19
Fan Powered Terminal Units IOM
FIELD ADJUSTMENT OF MINIMUM AND MAXIMUM AIRFLOW
SET POINTS
Each parallel fan unit is equipped with a four quadrant
multi-point center averaging airflow sensor that provides
an amplified differential pressure that is proportional to
the unit airflow. Output from this probe is used to provide a
flow signal to both pneumatic and electronic controls. Unit
airflow (cfm) can be read directly from the flow probe on the
unit.
1.
After the unit airflow from the fan has been set, turn on
primary (VAV) air supply and turn off the fan.
2.
To set cfm in the field, connect a gage to the flow probe
and check the differential pressure.
3. If a minimum VAV flow is required in heating mode, adjust
the volume controller until the differential pressure
corresponds to the cfm required.
4. Some control sequences allow the fan to start before the
VAV damper reaches minimum setting, for an overlapping
of fan and VAV flow. For these sequences, after controller
min airflow has been adjusted, the total airflow with
both fan and primary airflow should be checked. For
sequences that call for the fan to start as the first stage
of heat, the cooling minimum cfm can be verified at the
diffuser. Setting the minimum control point will typically
require careful adjustment of the thermostat to create a
minimum cooling demand signal.
a. Set the controller to provide maximum cooling
demand. This is typically accomplished by setting
the thermostat to the lowest possible temperature
setting. For most control sequences, this will cause
the fan to shut off.
b.
Adjust the volume controller until the differential
pressure (measured through the flow probe as
described above) corresponds to the cfm required.
6. Return all reheat options to normal connections.
7. Cap the ends of the inlet flow sensors.
8. Reset the thermostat to a normal setting.
5.
TABLE 11 - KQFP Parallel Fan Terminal Unit
UNIT SIZE
INLET SIZE
PRIMARY AIR FLOW
PCS MOTOR
ECM MOTOR
MAX
MIN
MOTOR HP
MAX FAN
MIN FAN
MOTOR HP
MAX FAN
MIN FAN
2
6
515
90
1/4
500
150
N/A
8
920
16
3
6
515
90
1/4
800
160
N/A
8
920
160
10
1430
250
4
6
515
90
1/4
900
190
1/2
1000
250
8
920
160
10
1430
250
12
2060
360
5
10
1430
250
1/2
1700
480
N/A
12
2060
360
14
2800
480
6
10
1430
250
1/2
1700
500
N/A
12
2060
360
14
2800
480
16
3660
630
7
10
1430
250
3/4
2000
780
1
1600
400
12
2060
360
14
2800
480
16
3660
630
TABLE 11 - KQFP Parallel Fan Terminal Unit
Summary of Contents for KLPP
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