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[EnergyPlus_Support] Compact HVAC simulation warnings



I've created a simple 13-zone model in which 5 of the zones are served
by a central VAV system (created using COMPACT HVAC:ZONE:VAV and
COMPACT HVAC:SYSTEM:VAV) objects, and 8 of the zones are served with
fan coils (created using the COMPACT HVAC:ZONE:FAN COIL object). At
the bottom of this message is some code showing how I've configured
these objects for typical zones. 

My problem is that I'm getting the following warnings in some abundance:

1. ** Warning ** SolveAirLoopControllers: Maximum iterations (50)
exceeded for AHU, at EDMONTON STONY PLAIN AB CAN WYEC2-B-25145
WMO#=711230, 05/02 12:30 - 12:45

2.    ** Warning ** SimHVAC: Maximum iterations (20) exceeded for all
HVAC loops, at EDMONTON STONY PLAIN AB CAN WYEC2-B-25145 WMO#=711230,
05/02 13:15 - 13:30
   **   ~~~   ** SimFlags=[TFFFFFFF]
AirLoops[T],ZoneEq[F],NonZoneEq[F],PlantLoops[F],CondLoops[F],ElecCircuits[F],PlantDemandLoops[F],CondDemandLoops[F]..F=ok,T=fail
   **   ~~~   ** HVAC Tolerance Flags=[0000010]
Enthalpy[0],MassFlow[0],HumRat[0],Pressure[0],FlowQual[0],Energy[1],Temp[0]..0=ok,1=fail
   **   ~~~   ** HVAC Tolerance Values, Most Recent listed first
   **   ~~~   ** HVAC EnthalpyTol=6.808E-002, MassFlowTol=1.014E-003,
HumRatTol=2.6818E-008, PressureTol=0
   **   ~~~   **      FlowQualTol=1.01E-003, EnergyTol=-24.525,
TempTol=1.85E-007
   **   ~~~   ** HVAC EnthalpyTol=39.282, MassFlowTol=0.000,
HumRatTol=2.5407E-008, PressureTol=3.E-011
   **   ~~~   **      FlowQualTol=0.00, EnergyTol=-8.744,
TempTol=3.86E-002
   **   ~~~   ** HVAC EnthalpyTol=7.025E-002, MassFlowTol=1.046E-003,
HumRatTol=2.7672E-008, PressureTol=0
   **   ~~~   **      FlowQualTol=1.05E-003, EnergyTol=25.306,
TempTol=1.91E-007
   **   ~~~   ** HVAC EnthalpyTol=40.538, MassFlowTol=0.000,
HumRatTol=2.6224E-008, PressureTol=3.E-011
   **   ~~~   **      FlowQualTol=0.00, EnergyTol=8.982, TempTol=3.98E-002
   **   ~~~   ** HVAC EnthalpyTol=7.251E-002, MassFlowTol=1.080E-003,
HumRatTol=2.8561E-008, PressureTol=0
   **   ~~~   **      FlowQualTol=1.08E-003, EnergyTol=-26.119,
TempTol=1.97E-007
   **   ~~~   ** Plant Tolerance Flags=[00000000]
Enthalpy[0],MassFlow[0],HumRat[0],Pressure[0],FlowQual[0],Energy[0],Temp[0],PlantFlowMassFlow[0]..0=ok,1=fail
   **   ~~~   ** Plant Tolerance Values, Most Recent listed first
   **   ~~~   ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
HumRatTol=0.0000, PressureTol=0
   **   ~~~   **      FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
   **   ~~~   ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
HumRatTol=0.0000, PressureTol=0
   **   ~~~   **      FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
   **   ~~~   ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
HumRatTol=0.0000, PressureTol=0
   **   ~~~   **      FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
   **   ~~~   ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
HumRatTol=0.0000, PressureTol=0
   **   ~~~   **      FlowQualTol=0.00, EnergyTol=0.000, TempTol=0.00
   **   ~~~   ** Plant EnthalpyTol=0.000, MassFlowTol=0.000,
HumRatTol=0.0000, PressureTol=0
   **   ~~~   **      FlowQualTol=0.00, EnergyTol=-1.701,
TempTol=2.46E-004
   **   ~~~   ** Plant Flow Tolerance Values, Most Recent listed first
   **   ~~~   ** PlantFlowFlowTol=0.000
   **   ~~~   ** PlantFlowFlowTol=0.000
   **   ~~~   ** PlantFlowFlowTol=0.000
   **   ~~~   ** PlantFlowFlowTol=0.000
   **   ~~~   ** PlantFlowFlowTol=0.000

Are these errors avoidable? If so, what can be done to prevent them
from occuring? Or, alternatively, will they significantly affect the
accuracy of the simulation, or can I more-or-less ignore them? Any
help would be much appreciated.

