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®
THX9321 PRESTIGE
2.0 AND THX9421 PRESTIGE
Press
Scroll to select DEHUMIDIFICATION
Set humidity to desired level
Press to review filter timer
This setting is only available if "User selectable" is set for
ISU 9005. See "Dehumidification Fan Speed Priority"
beginning on page 105.
Fig. 238.
Dehumidification - Commercial
The thermostat reads the indoor humidity level and allows
the user to set a dehumidification setting. The thermostat
controls the humidity level using the cooling system or a
dehumidifier.
If humidification and dehumidification are setup to
operate in the same system mode (Heat, Cool, Off) and
you are sensing humidity from one location, the
thermostat will automatically enforce a 15% deadband
between the humidification and dehumidification
settings. The thermostat will automatically switch
between humidification and dehumidification to maintain
the desired humidity level.
If humidification and dehumidification are setup to
operate in the same system mode (Heat, Cool, Off) and
you are sensing humidity from two different locations
using a remote wireless indoor sensor (for example, main
level and crawl space), the thermostat will allow
68-0311—07
®
IAQ WITH EIM
humidification and dehumidification to operate at the
same time, and there is no deadband between
humidification and dehumidification settings.
Dehumidification Equipment Options: (ISU 9000)
• A/C with Low Speed Fan
• A/C with High Speed Fan
• Hot Gas Bypass
• Dehumidifier
NOTE: Hot Gas Bypass - During a call for dehumidifica-
tion, the cooling capacity will be used to remove
more latent heat than sensible heat. The opera-
tion of Hot Gas Bypass varies by equipment. For
more details, contact the equipment manufac-
turer.
Dehumidification using the Cooling
System
Dehumidification using A/C with Low Speed Fan, A/C with
High Speed Fan or Hot Gas Bypass, has the following
methods of dehumidification control (ISU 9080):
Basic: This option uses the cooling system to reach the
desired humidity level. Minimum On Time, High Humidity
Comfort Reset and Reheat are not used with this method.
This setting is commonly used if your dehumidification
equipment is Hot Gas Bypass.
Minimum On Time (ISU 9090): This option ensures that
the compressor runs long enough to effectively reduce
humidity when the cooling equipment is cycled on. The
compressor will run for the minimum "on time" you set
until the desired humidity level is reached.
High Humidity Comfort Reset (ISU 9100): This option uses
the cooling system to lower the temperature up to 5° F
below the current cool setpoint until the desired humidity
is reached. The high humidity comfort range is from 1° to
5° F.
High Humidity Comfort Reset with Minimum On Time
(ISU 9090 and 9100): This method uses both options
above to reduce humidity while maintaining a comfortable
temperature.
Reheat (ISU 9080): This option allows heating to run
during dehumidification to help maintain a comfortable
temperature. If only cooling stage 1 is used, during the
"off" cycle, both cooling and heating run at the same time
as needed to dehumidify without overcooling. This option
110
Fig. 239.
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