Why Does My Furnace Smell Like Gas

A gas odor around a furnace should never be ignored. Although natural gas is naturally odorless, utility companies add a sulfur-like smell similar to rotten eggs to make it easier to detect leaks. While you may notice a brief odor at startup, any strong, persistent, or recurring gas smells require immediate action.

To help your family stay safe, we’ll look at what to do right away, common causes of gas odors, warning signs to watch out for, and when you need to call Rogue Valley Heating, Cooling & Electrical for help.

If You Smell Gas Right Now, Do This First

For the safety of your home and family, do the following emergency steps before worrying about anything else.

• Leave your home immediately with all people and pets.
• Do not turn your lights on or off.
• Do not use anything that makes a spark, such as lighters, matches, thermostats, or appliances.
• Call 911 or your gas utility once you are in a safe location.
• Do not go back inside your home until emergency responders or the gas utility say that it is safe to do so.

Once your home has been cleared and it is safe to go inside, you should schedule a furnace inspection or repair to resolve the issue.

Is It Ever Normal for a Furnace To Smell Like Gas?

Although a faint, brief odor may sometimes happen when your unit first starts up, it should disappear fairly quickly. Gas odors are not normal if:

• They recur frequently.
• The odor is especially strong.
• The smell lasts more than a few moments.
• You hear something hissing or whistling.
• The smell is throughout your home.
• Your carbon monoxide alarm goes off.

When unsure, it is always safer to treat a gas smell like a leak.

What Does a Gas Leak Smell Like?

Gas can smell like rotten eggs, sulfur, or a skunk. Because natural gas has no smell, the scent actually comes from the odor added to the gas. You may also notice hissing noises near your furnace or gas line, pilot light problems, or bubbles in any standing water that’s near the gas piping. If you check near the outdoor gas line, you may also see dead or discolored plants. Exposure to natural gas at high concentrations or to combustion byproducts such as carbon monoxide may cause symptoms including dizziness, headache, nausea, or fatigue.

It’s important to remember that carbon monoxide (CO) has no smell. This is why it’s so important to install CO detectors, test them monthly, and change dead batteries as recommended by the manufacturer.

Common Reasons Your Furnace Smells Like Gas

A furnace can smell like gas due to a few different problems.

1. A Gas Leak in or Near the Furnace

This is the most urgent cause. Gas odors can occur if there’s a leak in the gas line, connection, valve, or furnace component. If you even think this could be the cause, you should immediately evacuate your home and call for a professional inspection.

2. A Pilot Light Problem

Older furnaces typically have standing pilot lights. If the pilot light goes out, gas may continue to flow and cause this odor. For your safety, you should never relight the pilot if you smell gas.

3. Delayed Ignition

Gas can build up briefly before burners ignite. If this occurs, you may notice a small boom or hard start as well as a gas smell when your furnace kicks on. Because this issue can damage the furnace, you should always get it professionally inspected.

4. Dirty or Misaligned Burners

A dirty or misaligned burner can impact combustion and result in unusual smells. Often, you’ll also notice uneven flames, soot, yellow-colored flames, or rough startup. If this is the problem, the best option is to schedule a professional cleaning and adjustment.

5. Venting or Backdrafting Problems

Your furnace’s exhaust gases are supposed to leave your home through the venting system. If they don’t because of blocked, damaged, or improperly venting exhaust systems, the combustion byproducts can end up back in your home. Besides causing combustion or exhaust odors, this also creates a serious carbon monoxide concern.

6. A Cracked Heat Exchanger or Combustion Issue

Heat exchanger problems represent a major safety concern and should be checked out by a professional heating, ventilation, and air conditioning (HVAC) technician right away. When the heat exchanger cracks, it can release combustion byproducts. If this is the cause of the unusual odor, you’ll also potentially notice soot, a CO detector alarm going off, flame rollout, or system shutdowns.

7. New Furnace or First Startup Odors That Are Not Gas

When your furnace first starts up, dust, debris, and manufacturing oils can create a burning odor. This is especially common if the furnace runs after it has sat unused for a while. However, these startup odors should not smell like rotten eggs.

If the odor does smell like rotten eggs, you should follow the gas safety steps immediately.

8. The Smell May Be Coming From Somewhere Else

Sewer gas from a dry floor drain, nearby gas appliances, trash or compost near your windows and vents, or outdoor gas line work can result in a gas odor. For your safety, you should always rule out gas leaks before you assume that the odor is coming from a harmless source.

