Furnace gas smell: what to do before anything else

What to do when the furnace smells like gas

When there is a furnace gas smell, what to do comes down to leaving first. If you smell gas, leave the house, then call the gas utility from outside.

Don't stop to find the source, and don't touch a light switch on the way out. A carbon monoxide alarm gets the same treatment: nobody stays inside to look around.

Why does gas mean leaving before anything else?

Natural gas burns. In a closed space it can build up until a small spark sets it off. The first move is to get out of the house and leave the leak hunt to others.

The source is hard to pin down from the doorway. A furnace burner, a stove, a water heater or a line inside a wall can all let gas into a room.

Gas heat is common in Pueblo. About 78% of the 46,414 occupied homes in Pueblo are heated with utility gas, and the City of Pueblo lists Xcel Energy as a gas provider for Pueblo. A gas utility is the one to phone from outside the house when there is a smell.

For the wider picture on heating and cooling in Pueblo, see the main HVAC page.

What should you never do inside the house?

Anything that can make a spark is off the table while the air may hold gas. That includes small habits you do without thinking.

• Flip a light switch, or change the thermostat.
• Light a match, a lighter or a candle.
• Use the garage door opener, or plug in or unplug anything.
• Open the furnace panel or try to relight a pilot.

Use your phone only after you are outside. Bring everyone, pets included, and stay out of the house until the gas utility says it is fine to go back in.

What does a carbon monoxide alarm mean?

Carbon monoxide, or CO, is a gas you can't see or smell. It forms when fuel burns without enough air, and a gas furnace is one place it can come from. An alarm is the only way most people learn it is in the house.

If a carbon monoxide alarm sounds, get everyone out and call emergency services.

Headache, dizziness and nausea can come with CO exposure, so mention it if anyone feels that way. Don't silence the alarm and go back in to check. Once the house is cleared, keep the furnace off until a licensed contractor has looked at it, because the cause may be the furnace itself.

Two furnace problems can send exhaust into the living space. One is a blocked or damaged vent. The other is a cracked heat exchanger, the sealed metal part that keeps burner exhaust apart from the air you breathe. Both are contractor work.

How do you check things before using the furnace again?

Start with the all-clear. The gas utility decides when the house is safe to enter, and your nose is not the test. If the furnace could be the cause, leave it off.

Once you are back inside, a few simple looks are fine:

• The thermostat setting and its batteries.
• The air filter, which should not be packed with dust.
• The space around the furnace, which should be free of boxes and clutter.
• Registers and return grilles, which should not be covered by furniture or rugs.

None of those clears a gas or CO problem. A licensed contractor checks the burner, the gas valve, the vent pipe, the heat exchanger and any wiring. Ask what was found and which part, if any, failed.

An older house adds one more question. About 72% of the 49,813 homes in Pueblo were built before 1980, and a furnace and vent in a house that old may be just as old. Older-home ducts, wiring and equipment covers what that means for heating.

If a furnace has a cracked heat exchanger or a vent problem that keeps coming back, the talk may turn to replacement. ENERGY STAR suggests considering replacement when a furnace or boiler is more than 15 years old.

When does furnace safety matter most in Pueblo?

The furnace works through the cold months, and that is when a gas smell or an alarm is most likely to involve it. The NOAA weather station near Pueblo averages 152 days a year with a low of 32°F or below. The average December to February daily low there is 16.0°F.

In a house shut up against cold like that, less fresh air moves through to thin out a leak or exhaust. Test the alarms and swap their batteries before heating season starts, and don't wait for the first cold snap.

Keep the filter clean and the area around the furnace clear all season. A furnace that a licensed contractor has looked over is easier to rely on than one nobody has opened in years, and the contractor advises how often that should happen.

Next step: a contractor check on the furnace

After the house is cleared, a furnace that was part of the scare needs a licensed contractor to inspect it before it runs again. Where a contractor is available, the line connects the call to that contractor. The way it works is laid out on the HVAC page for Pueblo.

Until then, the safety steps come first.