Honeywell THX9321 Prestige 2.0 Product Data page 144

®
THX9321 PRESTIGE 2.0 AND THX9421 PRESTIGE
Fig. 332. Geothermal radiant heat with geothermal forced air and backup heat using separate transformer for the radiant
1 U1, U2 or U3 terminals must be used for geothermal radiant heat (ISU 2010). Thermostat allows 2 stages of radiant heat—geo-
thermal (stage 1) and boiler (stage 2).
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.
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 151.
4 Y2 used with heat pumps that have 2 compressor stages.
NOTE: For setup and operation, see "Geothermal Radiant Heat" beginning on page 100.
68-0311—02
®
IAQ WITH EIM
THERMOSTAT/EIM
TO THERMOSTAT
FURNACE
HEAT PUMP
O/B
AUX1
AUX2
L/A
3
1
HEAT PUMP
O O
W1 Y
4
W2 Y2
Y R
Y2
C
G
R
PUMP
C
RADIANT HEAT
ZONE MODULE
TRANSFORMER
C
24 120
VAC VAC
R
heat.
144
VALVE
M34525