Carrier 35L Series, Installation And Start-Up Instructions Manual

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6
CONTROL SET UP
General —
The 35L,N dual duct terminals are designed to
maintain optimum temperatures in the conditioned zone by
varying the air volume supplied by the hot and cold ducts while
providing the proper discharge air temperature.
To balance the unit it is necessary to set both the maximum
and minimum set points of the controllers. Many types of con-
trol options are available, each have specific procedures re-
quired for balancing the unit.
Set Points —
Maximum and minimum airflow set points
are normally specified for the job and specific for each unit on
the job. Where maximum and minimum airflow levels are not
specified on the order, default values are noted on unit ID label.
Field Adjustment of Minimum and Maximum
Airflow Set Points —
Each unit is equipped with a flow
probe which measures a differential pressure proportional to
the airflow. The relationship between flow probe pressures and
cfm is shown in the Flow Probe Chart (Fig. 4A-4C). This chart
is attached to each unit.
System Calibration of the Linear Averaging
Flow Probe —
To achieve accurate pressure independent
operation, the velocity sensor and linear averaging flow probe
must be calibrated to the controller. This will ensure that air-
flow measurements will be accurate for all terminals at system
start-up.
System calibration is accomplished by calculating a flow
coefficient that adjusts the pressure fpm characteristics. The
flow coefficient is determined by dividing the flow for a given
unit (design air volume in cfm), at a pressure of 1.0 in. wg
differential pressure, by the standard pitot tube coefficient of
4005. This ratio is the same for all sizes if the standard linear
averaging probe is used.
Determine the design air velocity by dividing the design air
volume (the flow at 1.0 in. wg) by the nominal inlet area
(sq ft). This factor is the K factor.
ANALOG OR DDC
CONTROLLER
24VAC
BLU
YEL
CLASS II
TRANSFORMER
(OPTIONAL)
120VAC
208VAC
240VAC
277VAC
L1
GROUND
24 VAC
POWER
927
3709 3709
1449
2086
2840
6 "
8 "
10 "
12 "
10
100
1000
10000
Flow
Constant
CFM A
T
ONE INCH SIGNAL
CFM
FLOW PROBE PRESSURE DIFFERENTIAL IN.WG
VOLTS (ANALOG CONTROLS)
0.01 0.1 1
Largest
Inlet Size
14-16"
LEGEND
NOTE: Drawing is typical — refer to actual unit wiring diagram for
details.
Fig. 3 — Wiring of Optional Factory-Mounted
Transformer
DDC — Direct Digital Controls
Field Wiring
Factory Wiring
NOTE: Size 16 discharge is same as inlet.
Fig. 4A — Dual Duct Outlet Flow Probe Chart
(35N only)
CFM A
T
ONE INCH SIGNAL
CFM
522
927
1449
2086
2840
10
100
1000
10000
3665
0.01
0.1
1
16 inch
14 inch
12 inch
10 inch
8 inch
6 inch
FLOW PROBE PRESSURE DIFFERENTIAL IN.WG
VOLTS (ANALOG CONTROLS)
NOTE: Size 16 discharge is same as inlet.
Fig. 4B — Dual Duct Inlet Flow Probe Chart
(35N only)