Daikin AVV Installation And Maintenance Manual page 43

Economizer Control Capabilities
Basic – Compares the inside and outside air
temperatures using item 13 (Room Temperature
Sensor) and item 15 (Outdoor Air Temperature Sensor)
to determine if outdoor air can be used for "free",
economizer cooling operation.
Expanded – Compares the inside and outside air
temperatures using item 13 (Room Temperature
Sensor) and item 15 (Outdoor Air Temperature Sensor)
and calculates the enthalpy of the outside air relative
humidity using item 16 (Outdoor Air Humidity Sensor)
to determine if outdoor air can be used for "free",
economizer cooling operation.
Leading Edge – True enthalpy comparison economizer
that compares the inside and outside air temperatures
using item 13 (Room Temperature Sensor) and item 15
(Outdoor Air Temperature Sensor) and compares the
enthalpy of the inside and outside air relative humidity
using item 16 (Outdoor Air Humidity Sensor) and item 17
(Room Humidity Sensor) to determine if outdoor air can
be used for "free", economizer cooling operation.
Economizer for Reheat
Basic – Uses items 13 (Room Temperature sensor, item
15 (Outdoor Air Temperature Sensor) and item 17 (Room
Humidity Sensor) for active dehumidification (reheat)
or to determine if outdoor air can be used for "free",
economizer cooling operation.
Leading Edge – Uses items 13 (Room Temperature
Sensor), item 15 (Outdoor Air Temperature Sensor), item
16 (Outdoor Air Humidity Sensor) and item 17 (Room
Humidity Sensor) for active dehumidification (reheat)
or to determine if outdoor air can be used for "free",
economizer cooling operation.
Local User Interface (LUI)
Figure 103: Local user interface (LUI)
The optional built-in LUI touch pad with digital OLED
display is located in the right hand compartment below
the top right access door. The 4 x 20 OLED display will
provide a variety of information including:
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Operating mode states
• Fan functions
• Room set point temperature
• Current room temperature
• Fault codes for quick diagnostics at the unit
The LUI has a built in menu structure (Password
protected) with 4 keys and 2 individual LED indicators to
adjust the unit ventilator operating parameters shown in
the following.
Operating Mode States (4)
Heat - Heating and economizer operation only
•
Cool – Cooling and economizer operation only
•
Fan Only – Fan operation only
•
Auto – Unit automatically switches between heating,
•
cooling and economizer operation to satisfy the
room load conditions. The current unit state is also
displayed.
Fan States (4)
High (constant speed)
•
Medium (constant speed)
•
Low (constant speed)
•
Auto (part load, variable air) – Varies the fan speed
•
automatically to meet the room load conditions
whether the unit is in heating, cooling or economizer
mode. The current fan speed is also displayed.
During low load or normal operation (about 60% of
the time) the fans will operate at low speed. When
the load increases to an intermediate demand the
fans automatically shift to medium speed. At near
design or design load conditions, the fans will operate
on high speed. A 10-minute delay between speed
changes is incorporated to minimize the awareness
of these changes. The outdoor air damper will index
based on the fan speed to maintain the required
minimum cfm (cubic feet per minute) of ventilation air.
Occupancy Modes (4)
Occupied – Normal, daytime operation where the
•
unit maintains the room set point.
Unoccupied – Night set back operating mode in which
•
the unit responds to a new room set point and cycles
to maintain the condition. The fan comes on when
heating or cooling is needed and runs until the load is
satisfied. The outside air damper is closed during this
mode. With direct expansion (DX) cooling units, when
a cooling load is satisfied by the refrigerant system,
the compressor is de-energized and the Unit Ventilator
indoor fan continues to run for a fixed period of time to
remove possible frost buildup on the evaporator coil.
Stand By Mode – The unit ventilator maintains the
•
stand by mode set point temperature with the outside
air damper closed. The fan runs continuously unless
it is configured to cycle in response to the room load.
43 IM 817-7