THX9321/9421 Prestige
®
IAQ and RF EIM
11
69-2490—05
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.
1
2
3
See guides on following pages for thermostat wiring and geothermal radiant heat wiring.
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.
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.
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
3
3
1
2
EIM
CONNECT OPTIONAL
SENSORS TO
S1 AND S2 TERMINALS
(MAX. 2 SENSORS)
2
MCR32946A