T874 MULTISTAGE THERMOSTATS AND Q674 SUBBASES
9
60-2485—8
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.
Table 5. Terminal Designations
a
Standard Terminal
Designation
Alternate Designations or
Customer Specials
Typical Connection
B
Heating damper motor; changeover valve
E
K
Emergency heat relay
G
F
Fan relay coil
L
System monitor
O
R
Cooling damper motor; changeover valve
R
V
Power connection to transformer (internally connected for heating
and cooling)
RC
Power connection to cooling transformer
RH
Power connection to heating transformer
W1
H1, R3
Stage 1 heating control
W2
H2, Y, R4
Stage 2 heating control
W3
Stage 3 heating control
b
Y1
C1, M
Stage 1 cooling control
Y2
C2
Stage 2 cooling control
Y3
Stage 3 cooling control
X
X1,X2,C
Clogged filter switch or common connection
T
A
Outdoor thermistor
L, C, H
HSII control panel
P
Defrost
O
Momentary circuit, changeover
A, A1, A2, Z, C, L
LEDs
a
Other terminal designations can be used that are not listed on this table. Refer to the hookup drawing and internal schematic
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.
M5899
1
1
1 TWO ADJACENT TERMINALS SHOWN JUMPERED ARE FOR EXAMPLE ONLY. COMPARE WIRING
DIAGRAM AND SUBBASE TO IDENTIFY TERMINALS TO BE JUMPERED.
JUMPER WIRE
(SUPPLIED WITH SOME MODELS)