3.3 Fan Coil Unit (FCU) Rules
3.3.1.1 - FCU Simultaneous Heating and Cooling
Summary
This unit is heating and cooling at the same time.
| Equipment Type |
Equipment Tag Constraints |
Tuple Constraints |
| fcu |
-- |
-- |
Input Points
| Name |
Point Template |
Positional Requirements |
Optionality |
Multiplicity |
| Cooling Command |
ClgCmd |
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 |
15 |
The delay represents a span of time in minutes during which the fcu 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 Command Threshold |
Numeric |
1 |
This number is the cooling command threshold indicating the command is “On.” If the fcu’s cooling command is greater than or equal to the cooling command threshold at the same time the fcu’s heating command is greater than or equal to the heating command threshold for a period longer than the delay in order for a fault condition to exist. |
| Heating Command Threshold |
Numeric |
1 |
This number is the heating command threshold indicating the command is “On.” If the fcu’s heating command is greater than or equal to the heating command threshold at the same time the fcu’s cooling command is greater than or equal to the cooling command threshold for a period longer than the delay in order for a fault condition to exist. |
3.3.6.1 - Occupied Zone Temperature Heating Setpoint Above High Limit
Summary
The occupied zone temperature heating setpoint is higher than the high setpoint limit.
| Equipment Type |
Equipment Tag Constraints |
Tuple Constraints |
| fcu |
-- |
-- |
Input Points
| Name |
Point Template |
Positional Requirements |
Optionality |
Multiplicity |
| 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 (minutes) |
Numeric |
15 |
The delay represents a span of time in minutes during which the fcu 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 Setpoint High Limit |
Numeric |
75 |
This number (in Fahrenheit) is the maximum allowed value of the vav temperature. The occupied heating setpoint must exceed the zone temperature setpoint high limit for a period longer than the delay in order for a fault condition to exist. |
3.3.7.1 - Occupied Zone Temperature Cooling Setpoint Below Low Limit
Summary
The zone temperature cooling setpoint is below the low setpoint limit.
| Equipment Type |
Equipment Tag Constraints |
Tuple Constraints |
| fcu |
-- |
-- |
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 |
Input Constants
| Name |
Data Type |
Default Value |
Description |
| Delay (minutes) |
Numeric |
15 |
The delay represents a span of time in minutes during which the fcu 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 Setpoint Low Limit |
Numeric |
66 |
This number (in Fahrenheit) is the minimum allowed value of the vav temperature. The occupied cooling setpoint must not exceed the zone temperature setpoint low limit for a period longer than the delay in order for a fault condition to exist. |
3.3.8.1- 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 |
| fcu |
-- |
EffCoolSp EffHeatSp or OccCoolSp OccHeatSp |
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. |
Optional |
Scalar |
| Occupied Heating Setpoint |
OccHeatSp |
This point must be a direct child of the equipment that the rule is attached to. |
Optional |
Scalar |
| Effective Cooling Setpoint |
EffCoolSp |
This point must be a direct child of the equipment that the rule is attached to. |
Optional |
Scalar |
| Effective Heating Setpoint |
EffHeatSp |
This point must be a direct child of the equipment thast the rule is attached to. |
Optional |
Scalar |
Input Constants
| Name |
Data Type |
Default Value |
Description |
| Delay (minutes) |
Numeric |
15 |
The delay represents a span of time in minutes during which the fcu 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. |
| DEADBAND |
Numeric |
5 |
The minimum temperature dead band allowed. This constant must be greater than either effective cooling setpoint minus effective heating setpoint or occupied cooling setpoint minus occupied heating setpoint for a period longer than delay for a fault to exist. |
3.3.9.1 - Zone Temperature Sensor Failure
Summary
The zone temperature sensor has failed. The temperature sensor point is invariant or is outside the expected range.
| Equipment Type |
Equipment Tag Constraints |
Tuple Constraints |
| fcu |
-- |
-- |
Input Points
| Name |
Point Template |
Positional Requirements |
Optionality |
Multiplicity |
| Zone Temperature |
ZoneTemp |
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 fcu 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 zone temperature. The zone 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 zone temperature. The zone 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 compared to the value of the difference between the high threshold and low threshold. The difference value must not exceed the variance threshold for a period longer than the delay in order for a fault condition to exist. |
3.3.10.1 - Unoccupied Cooling Setpoint Too Low
Summary
The unoccupied cooling setpoint is too low. The unoccupied cooling setpoint to be no less than 5°F higher than the occupied cooling setpoint.
| Equipment Type |
Equipment Tag Constraints |
Tuple Constraints |
| fcu |
-- |
-- |
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 |
15 |
The delay represents a span of time in minutes during which the fcu 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 |
This number is the unoccupied cooling setpoint threshold indicating the maximum difference in setpoints. If the fcu’s occupied cooling setpoint plus the unoccupied setpoint threshold is greater than the unoccupied cooling setpoint for a period longer than the delay in order for a fault condition to exist. |
3.3.11.1 - Unoccupied 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 10 deg. F lower than the occupied heating setpoint.
| Equipment Type |
Equipment Tag Constraints |
Tuple Constraints |
| fcu |
-- |
-- |
Input Points
| Name |
Point Template |
Positional Requirements |
Optionality |
Multiplicity |
| Unoccupied Heating Setpoint |
UnoccHeatSp |
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 |
15 |
The delay represents a span of time in minutes during which the fcu 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 |
This number (in Fahrenheit) is the maximum difference between unoccupied heating and occupied heating setpoints. The difference between unoccupied heating and occupied heating setpoints must not exceed the unoccupied heating setpoint threshold allowed for a period longer than the delay in order for a fault condition to exist. |
