3.1.20.1 - 3.1.49.1 AHU Rules
3.1.20.1 - Fan Status Off When Commanded On
Summary
The fan status is 'Off' but the fan is commanded 'On'.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Fan Command (open/closed) | DaFanCmd | 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 fan 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. |
3.1.21.1 Fan Status On When Commanded Off
Summary
The fan status is 'On' but is commanded 'Off'.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Fan Command (open/closed) | DaFanCmd | 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 fan 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. |
3.1.22.1 - Unoccupied Zone Temperature Cooling Setpoint Too Low
Summary
The unoccupied cooling setpoint is too low. ASHRAE Standard 90.1 - 2016 Section 6.4.3.3.2 Setback Controls requires the unoccupied cooling setpoint to be no less than 5ºF higher than the occupied cooling setpoint.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Unoccupied Cooling Setpoint | UnoccCoolSp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Occupied Cooling Setpoint | OccCoolSp | 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 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. |
| Unoccupied Cooling Setpoint Threshold | Numeric | 5 | |
| Occupied Cooling High Limit Temperature Setpoint Threshold | Numeric | 82 |
3.1.23.1 - Unoccupied Zone Temperature Heating Setpoint Too High
Summary
The unoccupied heating setpoint is too high. ASHRAE Standard 90.1 - 2016 Section 6.4.3.3.2 Setback Controls requires the unoccupied heating setpoint to be no greater than 10ºF lower than the occupied heating setpoint.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Unoccupied Cooling Setpoint | UnoccCoolSp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Occupied Cooling Setpoint | OccCoolSp | 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 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. |
| Unoccupied Heating Setpoint Threshold | Numeric | 10 | |
| Occupied Heating High Limit Temperature Setpoint Threshold | Numeric | 67 |
3.1.25.1 - Discharge Air Static Pressure Setpoint Can Be Decreased (Reset)
Summary
Most of the VAV box damper positions are less than a high damper limit, indicating an opportunity to decrease fan static pressure. Fan static pressure reset is required by ASHRAE Standard 90.1 - Section 6.5.3.2.3 VAV Set-Point Reset.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| VAV Damper Position | DmprCmd | 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 ahu 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. |
| Percent of VAV’s Required | Numeric | 90 | This number is the percentage of VAV damper positions served by the AHU that is required. If most (percentage of VAV’s required) of the VAV damper positions (DmprCmd's) of the VAV’s served by the AHU are less than the high damper limit for a period longer than the delay in order for a fault condition to exist. |
| High Damper Limit | Numeric | 90 | This number (as a percentage) is the maximum damper limit. damper positions threshold. If most (percentage of VAV’s required) of the VAV damper positions (DmprCmd's) of the VAV’s served by the AHU are less than the high damper limit for a period longer than the delay in order for a fault condition to exist. |
3.1.27.1 Operating During Unoccupied Mode
Summary
This rule identifies periods of time the AHU is in Unoccupied Mode, but the fan is operating.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Discharge Air Fan Command (open/closed) | DaFanCmd | This point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Occupied Mode | Occ | 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 ahu 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. |
Rule 3.1.28.1 - Zone Temperature Setpoint Dead Band is Too Low
Summary
The zone temperature setpoint dead band is too low. A minimum difference of 5°F between cooling and heating setpoints is required by ASHRAE Standard 90.1 2016 - Section 6.4.3.1.2 Dead Band.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Occupied Cooling Setpoint | OccCoolSp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Occupied Heating Setpoint | OccHeatSp | 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 ahu 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 Dead Band Allowed | Numeric | 5 | This number (in Fahrenheit) is the minimum difference between cooling and heating setpoints. The difference between cooling and heating setpoints must not exceed this threshold for a period longer than the delay in order for a fault condition to exist. |
3.1.29.1 - AHU Outside Air Temperature Sensor Differs From the Building Outside Air Temperature Sensor
Summary
The air handling unit outside air temperature sensor differs from the building outside air temperature sensor.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
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 |
| Outside Air Temperature | OaTempOnPremWS | This point must be a direct child of this rules ancestor building's weather station | 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 ahu 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 Teamperature Dead Band Allowed | Numeric | 5 | This number (in Fahrenheit) is the minimum difference between cooling and heating setpoints. The difference between cooling and heating setpoints must not exceed this threshold for a period longer than the delay in order for a fault condition to exist. |
3.1.30.1 - AHU Outside Air Humidity Sensor Differs From the Building Outside Air Humidity Sensor
Summary
The air handing unit outside air humidity sensor differs from the building outside air humidity sensor.
