When Airow is selected, the values “Min Clg Spt @” and “Max
Clg Spt @” are entered as percentage values. When Ext mA is
selected, the values “Min Clg Spt @” and “Max Clg Spt @” are
entered as mA values. When Ext VDC is selected, the values
“Min Clg Spt @” and “Max Clg Spt @” are entered as VDC
values.
If Ext mA or Ext V is selected as the type of reset, the Min Clg
Spt @ value may be set above the Max Clg Spt @ value to
cause a decrease in the DAT setpoint as the external signal or
the Min Clg Spt @ value may be set below the Max Clg Spt @
value to cause an increase in the DAT setpoint as the external
signal increase.
The Min Clg Spt @ value can be set below the Max Clg Spt @
value for all types of reset, but it only makes sense for external
reset.
When ever the Clg Reset Type or Engineering Units is
changed, the Min Clg Spt @ and Max Clg Spt @ values revert
to default values as follows:
• None: Min Clg Spt @=0NA, Max Clg Spt @=100NA
• Network: Min Clg Spt @=0NA, Max Clg Spt @=100NA
• Space, Return: Min Clg Spt @=73.0F, Max Clg Spt
@=71.0F
• OAT: Min Clg Spt @=90.0F, Max Clg Spt @=70.0F
• ExtmA: Min Clg Spt @=4.0mA, Max Clg Spt @=20.0mA
• ExtVDC: Min Clg Spt @=0.0V, Max Clg Spt @=10.0V
• Airow: Min Clg Spt @=33%, Max Clg Spt @=100%
Heating Control
(See page 49 and 83 for more information)
Entering Heating Operating State
The unit enters the Heating operating state from the Fan Only
operating state when the control temperature falls below the
Occupied Heating Set Point by more than half the Occupied
Heating Dead Band. The unit transitions from the Heating to
Fan Only operating state when the control temperature rises
above the Occupied Heating Set Point by more than half the
Occupied Heating Dead Band. The unit will also transition from
the Heating to Fan Only operating state if heating operation is
disabled due to OA ambient lockout.
Heating: Staged Zone Control
When the unit rst enters the Heating operating state the unit
goes directly to Stage # 1.
The number of heating stages increases when the time since
the last stage change exceeds the stage time, the Projected
Control Temperature and the actual Control Temperature are
less then the Occ Htg Spt (minus ½ the deadband), and the
DAT is less than the Max DAT Htg Spt.
The number of heating stages decreases when the time
since the last stage change exceeds the stage time, and the
Projected Control Temperature and actual Contro Temperature
are greater then the Occ Htg Spt (plus ½ the deadband).
The number of heating stages also decreases when the time
since the last stage change exceeds the stage time, and the
DAT is greater than the MaxDATHtgSpt.
Heating DAT Staging or MinDAT Staging
When the unit enters the Heating or Minimum DAT states and
all heating is off, the unit goes directly to Heating Stage # 1 so
that the rst stage of heat is turned on immediately.
The number of heating stages increases when the time since
the last stage change exceeds the stage time, and DAT is less
than the effective DAT setpoint (DAT staging) or the Min DAT
limit (MinDAT staging) by ½ the deadband. One exception
to this is that if the current heating stage is zero, the heating
stage can increase without regard to the stage timer.
The number of heating stages decreases when the time since
the last stage change exceeds the stage time, and the DAT is
greater than the effective DAT setpoint (DAT staging) or the
MIN DAT limit (MinDAT staging) by ½ the deadband.
The unit enters the Min DAT operating state during occupied
operation when neither cooling nor heating is required based
on the unit heat/cool changeover function but the discharge air
temperature falls below a minimum discharge temperature limit
by more than ½ the deadband. The Min DAT operating state
prevents cold discharge air temperatures during what would
normally be the Fan Only operating state.
Modulating
Entering Heating Operating State
The unit enters the Heating operating state from the Fan Only
operating state when the Control Temperature falls below the
Occupied Heating Set Point by more than half the Occupied
Heating Dead Band. The unit transitions from heating to Fan
only when the Control Temperature rises above the Occupied
Heating Set Point by more than half the Occupied Heating
Dead Band. The unit will also transition from the Heating to
Fan Only operating state if heating operation is disabled due to
OA ambient lockout. When the unit is in the Heating operating
state, heating capacity is modulated to maintain the discharge
air temperature at the Discharge Heating Set Point.
.
OM 1141-3 • MICROTECH UNIT CONTROLLER 108 www.DaikinApplied.com
operator’s guIde
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