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MODULATING POWER EXHAUST
48FK,JK and 50FK, JK Units
— The tubing for the building
pressure control (achieved via the Modulating Power Exhaust
option/accessory) should sample building pressure in the area
near the entrance lobby (or other appropriate and sensitive
location) so that location is controlled as closely to design pres-
sures as possible.
A differential pressure switch (DPS) is used to control the
actuator on the modulating discharge damper in exhaust fan
no. 1. The building pressure (BP) DPS is located in the auxilia-
ry control box of the unit. See Fig. 33 and 35. Use a nominal
3
/
8
-in. plastic tubing.
For instructions on adjusting BP control set points, refer to
Start-Up, Modulating Power Exhaust section in this book.
48FM and 50FM,FS Units
— The tubing for the building
pressure control (achieved through the High Capacity Modu-
lating Power Exhaust) should sample the building pressure in
the area near the entrance lobby (or other appropriate and sen-
sitive location) so that the location is controlled as closely to
design pressures as possible.
A building pressure transducer (BPT) is used to sense the
building pressure and supply a 4 to 20 mA signal to the power
exhaust VFD (PE VFD) which controls the speed of exhaust
fan motor no. 1 and stages on/off power exhaust fan motor
no. 2 to maintain the building pressure. The BPT is located in
the auxiliary control box. Use a nominal
1
/
4
-in. plastic tubing.
For instructions on adjusting the BP control set point, refer
to Start-Up, High Capacity Modulating Power Exhaust section
in this book.
START-UP
Initial Check
1. Verify unit has been installed per the Installation Instruc-
tions included in the unit installation packet.
2. Verify that all auxiliary components (sensors, controls,
etc.) have been installed and wired to the unit control
boxes per these instructions, the unit Installation Instruc-
tions, and the unit wiring label diagrams.
3. Verify that air pressure hoses (static, duct, etc.) are prop-
erly attached, routed, and free from pinches or crimps that
may affect proper control operation.
4. Set any control configurations that are required (field-
installed accessories, etc.). The unit is factory configured
for all appropriate factory-installed options with the ap-
plicable controls programmed to the default values.
5. Check and adjust unit set points. See Table 9.
6. Check tightness of all electrical connections.
7. Perform quick test (see Quick Test Program section on
page 31).
IMPORTANT: Do not attempt to start unit, even
momentarily, until all items on the Controls Start-Up
Checklist (in installation instructions) and the following
steps have been completed.
Fig. 33 — Modulating Power Exhaust and Inlet
Guide Vane Differential Pressure Switch
(Sizes 034-048)
Fig. 34 — Inlet Guide Vane Differential
Pressure Switch and Variable Frequency Drive
(Sizes 054-104)
Fig. 35 — Modulating Power Exhaust Differential
Pressure Switch (Sizes 054-104)