Honeywell PRESTIGE THX9321 System Installation Manual page 22

System Installation Guide
Commercial dehumidification
Dehumidification Equipment Options: (ISU 9000)
• A/C with Low Speed Fan
• A/C with High Speed Fan
• Hot Gas Bypass
• Dehumidifier
When set for A/C with Low Speed Fan, A/C with High Speed Fan or Hot Gas
Bypass, there are five methods of dehumidification control: (ISU 9080) See
descriptions of each, below.
1 Minimum On Time
2 High Humidity Comfort Reset
3 High Humidity Comfort Reset with Minimum On Time
4 Reheat
5 Reheat with Minimum On Time
1 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.
2 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.
3 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.
4 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 cannot
be used in the Heat mode. This option is effective only if using a system
with the A-Coil located before the plenum.
5 Reheat with Minimum On Time (ISU 9080 and 9090)
This method uses both Reheat and Minimum On Time options above to
reach the desired humidity level.
The Dehumidifier option requires a dedicated unit for dehumidification. The ther-
mostat can be set to control dehumidification in all modes (Heat, Off, Cool [ISU
9120]).
Hot Gas Bypass - During a call for dehumidification, the cooling capacity will be used to remove more latent heat
than sensible heat. The operation of Hot Gas Bypass varies by equipment. For more details, contact the equipment
manufacturer.
To see all dehumidification options, press MENU > INSTALLER OPTIONS > VIEW/EDIT CURRENT SETUP >
DEHUMIDIFICATION.
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