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20
SmartCommand Thermostat
Installation Manual
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
Old system
New system
4, 5, or 6 wires
18 Ga thermostat wiring
Replace existing thermostat
with SmartCommand WDU
4 wires
75
SmartCommand WDU
X
Insert control unit
into existing wiring
SmartCommand
control unit
4, 5, or 6 wires
as original installation
Heating and cooling
system
Heating and cooling
system
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