Lennox LGH094U Unit Information page 39

the Unit Controller will energize the unit after five (default)
minutes. While line voltage is continually checked by the
Unit Controller, the voltage phasing is not. If one or more
phases is interrupted, power to one or more transformers
is interrupted and the unit is shut down by either the Unit
Controller or the corresponding transformer.
Note - Optional phase/voltage detection is set at the factory
and is enabled by the Unit Controller internal logic. If an af­
ter market device is installed, refer to the device manufac­
turer's literature.
On units equipped with Unit Controller firmware version
7.06 and earlier:
Voltage, phase and frequency are checked on start-up
Blower Operation
NOTE-The following is a generalized procedure and does
not apply to all thermostat control systems.
1- Blower operation is dependent on the thermostat con­
trol system option that has been installed in the units.
Refer to operation sequence of the control system in­
stalled for detailed descriptions of blower operation.
2- Generally, blower operation is set at the thermostat fan
switch. With the fan switch in "ON" position and the OCP
input is "ON", the blower operates continuously. With
the fan switch in "AUTO" position, the blower cycles
with demand.
3- In most cases, the blower and entire unit will be off when
the system switch is in the "OFF" position. The only excep­
tion is immediately after a heating demand when the blow­
er control keeps the blower on until all heat is extracted
from the heat exchanger.
IMPORTANT
Three Phase Scroll Compressor Voltage Phasing
Three phase scroll compressors must be phased se­
quentially to ensure correct compressor and blower*
rotation and operation. Compressor and blower are wired
in phase at the factory. Power wires are color-coded as
follows: line 1-red, line 2-yellow, line 3-blue.
1-Observe suction and discharge pressures and blower*
rotation on unit start-up.
2-Suction pressure must drop, discharge pressure must rise
and blower* rotation must match rotation marking.
If pressure differential is not observed or blower* rotation
is not correct:
3-Disconnect all remote electrical power supplies.
4-Reverse any two field-installed wires connected to the
line side of S48 disconnect or TB13 terminal strip. Do not
reverse wires at blower contactor.
5-Make sure the connections are tight.
Discharge and suction pressures should operate at
their normal start‐up ranges.
*Supply air VFD motors should rotate in the correct di­
rection; verify scroll compressor rotation separately.
Contact technical support if the VFD blower is rotating
incorrectly.
Determining Unit Air Volume
IMPORTANT - VFD units are factory-set to run the blower
at full speed when there is a blower (G) demand without a
heating or cooling demand. Refer to the field-provided,
design specified CFM for all modes of operation. Use the
following procedure to adjust motor pulley to deliver the
highest CFM called for in the design spec. See Supply Air
Inverter Start-Up section to set blower CFM for all modes
once the motor pulley is set.
IMPORTANT - Direct drive variable blower unit CFM is de­
termined by the Unit Controller. Refer to the Direct Drive
Variable Speed Start-Up section.
1- The following measurements must be made with a dry
indoor coil. Run blower without a cooling demand.
Measure the indoor blower shaft RPM. Air filters must
be in place when measurements are taken.
2- With all access panels in place, measure static pres­
sure external to unit (from supply to return). Blower per­
formance data is based on static pressure readings
taken in locations shown in figure 19.
Note - Static pressure readings can vary if not taken where
shown.
3- Refer to blower tables in BLOWER DATA (table of con­
tents) in the front of this manual. Use static pressure and
RPM readings to determine unit air volume. Apply
accessory air resistance tables when installing units
with any of the optional accessories listed.
4- Standard Blowers -
The blower RPM can be adjusted at the motor pulley.
Loosen Allen screw and turn adjustable pulley clockwise
to increase CFM. Turn counterclockwise to decrease
CFM. See figure 16. Do not exceed minimum and maxi­
mum number of pulley turns as shown in table 1.
Tensioner Blowers -
Refer to label on motor base. See figure 17.
MINIMUM AND MAXIMUM PULLEY ADJUSTMENT
Belt
A Section
B Section
*No minimum turns open when B belt is used on pulleys 6" O.D. or larger.
Page 39
TABLE 1
Minimum Maximum
Turns Open Turns Open
0 5
1* 6