VISIONPRO® 8000 SMART THERMOSTAT
33-00096—04
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humidification and dehumidification settings. The
thermostat will automatically switch between
humidification and dehumidification to maintain the
desired humidity level.
Dehumidification Equipment Options: (ISU 900)
• A/C with Low Fan
• A/C with High 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 operation
of Hot Gas Bypass varies by equipment. For more
details, contact the equipment manufacturer.
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 908):
Fig. 144.
Basic (ISU 908): This option uses the cooling system to
reach the desired humidity level. Minimum On Time,
Cooling Droop 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 908 and 909): 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.
Cooling Droop (ISU 908 and 910): 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 Dehum Over Cooling Limit range is from 1° to
5° F.
Cooling Droop with Minimum On Time (ISU 908, 909, and
910): This method uses both options above to reduce
humidity while maintaining a comfortable temperature.
Reheat (ISU 908): 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
heating coil (heat exchanger). This feature requires a
conventional forced air heating system (gas, oil, or electric)
in the application.
NOTE:
Reheat can be used on heat pump applications
that have a forced air backup heat source (gas, oil,
or electric). The thermostat will turn on the first
stage of forced air backup heat during Reheat.
NOTE:
Reheat can be used on systems where the A-Coil is
located after the heating coil (heat exchanger), but
it is not effective at removing humidity.
Reheat with Minimum On Time (ISU 908 and 909): This
method uses both Reheat and Minimum On Time options
above to reach the desired humidity level.
If set for A/C with Low Speed Fan, configure U1 as normally
open or normally closed (ISU 905) and wire to the Low
Speed Fan terminal on the equipment. For example, if the
U1 terminal is normally closed, it will open when the
thermostat calls for dehumidification.
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 900.
See Fig. 145.
Fig. 145.
2.
Select the terminals wired to the A/C with Low Speed
Fan or Hot Gas Bypass. See Fig. 146.
Fig. 146.