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 |
| Outside Air Humidity | OaHumidityOnPremWS | This point must be a direct child of this rules ancestor building's weather station | 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 ahu 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. |
| Threshold | Numeric | 5 | The humidity sensor threshold. |
3.1.31.1 - Majority of VAV's in Heating Mode
Summary
The majority of the VAV's served by this air handling unit are in heating mode, indicating the discharge air temperature should be increased.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| VAV Reheating Command | RhtCmd | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Fan Status (single or common) | DaFanSts | 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 ahu 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. |
| VAV Heating Command Threshold | Numeric | 10 | This number (as a percentage) is the maximum allowed value of VAV’s that are reheating. The VAV heating command must exceed this threshold for a period longer than the delay in order for a fault condition to exist. |
| Percent of VAV’s In Heating Mode | Numeric | 70 | This number is the percentage of VAV’s served by the AHU that are reheating. If this percentage is greater than the VAV heating command threshold for a period longer than the delay in order for a fault condition to exist. |
3.1.32.1 - Discharge Air Temperature Setpoint is Less Than Low Limit
Summary
The discharge air temperature setpoint is less than the low limit and may be overridden. Excessively low discharge air temperatures can increase reheat and operating costs.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Temperature Setpoint | DaTempSp | 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 ahu 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. |
| Discharge Air Temperature Setpoint Low Limit | Numeric | 55 | This number (in Fahrenheit) is the minimum allowed value of the discharge air temperature. The discharge air temperature setpoint must not exceed this threshold for a period longer than the delay in order for a fault condition to exist. |
3.1.33.1 - Discharge Air Temperature is Greater Than Setpoint
Summary
The discharge air temperature is greater than the discharge air temperature setpoint and may be experiencing inefficient control or mechanical issues. This can lead to increased operating costs and comfort complaints.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Temperature | DaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Temperature Setpoint | DaTempSp | 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 ahu 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. |
| Discharge Temperature Threshold | Numeric | 2.0 | This number (in Fahrenheit) is the threshold value of the discharge fan pressure. The discharge air temperature must exceed this threshold added to the discharge air temperature setpoint or the discharge air temperature must exceed this threshold added to the default discharge temperature setpoint for a period longer than the delay in order for a fault condition to exist. |
| Default Discharge Temperature Setpoint | Numeric | 65 | This number (in Fahrenheit) is the default value of the discharge temperature. The discharge air temperature must exceed this threshold added to the default discharge temperature setpoint for a period longer than the delay in order for a fault condition to exist. |
3.1.33.2 - Hot Deck Air Temperature is Greater Than Setpoint
The hot deck air temperature is greater than the hot deck air temperature setpoint and may be experiencing inefficient control or mechanical issues. This can lead to increased operating costs and comfort complaints. Corresponds to FC#13 is ASHRAE Guideline 36-2018 High Performance Sequences 5.16.14.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Hot Deck Temperature | HotDeckTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Hot Deck Temperature Setpoint | HotDeckTempSp | 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 ahu 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. |
| Hot Deck Temperature Threshold | Numeric | 2.0 | This number (in Fahrenheit) is the threshold value of the hot deck temperature. The hot deck temperature must exceed this threshold added to the hot deck temperature setpoint for a period longer than the delay in order for a fault condition to exist. |
Rule 3.1.33.3 - Cold Deck Air Temperature is Greater Than Setpoint
Summary
The cold deck air temperature is grater than the cold deck air temperature setpoint and may be experiencing inefficient control or mechanical issues. This can lead to increased operating costs and comfort complaints. Corresponds to FC#13 in ASHRAE Guideline 36-2018 High Performance Sequences 5.16.14.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Cold Deck Temperature | ColdDeckTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Cold Deck Temperature Setpoint | ColdDeckTempSp | 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 ahu 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. |
| Cold Deck Temperature Threshold | Numeric | 2.0 | This number (in Fahrenheit) is the threshold value of the cold deck temperature. The cold deck temperature must exceed this threshold added to the hot deck temperature setpoint for a period longer than the delay in order for a fault condition to exist. |
3.1.34.1 - Discharge Air Temperature is Less Than Setpoint
Summary
The discharge air temperature is less than the discharge air temperature setpoint and may be experiencing inefficient control or mechanical issues. This will lead to increased operating costs and comfort complaints.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Temperature | DaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Temperature Setpoint | DaTempSp | 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 ahu 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. |
