Why Do I Smell Gas When My Furnace Kicks On?
Are you wondering, "Why do I smell gas when my furnace kicks on?" While a brief gas smell isn't an issue, staying vigilant about the dangers of a gas leak can keep you safe.
As a trusted HVAC company in Vero Beach, Bates Air and Heat can keep your furnace in working order and help you avoid gas leaks. Keep reading to learn everything you should know about how your furnace uses gas and what can cause leaks.
What Is Natural Gas?
Natural gas is a fossil fuel composed mostly of methane and ethane. Classified along with other combustion gases, like propane, its high flammability makes it a popular choice for furnaces, stoves, and hot water heaters.
Natural gas naturally produces no smell, but utility companies had a sulfuric or rotten egg smell to help alert homeowners to leaks. Because natural gas is extremely flammable, it indicates a serious emergency. A gas leak can also indicate other problems, such as a carbon monoxide leak.
What To Do If You Smell Natural Gas
If you only notice the smell occasionally for a few minutes at a time, you don't need to worry. However, if you smell the gas every time you turn on the furnace, or for more than several minutes, you likely have a gas leak.
Do not use any electronic devices, such as phones, and don't even flip a light switch. Even an internal spark in these devices can ignite the gas with a high enough concentration.
Exit the house and call your utility company from a safe distance. They can shut off the gas, at which point you should call a plumber to make repairs.
How Your Furnace Uses Gas
Both furnaces and boilers use gas as an ignition source for heat, but furnaces are the most popular form of heating in North America. While not all furnaces use gas as their fuel source, they remain a common option because natural gas is affordable and heats your home quickly.
When you need heat, your thermostat sends a signal to the device to start the furnace cycle. A valve opens to deliver gas into a chamber, and a blower turns on. The pilot light (or electronic igniter in newer models) ignites the gas.
The blower distributes the air through your ductwork, and the exhaust fan then expels extra gas and its byproducts, like carbon monoxide, out of your home.
What Causes the Gas Smell?
If you're wondering, "Why do I smell gas when my furnace kicks on?" you might not have anything to worry about. However, if you think it's a more serious issue, it's likely caused by one of the following problems.
Cracked Heat Exchanger
The heat exchanger is responsible for heating the air. When the gas ignites, it heats the metal coils that comprise the heat exchanger. The air then moves over the heated coils before passing into your ductwork.
The most common reason the heat exchanger cracks is overheating. With a crack, the heated air combines with gases and can blow into your home through the ducts.
Even if you don't smell gas, you might have a cracked heat exchanger if you notice the following signs:
- Excess soot building up in your furnace
- A pilot light that looks yellow rather than blue
- Visible cracks, corrosion, or damage
- Rattling, banging, or popping sounds
- Symptoms of carbon monoxide poisoning
Leaking Supply Line
Your supply line delivers the gas to your furnace, and it's one of the most vulnerable points for a leak. It runs from the main gas line outside your home into your home and can deliver the gas to multiple appliances. You can shut off the supply of gas coming into your home by closing the main valve.
Blocked Exhaust Vent
Your exhaust vent is where the gas exits your home and dissipates into the outside environment. Without a way to exit your home, the toxic exhaust enters back into your home. Common causes of a blocked exhaust vent include:
- Rodents or birds nesting in the vent
- Branches and leaves
- Snow buildup
- Accumulating soot
- Damage or corrosion on the interior part of the vent
Leaking Valves or Pipes
Your furnace relies on a series of gas pipes and valves to deliver, direct, and expel gas and other toxic chemicals. Leaks can occur anywhere along this network, allowing the gas to permeate your home and posing a serious risk to your safety.
Preventing Gas Leaks
You can help avoid gas leaks by practicing the following habits.
Regular Maintenance
Annual maintenance is the best way to keep your furnace in working order. Many homeowners prefer to schedule maintenance during the fall, giving the furnace the best chance to make it through the cold winter.
As part of routine maintenance, the HVAC technician will inspect every area of your furnace and gas line for leaks.
Detection Devices
While detection devices can't prevent gas leaks, they can give you an early warning of a problem and help keep you safe. If you have a gas furnace, install a gas leak detector and a carbon monoxide alarm so you can take quick action when a problem arises.
Constant Vigilance
If you stay aware of the signs you have a problem, you can call for repairs or inspection before the gas leak becomes serious.
Moderate Usage
The more you use your furnace, the faster it experiences wear and tear and the more likely it is to overheat. Use your furnace enough to stay minimally comfortable and safe within your home, but use other ways of staying warm when possible.
Bates Air and Heat Can Maintain Your Gas Furnace
Now that you know the answer to, "Why do I smell gas when my furnace kicks on?" you can stay vigilant and protect your family. Bates Air and Heat is a trusted HVAC provider, and we're passionate about keeping you both safe and comfortable in your home.
Whether we're installing a new furnace, doing routine furnace maintenance, or performing an HVAC inspection, we bring incredible passion, dedication, and knowledge to every job.
To book an appointment, call
772-271-7910 today.












