Furnace Smells Like Gas? Emergency Safety Guide for Portland Homes
Natural gas smells like rotten eggs for safety, but any gas smell from your furnace signals a serious problem. Portland homeowners face unique risks from older homes and humid crawlspaces. This guide covers emergency protocols, dangerous causes, and when to call professionals immediately.
IF YOU SMELL GAS: LEAVE IMMEDIATELY
Leave immediately if you smell gas or suspect a leak, even if the smell is faint.
Do not operate switches, appliances or phones, use flames, or start a vehicle near the suspected leak.
From a safe location away from the building, call 911.
From that safe location, call NW Natural's 24-hour gas-emergency line: 800-882-3377.
Do not re-enter until emergency responders or the utility say it is safe.
After safety clearance, contact EHC to request furnace service.
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Natural Gas Safety
How to Identify Natural Gas Leaks
Rotten egg smell - NW Natural adds mercaptan odorant for safety detection
Hissing sound - Gas escaping from pipes or connections
Dead plants/grass - Gas prevents oxygen uptake near leaks
White mist/cloud - Cold gas condensing in humid Portland air
Bubbles in water - If leak is near water source
What to Do If You Smell Gas
Do Not Dismiss a Faint Gas Smell
Do not assume a gas smell is normal during startup, while relighting a pilot, or near a closed furnace door. Leave immediately even if the smell is faint or brief. Do not attempt to relight the furnace or investigate the source. From a safe location outside, call 911 and NW Natural's gas-emergency line at 800-882-3377. Do not re-enter until emergency responders or the utility say it is safe.
Danger Signs That Require Immediate Action:
- Any gas smell or suspected gas leak, even if faint or brief
- Smell present when furnace is off
- Headaches, dizziness, or nausea (carbon monoxide symptoms)
- Hissing sounds from gas lines
- Dead vegetation near gas lines
- Multiple family members feeling ill simultaneously
Portland-Specific Gas Safety Issues
If you smell gas or suspect a gas leak, leave the building immediately, even if the smell is faint. Do not operate switches, appliances or phones inside, and do not stop to shut off the furnace or gas supply. From a safe location outside, call 911 and your gas utility's emergency line. Do not re-enter until emergency responders or the utility say it is safe. After emergency responders or the utility have cleared the building, contact EHC to request furnace service.
Cracked Heat Exchanger (EMERGENCY)
A damaged heat exchanger can allow combustion gases into the home's air. Carbon monoxide is odorless; a gas smell does not identify the failed component. Do not stay inside to diagnose a suspected gas leak or a sounding carbon monoxide alarm.
Portland-Proven Fix:
If you smell gas or suspect a gas leak, leave the building immediately, even if the smell is faint. Do not operate switches, appliances or phones inside, light a flame, or start a vehicle near the suspected leak. Do not search for the leak, relight the furnace, or stop to shut off the gas supply. From a safe location away from the building, call 911 and NW Natural's 24-hour gas-emergency line at 800-882-3377. Do not re-enter until emergency responders or the utility say it is safe.
Failed Gas Valve Seal
The gas valve contains internal seals that prevent gas leakage when the valve is closed. Over time, these seals can harden, crack, or wear out, allowing small amounts of natural gas to escape. This is more common in older Portland homes with 1980s-1990s furnaces.
Portland-Proven Fix:
If you smell gas or suspect a gas leak, leave the building immediately, even if the smell is faint. Do not operate switches, appliances or phones inside, light a flame, or start a vehicle near the suspected leak. Do not search for the leak, relight the furnace, or stop to shut off the gas supply. From a safe location away from the building, call 911 and NW Natural's 24-hour gas-emergency line at 800-882-3377. Do not re-enter until emergency responders or the utility say it is safe. After emergency responders or the utility have cleared the building, a qualified technician can inspect the furnace. A technician must inspect and replace the gas valve ($300-$600). This is not a DIY repair due to gas line safety requirements. We also check for proper gas pressure while we're there.
Loose Gas Line Connection
Vibration from the blower motor or settling of the home can loosen gas pipe connections. Portland's earthquake activity and older homes with crawlspace installations increase this risk. A hissing sound often accompanies the smell.