| Discharge Temperature Threshold | Numeric | 2.0 | This number (in Fahrenheit) is the threshold value of the discharge fan pressure. The discharge air temperature must not exceed this threshold subtracted from the discharge air temperature setpoint or the discharge air temperature must not exceed this threshold subtracted from the default discharge temperature setpoint for a period longer than the delay in order for a fault condition to exist. |
| Default Discharge Temperature Setpoint | Numeric | 55 | This number (in Fahrenheit) is the default value of the discharge temperature. The discharge air temperature must not exceed this threshold subtracted from the default discharge temperature setpoint for a period longer than the delay in order for a fault condition to exist. |
3.1.34.2 - Hot Deck Air Temperature is Less Than Setpoint
Summary
The hot deck air temperature is less than the hot deck air temperature setpoint and may be experiencing inefficient control or mechanical issues. This will lead to increased operating costs and comfort complaints. Corresponds to FC#7 in ASHRAE Guideline 36-2018 High Performance Sequences 5.16.14.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Hot Deck Temperature | HotDeckTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Hot Deck Temperature Setpoint | HotDeckTempSp | 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 ahu 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. |
| Hot Deck Temperature Threshold | Numeric | 2.0 | This number (in Fahrenheit) is the threshold value of the hot deck temperature. The hot deck temperature must not exceed this threshold subtracted from the hot deck temperature setpoint for a period longer than the delay in order for a fault condition to exist. |
3.1.34.3 - Cold Deck Air Temperature is Less Than Setpoint
Summary
The cold deck air temperature is less than the cold deck air temperature setpoint and may be experiencing inefficient control or mechanical issues. This will lead to increased operating costs and comfort complaints. Corresponds to FC#7 in ASHRAE Guideline 36-2018 High Performance Sequences 5.16.14.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Cold Deck Temperature | ColdDeckTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Cold Deck Temperature Setpoint | ColdDeckTempSp | 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 ahu 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. |
| Cold Deck Temperature Threshold | Numeric | 2.0 | This number (in Fahrenheit) is the threshold value of the cold deck temperature setpoint. The cold deck temperature must not exceed this threshold subtracted from the cold deck temperature setpoint for a period longer than the delay in order for a fault condition to exist. |
3.1.35.1 - Unexpected Temperature Decrease Across Cooling Coil
Summary
There is a decrease in temperature across the cooling coil with the valve closed, indicating the cooling valve may be leaking. This will lead to increased operating costs and comfort complaints.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Temperature | DaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Mixed Air Temperature | MaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| 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 ahu 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. |
| Closed Valve Threshold | Numeric | 1 | This number is the threshold value of the closed valve. The cooling command must not exceed the closed valve threshold for a period longer than the delay in order for a fault condition to exist. |
| Maximum Temperature Decrease Allowed Across Coil | Numeric | 3 | This number (in Fahrenheit) is the maximum value of the temperature decrease allowed across the cooling coil. The discharge air temperature subtracted from the mixed air temperature must exceed the maximum temperature decrease allowed across coil for a period longer than the delay in order for a fault condition to exist. |
3.1.36.1 - Unexpected Temperature Increase Across Heating Coil
Summary
There is an increase in temperature across the heating coil with the valve closed, indicating the heating valve may be leaking. This will lead to increased operating costs and comfort complaints
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Temperature | DaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Mixed Air Temperature | MaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Heating Command | HtgCmd | 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 ahu 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. |
| Closed Valve Threshold | Numeric | 1 | This number is the threshold value of the closed valve. The heating command must not exceed the closed valve threshold for a period longer than the delay in order for a fault condition to exist. |
| Maximum Temperature Increase Allowed Across Coil | Numeric | 6 | This number (in Fahrenheit) is the maximum value of the temperature increase allowed across the heating coil. The mixed air temperature subtracted from the discharge air temperature must exceed the maximum temperature increase allowed across coil for a period longer than the delay in order for a fault condition to exist. |
3.1.37.1 - Low Temperature Differential Across Cooling Coil
Summary
This unit is in cooling mode and has a low-temperature decrease across the cooling coil with the valve open, indicating a failed cooling valve, actuator, or coil. This may lead to increased operating costs and comfort complaints.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Temperature | DaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Mixed Air Temperature | MaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| 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 ahu 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. |
| Open Valve Threshold | Numeric | 20 | This number is the threshold value of the open valve. The cooling command must exceed the open valve threshold for a period longer than the delay in order for a fault condition to exist. |
