Honeywell Prestige 2.0 THX9421 - Page 142

THX9321 PRESTIGE
®
2.0 AND THX9421 PRESTIGE
®
IAQ WITH EIM
68-0311—07 142
Typical wiring of a heat pump system with up to four-stage heat and two-stage cool with one transformer.
Fig. 325. EIM wiring guide — heat pump systems.
1 See guides on following pages for thermostat wiring and geothermal radiant heat wiring.
2 Wire a maximum of 4 sensors using the S1-S4 terminals. S1-S4 terminals can be connected to an indoor sensor, out-
door sensor, discharge sensor, return sensor, dry contact device to display an alert or an occupancy sensor for remote
setback.
3 L/A terminal sends continuous output when thermostat is set to EM HEAT mode, except when set up for Economizer or
TOD. See “Economizer Module Wiring Diagrams” beginning on page 154.
4 Connect wireless adapter to ABCD for extended wireless range.
CHANGEOVER VALVE
BACKUP HEAT
STAGE 1
FAN RELAY
SENSORS
TO THERMOSTAT
HEAT PUMP
AIR HANDLER
TRANSFORMER
120
VAC
24
VAC
COMPRESSOR
STAGE 1
COMPRESSOR
STAGE 2
O/B
AUX1
AUX2
O/B
BACKUP HEAT
STAGE 2
COMPRESSOR
MONITOR OR
ZONE PANEL
R
C
AUX1
AUX2
G
L/A
Y2
Y
POWER
HEAT
COOL
FAN
U1
U2
U3
STATUS
LEDS
JUMPERS
L/A
EIM
CONNECT OPTIONAL
SENSORS TO
S1 AND S2 TERMINALS
S4
S4
S3
S3
CONNECT OPTIONAL
SENSORS TO
S3 AND S4 TERMINALS
A
B
C
D
2
2
3
1
3
4