2.1 Chiller Rules

2.1.3.1 - Chilled Water Leaving Temperature Greater Than Setpoint

Summary

The chilled water leaving temperature is greater than the leaving water temperature setpoint, indicating bad control, energy waste, and potential comfort complaints.


Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Leaving Temperature ChWLTemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Setpoint ChWSp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 60 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Temperature Threshold Numeric 2 This number (in Fahrenheit) is the temperature threshold. The chilled water leaving temperature must exceed the sum of the temperature threshold added to the chilled water setpoint for a period longer than the delay in order for a fault condition to exist.

2.1.4.1 - Chilled Water Leaving Temperature Less Than Setpoint

Summary

The chiller water leaving temperature is less than the leaving water temperature setpoint, indicating bad control and energy waste.


Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Leaving Temperature ChWLTemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Setpoint ChWSp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 60 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Temperature Threshold Numeric 2 This number (in Fahrenheit) is the temperature threshold. The chilled water leaving temperature must not exceed the difference between the temperature threshold subtracted from the chilled water setpoint for a period longer than the delay in order for a fault condition to exist.

2.1.5.1 - Chiller Low Temperature Differential (Low Delta T)

Summary

The chiller temperature differential (Delta T) is much lower than design.


Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chiller Water Entering Temperature ChWETemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Leaving Temperature ChWLTemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 120 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Minimum Temperature Differential Numeric 5 This number (in Fahrenheit) is the minimum temperature differential. The difference value of the chilled water leaving temperature subtracted from the chilled water entering temperature must not exceed the minimum temperature differential for a period longer than the delay in order for a fault condition to exist.

2.1.6.1 – Chilled Water Leaving Temperature Sensor Failure

Summary

The chilled water leaving temperature sensor has failed. The temperature sensor point is invariant or is outside the expected range.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Leaving Temperature ChWLTemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 120 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
High Threshold Numeric 70 This number (in Fahrenheit) is the maximum allowed value of the chilled water leaving temperature. The chilled water leaving temperature must exceed the high threshold for a period longer than the delay in order for a fault condition to exist.
Low Threshold Numeric 20 This number (in Fahrenheit) is the minimum allowed value of the chilled water leaving temperature. The chilled water leaving temperature must not exceed the low threshold for a period longer than the delay in order for a fault condition to exist.
Variance Threshold Numeric 0.01 This number (in Fahrenheit) is the variance threshold.  The difference value of the high threshold and low threshold must not exceed the variance threshold for a period longer than the delay in order for a fault condition to exist.

2.1.6.2 - Chilled Water Entering Temperature Sensor Failure

Summary

The chilled water entering temperature sensor has failed. The temperature sensor point is invariant or is outside the expected range.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Entering Temperature ChWETemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 120 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
High Threshold Numeric 70 This number (in Fahrenheit) is the maximum allowed value of the chilled water entering temperature. The chilled water entering temperature must exceed the high threshold for a period longer than the delay in order for a fault condition to exist.
Low Threshold Numeric 20 This number (in Fahrenheit) is the minimum allowed value of the chilled water entering temperature. The chilled water entering temperature must not exceed the low threshold for a period longer than the delay in order for a fault condition to exist.
Variance Threshold Numeric 0.01 This number (in Fahrenheit) is the variance threshold.  The difference value of the high threshold and low threshold must not exceed the variance threshold for a period longer than the delay in order for a fault condition to exist.

2.1.6.3 - Condenser Water Entering Temperature Sensor Failure

Summary

The condenser water entering temperature sensor has failed. The temperature sensor point is invariant or is outside the expected range.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Water Entering Temperature CWETemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 120 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
High Threshold Numeric 100 This number (in Fahrenheit) is the maximum allowed value of the condenser water entering temperature. The condenser water entering temperature must exceed this threshold for a period longer than the delay in order for a fault condition to exist.
Low Threshold Numeric 35 This number (in Fahrenheit) is the minimum allowed value of the condenser water entering temperature. The condenser water entering temperature must not exceed this threshold for a period longer than the delay in order for a fault condition to exist.
Variance Threshold Numeric 0.01 This number (in Fahrenheit) is the variance threshold.  The difference value of the high threshold and low threshold must not exceed the variance threshold for a period longer than the delay in order for a fault condition to exist.

