GE CC-SCSTAT User Manual download pdf (Page 27)

Control unit installation

Install the control unit in a protected, convenient, indoor location near the HVAC system or in a service

accessible area such as an equipment closet or garage. Mount the control unit in a vertical position on a wall or

sturdy structural member. If you mount the control unit on the HVAC system, be careful to avoid the hot burner

section and high vibration areas.

The control unit is connected to the HVAC system and to the WDU unit as well as the serial communication

and power connections.

Control unit to WDU wiring

Connect the WDU to the control unit with existing thermostat wiring in retrofit installations. For new

installations, 22/24 Ga twisted-pair, typically CAT 3 or CAT 5 wiring is preferred (Figure 17).

Figure 17. Control unit to WDU wiring

Control unit to HVAC wiring

Electrically, the control unit looks like a standard thermostat to your HVAC system. All connections to the

HVAC system are made at the normal thermostat connections on the HVAC unit. Refer to your HVAC system’s

documentation for specific information on its thermostat connections and set up requirements. You will need to

know the following:

HVAC system type. Gas, electric, heat pump, radiant, or hydronic.

Fan requirement. No fan with heat or fan with heat.

For heat pump system. Changeover with cool or with heat (O or B connection).

Retrofit wiring

You may find that you have additional wires when you disconnect your old thermostat. Usually these wires are

for auxiliary functions such as filter or trouble indicators. For heat pump systems there may be emergency heat

(EH) wiring or both O and B changeover connections. These wires are not used in the SmartCommand

installation and, in most cases, these extra wires are not required for normal HVAC system operation. See

HVAC wiring for wiring diagrams for your type of HVAC system: standard or heat pump.

CAUTION: Do not miswire the power and data lines, damage will result. Check your wiring before applying power.

Wall display unit

Control unit

GND

+12V

Clock

Data

GND

+12 VDC

Clock

Data

1 2 ... 22 23 24 25 26 27 28 29 30 31 32 ... 43 44

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GE CC-SCSTAT User Manual Page 27