Fireplace carbon monoxide risks when a storm cuts the power

An alarm or symptoms mean everyone goes outside

Carbon monoxide gives no warning you can see or smell. CPSC describes low exposure as feeling like the flu, with headache, tiredness, shortness of breath, nausea and dizziness. Higher exposure brings confusion, vomiting, loss of coordination and loss of consciousness. Do not wait to be sure. Symptoms that start while a generator runs or a fire burns are reason enough to act.

Get everyone out, pets included, without stopping to open windows or hunt for the source. Phone 911 once you are outside. CPSC says to stay out until emergency responders tell you it is safe to go back in. After that, every fuel-burning appliance in the house should stay off until someone has found the cause.

Why a storm outage changes the carbon monoxide picture

The National Hurricane Center dates the Atlantic hurricane season from June 1 through November 30. A storm that knocks out power changes how a household runs. Generators come out of the garage, candles replace lamps, and any appliance that still works gets pressed into service. Each of those habits brings flame or exhaust closer to where people sleep.

In a storm-outage warning, CPSC says portable generators create a risk of carbon monoxide poisoning that can kill in minutes. The fireplace belongs in the same conversation. An outage can also come outside hurricane season, on an evening when a fireplace that has not been lit in months looks like the easy answer for light or warmth. Hold that fire until the flue has been checked, because a flue that sat idle through a storm may not be clear.

Keep the generator away from doors, windows and vents

CPSC gives a short rule. Run a portable generator outside only, at least 20 feet from the house, with the exhaust pointed away from the home and from any building people could enter. Do not run it on a porch or in a carport. Never run it inside a home, garage, basement or shed. CDC gives the same distance from doors, windows and vents.

Count the fireplace among those openings. The wall termination of a direct-vent gas fireplace is a vent. Makers such as Heat & Glo design these units to draw all their combustion air from outside through it. Keep the generator well clear of that termination and of the windows on the same wall. CPSC also suggests choosing a generator with an automatic CO shut-off, but distance still matters with one.

Treat an idle fireplace as unchecked after a storm

A fireplace that is lit a few nights a year can go months without anyone looking up the flue. A storm can change it in an afternoon. Wind can loosen or remove a chimney cap, and fronds, leaves or nesting material can drop into an open flue. CPSC asks inspectors to check chimneys and flues for blockages. Exhaust that cannot rise can spill back into the room.

Leave the fireplace unlit if you notice any of these from the yard or the hearth.

• A cap that is missing, tilted or bent
• Leaves, twigs or nest material resting on the damper
• A damper that will not open fully, or a top damper lid that stays shut
• Water, rust streaks or fallen debris in the firebox
• Smoke that rolled into the room the last time the fireplace was used

Wood fires and gas units during an outage

A wood fire in an outage deserves extra care. Burn only dry, seasoned firewood, and keep the damper fully open until the fire is completely out. Storm debris is not firewood. EPA warns against burning wet or green wood, and its list of things never to burn includes coated, painted and pressure-treated wood. That rules out treated fence boards and deck lumber.

Whether a gas fireplace works without household power depends on its ignition, and a gas fireplace can make carbon monoxide like any other gas appliance. Heat & Glo explains that a standing pilot lights without electricity, while a unit made in recent years may have an intermittent pilot that needs power to spark. Some of those electronic systems carry a battery backup for outages. The owner's manual says which one you have. If the manual does not clearly allow use during an outage, leave the unit off.

Even a unit that can light needs a clear vent. The same manufacturer asks owners to check the outside termination cap for plants, nests, leaves and debris. After a storm, make sure no shutter panel, tarp or plywood sheet covers it. Never use a gas range, oven or clothes dryer to heat the house. CPSC names all three as appliances that must not be used for heat.

CO alarms that keep working when the power is out

An alarm that runs only on household current goes quiet at the moment the risk climbs. CPSC recommends CO alarms that run on batteries or carry a battery backup, placed on each floor and outside the rooms where people sleep. Test them every month. CPSC also favors interconnected alarms, since one alarm sounding sets off the rest. CDC outage guidance also calls for a battery-operated detector.

Florida law sets a floor for newer buildings. Section 553.885 of the Florida Statutes covers a building or addition constructed on or after July 1, 2008. Where that building has a fireplace, an attached garage or a heater or appliance burning fossil fuel, it needs a CO alarm within 10 feet of each sleeping room. An older house is not bound by that section, but the same placement still makes sense in it.

Mount each alarm where its maker's instructions allow, and check that list before placing a carbon monoxide detector by the fireplace room. Keep alarms away from heating vents and from spots where furniture or drapes can cover them. A CO alarm does not detect smoke unless it is a combination unit, so the smoke alarms need their own monthly test.

A gas smell is a different emergency

Carbon monoxide has no odor, so a smell of gas points to a leak rather than to exhaust. The instructions printed in gas fireplace manuals, such as Heat & Glo's, set the order. Leave the building right away, without lighting anything, touching a switch or using a phone inside. Call the gas supplier from outside or from a neighbor's phone, and call the fire department if the supplier cannot be reached.

What a post-storm chimney and vent check covers

Once the house is safe and the power is back, have the fireplace looked at before its next fire. A chimney inspection after a storm checks the cap and crown, looks up the flue for debris and nests, and confirms the damper opens fully. It also looks over the firebox and smoke chamber for water or fallen material. Under NFPA 211, a chimney, fireplace or vent should get an inspection once a year whether or not a storm has passed.

For a gas unit, the visit covers the accessible vent and its joints, the termination outside, and the burner and controls. When a finding calls for gas fireplace repair, you approve the written estimate before any work starts. The inspection itself is free, and any work we do is written up for you once it is finished. If a repair has to leave the chimney open, we cover the opening before we leave each work day, and the storm debris we pull out leaves with us.

Sources

• CPSC Carbon Monoxide Fact Sheet: Symptoms, leaving for fresh air and calling 911, alarm placement with battery backup, blocked flues and never heating with a range, oven or dryer.
• CPSC portable generator warning for storm outages (2022): Generator placement outside the house with the exhaust directed away, and the added risk when storms cut power.
• CPSC carbon monoxide and fire safety release (2023): No generator inside a home, garage, basement or shed, interconnected alarms, monthly testing and generators with a CO shut-off.
• CDC guidance on preventing carbon monoxide poisoning in disasters: Generator distance from doors, windows and vents, outages during hurricanes and battery-operated detectors.
• NOAA National Hurricane Center climatology: Dates of the Atlantic hurricane season.
• Heat & Glo guidance on fireplaces during a power outage: Which gas ignition systems can light without household power, and the owner's manual as the reference.
• Heat & Glo 6000CLX-IFT owner's manual: A manufacturer example of the seasonal check of the termination cap for debris and the steps for a gas odor.
• Florida Statutes section 553.885, carbon monoxide alarms: CO alarm placement near sleeping rooms in newer buildings that have a fireplace or another fuel-burning source.
• EPA Burn Wise best wood-burning practices: No wet or green wood, and wood never to burn, including coated, painted and pressure-treated wood.
• NFPA 211, Standard for Chimneys, Fireplaces, Vents and Solid Fuel-Burning Appliances: Chimneys, fireplaces and vents inspected at least once a year.
• Heat & Glo 6000CLX-IFT installation manual: Direct vent units that take all combustion air from outside the building and send all exhaust outside.