GE CC-SCSTAT User Manual

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.

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).

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).

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.