.Buildings.Obsolete.Controls.OBC.ASHRAE.G36_PR1.AHUs.SingleZone.VAV.SetPoints.Supply

Information

Block that outputs the set points for the supply air temperature for cooling, heating and economizer control, and the fan speed for a single zone VAV system.

For the temperature set points, the parameters are the maximum supply air temperature TSupSetMax, and the minimum supply air temperature for cooling TSupSetMin. The deadband temperature is equal to the average set point for the zone temperature for heating and cooling, as obtained from the input TZonSet, constraint to be within 21°C (≈70 F) and 24°C (≈75 F). The setpoints are computed as shown in the figure below. Note that the setpoint for the supply air temperature for heating and for economizer control is the same, and this setpoint is lower than TSupSetMin when the heating loop signal is zero and the economizer is in cooling mode, as shown in the figure.

For the fan speed set point, the parameters are the maximu fan speed at heating yHeaMax, the minimum fan speed yMin and the maximum fan speed for cooling yCooMax. For a cooling control signal of uCoo > 0.25, the speed is faster increased the larger the difference is between the zone temperature minus outdoor temperature TZon-TOut. The figure below shows the sequence.

The output TSupCoo is to be used to control the cooling coil, and the output TSupHeaEco is to be used to control the heating coil and the economizer dampers.

Note that the inputs uHea and uCoo must be computed based on the same temperature sensors and control loops.

Revisions

• April 30, 2021, by Michael Wetter:
  Added limiter to fan signal.
  This is for issue 2475.
• August 1, 2019, by Kun Zhang:
  Added a switch for fan control.
• March 21, 2019, by Jianjun Hu:
  Used line block to avoid use of block that is not in CDL. This is for issue 1389.
• March 25, 2018, by Michael Wetter:
  Revised implementation of fan speed control signal calculation to remove the hysteresis blocks.
  This is for issue 1153.
• April 26, 2017, by Michael Wetter:
  Updated documentation and renamed output signal to TSupHeaEco.
• January 10, 2017, by Michael Wetter:
  First implementation.