Furnace Smell Comparison: Gas vs. Other Odors

The type of odor you smell is a strong indication of the problem. For a suspected gas leak, follow the emergency steps above. Other strong, recurring, or unusual furnace odors should be professionally inspected.

• Rotten Eggs and Sulfur Odors: These smells often occur due to a gas leak.
• Burning Dust: You may notice the odor of burning dust when your furnace first switches on each season.
• Burning Plastic or Electrical Smells: These odors can occur due to electrical issues or overheating.
• Musty Odors: Often, these smells stem from dirty ducts, excess moisture, mold, or a clogged drain.
• Metallic Smells: This type of odor may happen when components overheat.

What Not To Do If Your Furnace Smells Like Gas

If your furnace smells like rotten eggs, you should never do the following things.

• Do not continue running the furnace.
• Do not turn on or off any switches.
• Do not look for the leak using a flame.
• Do not use any device that causes a spark, such as a lighter.
• Do not unplug any equipment.
• Do not attempt gas line repairs yourself.
• Do not ignore faint gas odors that keep returning.
• Do not go back into your home unless it has been cleared.

When To Call Rogue Valley Heating, Cooling & Electrical

Before you reach out to us for repairs, you should always call emergency responders or your gas utility first. Once they have confirmed that your home is safe, you can call us for services. We recommend scheduling a furnace inspection if you notice any of the following signs.

• The odor happens when your furnace starts up.
• You haven’t had your furnace serviced in over a year.
• Your furnace makes booming or popping noises.
• You are experiencing poor heat performance, odd odors, or short cycling.
• Your energy bills have jumped for no apparent reason.
• Your pilot light will not remain lit.
• Your burner flame is yellow or flickers.

At Rogue Valley, we are a local furnace repair and maintenance team. We serve Grants Pass, Medford, and the surrounding Southern Oregon area. Our experienced team offers 24/7 emergency furnace repairs, upfront pricing, same-day service, and safety-focused diagnostics.

How a Technician Checks for Furnace Gas Odors

Our HVAC technicians will perform a few checks to diagnose the source of your problem.

• First, we’ll test your gas connections.
• Our team will inspect gas valves and fittings. 
• We will check your burner operation.
• Then, we will inspect your ignition system and heat exchanger. 
• We will test for the presence of carbon monoxide.
• Our staff will check your venting and combustion air.
• Finally, we will review your furnace fault codes and check your safety controls.

At Rogue Valley, our goal is to find the cause of the problem. Gas odors are a serious issue, so it’s essential to discover and fix the source of the smell.

How To Help Prevent Gas Smell Problems

To avoid gas odors in the future, there are a few essential maintenance tasks you should carry out.

• Change your filter regularly.
• Install and maintain CO detectors.
• Verify that your vents and combustion air openings are not blocked.
• Never attempt DIY gas line or furnace combustion repairs.
• Make sure there are no flammable items or clutter stored in your furnace area.
• Call immediately if you notice changes in performance, unusual noises, or odd odors.

FAQs

To explore why gas odors occur and what to do, check out some of our most frequently asked questions.

Why does my furnace smell like gas when it turns on?

A faint gas odor may occasionally occur briefly during ignition. Any strong, persistent, or recurring gas smells may be due to a pilot light problem, gas leak, or delayed ignition.

Is a rotten egg smell from my furnace dangerous?

Yes, it is. A rotten egg or sulfur smell can indicate a natural gas leak and should be taken seriously. You should immediately evacuate your home and call 911 or your gas utility once you reach a safe location.

Can I relight my pilot light if I smell gas?

No, this poses a danger to yourself and your family. Instead, leave your home immediately. Once you and other occupants are in a safe location, you can call for help.

Does carbon monoxide smell like gas?

No, it doesn’t. Natural gas is odorless, but utilities add an odorant that produces a rotten-egg-like smell. Meanwhile, carbon monoxide is odorless and invisible. Because of this, it’s important to always have working CO detectors installed in your home.

Who should I call for furnace gas smell problems in Grants Pass or Medford?

Before you call anyone, immediately leave your home and get to a safe location. Then, call 911 or your gas utility. Once they have confirmed that your home is safe, you can call Rogue Valley Heating, Cooling & Electrical at 541-204-0966 to schedule furnace inspection and repair services.

Protect Your Home From a Furnace Leak

If you smell a gas odor, you should immediately leave your home. After you, your family members, and your pets have reached a safe location, you can call 911 or your utility provider to report the leak. After the area has been cleared, you can reach out to our team at 541-204-0966 to schedule a full safety inspection.

Contact us today for furnace repairs and inspections in Grants Pass, Medford, and Southern Oregon.