THX9321/9421 P restige® IAQ and RF EIM
11 69-2490 —03

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.
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)
2MCR32946
69-2490_B.indd 11 7/13/2011 1:41:54 PM