Determining Economizer Status; Determining Cooling Capacity; Determining Supply Air Fan Capacity; Determining Rf/Ef Capacity - Daikin MicroTech III Operation Manuals

Determining Economizer Status

If the unit is equipped with a 0-100% modulating economizer
(waterside or airside) and the conditions are suitable for free
cooling, the unit attempts to satisfy the cooling load by using
either outdoor air or the waterside economizer before using
mechanical cooling .
The following are descriptions of Economizer Status states
Off Ambient
• Unit is an SCU configured for waterside economizer
and the Entering Water Temperature (EWT) sensor is
unreliable .
• Unit is an SCU configured for waterside economizer
and the EWT exceeds (Mixed Air Temperature – EWT
Differential) . It is enabled if EWT drops below (Mixed Air
Temperature – EWT Differential) .
• Unit is configured for airside economizer and the outdoor
air temperature (OAT) sensor is unreliable .
• Economizer Changeover is set to Enthalpy and OAT and
the Enthalpy Input is in the High (Open) position .
• Economizer Changeover is set to Enthalpy and OAT
and the OAT rises above the Economizer Changeover
Temperature by a fixed 2°F differential. (OAT becomes
low enough for operation when the OAT drops to or below
the Economizer .
• Economizer Changeover is set to Enthalpy and OAT
and the OAT rises above the Economizer Changeover
Temperature by a fixed 2°F differential. (OAT becomes
low enough for operation when the OAT drops to or below
the Economizer Changeover Temperature) .
• Economizer Changeover is set to OAT_RAT and the OAT
rises above the RAT by a fixed 2°F differential. (OAT
becomes low enough for operation when the OAT drops
below the RAT a fixed 2°F differential).
Off Network
• A network signal is set to OFF
Off None
• Economizer Changeover is set to None
• Economizer capability is not provided
• Unit is not configured for an airside or waterside
economizer
NOTE: Economizer is not disabled based on Control Mode or
Application Mode .
Economizer operation is disabled via a network command .
Off Dehumidification
Economizer operation is disabled if dehumidification operation
is enabled .
OM 920-6 • MICROTECH UNIT CONTROLLER

Determining Cooling Capacity

Clg Capacity is a status item which indicates the percentage
of the unit maximum cooling capacity currently operating .
When the unit is equipped with chilled water cooling, 0-100%
is displayed as the cooling valve actuator strokes from the
closed to open position . When the unit is equipped with
compressorized cooling, the percentage value changes
incrementally based on the number of operating cooling
stages .
Determining Heating Capacity
Htg Capacity is a status item which indicates the percentage of
the unit maximum heating capacity currently operating . When
the unit is equipped with modulating heat, 0-100% is displayed
as the heating valve actuator strokes from the closed to open
position . When the unit is equipped with staged heat, the
percentage value changes incrementally based on the number
of operating heating stages .

Determining Supply Air Fan Capacity

SAF Speed is a status only item which indicates the supply air
fan capacity . 0-100% of VFD maximum speed is indicated if the
unit is equipped with a supply air fan VFD . 100% is indicated if
the supply fan is constant volume and is running .

Determining RF/EF Capacity

RF/EF capacity is a status only item which indicates the current
return or exhaust fan capacity . 0-100% of VFD maximum
speed is indicated if the unit is equipped with a modulating
return or exhaust fan VFD . 100% is indicated if the return/
exhaust fan is constant volume and is running . When the unit
is equipped with staged exhaust fans, the percentage value
changes incrementally based on the number of operating
exhaust fan stages .
Determining Outside Air Damper Position
OAD/Econo Cap is a status only item which indicates the
current outdoor air damper or economizer valve position .
Determining Emergency Mode
Emergency Mode is an adjustable item which is normally used
by a network system to shutdown the unit in an emergency
situation .
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