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McQuay MicroTech II User Manual

McQuay MicroTech II
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Page 114 OM 780-2
Decoupler Temperature Sensor Fail
If the temperature sensor in the decoupler line reads out of range (-10 to 135°F, -23.3 to 57.2°C), the decoupler temperature
sensor fail alarm occurs. As a result, the system continues to operate, but the decoupled sequencing logic is modified to
allow stage-ups only when additional capacity is required, not when additional primary water flow is required. The
decoupler line temperature is used to check the need for additional primary water flow. When the alarm condition is gone,
the alarm automatically clears.
If a decoupler line temperature sensor is not connected to the CSM, leave the Decoupler Sensor Present Flag = “No” (I/O
Config screen) so that the alarm is inhibited from changing.
Return Chilled Water Temperature Sensor Fail
If the temperature sensor in the return chilled water line reads out of range (-10 to 135°F, -23.3 to 57.2°C), the return
chilled water temperature sensor fail alarm occurs. As a result, the system continues to operate. The following features are
affected:
Optimal start
The optimal start feature acts as though the return water temperature is extremely high. Therefore, it uses 90°F (32°C),
which likely results in an earlier start-up time.
Chilled water reset based on return water temperature
The Return Water reset function acts as though the return water temperature is extremely high. Therefore, it sets the
System Setpoint equal to the Minimum System Setpoint.
Chilled water reset for constant return water temperature
The Constant Return reset function acts as though the return water temperature is extremely high. Therefore, it sets the
System Setpoint to the Minimum System Setpoint.
When the alarm condition is gone, the alarm automatically clears.
If a return chilled water temperature sensor is not connected to the CSM, leave the Return Chilled Water Sensor Present
Flag = “No” (I/O Config screen) so that the alarm is inhibited from changing.
Supply Chilled Water Temperature Sensor Fail
If the temperature sensor in the supply chilled water line reads out of range (-10 to 135°F, -23.3 to 57.2°C), the supply
chilled water temperature sensor fail alarm occurs. As a result, the system continues to operate. The following features are
affected:
Standard chiller sequencing
Standard sequencing logic acts as though the supply water temperature is extremely high. Therefore, stage-up control
is based on chiller full load status and the chiller stage delay time only.
Decoupled chiller sequencing
Decoupled sequencing logic acts as though the supply water temperature is extremely high. Therefore, stage-up control
is based on chiller full-load status and the chiller stage delay time only. A stage-up does not occur if additional primary
water flow is required.
Common chilled water temp control option
The Common chilled water temp control option acts as though the supply water temperature is extremely high.
Therefore, it quickly reduces the Chiller Setpoint to the Minimum Chiller Setpoint.
Optimal start
The optimal start feature disables its adaptation process. Thus, an optimal start can still occur, but the time increment
used is not updated.
When the alarm condition is gone, the alarm automatically clears. This sensor is required for all CSM applications and
there is no means to disable the alarm.
Loop Differential Pressure Sensor Fail
If the conditioned analog signal from the loop differential pressure sensor falls below 1 Vdc, the loop differential pressure
sensor fail alarm occurs. As a result, the system continues to operate, but the following features are affected:
Sequencing pump logic

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McQuay MicroTech II Specifications

General IconGeneral
BrandMcQuay
ModelMicroTech II
CategoryController
LanguageEnglish

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