028 -0427-15 _UI-V T8350_ A4 _ EN www.viconics.com June 2020
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VT8350 [ User Interface Guide ]
Conguration Parameters Default Value Signicance and Adjustments
Operation seq.
Default: Heat only
Sequence of Operation
Selects the initial sequence of operation required by the installation type and the
application.
Cool only: cooling only
Heat only: heating only
Cool-rht: cooling with reheat
Heat-rht: heating with reheat
Cool/heat: cooling and heating
Cl/ht-rht: cooling and heating with reheat
When “Pipe Number” is set to 2 and UI19 is set to COC-NH, COC-NC or COS the
“Sequence of operation” is as follows:
• “Cool only” or “Heat only” will be determined by the UI19 contact status or
sensor temperature.
• For 2-Pipe application (no reheat): set “Sequence of operation” to “Cool only”
or “Heat only”
• For 2-Pipe application (with reheat): set “Sequence of operation” to “Cool-rht”
or “Heat-rht”
Choices: Cool only, Heat only, Cool-rht, Heat-rht, Cool/heat and Cl/ht-rht
Purge sample
Default: 2.0 hrs
Purge Sample Period
Time interval between valve samples. Will open valve for a short period adjusted
by “Purge open” parameter to sample pipe temperature to decide between
heating or cooling mode.
Adjustable: 0.0 to 4.0 hours (0 hours disables the function)
Purge open
Default: 2 min
Purge Open
Time the valve opens to sample pipe temperature to decide between heating or
cooling mode.
Adjustable: 1 to 3 minutes
Temp. sensor
Default value: Wired
Room Temperature Sensor
Sets the source of the indoor room temperature. This parameter allows the user
to designate either the Room Controller or any of the paired wireless devices that
support temperature to act as the source for the room temperature.
Wired: sets the thermistor connected to UI20 (RS) as the source to report room
temperature.
Internal: sets the Room Controller as the source for the room temperature.
WL 1 to WL 20: sets the selected ZigBee wireless device as the source for the
room temperature. Only one device can be selected.
Note: The Room Controller uses the internal temperature sensor only if the
UI20 (RS) terminal is empty. If a valid temperature sensor is connected to the
UI20 terminal, the Room Controller will use the sensor as the control point.
Disconnecting the sensor, or if the sensor is faulty, the Room Controller will
automatically revert to its internal temperature sensor.
Choices: Wired, Internal and WL 1 to WL 20
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