4
Correct Ducting and Venting
Use proper sized smooth galvanized ductwork.
Do not use flexible duct.
Ribbing creates resistance to airflow, reducing exhaust efficiency.
Make gradual turns in duct run.
Do turn sharp corners. Air cannot make 90° turns.
Do not reduce suggested minimum size anywhere in duct run.
Even in wall louvers and roof jacks.
Use the shortest and straightest duct run possible.
Maximum duct run is 51’, including elbows.
Do not space elbows closer than 4’ to each other.
Do not make "S" turns or double elbows anywhere in duct run.
Maximum number of elbows in a duct run is 3.
Each elbow is equal to 6’ of duct run.