the fumes from a gas leak, so keep an eye out for any dying plants in your home.

What Are the Health Risks of a Gas Leak?

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. Direct contact with compressed or liquid gas can also cause skin irritation and blisters.

Many of the short-term symptoms of less-serious exposure will often resolve if the affected person is removed from exposure.

Carbon monoxide poisoning can also cause more serious issues like fatigue, memory and concentration problems, chest and stomach pain, vision problems, and loss of motor control. In extreme cases of exposure, you may suffer from a reddening of the skin and lips, unconsciousness, and even death.

What Should You Do If You Suspect a Gas Leak?

Even if you aren't exhibiting any symptoms of exposure to gas or carbon monoxide, you should take quick action if you suspect a furnace gas leak. Shut your HVAC system off, avoid lighting matches or candles, open doors and windows to ventilate your home, and exit the area. You should call your gas company if you notice an emergency leak in your home before reentering.

Once any emergency leak has been dealt with and your home is safe to enter, you will want to get your furnace inspected before using it again. An HVAC technician can test your system thoroughly for leaks and perform any required replacements or repairs. This will give you peace of mind that a leak is not likely to reoccur any time soon.

Furnace gas leaks are a rare problem, and with these tips, you can ensure that you are always ready to respond to a gas leak in your home. For more safety tips and all of your HVAC service needs, contact Dick Kearsley Service Center today!


520 S State, Clearfield, UT 84015

[email protected]

Hours Of Operation:

Mon-Fri: 8:00 am - 5:00 pm

Saturday: 8:00 am - 4:00 pm

Sunday: Closed

Find Us On:


Davis/Morgan: 801-773-4836

Weber County: 801-393-1265

Brigham City: 435-553-4556

Salt Lake: 801-292-1636


© Dick Kearsley Service Center 2023