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FourPipeFanCoil actuators for external control

asked 2022-06-16 08:52:31 -0500

lobo's avatar

updated 2022-06-17 08:16:59 -0500

Dear All,

I'm trying to control with actuators a ZoneHVAC:FourPipeFanCoil since now I was able to control the mass flow rate with the following actuator:

EnergyManagementSystem:Actuator,
    m_42,                    !- Name
    ZONE1  FAN COIL UNIT SUPPLY FAN,  !- Actuated Component Unique Name 
    Fan,    !- Actuated Component Type System Node Setpoint
    Fan Air Mass Flow Rate; !- Actuated Component Control Type Mass Flow Rate Setpoint

I have tried to control the out temperature from the heating coil with the following actuator but I was not able to achieve it:

EnergyManagementSystem:Actuator,
    t_42,                    !- Name
    ZONE1 FAN COIL UNIT SUPPLY OUTLET,  !- Actuated Component Unique Name 
    System Node Setpoint,    !- Actuated Component Type
    Temperature Setpoint;    !- Actuated Component Control Type

Any Idea on how I can control the air temperature outlet?

I'm able to do it in an air terminal with AirTerminal:SingleDuct:ConstantVolume:NoReheat like the following :

AirTerminal:SingleDuct:ConstantVolume:NoReheat, ZONE2 Single Duct CAV No Reheat, !- Name On 24/7, !- Availability Schedule Name Air Loop Zone Splitter Outlet Node 3, !- Air Inlet Node Name ZONE2 Single Duct CAV No Reheat Supply Outlet, !- Air Outlet Node Name 433.830000; !- Maximum Air Flow Rate {m3/s}

By controlling the flowing actuators:

EnergyManagementSystem:Actuator,
    t_41,                    !- Name
    AIR LOOP AHU HEATING COIL AIR OUTLET NODE,  !- Actuated Component Unique Name
    System Node Setpoint,    !- Actuated Component Type
    Temperature Setpoint;    !- Actuated Component Control Type

EnergyManagementSystem:Actuator,
    m_41,                    !- Name
    AIR LOOP AHU SUPPLY FAN,  !- Actuated Component Unique Name
    Fan,    !- Actuated Component Type System Node Setpoint
    Fan Air Mass Flow Rate; !- Actuated Component Control Type Mass Flow Rate Setpoint

Here you find the details of the ZoneHVAC:FourPipeFanCoil

ZoneHVAC:FourPipeFanCoil,
    ZONE1 Fan Coil Unit,  !- Name
    FAN COIL_FCA_Heating control schedule,  !- Availability Schedule Name
    ConstantFanVariableFlow, !- Capacity Control Method
    autosize,                !- Maximum Supply Air Flow Rate {m3/s}
    0.33,                    !- Low Speed Supply Air Flow Ratio
    0.66,                    !- Medium Speed Supply Air Flow Ratio
    0.0,                     !- Maximum Outdoor Air Flow Rate {m3/s}
    ,                        !- Outdoor Air Schedule Name
    ZONE1 Fan Coil Unit Return,  !- Air Inlet Node Name
    ZONE1  Fan Coil Unit Supply Outlet,  !- Air Outlet Node Name
    OutdoorAir:Mixer,        !- Outdoor Air Mixer Object Type
    ZONE1  Fan Coil Unit Outdoor Air Mixer,  !- Outdoor Air Mixer Name
    Fan:ConstantVolume,      !- Supply Air Fan Object Type
    ZONE1 Fan Coil Unit Supply Fan,  !- Supply Air Fan Name
    Coil:Cooling:Water,      !- Cooling Coil Object Type
    ZONE1 Fan Coil Unit Cooling Coil,  !- Cooling Coil Name
    autosize,                !- Maximum Cold Water Flow Rate {m3/s}
    0.000000,                !- Minimum Cold Water Flow Rate {m3/s}
    0.0010,                  !- Cooling Convergence Tolerance
    Coil:Heating:Water,      !- Heating Coil Object Type
    ZONE1 Coil Unit Heating Coil,  !- Heating Coil Name
    autosize,                !- Maximum Hot Water Flow Rate {m3/s}
    0.000000,                !- Minimum Hot Water Flow Rate {m3/s}
    0.0010;                  !- Heating Convergence Tolerance


Coil:Heating:Water,
    ZONE1 Fan Coil Unit Heating Coil,  !- Name
    On 24/7,                 !- Availability Schedule Name
    autosize,                !- U-Factor Times Area Value {W/K}
    autosize,                !- Maximum Water Flow Rate {m3/s}
    ZONE1 Fan Coil Unit Heating Coil Water Inlet Node,  !- Water Inlet Node Name
    ZONE1 Fan Coil Unit Heating Coil Water Outlet Node,  !- Water ...
(more)
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answered 2022-06-16 15:34:34 -0500

updated 2022-06-16 20:09:36 -0500

The zone fan coil units operate to meet the zone load, not a set point temperature. The fan coil will ignore a node set point temperature at the fan coil's coil outlet nodes. You would somehow have to adjust the zone load. If the air mass flow rate is adjusted, the fan coil will try to compensate by providing a lower outlet temperature in cooling mode (or higher in heating mode) to meet the zone load.

There are EMS actuators that can override the zone thermostat (or humidistat) temperature. I am not sure if there is an actuator for the actual zone load.

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Asked: 2022-06-16 08:52:31 -0500

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Last updated: Jun 16