Lennox CHA16, Service Manual

Page: 54 / 86

FIGURE 67
CMC3-1 TIME CLOCK FIELD WIRING
120V
120V
TO TB1 TERMINAL 6*
TO TB1 TERMINAL 11
LINE
FRONT TERMINALS
TIME CLOCK
REAR TERMINALS
1 2 3
1 3
* IF SSP11 IS USED CONNECT
TO SSP11 TERMINAL 20
Page 54
The Honeywell W7400/T7400 control system, when
applied to the CHA16, allows fully programmable op
eration of the unit during occupied and unoccupied pe
riods. Morning warm-up capabilities are built in to the
control system. An external warm-up kit is not needed.
CAUTION
Do not connect a warmup kit to jack J5 of the
W7400 relay kit. Warm-up kit wiring is not compat
ible with W7400 wiring and component damage
will result. The W7400 system has a warm-up fea
ture built in. A warm-up kit is not needed.
11 - C8-1 Wiring Diagram
W973 control system for units without economizer or
warm-up. See figure 65. Requires W973 relay kit and
CMC3-1 clock for night setback. W973 control module
jackplugs J17/P17 connect to the unit control har
ness at jackplug J16/P16. W973 relay kit plug P6 con
nects to unit jack J3 and relay kit jack J6 connects to
unit plug P3 or economizer plug P4. Room tempera
ture sensor connections are made to the unit's low
voltage terminal strip.
FIGURE 66
W973 THERMOSTAT CONTROL KIT
Control Module
Relay Kit
J17
P19/J19
P17
P6
J6
The W973 is used only with the C81 and C141 wiring
diagrams. It cannot be used with any other control sys
tem options or control damage will result.
The Honeywell W973 control, when added to a
CHA16, allows use of electronic ramping" thermo
stats, discharge temperature sensors, return air tem
perature sensors and/or remote thermostats and
transmitters. The W973 control system is designed
for use with Honeywell T7067 electronic ramping"
thermostat and Q667 subbase.
An interconnecting W973 relay kit must be used to
adapt the W973 to the CHA16. Optional CMC3-1
time clock must also be used for night setback capa
bilities.
The relay kit changes the thermostat setpoints for
night setback. A night thermostat is not needed.
12 - C14-1 Wiring Diagram
W973 control system for units with economizer and
warm-up. Requires W973 relay kit. Also requires
CMC3-1 clock and night relay for night setback. Wir
ing connections are similar to
C81 diagram except
with addition of warm up kit. Warm up kit plug P8 con
nects to W973 relay Kit jack J5 and all other jackplug
connections are made as described in previous sec
tions. Room temperature sensor connections are
made to the unit's low voltage terminal strip.
13 - C12 Wiring Diagram
T7300 electronic thermostat for units without econo
mizer. T7300 thermostat wiring connections are made
to the unit's low voltage terminal strip.
14 - C12-2 Wiring Diagram
T7300 electronic thermostat for units with economiz
er. Warm-up is built in.
L-Clocks / Timers (CMC3-1)
Two optional clocks (both designated model# CMC3-1)
are available for use with either the electromechanical
thermostat or the Honeywell W973 control system. Both
allow mechanical thermostats to set back" during unoccu
pied periods. The clocks, models 202A and 702A, allow
24hour and 7day programmability respectively.
Other CHA16 control system options (W7400, T7300,
Pro-stat, etc.) are equipped with builtin clocks for this pur
pose and do not need CMC3-1.
Both CMC3-1 clocks are alike except for programmability.
The clocks are rated 24VAC*, 60Hz and have SPDT con
tacts rated at 15A and 120VAC.
*NOTE-Some clocks may be 120VAC while most are
24VAC. Be sure to check clock motor rating and wire
clock according to its rating.
Wiring connections
should be made to
N.O. terminal 1 and 3
(see figure 67). Refer
to the sequence of
operation for the con
trol system being
used (back of this
manual) for correct
wiring connections.
Refer to the manufac
turer's operation and installation instructions printed inside
the front cover of each clock.