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505023M 04/06
The Harmony III
t
zone control system uses off−the−shelf,
single-stage, non-heat pump, non−power-robbing elec-
tronic thermostats and motorized dampers in any of the ap-
plications to distribute conditioned air to different zones.
This control allows conditioning of different zones within a
residence while using a single HVAC system.
The zone control system operates in two modes:
central
control
(vacation mode) or
zone control
. LEDs indicate
the current operating mode. Based on a demand from the
central control thermostat, the central control mode allows
the heating and cooling system to condition all of the
zones. In this mode, zone 1 thermostat is designated as
the controlling thermostat; other thermostats are not used.
When the system is in the zone control mode, a zone is
conditioned only upon demand. All wiring connections to
the zone control board are made using low voltage, 18
AWG thermostat wire.
The zone control system is ideal for retrofit applications as
well as new construction. The system controls the air vol-
ume, eliminating the need for bypass dampers in most ap-
plications. The homeowner controls the system using
zone thermostats to make comfort settings for each zone.
A programmable thermostat should be used to provide a
specialized heating and cooling sequence. While the sys-
tem is in the zone mode, a programmable thermostat con-
trols the temperature for its particular zone.
Residential Zone Control System − Overview of Field Wiring
COIL
ZONE
DAMPER
VARIABLE
SPEED
FURNACE
OR COIL
BLOWER
ZONE 1
ZONE 2
*ZONE 3
*ZONE 4
POWER
THERMOSTAT
(ZONE 1 or CEN-
TRAL CONTROL
thermostat when
in Vacation Mode)
ZONE
DAMPER
THERMOSTAT
(ZONE)
CONDENSING
UNIT
OR
HEAT PUMP
OUTDOOR
UNIT
ZONE
DAMPER
ZONE
DAMPER
F
ZONE CONTROL
SYSTEM, THERMO-
STAT AND DAMPER
TRANSFORMER
THERMOSTAT
(ZONE)
THERMOSTAT
(ZONE)
NOTE − Zone 3 and zone 4 not available with single-stage outdoor unit.
LEGEND −
A
Five wire low voltage 18 ga. minimum
B
Two wire low voltage 18 ga. minimum
C
Up to nine wire low voltage 18 ga. minimum
D
Two wire low voltage (single-stage condensing unit) 18 ga. minimum
Three wire low voltage (two-stage condensing unit) 18 ga. minimum
Up to seven wire low voltage (single-stage heat pump outdoor unit) 18 ga. minimum
Up to eight wire low voltage (two-stage heat pump outdoor unit) 18 ga. minimum
E
Two wire low voltage (discharge air sensor) 18 ga. minimum
F
Two wire low voltage pressure switch (heat pump only) 18 ga. minimum
G
Two wire 18 ga. minimum
OUTDOOR
THERMOSTAT /
BALANCE
POINT SENSOR
ZONE
CONTROL
SYSTEM
BOARD
A
B
B
A
A
B
B
B
A
E
C
D
G