Chimney Fire Extinguishers and Suppressants

Two different fires at the same fireplace

It helps to separate the fire you light from the fire you never meant to have.

• A fire that escapes the firebox. An ember pops onto the rug, a log rolls against the screen, a kindling box catches. These are small fires in the room, at floor level, where you can see them and reach them.
• A chimney fire. Creosote or other deposits on the flue walls ignite. The fire runs inside the chimney, above the damper and behind masonry or metal. The Chimney Safety Institute of America describes the masonry chimney version as extremely dangerous and says to call 911 immediately. Our guide to signs of a chimney fire covers what it sounds and looks like.

A portable extinguisher is a tool for the first kind. For the second, the right tools are distance and the fire department.

Why a chimney fire fails the extinguisher test

The U.S. Fire Administration lists questions to answer before anyone uses an extinguisher, and says to use one only if every answer is yes. Run a chimney fire through them:

• Have others been alerted, and has someone called the fire department? Those come first in any case.
• Is the fire small and contained in a single object or to a surface, like a pan or a wastebasket? A fire spread along the inside of a flue is neither small nor in reach.
• Am I safe from the fire's toxic smoke? A chimney fire can push smoke into the room and through cracks in the masonry.
• Do I have a clear escape route? Standing at the fireplace with your back to the room is the wrong place to be.
• Am I physically able to use one? USFA notes that young children and older adults should not use fire extinguishers.

USFA's direction for every other situation is to warn others, leave the building and call 911 from a cell phone or a neighbor's phone.

The tools, side by side

USFA's guide to extinguisher classes lists Class A for ordinary combustibles, B for flammable liquids, C for electrical fires, D for metals and K for cooking oils, and says multipurpose units labeled B-C or A-B-C cover most home fires. It also advises choosing one listed by a nationally recognized testing laboratory, in the largest size you can handle safely and comfortably.

About chimney fire suppressant products

Some products are marketed specifically for chimney fires. They differ in form and in their directions, and none is a substitute for a working chimney or a fire department. If you own one, read its label now, while nothing is burning, so you know whether the damper should be open, whether glass doors should be closed and how far to stand back.

Keep the order straight. Everyone out and 911 called comes first. Using a suppressant is a step you take only if the label's directions can be followed on your way out of the room, and only if it does not delay leaving. A fire that appears to be out may still be burning between the flue liner and the masonry, which is a job for firefighters with the tools to check.

Why water is the wrong reflex

Throwing water into a fireplace or onto a stove during a chimney fire is a common instinct. The Anderson Township Fire Department's wood-burning safety sheet says plainly to never throw water on a hot stove. Water hitting hot surfaces flashes to steam that can carry hot ash back into the room, and sudden cooling can damage hot metal, glass and masonry. Firefighters decide when and how water is used.

The same fire department sheet gives the actions that can help on the way out for a wood stove: call the fire department, get everyone out of the house, and close the stove door, draft opening and damper to cut off air to the fire. Do these only if they take seconds and the room is safe.

Keeping an extinguisher ready

A portable extinguisher near a fireplace or stove still makes sense for the small, room-level fires described above. A few habits keep it useful:

• Placement. Keep it where you can grab it on the way to the fire and still keep an exit behind you, and where furniture will not block it. USFA advises keeping extinguishers unblocked.
• Monthly glance. USFA advises checking the pressure gauge if there is one, and making sure the can, hose and nozzle are not damaged, dented or rusted.
• Upkeep by type. USFA notes that some units need to be shaken monthly, others need pressure testing every few years, and some can be recharged while others must be replaced when pressure is low. Follow the instructions printed on yours.
• Recalls. Extinguishers are recalled from time to time. In 2017 the U.S. Consumer Product Safety Commission announced a recall of about 37.8 million extinguishers in the U.S. that could fail to discharge. Check yours against CPSC's recall listings.
• Training. USFA notes that fire departments can offer extinguisher training. The PASS method it teaches is pull the pin, aim low at the base of the fire, squeeze the lever slowly and evenly, and sweep from side to side.

Alarms do the early work

Many chimney fires are noticed by sound or smell, but a quiet one may not be noticed at all, and smoke can reach bedrooms before anyone smells it. The New Jersey Division of Fire Safety advises installing and maintaining smoke and carbon monoxide alarms on all levels of your home. Those alarms buy the minutes that make getting out and calling 911 possible, which an extinguisher on the wall cannot do.

Plan the exit the same way you plan where the extinguisher hangs. Everyone in the house should know two ways out of each room and a meeting place outside, so a chimney fire at night turns into a head count on the lawn instead of a search. Our guide to carbon monoxide alarms covers placement and testing.

After any chimney fire, even a small one

A chimney fire that burned out on its own, or that seemed to stop after a suppressant was used, can still have cracked the flue liner, warped the damper or heated nearby framing. Keep the fireplace or stove out of service until the chimney has been inspected. The steps are in what to do after a chimney fire, and our chimney fire damage inspection documents the flue with photos and a camera when the flue allows.

The better plan is the one that keeps the extinguisher on the wall: dry wood, moderate fires, and a chimney inspected every year and swept when it needs it. See preventing chimney fires.

Questions homeowners ask

Sources

1. U.S. Fire Administration: Choosing and using fire extinguishers
2. CSIA: Preventing chimney fires
3. Anderson Township Fire and Rescue (Ohio): Burning wood safely (PDF)
4. NJ Division of Fire Safety: Fire safety facts, fireplaces and chimneys (PDF)
5. U.S. CPSC: Fire extinguisher recall announcement, November 2, 2017

This guide is general information. It can't diagnose a specific chimney; an inspection can.