Rule 2.1.6.4 - Condenser Water Leaving Temperature Sensor Failure

Summary

The condenser water leaving temperature sensor has failed. The temperature sensor point is invariant or is outside the expected range.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Water Leaving Temperature CWLTemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 120 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
High Threshold Numeric 100 This number (in Fahrenheit) is the maximum allowed value of the condenser water leaving temperature. The condenser water leaving temperature must exceed this threshold for a period longer than the delay in order for a fault condition to exist.
Low Threshold Numeric 35 This number (in Fahrenheit) is the minimum allowed value of the condenser water leaving temperature. The condenser water leaving temperature must not exceed this threshold for a period longer than the delay in order for a fault condition to exist.
Variance Threshold Numeric 0.01 This number (in Fahrenheit) is the variance threshold.  The difference value of the high threshold and low threshold must not exceed the variance threshold for a period longer than the delay in order for a fault condition to exist.

2.1.6.5 - Outside Air Temperature Sensor Failure

Summary

The outside air temperature sensor has failed. The temperature sensor point is invariant or is outside the expected range.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Outside Air Temperature OaTemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 60 The delay represents a span of time in minutes during which the sensor must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
High Threshold Numeric 130 This number (in Fahrenheit) is the maximum allowed value of the outside air temperature. The outside air temperature must exceed this threshold for a period longer than the delay in order for a fault condition to exist.
Low Threshold Numeric -40 This number (in Fahrenheit) is the minimum allowed value of the outside air temperature. The outside air temperature must not exceed this threshold for a period longer than the delay in order for a fault condition to exist.
Variance Threshold Numeric 0.01 This number (in Fahrenheit) is the variance threshold.  The difference value of the high threshold and low threshold must not exceed the variance threshold for a period longer than the delay in order for a fault condition to exist.

2.1.7.1 - Chiller Status is Off When Commanded On

Summary

The chiller status indicates it is 'Off', but the chiller is being commanded 'On', indicating a problem, inefficient operation, and potential comfort complaints.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chiller Command ChrCmd This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 15 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.

2.1.8.1 - Chiller Status is On When Commanded Off

Summary

The chiller status indicates it is 'On', but the chiller is being commanded 'Off', potentially wasting energy.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chiller Command ChrCmd This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 15 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.

2.1.9.1 - Chilled Water Supply Temperature Setpoint is Less Than Low Limit

Summary

The chilled water supply temperature setpoint is less than the low limit, wasting energy. The setpoint may be overridden or set lower than design.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Setpoint ChWSp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 15 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Low Temperature Setpoint Limit Numeric 42 This number (in Fahrenheit) is the minimum allowed value of the chiller supply water temperature. The chilled water setpoint must not exceed this threshold for a period longer than the delay in order for a fault condition to exist.

2.1.10.1 - Chiller Chilled Water Flow Rate is Too High

Summary

Manufacturers have minimum chilled water flow rates through the evaporator. It is determined the flow rate for this chiller is below manufacturer's recommendations. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- (CHWFlow) || (ChWPressDiff & ChWPressDiffSp) || (EvFlowSw)

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Pump Status ChWCPSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Flow CHWFlow This point must be a direct child of the equipment that the rule is attached to. Optional Scalar
Evaporator Differential Pressure EvDifPrsSp This point must be a direct child of the equipment that the rule is attached to. Optional Scalar
Evaporator Differential Pressure Setpoint EvDifPrsSp This point must be a direct child of the equipment that the rule is attached to. Optional Scalar
Evaporator Flow Switch EvFlowSw This point must be a direct child of the equipment that the rule is attached to. Optional Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 60 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
MIN_CHW_FLOW Numeric 100 The Minimum chilled water flow threshold.

2.1.11.1 - Chiller Chilled Water Valve is Open When Chiller is Off

Summary

Isolation valves are required when more than one chiller is serving a chilled water system and should be closed when the chiller and associated chiller pump are off. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Pump Status ChWCPSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Isolation Valve ChWIsoVlvCmd This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 60 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.

2.1.12.1 - Chiller Water Supply Temperature Setpoint Can Be Increased (Reset)

Summary

Most of the chilled water valve positions are less than a high valve limit, indicating an opportunity to increase the chilled water supply temperature setpoint. Chilled water supply temperature reset is required by ASHRAE Standard 90.1.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
VAV Cooling Command ClgCmd This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 60 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Cooling Value Threshold Numeric 90 This number is the cooling value threshold in percent. If most of the hot water valve positions (ClgCmd's) of the VAV/AHU/HX/FCU served by the chiller are less than the cooling valve threshold for a period longer than the delay in order for a fault condition to exist.
% of Cooling Equipment Valves Below Threshold Numeric 90 This number is the % of cooling equipment valves below threshold. If most of the cooling water valve positions (ClgCmd's) of the VAV/AHU/HX/FCU served by the chiller are less than the cooling valve threshold for a period longer than the delay in order for a fault condition to exist.

