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SUPPLY FAN DUCT STATIC PRESSURE
This feature allows the setting of the duct static control
point.
Field Wiring
None required.
Programming
The following item must be programmed through the
"Setpoints" section of the User Interface:
•
"Fan-S/A Pres SP" – must be set to the duct
static value you want to maintain. The range is
0.0" WC to 2.0" WC. The default value is 0.5"
WC.
•
"# of SP Sensors" – The control has the capability
to use one or two duct static sensors. If a single
sensor is used this value would be set to 1. If two
sensors are used this value would be set to 2.
•
"SP Calc Method" – If the unit uses two sensors
this value can be set to "High, Avg, or Low". If
the control is programmed to "High", the con-
trol will compare the higher of the two sensor
inputs to the "Fan- S/A Pres SP" and control
the speed of the VFD based on these values. If
the control is programmed to "Low" the control
will compare the lower of the two sensor inputs
to the "Fan- S/A Pres SP" and control the speed
of the VFD based on these values. If the control
is programmed to "Avg" the control will compare
the average of the two sensors to the "Fan- S/A
Pres SP" and control the speed of the VFD based
on these values.
JOHNSON CONTROLS
FLEXSYS (continued)
SUPPLY AIR PROVING SET POINT
The Unit Control monitors the pressure drop across
the evaporator coil to determine if the supply fan is
operating. If the pressure drop is equal to or greater then
this value the Unit Control allows the unit to operate.
Field Wiring
None required.
Programming
The following item must be programmed through the
"Setpoints" section of the User Interface:
•
MINIMUM COIL PRESSURE DROP
The Unit Control uses the pressure drop across the
evaporator coil as an indicator of the airflow across the
coil. When the bypass damper opens, it bypasses air
around the evaporator coil. If too much air is bypassed
the pressure drop (airflow) across the coil decreases.
This parameter establishes the minimum pressure drop
(airflow) allowed across the evaporator coil.
Field Wiring
None required.
Programming
The following item must be programmed through the
"Setpoints" section of the User Interface:
•
"POA DX Prs Drop" – this parameter can be set
between 0.06" WC and 1.0" WC. The default
value is 0.10" WC.
"Min DX Prs Drop" – this parameter can be set
between 0.20" WC and 1.0" WC. The default
value is 0.5" WC.
FORM 145.05-SU2 (1207)
11
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