OM 1280-2 • MICROTECH UNIT CONTROLLER 12 www.DaikinApplied.com
Description of Operation
Discharge Air Temperature Control
The unit will remain in one of the cooling states, heating state,
or fan only/dehumidification state until the control temperature
transitions through either the cooling setpoint or heating
setpoint. The amount of heating and cooling commanded is
based on the discharge air temperature and discharge air
temperature setpoint. Cooling and heating stage-up and stage-
down commands are based on the discharge air temperature.
These commands are one of the parameters used to command
different states in the main state machine.
Discharge Air Temperature Resets
An optional discharge air temperature reset can be programmed
into the UVC that will automatically adjust the discharge air
temperature setpoint based on the control temperature. There
are four parameters for heating and cooling respectively.
Control Temperature:
Current measured space temperature
by a unit mounted sensor, a remote mounted wall sensor, or an
average of the two (See “Control Temperature” on page 30).
Heating Mode
Default Values:
1. Min DAT HTG Setpoint = 80
2. Max DAT HTG Setpoint = 120
3. Min DAT HTG Ctrl Setpoint = 67
4. Max DAT HTG Ctrl Setpoint = 70
Min DAT Htg Setpt:
Minimum heating discharge air temperature
allowed when unit is in heating mode and the reset is enabled.
Max DAT Htg Setpt:
Maximum heating discharge air temperature
allowed when unit is in heating mode and the reset is enabled.
Min DAT Htg Ctrl Setpt:
Minimum discharge air temperature
control value. When the control temperature is less than or equal
to MinDAT Ctrl, the DAT Heating value = Max DAT Htg Setpt.
Max DAT Htg Ctrl Setpt:
Maximum discharge air temperature
control value. When the control temperature is equal to or greater
than MaxDAT Ctrl, the DAT Heating value = Min DAT Htg Setpt.
The unit enters heating mode when the control temperature is
below the effective heating setpoint.
If the heating reset is enabled, when the control temperature is
between the MinDAT Htg Ctrl Setpt and the MaxDAT Htg Ctrl
Setpt, the DAT setpoint will vary linearly between the Max DAT
Htg Setpt and Min DAT Htg Setpt values as depicted in Figure 4.
Figure 4: Discharge Air Temperature Heating vs. Discharge Air Temperature Heating Setpoint
DATControlTempHtg Vs. DAT HtgSetpt
cpMaxDATHtgSetpt
(default: 120°F)
cpMaxDATHtgCntlSetpt (default: 70°F)
cpMinDATHtgCntlSetpt (default: 67°F)
cpMinDATHtgSetpt
(default: 80°F)
DATControlTempHtg
D
ATHtgSetpt
Control Temperature (
example: 68.5°F
)
Effective DAT Heating
Setpoint (
example: 100°F
)
Summary of Contents for MicroTech
Page 77: ......