Portland-Proven Fix:
If you smell gas or suspect a gas leak, leave the building immediately, even if the smell is faint. Do not operate switches, appliances or phones inside, light a flame, or start a vehicle near the suspected leak. Do not search for the leak, relight the furnace, or stop to shut off the gas supply. From a safe location away from the building, call 911 and NW Natural's 24-hour gas-emergency line at 800-882-3377. Do not re-enter until emergency responders or the utility say it is safe.
Pilot Light Out (Standing Pilot Systems)
Older furnaces with standing pilot lights burn a small flame 24/7. If the pilot goes out due to drafts, dirty thermocouple, or low gas pressure, unburned gas can accumulate. Most Portland homes built after 2000 use electronic ignition, but older homes still have these systems.
Portland-Proven Fix:
If you smell gas or suspect a gas leak, leave the building immediately, even if the smell is faint. Do not operate switches, appliances or phones inside, light a flame, or start a vehicle near the suspected leak. Do not search for the leak, relight the furnace, or stop to shut off the gas supply. From a safe location away from the building, call 911 and NW Natural's 24-hour gas-emergency line at 800-882-3377. Do not re-enter until emergency responders or the utility say it is safe.
Incomplete Combustion
Dirty burners, blocked vents, or insufficient air supply can cause incomplete gas burning. This produces carbon monoxide and unburned hydrocarbons that smell like gas. Portland's high humidity can accelerate burner corrosion.
Portland-Proven Fix:
If you smell gas or suspect a gas leak, leave the building immediately, even if the smell is faint. Do not operate switches, appliances or phones inside, light a flame, or start a vehicle near the suspected leak. Do not search for the leak, relight the furnace, or stop to shut off the gas supply. From a safe location away from the building, call 911 and NW Natural's 24-hour gas-emergency line at 800-882-3377. Do not re-enter until emergency responders or the utility say it is safe. After emergency responders or the utility have cleared the building, a qualified technician can inspect the furnace. Professional burner cleaning and combustion analysis ($150-$250). We also inspect intake and exhaust vents for blockages from leaves, moss, or bird nests. Annual maintenance prevents this issue.
Venting Issues
Blocked or disconnected vent pipes prevent proper exhaust of combustion gases. High-efficiency furnaces with PVC pipes are especially vulnerable to blockages from Portland's vegetation and weather. Backdrafting can pull exhaust back into the home.
Portland-Proven Fix:
If you smell gas or suspect a gas leak, leave the building immediately, even if the smell is faint. Do not operate switches, appliances or phones inside, light a flame, or start a vehicle near the suspected leak. Do not search for the leak, relight the furnace, or stop to shut off the gas supply. From a safe location away from the building, call 911 and NW Natural's 24-hour gas-emergency line at 800-882-3377. Do not re-enter until emergency responders or the utility say it is safe. After emergency responders or the utility have cleared the building, a qualified technician can inspect the furnace. We check for proper venting and may install vent guards or extend pipes above expected snow/moss lines. Cost: $100-$400 depending on extent.
Call Emergency Services If You Notice:
After emergency responders or the utility have cleared the building, contact EHC to request furnace service.
Any suspected gas leak, a sounding carbon monoxide alarm, or symptoms of possible carbon monoxide exposure
Gas smell present when furnace is completely off
Hissing sounds from gas pipes or furnace area
Dead plants or vegetation near gas lines
If you smell gas or suspect a gas leak, leave the building immediately, even if the smell is faint. Do not operate switches, appliances or phones inside, and do not stop to shut off the furnace or gas supply. From a safe location outside, call 911 and your gas utility's emergency line. Do not re-enter until emergency responders or the utility say it is safe.
Portland Furnace Gas Smell FAQs
Suspect a Gas Leak? Leave First, Then Call 911 From Safety
If you smell gas or suspect a gas leak, leave the building immediately, even if the smell is faint. Do not operate switches, appliances or phones inside, and do not stop to shut off the furnace or gas supply. From a safe location outside, call 911 and your gas utility's emergency line. Do not re-enter until emergency responders or the utility say it is safe. After emergency responders or the utility have cleared the building, contact EHC to request furnace service.