Honeywell T874 Product Data

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
PDefrost
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)

Honeywell T874 Specifications

General

Brand	Honeywell
Model	T874
Category	Thermostat
Language	English