OM 1280-2 • MICROTECH UNIT CONTROLLER 34 www.DaikinApplied.com
Indoor Air Fan Operation
The UVC supports a variable speed, or three-speed indoor
air fan (IAF); low, medium, and high. The UVC calculates the
occupancy mode, and the values of several network variables.
Figure 21: Fan Only State Diagram
Auto Mode
The UVC is provided with a user selectable auto fan mode
feature. When in auto fan mode, the UVC uses the space
temperature PI loop to automatically adjust the fan speed as
needed to maintain space temperature. This ensures that the
UVC maintains the lowest and quietest fan speeds whenever
possible. When in auto fan mode, a maximum of six fan speed
changes per hour is allowed (by default). This prevents frequent
automatic fan speed changes from disturbing room occupants.
the LUI keypad or ServiceTools software.
Manual Fan Mode
The indoor fan may be manually set locally to Low, Medium or
High speed through the LUI keypad or using the ServiceTools
software. When the fan speed is selected this way, the setting
A remote wall sensor with fan speed switch may be used to
locally change the fan speed.
Figure 22: Fan Control - 3-Speed Fixed/Adjustable
Occupied, Standby, and Bypass Operation
During Occupied Standby and Bypass modes, the IAF, by
the LUI keypad or ServiceTools software.
Unoccupied Operation
cycles with calls for heating and cooling. The IAF can optionally
when there’s no call for heating or cooling through the LUI
keypad or ServiceTools software.
Cycle Fan
variable that can be used to force the IAF to cycle with calls for
heating and cooling during the occupied, standby, and bypass
closed. Daikin recommends using this feature only when it is
acceptable that normal ventilation is not required.
fan operation for a time period after heating or cooling is complete.
period and then shutdown.
Fan Control
ways depending on the type of fan the unit has (Figure 21).
3-Speed Fixed
The UVC uses three binary outputs to control a fan to low,
medium, or high speed. When fan control is in the Auto
mode, the UVC adjusts the fan speed up and down in an
attempt to maintain the control temperature setpoint. The fan
capacity percentage required will be calculated using a PI loop
fan speed increases when the capacity percentage required
is greater than or equal to the break point + the break point
The fan speed decreases when the capacity percentage
required is less than the break point.
remains at low speed when no capacity is required.
OFF
Mode
(State 9)
Is SpaceTemp
< EHS
No
EMERGENCY
HEAT
Mode
Yes
Enter from:
LUI Input
Network Input
0%
100%
Secondary
Cooling
Capacity
Degrees from
Setpoint and Time
Satisfied
Control Temperature
SatLo
SatHi
Staging
Down
Staging
Up
95%
93%
75%
73%
Fan Speed
OA Damper at 20% Open –
IA Fan High Speed –
OA Damper at 25% Open –
IA Fan Medium Speed –
OA Damper at 30% Open –
IA Fan Low Speed –
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