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McQuay OM 920-1
Operator’s Guide
Building Static Pressure Control
A PI control loop is used to modulate the variable frequency drive of the exhaust fans to
maintain a measured building static pressure at a setpoint. The BSP Gain, Project Ahead Time,
and Sample Time are editable via the keypad
The Building Static Pressure setpoint may be set through the keypad or via a network signal.
The active setpoint is changed whenever either of these values changes so it equals whichever
value was changed most recently.
Speed Control
When speed control is selected, the fan operates at the larger of its minimum speed or a value
provided via a connected network or the keypad/display. This value reverts to zero when the
unit is off and remains at that value after startup until a non zero value is written via the
network or the keypad/display. The exhaust fan does not start until a value greater than the
minimum value is written by the network or keypad/display.
