Honeywell Home Prestige TH9321 System Installation Manual page 11

EIM wiring guide — heat pump systems
Typical wiring of a heat pump system with up to four-stage heat and two-stage
cool with one transformer.
POWER
STATUS
LEDS
1
See guides on following pages for thermostat wiring and geothermal radiant heat wiring.
2
Wire a maximum of 2 sensors using the S1 and S2 terminals. See ISU 5000-6190 for options. S1 and S2 terminals can be
connected to an indoor sensor, outdoor 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 wiring section.
4
This document is for legacy models of Prestige and EIM. On the current THM5421R1021 EIM, there are S3, S4, and ABCD
terminals on the left.
EIM
HEAT
COOL
FAN
U1
U2
U3
4
SENSORS
THX9321/9421 Prestige
TO THERMOSTAT
HEAT PUMP
O/B
AUX1
AUX2
L/A
3
1
11
IAQ and RF EIM
®
O/B
CHANGEOVER VALVE
BACKUP HEAT
STAGE 1
AUX1
BACKUP HEAT
AUX2
STAGE 2
COMPRESSOR
Y
STAGE 1
COMPRESSOR
Y2
STAGE 2
G
FAN RELAY
L/A
COMPRESSOR
MONITOR OR
3
ZONE PANEL
JUMPERS
AIR HANDLER
TRANSFORMER
R
24
C
VAC VAC
2
CONNECT OPTIONAL
SENSORS TO
S1 AND S2 TERMINALS
(MAX. 2 SENSORS)
2
MCR32946A
69-2490—07
120