McQuay OM 920-1 69
Operator’s Guide
Off Ambient
The unit is configured for waterside economizer and the EWT exceeds the mixed air
temperature minus the EWT differential set point. OR
The unit is configured for airside economizer and the outdoor air temperature (OAT) is too
high for operation. OR
Unit is configured for waterside economizer and the Entering Water Temperature (EWT)
sensor is unreliable. OR
Unit is configured for airside economizer and the outdoor air temperature (OAT) sensor is
unreliable.
OffAlarm
The unit operation is disabled by an alarm condition.
Off Network
The unit is disabled via a network command.
OffMan
Control mode is set to Off via the System Menu.
Off Dehumidification
Economizer operation will be disabled if dehumidification operation is enabled.
Determining Cooling Capacity
Clg Capacity is a status item which indicates the percentage of the unit maximum cooling
capacity currently operating. The current Cooling Capacity can be view via the following
path: Standard Menus/System/Clg Capacity. 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 operating cooling stages.
Determining Heating Capacity
Htg Capacity is a status item which indicates the percentage of the unit maximum heating
capacity currently operating. The current Heating Capacity can be view via the following path:
Standard Menus/System/Htg Capacity. 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 operating heating stages.
Determining Supply Air Fan Capacity
SAF Speed is a status only item which indicates the Supply Air Fan capacity. The current SAF
Capacity can be view via the following path: Standard Menus/System/SAF 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 Speed is a status only item which indicates the current return or exhaust fan capacity.
The current RF/EF Capacity can be view via the following path: Standard
Menus/System/RF/EF Capacity. 0-100% of VFD maximum speed is indicated if the unit is
equipped with a return or exhaust fan VFD. 100% is indicated if the return/exhaust fan is
constant volume and is running.