.Buildings.Fluid.ZoneEquipment.FourPipe

Information

This is a four-pipe fan coil unit system model. The system consists of the following components:

• A supply fan fan of class Buildings.Fluid.Movers.FlowControlled_m_flow.
• Heating coil options for no heating coil, a hot-water heating coil or an electric heating coil determined by the user selection for parameter heaCoiTyp as follows:
  1. No heating coil with bypass connector pipByp of class Buildings.Fluid.FixedResistances.PressureDrop if heaCoiTyp is set to Buildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.None.
  2. A hot-water heating coil heaCoiHW of class Buildings.Fluid.HeatExchangers.DryCoilCounterFlow if heaCoiTyp is set to Buildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.WaterBased.
  3. An electric heating coil heaCoiEle of class Buildings.Fluid.HeatExchangers.HeaterCooler_u if heaCoiTyp is set to Buildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.Electric.
• A chilled-water cooling coil cooCoi of class Buildings.Fluid.HeatExchangers.WetCoilCounterFlow.

For examples of how to use the model, refer to Buildings.Examples.FanCoils.FourPipe. The following points are salient when using the model:

• The connected air-loop does not need an additional fan, since the fan in this model generates flow.
• The fluid loop connections for hot-water and chilled-water require an external pressure difference between the inlet and the outlet sufficient to overcome the pressure drop across the two respective coils.

The figure below shows the schematic diagram of the four pipe system when heaCoiTyp is set to water based using the enumeration Buildings.Controls.OBC.ASHRAE.G36.Types.HeatingCoil.

Contents

Name	Description
MediumA	Medium for air
MediumHW	Medium for hot water
MediumCHW	Medium for chilled water

Revisions

• September 22, 2025, by Michael Wetter:
  Exposed parameters, reviewed model for first release.
  This is for issue 2885.
• August 03, 2022 by Karthik Devaprasad, Sen Huang:
  First implementation.