Field Control Wiring
ZONE THERMOSTATS — Install a Carrier approved ac-
cessory zone thermostat assembly in each zone according to
installation instructions included in the accessory. Locate each
thermostat assembly in the space where it will sense average
zone temperature.
Route thermostat cable or equivalent single leads of no.
18 AWG (American Wire Gage) colored wire from thermo-
stat subbase terminals through opening on base unit
(Fig. 1, 2, 4, and 5) to low-voltage thermostat connections
on zone control board (Fig. 10). Use no. 16 AWG wire for
lengths exceeding 50 ft.
ZONE MODULE CONNECTIONS — Any module may be
controlled independently or jointly with another module or
modules. Modules are combined into nests that form indi-
vidual Class II circuits (40 va) as follows:
Modules no. 1 and 2, 3 and 4, 5 and 6, 7 and 8, 9 and 10
(028-040 units), 11 and 12 (034,040 units).
The control signal can be transferred from one nest
to another nest by using factory-supplied jumpers on
quick-connect type multiplexing terminals. This prevents over-
loading the nest control transformers. Factory-supplied jump-
ers with quick-connect terminals are shipped in the zone con-
trol and thermostat panel compartment.
Under no circumstances shall the transformer power from
one Class II circuit be interconnected with any other circuit.
Thermostat heat anticipator settings are indicated for each
permitted zone module connection arrangement illustrated
in Fig. 11-28.
To Join Modules of the Same Nest Into the Same Zone (i.e.,
modules no. 1 and 2) — Install field-supplied jumpers on
thermostat connections (screw terminals) Y to Y and W2 to
W2 as shown in Fig. 11. Connect thermostat wires to ter-
minal connections of first module in zone (for consistency).
Two-stage cooling may be obtained in this example as shown
in Fig. 12 (using a 2-stage thermostat).
To Join Modules Not of the Same Nest Into the Same Zone
(i.e., modules no. 2 and 3) — Install the factory-supplied jump-
ers on quick-connect terminals 6 to 1, 7 to 2, and 8 to 3 as
shown in Fig. 13. Note that module no. 1 is independently
controlled by its own thermostat (in Fig. 13).
LEGEND
AFS — Airflow Switch
CR — Control Relay
ECR — Economizer Relay
ECT — Economizer Outdoor-Air Thermostat
GV — Gas Valve (not used on 50ME units)
HC — Heater Contactor
HR — Heater Relay
IFC — Indoor (Evaporator) Fan Contactor
LLS — Liquid Line Solenoid
MC — Master Cooling
MCR — Master Cooling Relay
MH — Master Heating
MHR — Master Heating Relay
MU — Master Unit
MUR — Master Unit Relay
NC — Normally Closed
NO — Normally Open
NS — Night Setback
SW — Switch
TRAN — Transformer
Quick-Connect Type Terminals (for multiplexing)
Screw-Type Terminals
NOTE: Twelve-zone unit shown. Eight-zone units have modules
1-8 only. Ten-zone units have modules 1-10 only.
Fig. 10 — Zone Control Board Component Location
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