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Table 12 — Secondary Damper Service Configuration Screen
Secondary Duct Size
— The Secondary Duct Size setting is
used to input the inlet diameter of the terminal, if used with a
round inlet. The Inlet Area configuration is used for oval or
rectangular inlets. The zone controller will use the larger value
for CFM calculations if both values are configured.
Secondary Duct Size
(Inlet Diameter): Units Inches
Range 3.0 to 24.0
Default Value 6.0
Inlet Area — The Inlet Area configuration is used if the termi-
nal has an oval or rectangular inlet. The Primary Inlet Size
configuration is used for round inlets. The zone controller will
use the larger value for CFM calculations if both values are
configured.
Inlet Area: Units Square Inches
Range 0.0 to 500.0
Default Value 0.0
Probe Multiplier
— This configuration is used to input a fac-
tor for the velocity pressure probe characteristics installed in
the inlet. All averaging probes will have some aerodynamic
characteristics which will amplify the pressure difference read
at the inlet of the terminal. The default of 2.443 is the correct
value to use if the probe is a Carrier probe in a 35 or 45 Series
terminal.
The formula for calculating velocity using an Ideal probe is:
Velocity = 4005* SQRT (Velocity Pressure)
Most manufactures will provide a probe constant for the
probe supplied. For example, Velocity = 2213*SQRT(Velocity
Pressure). To calculate the number to input in this decision
(Probe Multiplier) use the formula. (4005/2213)
2
= 3.3. So you
would use 3.3 in place of 2.443 for a probe with a probe con-
stant of 2213.
An easy way to determine the probe constant for a probe
without documentation is to measure the velocity pressure with
a Magnahelic gage. Open the damper and adjust the static pres-
sure until you have one inch of velocity pressure on the Magna-
helic gage. Measure the total CFM of air being produced. The
CFM just measured divided by the inlet area in feet should
equal the probe constant for the formula. Velocity = (CFM just
measured/inlet area) * SQRT (1.0). Now use the constant that
was empirically derived to determine the probe multiplier
(4005/(CFM at 1.0 Inch/Inlet area))
2
= Probe Multiplier.
Probe Multiplier: Range 0.250 to 9.999
Default Value 2.443
Calibration Gain
— Air terminal testing by industry standards
is done with straight duct, upstream of the terminal. Since most
applications do not get installed in this manner, the actual air-
flow from the terminal at balancing may not equal the reading
from the zone controller.
The calibration gain is used for the fine tuning adjustments
which might need to be made to the airflow calculation.
If the Calibration Gain must be configured manually. It is
determined as a percentage up or down that the CFM indicated
will be offset. A number of .95 will cause the maximum air-
flow calculated to be reduced to 95% of the value. A Calibra-
tion Gain of 1.00 will cause no change. A number of 1.05
would cause readings to become 5% higher.
Any error in reading at minimum airflow is adjusted by cal-
culating the Offset configuration value.
Calibration Gain: Range 0.000 to 9.999
Default Value 1.000
Offset
— The Offset configuration is included for precision
applications where the minimum airflow is critical and not
zero. The cfm will be offset by the value entered in the Mini-
mum Cfm variable and will zero at the value entered in the
Maximum Cfm variable. There will be a linear relationship be-
tween the two set points.
Offset: Units cfm
Range –250 to 250
Default Value 0
Clockwise Rotation
— This configuration is used to define
what effect a clockwise rotation of the actuator will have on the
damper. If the actuator rotates clockwise to closed position, the
configuration should be set to Close. If the actuator rotates
clockwise to open, the configuration should be set to open.
This configuration is used to change the rotation of the actuator
so that the damper transducer calibration will work properly.
The actuator does not have to be reinstalled nor any switches
changed to reverse the action.
Clockwise
Rotation: Range Close/Open
Default Value Close
Maintenance Table Menu Screen —
The Mainte-
nance Table Menu screen allows the user to select one of 4
available maintenance tables: the Linkage Maintenance Table,
the Occupancy Maintenance Table, the Zone Air Balance
Table, and the Zone Maintenance Table.
LINKAGE MAINTENANCE TABLE — The Linkage
Maintenance table is used to view the zone linkage variables.
See Table 13.
Air Source Bus Number
— This variable will display the bus
number of the air source that the zone controller will be com-
municating Linkage to, if this zone is the Linkage Master.
Air Source
Bus Number: Range 0 to 239
Default Value 0
Network Access None
Air Source Element Number
— This variable will display the
Element Address of the Air Source that the zone controller
will be communicating Linkage to, if this zone is the Linkage
Master.
Air Source
Element Number: Display Range 1 to 239
Default Value 0
Network Access None
DESCRIPTION DEFAULT POINT NAME
Zone Pressure Control
Dsable ZPCNTL
Dual Duct Type
0 DDTYPE
Secondary Duct Size
Inlet Diameter
Inlet Area
6.0 in.
0.0 sq. in.
SRNDSZ
SSQA
Probe Multiplier
2.443 SPMF
Calibration Gain
1.000 CAL_GAIN
Offset
0 cfm SOFFSET
CW Rotation
Close DMPDIR
501
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