| Minimum Temperature Decrease Allowed Across Coil | Numeric | 2 | This number (in Fahrenheit) is the minimum value of the temperature decrease allowed across the cooling coil. The discharge air temperature subtracted from the mixed air temperature must not exceed the minimum temperature decrease allowed across coil for a period longer than the delay in order for a fault condition to exist. |
3.1.38.1 - Low Temperature Differential Across Heating Coil
Summary
This unit is in heating mode and has a low temperature increase across the heating coil with the valve open, indicating a failed heating valve, actuator, or coil. This may lead to increased operating costs and comfort complaints.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Temperature | DaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Mixed Air Temperature | MaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Heating Command | HtgCmd | 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 ahu 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. |
| Open Valve Threshold | Numeric | 20 | This number is the threshold value of the open valve. The heating command must exceed the open valve threshold for a period longer than the delay in order for a fault condition to exist. |
| Minimum Coil Temperature Differential Threshold | Numeric | 3 | This number (in Fahrenheit) is the minimum value of the temperature increase allowed across the heating coil. The mixed air temperature subtracted from the discharge air temperature must not exceed the minimum coil temperature differential threshold for a period longer than the delay in order for a fault condition to exist. |
3.1.39.1 - Optimum Start Control Sequencing Can Be Improved or Implemented
Summary
This air handling unit is operating before the building is scheduled to be occupied and all zones served by this air handling unit are meeting the space temperature setpoints. This indicates there is an opportunity to start this unit later, reducing operation times and saving energy. Optimum Start Controls is required by ASHRAE Standard 90.1 - 2016 Section 6.4.3.3.3.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Discharge Air Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Zone Temperature | ZoneTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Occupied Cooling Setpoint | OccCoolSp | This point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Occupied Heating Setpoint | OccHeatSp | This point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Scheduled Occupancy Status | ScheduledOccSt | This point must be a direct child of the building that the AHU resides in. | 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 ahu 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 value. The zone temperature must exceed the threshold temperature added to the cooling setpoint or heating setpoint for a period longer than the delay in order for a fault condition to exist. |
| Cooling Setpoint | Numeric | 72 | This number (in Fahrenheit) is the cooling setpoint value. The cooling setpoint plus the temperature threshold must exceed the zone temperature for a period longer than the delay in order for a fault condition to exist. |
| Heating Setpoint | Numeric | 68 | This number (in Fahrenheit) is the heating setpoint value. The zone temperature must exceed the temperature threshold subtracted from the heating setpoint for a period longer than the delay in order for a fault condition to exist. |
3.1.40.1 - Freezestat Has Tripped
Summary
The freezestat has sensed a potential freezing condition and has shut down the unit to prevent any damage to the unit.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Freeze Status | FreezeStat | 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 ahu 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. |
3.1.41.1 - Filter Differential Pressure Above Setpoint or Switch Has Been Activated
Summary
Differential pressure across the bank of filters exceeds differential pressure setpoint.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | FilterSts or (FilterPressDelta and FilterPressDeltaSp) |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| DA Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Filter Pressure Delta | FilterPressDelta | This point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Filter Status | FilterSts | This point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Filter Pressure Delta Setpoint | FilterPressDeltaSp | This point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Name | Data Type | Default Value | Description |
|---|---|---|---|
| Delay | Numeric | 0 | The delay represents a span of time in minutes during which the ahu 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. |
3.1.42.1 - Filter Differential Pressure At Zero
Summary
Differential pressure across the bank of filters exceeds differential pressure setpoint.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| DA Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Filter Pressure Delta | FilterPressDelta | 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 ahu 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. |
| Threshold | Numeric | 0 | This number is the filter pressure threshold. The filter pressure delta must be equal to or less than this threshold for a period longer than the delay in order for a fault condition to exist. |
3.1.43.1 - Outside Air Damper Position is Less Than The Minimum Damper Position Setpoint
Summary
A less amount of outside air is being brought into the building with the outdoor air damper position setpoint.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| DA Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Outside Air Damper Position | OaDmprPos | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Outside Air Damper Minimum Position Setpoint | OaDmprMinPosSp | 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 ahu 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. |
3.1.44.1 - Leaving Preheat Coil Temperature is Falling Below Low Limit Temperature Sensor
Summary
