7
START-UP
Unit Preparation
Check that unit has been installed in accordance with the in
-
stallation instructions and applicable codes. Make sure that the
economizer hoods have been installed and that the outdoor fil
-
ters are properly installed.
Internal Wiring
Ensure that all electrical connections in the control box are
tightened as required. If the unit has modulating gas or SCR
electric heat, make sure that the LAT (leaving air temperature)
sensors have been routed to the supply ducts as required.
Accessory Installation
Check to make sure that all accessories, including space ther
-
mostats and sensors, have been installed and wired as required
by the instructions and unit wiring diagrams.
Crankcase Heaters
Crankcase heaters are energized as long as there is power to the
unit, except when the compressors are running.
Evaporator Fan
Fan belts and fixed pulleys are factory-installed. See Tables 3-
22 for fan performance. Be sure that fans rotate in the proper
direction. Component pressure drop data is shown in Tables 19
and 20. See Tables 21 and 22 for motor limitations.
FIELD-SUPPLIED FAN DRIVES
Supply fan and power exhaust fan drives are fixed-pitch, non-
adjustable selections for maximum reliability and long belt
life. If the factory drive sets must be changed to obtain other
fan speeds, consult the nearest Browning Manufacturing Co.
sales office with the required new wheel speed and the data
from Physical Data and Supply Fan Drive Data tables (center
distances, motor and fan shaft diameters, motor horsepower) in
Installation Instructions for a modified drive set selection. For
minor speed changes, the VFD can be used to provide speed
control. See page 169 for belt installation procedure.
Controls
Use the following steps for the controls:
1. Set any control configurations that are required (field-
installed accessories, etc.). The unit is factory configured
for all appropriate factory-installed options.
2. Enter unit set points. The unit is shipped with the set point
default values. If a different set point is required, use the
Navigator™ display or CCN interface to change the con
-
figuration values.
3. If the internal time schedules are going to be used, config
-
ure the Occupancy schedule.
4. Verify that the control time periods programmed meet cur
-
rent requirements.
5. Use Auto Commisioning mode to verify operation of all
major components.
6. If the unit is a VAV unit, make sure to configure the static
pressure set point. To check out the VFD, use the VFD
instructions shipped with the unit.
Gas Heat
Verify gas pressure before turning on gas heat as follows:
1. Turn off field-supplied manual gas stop, located external
to the unit.
2. Connect pressure gages to supply gas tap, located at field-
supplied manual shutoff valves.
3. Connect pressure gages to manifold pressure tap on unit
gas valve.
4. Supply gas pressure must not exceed 13.5 in. wg. Check
pressure at field-supplied shut-off valve.
5. Turn on manual gas stop and initiate a heating demand.
Jumper R to W1 and R to W2 in the control box to initiate
high fire heat.
6. After the unit has run with high fire energized for several
minutes, verify that incoming pressure is 5.0 in. wg or
greater and that the manifold pressure is 3.1 in. wg. If
manifold pressure must be adjusted, refer to Gas Valve
Adjustment section on page 184.
7. Use the Service Test procedure to verify all heat stages of
operation.
IMPORTANT: Do not attempt to start unit, even momentar
-
ily, until all items on the Start-Up Checklist (at the back of
this book) and the following steps have been completed.
IMPORTANT: The unit is shipped with the unit control dis
-
abled. To enable the control, set Local Machine Disable
(
Service Test
STOP
) to No.
IMPORTANT: Unit power must be on for 24 hours prior to
start-up of compressors. Otherwise, damage to compressors
may result.
IMPORTANT: The unit is shipped with the unit control dis
-
abled. To enable the control, set Local Machine Disable
(
Service Test
STOP
) to No.
Summary of Contents for WeatherExpert 48N2
Page 135: ...135 Fig 18 48 50N Typical Power Schematic Nominal 075 Ton Unit Shown ...
Page 136: ...136 Fig 19 48 50N Typical Power Schematic Nominal Ton 90 150 Units Shown ...
Page 137: ...137 Fig 20 48 50N Main Base Board Input Output Connections ...
Page 138: ...138 Fig 21 48 50N RXB EXB CEM Input Output Connections a48 9307 ...
Page 139: ...139 Fig 22 48 50N EXV SCB Input Output Connections a48 9308 ...
Page 140: ...140 Fig 23 48N Typical Modulating Gas Heat Unit Control Wiring ...
Page 141: ...141 Fig 24 50N Typical Electric Heat Unit Control Wiring ...
Page 144: ...144 Fig 27 48N Typical Gas Heat Section Wiring Nominal Ton 120 to 150 Units ...
Page 145: ...145 Fig 28 48 50N Typical Power Component Control Wiring 460 v ...
Page 146: ...146 Fig 29 48 50N Component Control Wiring 575 v Nominal Ton 075 to 150 Units ...
Page 147: ...147 Fig 30 48 50N Component Arrangement Power Box ...
Page 148: ...148 Fig 31 48 50N Component Arrangement Control Box ...
Page 240: ...240 APPENDIX D VFD INFORMATION CONT Fig G VFD Bypass Wiring Diagram WHEN USED ...