Terminal Designations - Honeywell T874 Product Data

Fig. 8. Jumper adjacent terminals for special system hookup using stripped wire 3/4 in. (19 mm).
For nonadjacent terminals and using jumper wire supplied with subbase.
Standard Terminal
Designation
B
E
G
L
O
R
RC
RH
W1
W2
W3
Y1
Y2
Y3
X
T
Other terminal designations can be used that are not listed on this table. Refer to the hookup drawing and internal schematic
a
for exact connections.
b W3 controls the auxiliary heat like W2, and allows adding additional stages of auxiliary heat with outdoor thermostats while
maintaining the proper second stage anticipation.
1
1
1 TWO ADJACENT TERMINALS SHOWN JUMPERED ARE FOR EXAMPLE ONLY. COMPARE WIRING
DIAGRAM AND SUBBASE TO IDENTIFY TERMINALS TO BE JUMPERED.
Table 5. Terminal Designations
Alternate Designations or
Customer Specials
K
F
R
V
H1, R3
H2, Y, R4
C1, M
C2
X1,X2,C
A
L, C, H
P
O
A, A1, A2, Z, C, L
T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
JUMPER WIRE
(SUPPLIED WITH SOME MODELS)
a
Typical Connection
Heating damper motor; changeover valve
Emergency heat relay
Fan relay coil
System monitor
Cooling damper motor; changeover valve
Power connection to transformer (internally connected for heating
and cooling)
Power connection to cooling transformer
Power connection to heating transformer
Stage 1 heating control
Stage 2 heating control
b
Stage 3 heating control
Stage 1 cooling control
Stage 2 cooling control
Stage 3 cooling control
Clogged filter switch or common connection
Outdoor thermistor
HSII control panel
Defrost
Momentary circuit, changeover
LEDs
9
M5899
60-2485—8