The flue was the throat of the chimney. A metal plate on a hinge that you opened to let the smoke out and closed to keep the cold from coming in. Open the flue and the fire drew. Close the flue and the heat stayed. The flue was the building's valve between inside and outside. One lever and you controlled the conversation between the fire and the sky.

You forgot to open the flue. Everybody forgot at least once. You lit the fire and the smoke had nowhere to go and the apartment filled up and your eyes burned and you ran to the fireplace and pulled the lever and the smoke went up the chimney like it had been waiting. The flue taught you that fire needs permission. You forgot the flue once and you never forgot again. The lesson cost you nothing but a cough and some tears.

The flue was a damper. That was the other word. The damper damped the draft. You opened the damper halfway and the fire burned slow. You opened it all the way and the fire roared. The flue was the throttle on the building's engine. You learned to read the fire by the sound of the draft. A low hum meant the flue was right. A whistle meant too much air. The flue talked to you if you listened.

The flue needed cleaning. Creosote built up on the inside of the chimney like cholesterol in an artery. The chimney sweep came with brushes on a long rod and scraped the flue clean and the building breathed again. A dirty flue was a fire waiting to happen. The chimney sweep was the building's doctor. The building coughed and the sweep came and the building stopped coughing. The gas furnace does not cough. The gas furnace does not breathe. The gas furnace does not need a sweep. The building lost its doctor when it lost its chimney.

They sealed the flue. Bricked it up or cemented it shut when the fireplace became decorative. The flue is closed forever. The fire that used to heat the apartment now decorates the apartment. A candle in a fireplace with a sealed flue. The flame that used to need the sky now needs nothing. The flue was the connection between the fire and the air and they severed it and called it renovation.

See also: Chimney Cap, Coal Stove