blockSupplyAirTemperature
Subsequence for calculating supply air temperature setpoint
Information
Block that outputs the supply air temperature setpoint, as well as the control signals for the cooling and heating coils in a fan coil unit system. The implemented sequence is based on ASHRAE Guideline 36, 2021, Part 5.22.4.
The supply air temperature
TSupSet is varied from the zone cooling setpoint temperature
TZonCooSet to the minimum supply air temperature for cooling
TSupSet_min, when the cooling loop signal
uCoo varies from the minimum limit
uCoo_min to the maximum limit
uCoo_max.
Similarly, TSupSet is varied from the zone heating setpoint temperature
TZonHeaSet to the maximum supply air temperature for heating
TSupSet_max, when the heating loop signal
uHea varies from the minimum limit
uHea_min to the maximum limit
uHea_max. The setpoint in deadband mode is equal to the current
measured supply air temperature TAirSup.
yCooCoi and yHeaCoi are set to zero when the fan proven on signal
u1Fan is false.
Parameters
| Type | Name | Default | Description |
|---|---|---|---|
| Boolean | have_cooCoi | True if the unit has a cooling coil | |
| Boolean | have_heaCoi | True if the unit has a heating coil | |
| Heating loop | |||
| Real | uHea_min | heaDea | Minimum heating loop signal at which supply air temperature is modified |
| Real | TSupSet_max | 305.15 | Supply air temperature setpoint at maximum heating loop signal |
| Real | uHea_max | 0.5 | Maximum heating loop signal at which supply air temperature is modified |
| Cooling loop | |||
| Real | uCoo_min | cooDea | Minimum cooling loop signal at which supply air temperature is modified |
| Real | TSupSet_min | 285.95 | Supply air temperature setpoint at maximum cooling loop signal |
| Real | uCoo_max | 0.5 | Maximum cooling loop signal at which supply air temperature is modified |
| Deadband | |||
| Real | heaDea | 0.1 | Heating loop signal limit above which setpoint operation changes from deadband mode to heating mode |
| Real | cooDea | 0.1 | Cooling loop signal limit above which setpoint operation changes from deadband mode to cooling mode |
| PID controller parameters › Cooling coil | |||
| Buildings.Controls.OBC.CDL.Types.SimpleController | cooCoiConTyp | Buildings.Controls.OBC.CDL.Types.SimpleController.PI | Type of cooling coil controller |
| Real | kCooCoi | 1 | Controller gain |
| Real | TiCooCoi | 60 | Integrator time constant |
| Real | TdCooCoi | 0.1 | Derivative block time constant |
| PID controller parameters › Heating coil | |||
| Buildings.Controls.OBC.CDL.Types.SimpleController | heaCoiConTyp | Buildings.Controls.OBC.CDL.Types.SimpleController.PI | Type of heating coil controller |
| Real | kHeaCoi | 1 | Controller gain |
| Real | TiHeaCoi | 60 | Integrator block time constant |
| Real | TdHeaCoi | 0.1 | Derivative block time constant |
| Advanced | |||
| Real | deaHysLim | 0.05 | Hysteresis limits for deadband mode transitions |
Connectors
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Interfaces.BooleanInput | u1Fan | Fan proven on signal | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | uHea | Heating loop signal | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | uCoo | Cooling loop signal | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | TAirSup | Measured supply air temperature | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | TZonHeaSet | Zone heating temperature setpoint | |
| Buildings.Controls.OBC.CDL.Interfaces.RealInput | TZonCooSet | Zone cooling temperature setpoint | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | yHeaCoi | Heating coil signal | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | yCooCoi | Cooling coil signal | |
| Buildings.Controls.OBC.CDL.Interfaces.RealOutput | TSupSet | Supply air temperature setpoint |
Components
| Type | Name | Default | Description |
|---|---|---|---|
| Buildings.Controls.OBC.CDL.Reals.Switch | swiDeaCoo | Switch for turning on cooling mode from deadband mode | |
| Buildings.Controls.OBC.CDL.Reals.Switch | swiCooCoi | Switch cooling coil signal to zero in deadband mode | |
| Buildings.Controls.OBC.CDL.Reals.Switch | swiHeaCoi | Switch heating coil signal to zero in deadband mode | |
| Buildings.Controls.OBC.CDL.Reals.Line | linTHeaSupAir | Convert heating loop signal to supply air temperature setpoint | |
| Buildings.Controls.OBC.CDL.Reals.Line | linTCooSupAir | Convert cooling loop signal to supply air temperature setpoint | |
| Buildings.Controls.OBC.CDL.Reals.PID | conPIDHea | PID controller for heating coil | |
| Buildings.Controls.OBC.CDL.Reals.PID | conPIDCoo | PID controller for cooling coil | |
| Buildings.Controls.OBC.CDL.Reals.Hysteresis | hysDeaHea | Hysteresis for switching between deadband mode and heating mode | |
| Buildings.Controls.OBC.CDL.Reals.Switch | swiDeaHea | Switch for turning on heating mode from deadband mode | |
| Buildings.Controls.OBC.CDL.Reals.Hysteresis | hysDeaCoo | Hysteresis for switching on cooling mode from deadband mode | |
| Buildings.Controls.OBC.CDL.Conversions.BooleanToReal | booToRea2 | Boolean to Real conversion | |
| Buildings.Controls.OBC.CDL.Reals.Multiply | mul2 | Output heating coil signal only when fan is proven on | |
| Buildings.Controls.OBC.CDL.Reals.Multiply | mul3 | Output cooling coil signal only when fan is proven on | |
| Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter | gai | Dummy gain | |
| Buildings.Controls.OBC.CDL.Reals.MultiplyByParameter | gai1 | Dummy gain |
Revisions
-
November 20, 2025, by Karthik Devaprasad:
Added error scaling factors to PI controllers regulating supply air temperature at temperature setpoint. -
March 17, 2022, by Karthik Devaprasad:
First implementation.