Chimney fire or smoke in the room: closing the door on a pizza oven flue

Flame at the chimney cap or smoke indoors: which one you have

Flame curling out of the oven mouth during a big fire is overfiring, not a chimney fire. Coyote's Duomo manual says flames should never come out of the mouth or up from the chimney, and that too much wood causes it; Alfa warns that a load of wood big enough to push flames out of the chimney cap can cause property damage, injury or death. Both are warnings about the next step: once the flue lining is coated, a run of flame up the pipe can light the coating itself.

Smoke in the room is the other failure. It means the flue is not drawing, because it is blocked, too short, cold, or fighting a kitchen exhaust or a gust of wind. It rarely comes with the roar of a flue fire, but it brings carbon monoxide and fine particles into the space where people are standing, so it is treated as urgent too.

Source: Coyote — Duomo Wood Fired Pizza Oven Owner's Manual — No flames from the mouth or chimney; if it happens, close the door and wait for the fire to die down; never use water on the bricks or to put out the flame; soft and painted wood coat the flue with creosote; Alfa Forni — User manual, domestic ovens (North America) — Never use so much wood that flames exit the chimney cap; slow burning forms creosote in the flue; inspect for creosote at least twice a year and sweep the flue once a year

Starving a pizza oven chimney fire of air

A wood fire needs air coming in at the mouth to feed anything burning up the flue. Coyote tells owners who see flames from the mouth or chimney to close the oven door and wait for the fire to die down, and NFPA's advice for any oven fire is to turn off the heat and keep the door closed. On a hybrid or gas-fired dome, close the gas at the burner knob and the supply valve if you can reach them without standing under the cap or beside a glowing pipe.

Chicago Brick Oven asks every owner to have a clearly understood plan for handling a chimney fire and to ask the local fire authority how to go about it. The plan is short: who closes the door, who closes the gas, who moves guests back, who calls. Settle it before the first party, not while the pipe is roaring.

Source: Coyote — Duomo Wood Fired Pizza Oven Owner's Manual — No flames from the mouth or chimney; if it happens, close the door and wait for the fire to die down; never use water on the bricks or to put out the flame; soft and painted wood coat the flue with creosote; Chicago Brick Oven — CBO-500/750/1000 User Manual — Creosote makes an extremely hot fire when ignited; have a clearly understood plan for a chimney fire and ask the local fire authority; use hardwood dried at least two years; NFPA — Cooking safety — For an oven fire, turn off the heat and keep the door closed; get out, close the door behind you and call 9-1-1 after you leave

Smoke rolling into the room or the covered patio

EPA's Burn Wise guidance for smoke inside a home is to shut down the wood-burning appliance, open a window, make sure the flue is open and call a professional installer or chimney sweep. For a pizza oven that means no more wood, the door set as the manual allows so the fire burns down, windows and doors opened to the outside, and people who are sensitive to smoke taken out of the room first. EPA names children, older adults and anyone with heart or lung disease, asthma included, as more at risk from wood smoke.

If there is a carbon monoxide alarm, it overrides everything else. NFPA says that when a CO alarm sounds, move to fresh air outdoors or by an open window or door, make sure everyone is accounted for, and call for help from that fresh-air spot.

Source: NFPA — Carbon monoxide safety — If the CO alarm sounds, move to fresh air outdoors or by an open window or door, account for everyone and call for help from there; EPA Burn Wise — Wood-burning installation and maintenance — If you smell smoke in the home, shut down the appliance, open a window, make sure the flue is open and call a professional installer or chimney sweep; chimney cracks can let smoke in and expose parts to high temperatures; EPA Burn Wise — Wood smoke and your health — Children, older adults and people with heart or lung disease, including asthma, are at greater risk from wood smoke

Where the fuel for a flue fire comes from

Alfa and Chicago Brick Oven describe the same process: wood burned slowly gives off tar and organic vapors that mix with moisture from the wood, condense on the cooler walls of the flue and build up as creosote. Wet wood, soft wood and long smoldering fires feed it fastest. Coyote warns that pine, fir, cedar, painted wood and plywood coat the oven and the flue with creosote, and Chicago Brick Oven asks for hardwood dried at least two years.

How often the flue needs attention depends on use. Alfa asks home owners to inspect the chimney for creosote at least twice a year and to sweep it once a year, partly because nesting birds can block it. Marra Forni asks restaurants to inspect the flue, the exhaust duct and the power ventilator at least twice a month and to hire experienced duct-cleaning crews to remove creosote and grease.

Source: Coyote — Duomo Wood Fired Pizza Oven Owner's Manual — No flames from the mouth or chimney; if it happens, close the door and wait for the fire to die down; never use water on the bricks or to put out the flame; soft and painted wood coat the flue with creosote; Alfa Forni — User manual, domestic ovens (North America) — Never use so much wood that flames exit the chimney cap; slow burning forms creosote in the flue; inspect for creosote at least twice a year and sweep the flue once a year; Chicago Brick Oven — CBO-500/750/1000 User Manual — Creosote makes an extremely hot fire when ignited; have a clearly understood plan for a chimney fire and ask the local fire authority; use hardwood dried at least two years; Marra Forni — Static oven manual (Rev. 5-2026) — Hood and makeup-air blowers must run whenever the oven is fired; if the power ventilator fails, close the oven door to extinguish the fire; inspect flue, duct and ventilator at least twice monthly

After the fire, before the next bake

A chimney fire can crack a clay or masonry liner, separate pipe joints, buckle a rain cap and scorch framing where the flue passes a roof or wall. EPA notes that chimney cracks can let smoke into the home and expose surrounding parts to temperatures high enough to start a fire. Most of that damage cannot be seen from the patio, so the oven stays cold until someone qualified has looked at the whole run.

What you can do from the ground is gather details for the visit: photos of the cap and the outside of the pipe, a note of how long the roar lasted, what wood was burned that night and when the flue was last swept.

• The flue lining and every pipe joint, from the oven collar to the cap
• The rain cap and spark screen, often clogged with soot flakes
• Clearances where the pipe passes a roof, pergola or wall
• The dome and floor near the flue opening for new cracks
• On commercial ovens, the hood, the duct and the fan

Source: EPA Burn Wise — Wood-burning installation and maintenance — If you smell smoke in the home, shut down the appliance, open a window, make sure the flue is open and call a professional installer or chimney sweep; chimney cracks can let smoke in and expose parts to high temperatures; USFA — Heating fire safety — Have heating equipment and chimneys cleaned and inspected each year by a professional