8
U1, U2 or U3 terminals must be used for geothermal radiant heat. Thermostat
allows 2 stages of radiant heat—geothermal (stage 1) and boiler (stage 2).
“U” terminals are normally open dry contacts when set up for geothermal
radiant heat. You must install a field jumper if radiant heat is powered by
system transformer. Do NOT install a field jumper if radiant heat has its own
transformer.
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.
O/B
AUX1
AUX2
O/B
R
C
AUX1
AUX2
G
L
Y2
Y
L/A
CHANGEOVER VALVE
BACKUP HEAT
STAGE 1
FAN RELAY
120
VAC
24
VAC
COMPRESSOR
STAGE 1
COMPRESSOR
STAGE 2
BACKUP HEAT
STAGE 2
COMPRESSOR MONITOR
OR ZONE PANEL
GEOTHERMAL RADIANT
HEAT STAGE 1
AIR HANDLER
TRANSFORMER
STATUS
LEDS
JUMPERS
OPTIONAL
JUMPER
POWER
HEAT
COOL
FAN
U1
U2
U3
TO THERMOSTAT
HEAT PUMP
EIM
3
1
3
S4
S4
S3
S3
CONNECT OPTIONAL
SENSORS TO
S3 AND S4 TERMINALS
A
B
C
D
4
SENSORS
2
CONNECT OPTIONAL
SENSORS TO
S1 AND S2 TERMINALS
M34251
4
2
5
EIM wiring guide — geothermal radiant heat
(Prestige and RedLINK VisionPRO models only.)
Typical wiring for geothermal radiant heat, geothermal forced-air, and backup
heat with one transformer.
1
2
3
Wire a maximum of 4 sensors using the S1-S4 terminals. S1-S4 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.
4
Connect wireless adapter to ABCD for extended wireless range.
5
