Honeywell Round CT87A Installation Instructions Manual page 7

Fig. 8. CT87A for a 2-wire heating only system.
Fig. 9. CT87A for a 3-wire hot water heating only system
Fig. 10. CT87B for a 4-wire heating/cooling system
JUMPER R
R
Y
W
R
Y
W
R G
H
R
C
Y
W
TO R
H C
7
CT87A,B,J ROUND® THERMOSTAT
CT87A WALLPLATE
POWER
HEAT
CT87A WALLPLATE
WIRE LABELS
(LETTERS
ON ORIGINAL
THERMOSTAT
TERMINALS)
R
W
B
.
CT87B SUBBASE
POWER
FAN
COOL
HEAT
TO
SYSTEM
M20183
.
3-WIRE
HOT WATER
ZONE VALVE
M20184
TO
SYSTEM
M20185
69-0274-6