Data Manual

16
Some installations may want to govern the ability of the
unit to operate from a control device remote to the unit or
even remote to the room in which the unit is located. The
general term given to systems such as this is Central Desk
Control (CDC). The most common installation of this type
of system is a switch mounted at the registration desk
and, upon guest check-in, a button is pushed or a switch
is moved to allow the air conditioner to operate. Likewise,
when the guest checks out, the device is put into the
“OFF” position so the unit will not operate while the room
is vacant.
It is not necessary that the controlling device be located
at a central desk to employ a device that will control the
unit operation. For instance, in some resort areas, devices
are connected to sliding glass doors and opening the door
causes a contact to close, turning the air conditioner off.
This prevents energy being wasted by operating the air
conditioner when warm, humid air is entering the room.
Some systems operate by motion sensors or heat-sensing
detectors mounted in the room. These types of systems
determine occupant presence in the room and allow the
unit to operate; if no one is in the room the device signals
the air conditioner to turn off.
There is a wide variety of devices available, each with
its own benefits and constraints. While GE Appliances
does not offer components that are external to the
unit for a Central Desk Control system, GE Appliances
Zoneline units are compatible with most CDC and energy
management systems.
All GE Zoneline AZ45 and AZ65 Series units are
compatible with simple on/off 2-wire Central Desk Control
(CDC) systems. Consult with the provider of the energy
management system to be sure it is compatible with
GE Zoneline units.
All GE Zoneline units have a port available and offer
accessory (RAKCDC) to provide an CDC interface to most
of the energy management systems.
Control power to the switch (24 VAC) is provided by
the GE Zoneline unit.
IMPORTANT CDC COMMENTS
(ALL SERIES APPLICABLE)
1. When the switching device closes the circuit of the CDC
conductors, the unit operation stops.
2. Do not use a common bus (at the unit or at the switch
panel) in the wiring. Both wires comprising the circuit
must connect to the unit connectors and to the
controlling switch. Running one wire from one unit
to another unit is common busing and may damage
internal components or cause erratic operation of the
system.
3. A 24-volt transformer is contained within the Zoneline
unit. No external voltage may be applied to the unit
through the CDC terminals. (Voltage on the CDC
conductors is 24 volts AC.)
4. When the remote switch is closed, the unit cannot be
operated in the fan, cool or heat modes. Recommended
wire size must be followed as a minimum requirement.
Freeze Sentinel and Heat Sentinel remain operational
when the unit is connected to a CDC system. Even if the
unit is turned “OFF” at the central location, if the sensor
at the unit detects the low or high limit temperature, the
unit will automatically turn on until it reaches the preset
shutdown temperature (46°F heating, 80°F cooling).
Connecting the Zoneline unit to a CDC system does
not eliminate the ability to connect the unit to a remote
thermostat. Once the circuit is “opened,” and control
of the unit removed from the CDC system, the selected
controls—either the unit-mounted control or the remote
thermostat—govern the operation of the unit.
Please see page 55 for installation recommendations
for the Central Desk Control wiring.
CDC TERMINAL LOCATION AND TYPICAL WIRING
See page 19 for location of CDC terminals on unit.
WIRE SIZE #AWG MAXIMUM ALLOWABLE LENGTH
#22 600 Ft.
#20 900 Ft.
#18 1,500 Ft.
#16 2,000 Ft.
CENTRAL DESK CONTROL
RAKCDC
EXAMPLE OF COMMON BUSING
NOT PERMITTED
TYPICAL WIRING
(Wiring from RAKCDC connector to
field devices is field supplied)
RAKCDC
CONNECTOR
(sold separately)
FIELD SUPPLIED
CDC SWITCH
INCORRECT COMMON BUSING
NORMALLY OPEN SWITCH=
UNIT OPERATIONAL
POWER RED
CDC BLUE
E. FAN YELLOW
ARCHITECTS & ENGINEERS DATA MANUAL AZ45/AZ65 SERIES