EXTENDING DUCT LENGTH ON THE VENT-SURE VENT
The duct can be 60 feet in length and include up to four 90° bends, without a significant drop in static airflow or a reduction in kiln air pull. You may use any galvanized, stainless, or aluminum duct. The outlet duct size (after the motor) is 4” in diameter. The inlet duct (before the motor) is 3” in diameter. L&L used the experience of Orton to determine these instructions. If you are trying to make a longer duct with more bends or a different diameter duct that is 4" then you will need to calculate the static pressure of your system. If you keep your static pressure below 0.50 in, generally you will be fine.
Here are the airflow stats from the blower motor:
Airflow @ 0.000 in SP: 146 cfm
Airflow @ 0.100 in SP: 140 cfm
Airflow @ 0.250 in SP: 130 cfm
Airflow @ 0.400 in SP: 120 cfm
Airflow @ 0.500 in SP: 110 cfm
The maximum Static Pressure that the motor can handle is 3/4 in wc
