11
OVERVIEW
The SYGE Switching Center is a manual changeover, Gas/Electric System
Controller. It can control up to 7 zone thermostats. Its function is to look
for calls from the zone thermostats for the mode (heat/cool) selected. If a
call is received, it sends a signal to close the dampers of all zones not
calling and sends a signal to the HVAC unit to energize heating or cooling.
The Mode, Power and Fan control switches are located at the Switching
Center. The Switching Center should be placed in a location that provides
easy access to these switches.
The Switching Center is used in conjunction with a Capacity Controller.
The Capacity Controller protects the evaporator coil from freezing and the
heat exchanger from overheating. The Capacity Controller also controls
staging for multistage HVAC systems. Refer to the Capacity Controller
section (pg. 28) for more information.
OPERATION
The user manually selects the mode (heat/cool) at the Switching Center.
Heat mode
– If any zone thermostat calls for heat, electrical current
flows in WD. The Switching Center senses this current, turns on the green
Call light, energizes RD (RD made to GD) which tells the dampers of all
zones not calling to close and energizes W (W made to R) which tells the
HVAC unit to turn on heat.
Cool mode
– If any zone thermostat calls for cool, electrical current
flows in YD. The Switching Center senses this current, turns on the green
Call light, energizes RD (RD made to GD) which tells the dampers of all
zones not calling to close, and energizes Y and G (Y and G made to R)
which tells the HVAC unit to turn on cooling and the indoor blower fan.
No calls
– When no thermostats are calling, the green Call light is off,
RD is not energized so all dampers are open, and W, Y are not energized
so the HVAC unit is off. If the FAN switch is ON, then G is energized (G
made to R), and the indoor blower fan will run. This allows ventilation
in all zones.
1.
5 Wire Link Terminals
– Daisy chain wires to zone dampers.
YD – Cool call input signal. Current flows in this terminal when Mode
switch at COOL, Power switch ON and thermostat calling for cool.
WD – Heat call input signal. Current flows in this terminal when
Mode switch at HEAT and thermostat calling for heat.
BD – 24V return. Same as TR2.
GD – 24V hot. Same as TR1.
RD – Unit on output signal. Energized (RD made to GD) when
Switching Center acknowledges thermostat call. See 7.
2.
Transformer Terminals
– 24V AC transformer terminals. This
transformer powers the dampers, thermostats and Switching Center.
It does not power the HVAC unit. That power comes from terminal
R; see 3.
3.
HVAC Unit Terminals
– Connect to HVAC unit via Capac-
ity Controller. See Capacity Controller section for wiring
information.
W – Heat enable. Energized (W made to R) when Switch-
ing Center acknowledges a heat call. See 7.
Y – Cool enable. Energized (Y made to R) when Switch-
ing Center acknowledges a cool call. See 7.
R – HVAC unit 24V power.
G – Fan enable. Energized when FAN switch is at ON posi-
tion or when FAN switch is at AUTO position and Switch-
ing Center acknowledges a cool call. See 7.
4.
Mode Switch
– Selects mode (heat/cool) to run system.
Switching Center will only respond to thermostats calling
for mode selected.
5.
Power Switch
– When OFF the Switching Center will not respond to
thermostat calls. Power remains to all dampers and thermostats.
The indoor blower fan will run if fan switch is on.
6.
Fan Switch
– Controls the indoor blower fan (G).
AUTO – Indoor blower fan turns on when air conditioner is on.
Note:
In heat mode, furnace controls indoor blower fan.
ON – Indoor blower fan continuously on as long as Power switch
is ON.
7.
Call Light
– On when Switching Center responds to a calling
thermostat.
AUTO
ON
FAN
ON
OFF
SYSTEM 1000
GAS/ELECTRIC
SWITCHING CENTER
(SYGE)
HEAT
COOL
GREEN CALL
LIGHT
YD WD BD GD RD TR1 TR2 W Y R G
4
5
6
7
1
2
3
SYSTEM 1000 SWITCHING CENTERS – GAS/ELECTRIC SYGE
COMPONENTS
