FAN FILTER UNIT
BALANCING
Balancing Ducted Supply – Pressure Independent and Dependent Airflow Control
NOTE:
If there is a pressure independent device upstream of the FFU then PSC or ECM with constant torque motors should be
used.
If FFU is not already installed:
Step 1:
Set FFU with filter installed, on benchtop and set to desired airflow. See
Airflow Setpoint
section to determine initial setpoint.
Step 2:
Confirm airflow using a flow hood and adjust speed controller as required.
Step 3:
Ensure each supply air duct is balanced to scheduled airflow and matches FFU set point.
Step 4:
Turn off primary air source.
Step 5:
Install FFU into ceiling, connect ductwork.
Step 6:
Turn all FFUs on – ensure all FFUs are running before proceeding to next step.
Step 7:
Turn on primary air source.
Step 8:
Measure airflow using flow hood and compare against scheduled flow. FFU inlet static should be verified to be neutral.
See table below if proper operation is not achieved.
DUCTED UNIT: CONSTANT TORQUE FFU WITH
UPSTREAM PRESSURE INDEPENDENT TERMINAL
DUCTED UNIT: CONSTANT FLOW
FFU WITH UPSTREAM PRESSURE
DEPENDENT TERMINAL AND MANUAL DAMPER
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