The temperature leaving the preheat coil is dropping below the low limit temperature setpoint, which could lead to freezestat trips or freezing coils.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Mixed Air Temperature Low Limit Setpoint | MaTempLoLmtSp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| PreHeat Coil Air Leaving Temp | PreHCALTemp | 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 ahu 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. |
| THRESHOLD | Numeric | 0.5 | The preheat coil leaving air temperature threshold. The preheat coil air leaving temp must be less than the mixed air temperature low limit setpoint minus this constant for a period longer than delay for a fault to exist. |
3.1.45.1 - Mixed Air Dampers Unable to Meet Discharge Air Temperature Setpoint When Outside Air Temperature is Low Enough
Summary
When mixed air dampers are 100% and outside air temperature is low enough to meet discharge air temperature setpoint, but cannot meet setpoint.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| DA Temp Setpoint | DaTempSp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| DA Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Discharge Air Temperature | DaTemp | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Outside Air Temperature | OaTemp | The point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Outside Air Temperature | OaTempOnPremWS | This point has an ancestor of building and is off prem child of weather station. | Optional | Scalar |
| Outside Air Temperature | OaTempOffPremWS | This point has an ancestor of building and is on prem descendant of weather station. | 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 ahu 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. |
| Threshold | Numeric | 10 | The temperature threshold |
3.1.46.1 - Cold Deck Temperature Setpoint Could Be Raised
Summary
No zones served by this air handling unit are at a 100% cooling mode, zone temperature is being met, and return air humidity (if available) is at or below return air relative humidity setpoint, indicating the cold deck temperature setpoint could be raised.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| RA Humidity | RaHumidity | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| DA Fan Status (single or common) | DaFansSts | This point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Return Air Humidify Setpoint | RaLowHumiditySp | This point must be a direct child of the equipment that the rule is attached to. | Optional | Scalar |
| Damper Command | DmprCmd | This point must be a direct child of a vav | Mandatory | Vector |
| Zone Temp | ZoneTemp | This point must be a direct child of a vav | Mandatory | Scalar |
| Eff Cool Setpoint | EffCoolSp | This point must be a direct child of a vav | 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 ahu 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 Threshold | Numeric | 100 | The damper command threshold. |
| Temperature Threshold | Numeric | 0.5 | The zone temperature threshold. |
3.1.47.1 - Cold Deck Temperature Setpoint Could Be Lowered
Summary
One or more zones served by this air handling unit are at a 100% cooling mode and zone temperature is not being met, indication the cold deck temperature setpoint could be lowered.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| DA Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Damper Command | DmprCmd | This point must be a direct child of a vav. | Mandatory | Vector |
| Zone Temp | ZoneTemp | This point must be a direct child of a vav. | Mandatory | Scalar |
| Eff Cool Setpoint | EffCoolSp | This point must be a direct child of a vav | 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 ahu 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 Threshold | Numeric | 100 | This number is the filter pressure threshold. The filter pressure delta must be equal to or less than this threshold for a period longer than the delay in order for a fault condition to exist. |
| Temperature Threshold | Numeric | 0.5 | The zone temperature threshold. |
3.1.48.1 - Hot Deck Temperature Setpoint Could Be Raised
Summary
One or more zones by this air handling unit are at a 100% heating mode and zone temperature setpoint is not being met, indicating the hot deck temperature setpoint could be raised.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| DA Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Damper Command | DmprCmd | This point must be a direct child of a vav. | Mandatory | Vector |
| Zone Temp | ZoneTemp | This point must be a direct child of a vav. | Mandatory | Scalar |
| Eff Heat Setpoint | EffHeatSp | This point must be a direct child of a vav. | 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 ahu 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. |
| Heating Threshold | Numeric | 10 | The damper command threshold. |
| Temperature Threshold | Numeric | 0.5 | The zone temperature threshold. |
3.1.49.1 - Hot Deck Temperature Setpoint Could be Lowered
Summary
None of the zones served by this air handling unit are at a 100% heating mode and zone temperature setpoint is being met, indicating the hot deck temperature setpoint could be lowered.
| Equipment Type | Equipment Tag Constraints | Tuple Constraints |
|---|---|---|
| ahu | -- | -- |
Input Points
| Name | Point Template | Positional Requirements | Optionality | Multiplicity |
|---|---|---|---|---|
| Da Fan Status (single or common) | DaFanSts | This point must be a direct child of the equipment that the rule is attached to. | Mandatory | Scalar |
| Damper Command | DmprCmd | This point must be a direct child of a vav | Mandatory | Vector |
| Zone Temperature | ZoneTemp | This point must be a direct child of a vav. | Mandatory | Scalar |
| Effective Heating Setpoint | EffHeatSp | This point must be a direct child of a vav. | 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 ahu 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. |
| Heating Threshold | Numeric | 0 | The damper command threshold. |
| Temperature Threshold | Numeric | 0.5 | The zone temperature threshold. |