IMPORTANT SAFETY INFORMATION
WARNING:
•Always turn off power at the main power source by unscrewing fuse
or switching circuit breaker to the off position before installing,
removing, cleaning, or servicing thermostat.
• Read all the information in this manual before installing or program-
ming this thermostat.
• This is a 24 VAC low-voltage thermostat. Do not install on voltages
higher than 30 VAC.
• All wiring must conform to local and national building and electrical
codes and ordinances.
• Do not short (jumper) across terminals on the gas valve or at the
system control to test installation. This will damage the thermostat
and void the warranty.
Step 1: Replacing Existing Thermostat
1. Turn off power to heating and cooling system.
2. Remove cover from old thermostat to expose wires (Figure 1).
3. Disconnect wires one at a time from existing terminals. Use enclosed labels
to mark existing wires. Refer to cross references in Table 1 if existing wiring
does not directly match the labels.
Old Terminal New Label Description
LLSystem Check
R, V-VR or VR-R R 24 VAC, Return
Y, Y1 or M Y1 1st Stage Cooling Control
O or R O Cool Active Reversing Valve
BBHeat Active Reversing Valve
F or G G Fan Control Relay
Y2 Y2 2nd Stage Cooling Control
W2 or W-U W2 2nd Stage Heating Control
C, X or B C 24 VAC, Transformer Common Side
W1 or W E Emergency Heating Relay
NOTE: THIS THERMOSTAT REQUIRES A 24V COMMON WIRE FOR PROPER OPERATION.
2
Figure 1
Table 1
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