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THX9321 PRESTIGE
®
2.0 AND THX9421 PRESTIGE
®
IAQ 2.0 WITH EIM
19 68-0311—01
2140 What Terminals are
Wired to Backup
Heat?
None
U1
U2
Default varies
based on
previous
selections
Both No THX9321 Thermostat Only:
This ISU is only displayed on the THX9321
thermostat when it is wired directly to the
equipment (Equipment Interface Module is NOT
used).
The thermostat can support up to 3 conventional
heat stages. When there are a total of 3
conventional heat stages, the last stage of heat
must be wired to U1 or U2.
U1 and U2 are normally open dry contacts when
configured for a stage of Heat. U1 and U2 require
power from a system transformer or a separate
transformer.
2150 Backup Heat
Operation
NOT Allowed to Run with Primary
Heat
Allowed to Run with Primary Heat
NOT allowed to
run with Primary
Heat
Both No This ISU is only displayed when ISU 2010 Heating
Equipment Type is Hot Water Fan Coil, Electric
Forced Air or Other.
When ISU 2010 Heating Equipment Type is Hot
Water Fan Coil, Electric Forced Air or Other, you
can select how the Backup Heat operates. The
thermostat can be setup to keep the primary heat
source on when it calls for Backup Heat or the
thermostat can be setup to turn off the primary heat
source when it calls for Backup Heat.
When ISU 2010 Heating Equipment Type is Hot
Water Radiant Heat, the thermostat keeps the Hot
Water Radiant Heat on when it calls for Backup
Heat.
When ISU 2010 Heating Equipment Type is Steam,
the thermostat keeps the Steam Heat on when it
calls for Backup Heat.
2160 Backup Heat Fan
Operation
No Fan
Equipment Controls Fan
Thermostat Controls Fan
Thermostat
Controls Fan
Both No This ISU is only displayed for conventional systems
when ISU 2120 Backup Heat Type is Electric Forced
Air, Hot Water Fan Coil or Other.
Backup Heat Fan Operation automatically defaults to
Equipment Controls Fan when ISU 2120 Backup
Heat Type is Standard Efficiency Gas Forced Air,
High Efficiency Gas Forced Air or Oil Forced Air.
No Fan is only displayed when ISU 2120 Backup
Heat Type is Other.
2170 What Terminals are
Wired to Backup Heat
- Stage 2?
None
U1
U2
Default varies
based on
previous
selections
Both No THX9321 Thermostat Only:
This ISU is only displayed on the THX9321
thermostat when it is wired directly to the
equipment (Equipment Interface Module is NOT
used).
The thermostat can support up to 2 backup heat
stages for heat pump applications. When there are 2
backup heat stages, backup heat stage 2 must be
wired to U1 or U2.
U1 and U2 are normally open dry contacts when
configured for a stage of Heat. U1 and U2 require
power from a system transformer or a separate
transformer.
2180 Backup Heat Type Electric Forced Air
Standard Efficiency Gas Forced Air
High Efficiency Gas Forced Air
Oil Forced Air
Hot Water Fan Coil
Hot Water Radiant Heat
Other
Electric Forced
Air
Both No This ISU is only displayed when ISU 2010 Heating
Equipment Type is Air to Air Heat Pump,
Geothermal Heat Pump or Geothermal Radiant
Heat and there is at least one stage of backup heat.
See “Heat Pump and Backup Heat Operation”
beginning on page 62.
Table 2. Installer Setup (ISU) Table. (Continued)
ISU
Number Installer Setup Name Settings Default
Residential,
Commercial
or Both
Requires
EIM Notes