2.1.13.1 - Chiller Evaporator Saturated Refrigerant Temperature Too Low

Summary

The temperature at that a fluid will phase change from liquid to vapor is too low.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Saturation Refrigeration Temperature EvSatRfgTmp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Saturation Refrigeration Temperature Setpoint EvSatRfgTmpSp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the cooling tower must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
TEMP_ERR Numeric 2 Temperature sensor error threshold. The evaporator saturation refrigeration temperature setpoint must be greater than the evaporator saturation refrigeration temperature plus this constant for a period longer than the delay for a fault to exist.

2.1.14.1 - Chiller High Evaporator Pressure

Summary

The pressure at which the refrigerant is a phase changing from a liquid to a vapor and is too high.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Refrigeration Pressure EvRfgPrs This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Saturation Refrigeration Pressure Setpoint EvRfgPrsSp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the cooling tower must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
PRS_ERR Numeric 5 Pressure sensor error threshold.

2.1.15.1 - Chiller Low Evaporator Pressure

Summary


The pressure at which the refrigerant is a phase changing from a liquid to a vapor and is too high.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Refrigeration Pressure EvRfgPrs This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Refrigeration Pressure Setpoint EvRfgPrsSp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the cooling tower must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
PRS_ERR Numeric 5 Pressure sensor error threshold.

Rul 2.1.16.1 - Chiller Evaporator Approach Temperature is Too Large

Summary

The difference between the leaving chilled water temperature and the saturated refrigerant evaporating temperature exceeds the design approach temperature. By monitoring this and addressing the cause can extend the life of the chiller. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chilled Water Leaving Temperature ChWLTemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Saturation Refrigeration Temperature EvSatRfgTmp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
EV_APPROACH Numeric 8 The evaporator approach threshold

2.1.17.1 - Chiller Condenser Water Temperature Difference is Higher Than Normal

Summary

The condenser water temperature difference is higher than normal. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- -

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Water Circ Pump Status CWCPSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Water Entering Temperature CWETemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Water Leaving Temperature CWLTemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Chilled Water Temperature Differential Numeric 10 The condenser water temperature differential threshold.
Chilled Water Temperature Error Numeric 2 The condenser water temperature error threshold.

2.1.18.1 - Chiller Condenser Approach Temperature is Too Large

Summary 

The difference between the condenser liquid refrigerant temperature and the leaving condenser water temperature exceeds the design approach temperature. By monitoring this and addressing the cause can extend the life of the chiller. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Water Leaving Temperature CWLTemp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Saturation Refrigeration Temperature CdSatRfgTmp This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Condenser Approach Numeric 3 The condenser approach threshold.

2.1.19.1 - Chiller Condenser Water Flow Rate is Too Low

Summary

Manufacturers have minimum condenser water flow rates through the condenser. It is determined the flow rate for this chiller is below manufacturer's recommendations. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- (CWFlow & CWFlowSp) || (CWFlow) || (CdDifPrs & CdDifPrsSp) || CdFlowSw

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Water Circ Pump Status CWCPSts This point must be a direct child of the equipment that the rule is attached to. Mandatory  Scalar
Condenser Differential Pressure CdDifPrs This point must be a direct child of the equipment that the rule is attached to. Optional Scalar
Condenser Differential Pressure Setpoint CdDifPrsSp This point must be a direct child of the equipment that the rule is attached to. Optional Scalar
Condenser Flow Switch CdFlowSw This point must be a direct child of the equipment that the rule is attached to. Optional Scalar
Condenser Water Flow CWFlow This point must be a direct child of the equipment that the rule is attached to. Optional Scalar
Condenser Water Flow Setpoint CWFlowSp This point must be a direct child of the equipment that the rule is attached to. Optional Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Min Condenser Water Flow Numeric 100 The minimum condenser water flow threshold. 

2.1.20.1 - Chiller Could Be in a Surge Condition

Summary

Chiller Lift, which is the difference between condenser refrigerant pressure and evaporator refrigerant pressure. If this differential increases to where it exceeds the system's pumping capacity, refrigerant will flow backward through the compressor wheel every few seconds. Pressure builds up in the compressor, causing the refrigerant to surge forward again, and the cycle repeats.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Saturation Refrigeration Pressure EvSatRfgPrs This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Max Refrigerant Pressure Numeric 110 The maximum refrigerant pressure differential threshold. 

