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SmartCommand Thermostat
Installation Manual
20
Installation overview
Before you remove an existing thermostat and install the SmartCommand thermostat, follow these guidelines:
• Record existing wiring information.
• Do the bench test.
• Check WDU wiring before applying power to the control unit.
• Be sure to install a freeze protection device as required.
Figure 14 shows the standard thermostat wiring versus retrofit applications.
Figure 14. Wiring overview
75
X
Heating and cooling
system
Heating and cooling
system
Old system
New system
SmartCommand WDU
SmartCommand
control unit
Replace existing thermostat
with SmartCommand WDU
Insert control unit
into existing wiring
4, 5, or 6 wires
as original installation
4, 5, or 6 wires
18 Ga thermostat wiring
4 wires