Specifications
LIFTING BRACKETS (4)
TWO EACH SIDE
FIGURE 3
LIFTING BRACKETS
SIDE VIEW
Page 7
I-APPLICATION
GCS24 units are factory equipped with the hardware re
quired for installing Lennox' optional thermostat control sys
tems. Lennox' optional thermostat control systems are the
same controls, harnesses, and harness plugs used in all pre
viously released GCS16 commercial units. For example, a
Honeywell W973 control will plug in to a GCS16-1603 as eas
ily as it will plug in to a GCS24-1603 (and no field wiring is re
quired for either).
II-UNIT COMPONENTS
For GCS24 series unit components see figure 1.
A-Lifting Brackets
Each unit is equipped with factory
installed lifting brackets as shown
in figure 3. Brackets are used for
lifting the unit during installation or
servicing. Lifting brackets can be
removed from the unit and reused.
If unit must be lifted for service, use
only lifting brackets to lift unit.
B-Control Box Components
GCS24 control box is shown in figure 2. The control box is
located in the upper portion of the compressor compartment.
The control box has a hinged cover for easy access.
1-Transformer T1 (all units)
All GCS24 series units use a single line voltage to 24VAC
transformer mounted in the control box. Transformer supplies
power to control circuits
in the unit (except the
heating section). Trans
former is rated at 70VA.
208/230 (Y) voltage
transformers use two pri
mary voltage taps as
shown in figure 4.
2-Transformer Fuse F1 (all units)
T1 transformer is equipped with an integral fuse connected in
series with the blue secondary voltage wire. The fuse may be
accessed outside the transformer and is rated 3.5A.
3-Transformer T3 (all 460V and 575V units)
All 460 (G) and 575 (J) voltage units use a single line voltage
to 230VAC transformer mounted in the control box. The trans
former supplies power to the combustion air blower at all
times. It has an output rating of 0.5A.
4-Terminal Strip TB29 and TB30
(late models only)
TB29 and TB30 are terminal strips used for the distribution of
24V power and common from transformer T1 to the control
box components. TB29 is for the 24V power and TB30 is for
the 24V common.
5-Time Delay DL26 and DL27 (-1603 only)
Time delays DL26 (first stage) & DL27 (second stage) are
SPST N.C. timedelay switches. Once energized by the ther
mostat, the delay waits 12 minutes before opening. The delay
protects the compressor from short cycling by bypassing the
S87 (first stage) and S88 (second stage) low pressure
switches for the first 12 minutes after cooling demand is sig
naled.
DL26 is wired in series with compressor contactor coil (K1),
and DL27 is wired in series with (K2).
6-Compressor Contactor K1 & K2 (all units)
K1 (first stage) & K2 (second stage) are 24V to line voltage
contactors used to energize compressors B1 (first stage) &
B2 (second stage) in response to first or second stage cooling
demands. All units use threepoledoublebreak contactors
with a 24VAC coil.
NOTE-Contactor K1 is energized by the thermostat con
trol system. Depending on the control system installed,
the contactors may or may not be immediately energized
upon demand. Refer to the operation sequence for the
control system installed.
7-Condenser Fan Relay K127 (all units)
Relay K127 is a 24V to line SPDT pilotrelay used to energize
condenser fan contactor K10 during first stage cooling de
mand from the thermostat.
8-Low Ambient Relay K128 (all units)
K128 is a 24V to line SPDT pilotrelay used to energize con
denser fan contactor K68 during second stage cooling de
mand from the thermostat. In order for K68 to be energized
the demand must pass through S84 and S41 (low ambient
kit), which are in series with K128.
9-Condenser Fan Contactor K10 & K68
(all units)
Contactors K10 (fan 1) & K68 (fan 2) are 24V to line voltage
contactors used to energize condenser fans B4 (fan 1) & B5
(fan 2) in response to thermostat demand. B4 operates
throughout all cooling (compressor) demands, while B5 only
operates during second stage demand. All units use two
poledoublebreak contactors with a 24VAC coil.
FIG
BLUE YELLOW
ORANGE
RE
D
BLACK
230 VOLTS
208 VOLTS
PRIMA
RY
SEC
ONDARY
208/230V TRANSFORMER