March 17, 2021

Wintertime in Layton, UT, is cold, and you’ll need a dependable heating system for indoor comfort. If your home has a gas furnace, you might notice the faint odor of the gas once in a while, especially if you’re standing right next to the furnace when it turns on for a heating cycle. Here’s what you need to know about whether or not it is ever normal to smell gas near a furnace.

What Causes the Smell in Natural Gas

Natural gas has no odor, color, or taste of its own. Gas supply companies are required by federal law to add mercaptan to the gas when it is put in supply lines for residential or commercial use. The mercaptan is what causes the odor. Its purpose is to alert you to the presence of gas. Your nose can detect mercaptan at a concentration of 10 parts per billion. For most people, mercaptan is a strong, unpleasant odor that smells like the spray of a skunk.

How Gas Furnaces Work

Gas furnaces have a supply valve. When the thermostat triggers the initiation of a heating cycle, the supply valve opens and releases gas to the burner. If there’s not a constant-on pilot, the intermittent pilot or ignition might take a fraction of a second to ignite the gas. The gas burns in the combustion chamber. The process causes the heat exchanger to get hot. The forced-air blower pushes air across the heat exchanger. That heated air passes through a filter and enters your home’s living space. The waste products from combustion are released by the flue. Some furnaces have a heat energy recovery ventilator that traps the heat from the flue gases and uses it to pre-heat incoming fresh air from the outdoors.

When It Is Normal To Smell Gas By a Furnace

The only time you should ever be able to smell gas when standing next to your furnace is the fraction of a second between when the thermostat starts a heating cycle and when the ignition or pilot ignites the gas. You might notice the odor if you’re standing within a few feet of the furnace when it begins a heating cycle.

What To Do About a Persistent Gas Odor During Heating Cycles

Once the furnace ignites the gas, the odor should go away. If you keep smelling the stench of natural gas for a few minutes or for the entire duration of the heating cycle, this isn’t normal. Your furnace could have a safety or mechanical issue that requires professional attention.

What To Do If the Odor of Gas Gets Stronger or Spreads

If the odor of natural gas gets stronger during a heating cycle, this isn’t normal. It’s also not normal for the odor of gas to spread more than a few feet away from the furnace. If you’re able to smell the odor of gas from across the room or in a different room, this is an emergency. Your home could have a gas leak. Evacuate all people and pets, then call for emergency furnace repair services.

Causes of Foul Odors From a Furnace

Mercaptan smells like stinky feet, old cheese, or putrid food to most people. Some liken it to the smell of skunks spraying nearby. The odor is from the sulfur molecule in the gas. Mercaptan itself is harmless, but natural gas is not. If you notice other odors from your furnace, such as a chemical, metallic, or burning electrical smell, this is also not normal. It’s best to evacuate your home and call for urgent furnace repairs.

How To Protect Yourself From a Gas Leak

All homes with natural gas service need to have a carbon monoxide detector on every level. You should also place one about 10 feet away from the furnace. Schedule a furnace tune-up once each year. During the tune-up, our technicians check for problems that could lead to a gas leak or allow combustion byproducts to seep into your home.

Smedley Service is Layton’s trusted provider of gas furnace repairs. You can also count on us for heat pump and air conditioner repairs and heating and cooling replacement, installation, and maintenance services. Our indoor air quality and plumbing services keep your home safe, sanitary, and comfortable. For more details about whether or not it is normal to smell gas near your furnace, get in touch with us at Smedley Service today.

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