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THX9321 PRESTIGE
®
2.0 AND THX9421 PRESTIGE
®
IAQ 2.0 WITH EIM
67 68-0311—01
NOTE: The thermostat will not lower the fan speed when
the second stage of cooling is on.
Set up Dehumidification With Cooling
System
Some screens shown in this section may not appear on the
thermostat, depending on how you set up dehumidification.
1. Select the Dehumidification Equipment in ISU 9000. See
Fig. 112.
Fig. 112.
2. If optional remote wireless indoor sensors are installed,
you can choose which sensor you want to use for dehu-
midification control. For example, you can use one sen-
sor for humidification control, and another for
dehumidification. See “Wireless Indoor Sensor” begin-
ning on page 96 for more information.
Fig. 113.
3. If you are sensing humidity from two separate locations
(one for humidification and another for dehumidification),
you can select which humidity reading to display on the
home screen. See “Wireless Indoor Sensor” beginning
on page 96 for more information.
Fig. 114.
4. Select the terminals wired to the A/C with Low Speed
Fan. See Fig. 115.
Fig. 115.
5. Select whether the U1, U2, or U3 terminals are Normally
Open or Normally Closed. See Fig. 116.
• Normally Open – contacts are normally open and will
close during a call for dehumidification
• Normally Closed – contacts are normally closed and
will open during a call for dehumidification.
Fig. 116.
6. Set the Overcooling Limit. See Fig. 117. Options:
• 0 °F to 3 °F (A/C with Low Speed Fan)
• 1 °F to 3 °F (A/C with High Speed Fan)
Fig. 117.
NOTE: ISU 10140 gives the option to lockout ventila-
tion on calls for dehumidification. This helps
maintain the desired humidity level.
Dehumidification using a Whole House
Dehumidifier
The Whole House Dehumidifier option requires a dedicated
unit for dehumidification. The thermostat can be set to control
dehumidification in all modes (Heat, Off, Cool [ISU 9120]).