Existing
Function
Terminals
Common
C
Power
R
Compressor
Y
1st Stage
–
Heat
or
Auxiliary
OTC
W2
Heat
Fan
G
or
C/O Valve
B
W1
Heat
C/O Valve
O
Cool
System
–
Monitor
EM. Heat
E
Multiple Aux.
–
Heat Loads
LED Indication
–
2nd Stage
–
Compressor
2nd Stage
–
Cool
Configure O/B (select models) in Installer Setup.
Both First stage heat and cool are connected to Y terminal.
Terminal is for multiple auxiliary heat loads such as contactors, sequencers,
or relays.
Terminal must be connected to the transformer common.
Do not remove factory-installed jumper.
TYPICAL THERMOSTATS AND SUBBASES — HONEYWELL MODEL NUMBER (CUSTOMER PART NUMBER)
Electromechanical
X
X
X
R
R
R
Y
Y
Y1
–
W1
W1
W2
W2
W2
G
G
G
B
B
O
O
O
–
L
–
E
E
E
W3
W3
W3
–
X2
X1 X2
–
–
–
–
–
–
T872G1109/Q672F1117 (080-13708-52/080-13708-53)
T874G1147/Q674F1139
Electronic Replacement or Upgrade
Chronotherm
®
III
C
C
R
R
or
Y1
Y
Y
W1
W1
W2
W2
G
G
B
B
O
O
L
L
E
E
X1 X2
–
–
–
–
–
Optional LED indication activated with completed circuit on X1 and
X2 terminals.
Thermostat will have connection to either O or B terminal, not both.
If multiple auxiliary heat loads are used connect to W2 (Aux W8900B)
terminal.
When W2 is not used, configure W2 cycle rate to NC.
JANITROL/TAPPAN
Chronotherm
IV
C
C
C
R
R
R
Y1
Y
Y1
W1
W1
W1
W2
W2
W2
G
G
G
or
or
B
O/B
B
B
or
or
O
O/B
O
O
L
L
L
E
E
E
–
–
X1 X2
–
–
–
–
–
–
C
R
Y1/W1
–
Aux.
G
O/B
O/B
O/B
O/B
L
E
–
W2
Y2
M13223
70-6627 • 73