Fireplaces, Stoves, and Chimneys:Chimney Draft

Chimney Draft

A properly designed and constructed chimney is essential to a fire- place because it provides the draft necessary to remove the smoke and flue gases. The motive power that produces this natural draft is the slight difference in weight between the column of rising hot flue gases inside the chimney and the column of colder and heavier air outside the chimney.

For altitudes higher than sea level, the calculations obtained in the formula should be corrected by the factors listed in Table 3-2. Thus, if the structure is located at an altitude of approximately 1000 feet, the results obtained in the formula should be multiplied by the correction factor 0.966 to obtain the correct draft for that altitude.