Step 1: Replacing Existing Thermostat; Important Safety Information - Robertshaw 9555 User Manual

110-975D En.qxd
!

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
C, X or B
R, V-VR or VR-R
W1 or W
Y, Y1 or M
O or R
B
F or G
Y2
W2 or W-U
NOTE: THIS THERMOSTAT REQUIRES A 24V COMMON WIRE FOR PROPER OPERATION.
5/13/03 2:43 PM
Figure 1
New Label
C 24 VAC, Transformer Common Side
R 24 VAC, Return
W1 1st Stage Heating Control
Y1 1st Stage Cooling Control
O Reversing Valve (Cooling Mode)
B Reversing Valve (Heating Mode)
G Fan Control Relay
Y2 2nd Stage Cooling Control
W2 2nd Stage Heating Control
Table 1
2
Page 2
Description
(Black plate)