Existing
Function
Terminals
Common
X
Power
R
Compressor
Y
1st Stage
–
Heat
Aux. Heat
W2
Fan
G
C/O Valve
–
Heat
C/O Valve
O
Cool
System
–
Monitor
EM. Heat
E
Multiple Aux.
–
Heat Loads
LED Indication
Defrost
B
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 second stage loads such as contactors, sequencers,
or relays.
Terminal X (C) must be connected to transformer common.
T872G1232/Q672F1224
Electromechanical
X
X
X
R
R
R
Y
Y
Y1
–
W1
W1
W2
W2
W2
G
G
G
B
B
B
O
O
O
–
L
–
E
E
E
W3
W3
W3
X2
X1 X2
–
–
–
–
–
–
–
–
–
TYPICAL THERMOSTATS AND SUBBASES — HONEYWELL MODEL NUMBER
T874G1105/Q674F1097
HEATWAVE/SOUTHWEST MFG.
Electronic Replacement or Upgrade
®
Chronotherm
III
C
C
R
R
or
Y1
Y
Y
W1
W1
W2
W2
G
G
B
B
O
O
O
L
L
E
E
–
–
X1 X2
–
–
–
–
–
–
–
Do not remove factory-installed jumper.
Optional LED indication activated with completed circuit on X1 and
X2 terminals.
When W2 is not used, configure W2 cycle rate to NC.
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/B
O
O
L
L
L
E
E
E
–
–
–
–
–
X1 X2
–
–
–
–
–
–
–
–
–
T874G1105/Q674F1170
C
R
Y1/W1
–
Aux.
G
O/B
O/B
O/B
O/B
L
E
–
–
–
W2
Y2
M13218
70-6627 • 61