Robertshaw 8425 User Manual page 2

110-1090.qxd 7/22/04
! IMPORTANT SAFETY INFORMATION WARNING:
• Always turn off power at main fuse or circuit breaker panel before
installing, removing, cleaning, or servicing thermostat.
• Read all the information in this manual before installing this thermostat.
• DO NOT CONNECT TO 120 VAC. 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.
• Do not connect ground to any terminal in this unit.
Recycling Thermostat
If this thermostat REPLACES a thermostat that contains mercury,
DO NOT discard the old thermostat in the regular trash. Mercury
is harmful to humans and the environment. For this reason, do
not open, break, or crush the mercury cell. If mercury leaks from
a damaged cell, DO NOT touch or handle mercury with bare
hands. Use protective, non-absorbent gloves to place mercury
into a sealable container. Fill the container with sand or another
absorbent material and seal the container completely.
Return the mercury or mercury products, in a sealed container, to
Invensys Climate Controls or a local recycling center for proper
disposal. If you have any questions, call Robertshaw technical
support at 1-800-445-8299.
Step 1: Replacing Existing Thermostat
Wiring Table
Old Terminal New Label
R, V-VR or VR-R
Y, Y1, M
O or R
B
F or G
Y2
W2, W-U or E
C, X or B
L or X
W or W1
NOTE: THIS THERMOSTAT REQUIRES A 24 VAC COMMON WIRE FOR PROPER OPERATION.
NOTE: ON SOME OLDER MODELS, THE C TERMINAL CAN BE EITHER THE COOLING CONTROL OR
THE COMMON SIDE OF THE TRANSFORMER. CHECK FURNACE WIRING DIAGRAM TO VERIFY C
TERMINAL. IF IT IS THE COMMON SIDE OF THE TRANSFORMER, CONNECT TO THE C TERMINAL.
8:39 AM Page 2
Invensys Climate Controls
28C Leigh Fisher Blvd.
El Paso, TX 79906
Attn: Mercury Recycling Center
Description
R 24VAC, return
Y1 Compressor relay (Stage 1)
O Reversing valve (cool active)
B Reversing valve (heat active)
G Fan control relay
Y2 2 nd stage cooling circuit
W2/E 2 nd stage heating control or
emergency heating for heat pumps
C 24 VAC, transformer common side
L System monitor
W1 1st stage heat - non heat pump
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