2.1.21.1 - Chiller Condenser Water Isolation Valve is Open When Chiller is Off

Summary

Isolation valves are required when more than one chiller is served by a condenser water system and should be closed, when the chiller and associated chiller pump are off. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Water Circ Pump Status CWCPSts This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar
Condenser Water Isolation Valve CWIsoVlvCmd This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.

2.1.22.1 - Compressor Discharge Refrigerant Temperature is Too High

Summary

The compressor discharge refrigerant temperature is too high.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Refrigeration Temperature CdRfgTmp This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Temperature Limit Numeric 200 The temperature limit threshold.

2.1.23.1 - Compressor Discharge Refrigerant Pressure is Too High

Summary

Compressor discharge refrigerant pressure is too high. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Refrigeration Pressure CdRfgPrs This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constant

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Pressure Limit Numeric 136.5 The pressure limit threshold.

2.1.24.1 - Compressor Suction Refrigerant Pressure is Too Low

Summary

Compressor suction refrigerant pressure is too low. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Refrigeration Pressure EvRfgPrs This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Pressure Limit Numeric 31.5 The pressure limit threshold.

2.1.25.1 - Compressor Suction Refrigerant Pressure is Too High

Summary

Compressor suction refrigerant pressure is too high.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Refrigeration Pressure EvRfgPrs This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Pressure Limit Numeric 38.5 The pressure limit threshold.

2.1.26.1 - Chiller Lift is Greater Than the Rating of the Compressor

Summary 

When the compressor suction pressure is low and the compressor discharge pressure is high, the chiller could be experiencing a surge situation.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Evaporator Refrigeration Pressure EvRfgPrs This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar
Condenser Refrigeration Pressure CdRfgPrs This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 0 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Chiller Lift Threshold Numeric 130

2.1.27.1 - Chiller Low Oil Pressure Differential

Summary 

When the oil pressure differential is lower than its threshold value while the chiller is operational.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chiller Oil Pressure Differential  ChrOilPrsDiff This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 30 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Low Oil Differential Pressure Threshold Numeric

10


The pressure limit threshold.

2.1.28.1 - Chiller High Oil Pressure Differential

Summary 

When the oil pressure differential is high than its threshold value while chiller is operational. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chiller Oil Pressure Differential ChrOilPrsDiff This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 30 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
High Oil Differential Pressure Limit Threshold Numeric 25 The pressure limit threshold.

2.1.29.1 - Chiller High Oil Temperature

Summary 

When the oil sump temperature is greater than its threshold value when the chiller is operational.

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chiller Oil Temp ChrOilTemp This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 30 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Oil Sump Temperature Limit Threshold Numeric 38.5 The pressure limit threshold.

2.1.30.1 - Chiller Low Compressor Discharge Superheat

Summary 

Discharge temperature minus the condenser refrigerant saturated temperature represents the discharge superheat differential temperature. The fault occurs when the compressor discharge superheat differential temperature is lower than its threshold value while chiller is operational. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Condenser Refrigeration Temperature CdRfgTmp This point must be a direct child of the equipment that the rule is attached to. Optional Scalar
Compressor Discharge Superheat Differential Temperature CmpDisSprHtDifTmp This point must be a direct child of the equipment that the rule is attached to. Optional Scalar
Compressor Discharge Temperature CmpDisTmp This point must be a direct child of the equipment that the rule is attached to. Optional Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 30 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Low Discharge Superheat Limit Threshold Numeric 10 The pressure limit threshold.

2.1.31.1- Chiller Continuous Operations at High Load

Summary 

When the chiller is consistently operated at a load greater than its threshold. 

Equipment Type Equipment Tag Constraints Tuple Constraints
chiller -- --

Input Points

Name Point Template Positional Requirements Optionality Multiplicity
Chiller Status ChrSts This point must be a direct child of the equipment that the rule is attached to. Mandatory Scalar
Chiller Load ChrLoad This point must be a direct child of the equipment that the rule is attached to.  Mandatory Scalar

Input Constants

Name Data Type Default Value Description
Delay Numeric 240 The delay represents a span of time in minutes during which the chiller must be in a fault state before the rule starts to actually report that it is in a fault state. The intent of the delay is to reduce the level of alert noise by ensuring that the system does not alert until the fault condition has been in effect for some minimal interval of time.
Chiller Max Load Threshold Numeric

95


The pressure limit threshold.
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