Ii-Placement And Installation; Iii-Charging - Lennox Enlight LGT Series Manual

IGNITOR
Electrode
FIGURE 27
11-Flame Sensors
A flame sensor is located on the right side of each burn-
er support. The sensor is mounted through a hole in the
burner support and the tip protrudes into the flame enve-
lope of the right most burner. The sensor assembly is fas-
tened to burner supports and can be removed for service
without removing any part of the burners.
When flame is sensed by the flame sensor (indicated by
microamp signal through the flame) sparking stops im-
mediately. During operation, flame is sensed by current
passed along the ground electrode (located on the spark
electrode), through the flame and into the sensing elec-
trode. The ignition control allows the gas valve to stay
open as long as a flame signal (current passed through
he flame) is sensed.
SENSOR
FIGURE 28

II-PLACEMENT AND INSTALLATION

Make sure the unit is installed in accordance with the in-
stallation instructions and all applicable codes. See ac-
cessories section for conditions requiring use of the op-
tional roof mounting frame.

III-CHARGING

A-Refrigerant Charge and Check - All-Aluminum Coil
WARNING-Do not exceed nameplate charge under any
condition.
This unit is factory charged and should require no further
adjustment. If the system requires additional refrigerant,
reclaim the charge, evacuate the system, and add re-
quired nameplate charge.
NOTE - System charging is not recommended below 60F,
In temperatures below 60F, the charge must be weighed
into the system.
Ground
Page 37
If weighing facilities are not available, or to check the
charge, use the following procedure:
IMPORTANT - Charge unit in normal cooling mode.
1 - Attach gauge manifolds to discharge and suction
lines. With the economizer disabled, operate the unit
in cooling mode at high speed using the following
mobile service app menu path:
SERVICE>TEST>COOL>COOL 4
2 - Use a thermometer to accurately measure the
outdoor ambient temperature.
3 - Apply the outdoor temperature to tables 9 through
18 to determine normal operating pressures.
Pressures are listed for sea level applications at
80°F dry bulb and 67°F wet bulb return air.
4 - Compare the normal operating pressures to
the pressures obtained from the gauges. Minor
variations in these pressures may be expected due
to differences in installations. Significant differences
could mean that the system is not properly charged
or that a problem exists with some component in
the system. Correctany system problems before
proceeding.
5 - If discharge pressure is high, remove refrigerant
from the system. If discharge pressure is low, add
refrigerant to the system.
• Add or remove charge in increments.
• Allow the system to stabilize each time refrigerant is
added or removed.
6 - Confirm charge amount using liquid temperature
plots. Fine tune charge amount(s) to match liquid
temperature plots as needed per the next section.
E-Charge Confirmation and Fine Tuning - Liquid Tem-
perature Check
Note - Pressures are listed for sea level applications.
1 - Use the same thermometer to accurately measure
the liquid temperature (in the outdoor section).
• If measured liquid temperature is higher than the
target liquid temperature, add refrigerant to the sys-
tem.
• If measured liquid temperature is lower than the
target liquid temperature, recover some refrigerant
from the system.
2 - Add or remove charge in increments. Allow the
system to stabilize each time refrigerant is added
or removed.
3 - Continue the process until measured liquid
temperature agrees
temperature. Do not go below the target liquid
temperature when adjusting charge. Note that
suction pressure can change as charge is adjusted.
4 - Example: At 95°F outdoor ambient and a
measured suction pressure of 130psig, the target
liquid temperature is 98°F. For a measured liquid
temperature of 106°F, add charge in increments
until measured liquid temperature agrees with the
target liquid temperature.
with the target liquid