Many thanks,

Josh

COMPACT HVAC CONFIGURATIONS:

!-   ===========  ALL OBJECTS IN CLASS: COMPACT HVAC:ZONE:FAN COIL
===========

COMPACT HVAC:ZONE:FAN COIL,
    zone-1,                  !- Zone Name
    office-thermostat,       !- Thermostat Name
    autosize,                !- Zone Supply Air Max Flow Rate {m3/s}
    1,                       !- Zone Supply Air Sizing Factor
    flow/zone,               !- Zone Outside Air Method
    ,                        !- Zone Outside Air Flow Rate per Person
{m3/s}
    ,                        !- Zone Outside Air Flow per Zone Area
{m3/s-m2}
    0.018,                   !- Zone Outside Air Flow per Zone {m3/s}
    always-1,                !- System Availability Schedule
    0.7,                     !- Supply Fan Total Efficiency
    75,                      !- Supply Fan Delta Pressure {Pa}
    0.9,                     !- Supply Fan Motor Efficiency
    1,                       !- Supply Fan Motor in Air Stream Fraction
    Chilled Water,           !- Cooling Coil Type
    always-1,                !- Cooling Coil Availability Schedule
    14,                      !- Cooling Coil Design Setpoint {C}
    Hot Water,               !- Heating Coil Type
    always-1,                !- Heating Coil Availability Schedule
    50;                      !- Heating Coil Design Setpoint {C}

!-   ===========  ALL OBJECTS IN CLASS: COMPACT HVAC:ZONE:VAV ===========

COMPACT HVAC:ZONE:VAV,
    zone-2,                  !- Zone Name
    ahu,                     !- Air Handling System Name
    office-thermostat,       !- Thermostat Name
    autosize,                !- Zone Supply Air Max Flow Rate {m3/s}
    ,                        !- Zone Supply Air Sizing Factor
    0,                       !- Zone Supply Air Min Flow Fraction
    flow/zone,               !- Zone Outside Air Method
    ,                        !- Zone Outside Air Flow Rate per Person
{m3/s}
    ,                        !- Zone Outside Air Flow per Zone Area
{m3/s-m2}
    0.0288,                  !- Zone Outside Air Flow per Zone {m3/s}
    Hot Water,               !- Reheat Coil Type
    fans-schedule,           !- Reheat Coil Availability Schedule
    Normal,                  !- Zone Damper Heating Action
    ,                        !- Zone Supply Plenum Name
    ,                        !- Zone Return Plenum Name
    Hot Water,               !- Baseboard Heating Type
    fans-inv-schedule,       !- Baseboard Heating Availability Schedule
    autosize;                !- Baseboard Heating Capacity {W}

!-   ===========  ALL OBJECTS IN CLASS: COMPACT HVAC:SYSTEM:VAV
===========

COMPACT HVAC:SYSTEM:VAV,
    ahu,                     !- Air Handling System Name
    fans-schedule,           !- System Availability Schedule
    autosize,                !- Supply Fan Max Flow Rate {m3/s}
    autosize,                !- Supply Fan Min Flow Rate {m3/s}
    0.7,                     !- Supply Fan Total Efficiency
    1000,                    !- Supply Fan Delta Pressure {Pa}
    0.9,                     !- Supply Fan Motor Efficiency
    1,                       !- Supply Fan Motor in Air Stream Fraction
    Chilled Water,           !- Cooling Coil Type
    always-1,                !- Cooling Coil Availability Schedule
    ,                        !- Cooling Coil Setpoint Schedule
    13,                      !- Cooling Coil Design Setpoint {C}
    None,                    !- Heating Coil Type
    ,                        !- Heating Coil Availability Schedule
    ,                        !- Heating Coil Setpoint Schedule
    10,                      !- Heating Coil Design Setpoint {C}
    0.8,                     !- Gas Heating Coil Efficiency
    ,                        !- Gas Heating Coil Parasitic Electric
Load {W}
    None,                    !- Preheat Coil Type
    ,                        !- Preheat Coil Availability Schedule
    ,                        !- Preheat Coil Setpoint Schedule
    7.2,                     !- Preheat Coil Design Setpoint {C}
    0.8,                     !- Gas Preheat Coil Efficiency
    ,                        !- Gas Preheat Coil Parasitic Electric
Load {W}
    autosize,                !- Maximum Outside Air Flow Rate {m3/s}
    autosize,                !- Minimum Outside Air Flow Rate {m3/s}
    PROPORTIONAL MINIMUM,    !- Minimum Outside Air Control Type
    ,                        !- Minimum Outside Air Schedule Name
    None,                    !- Economizer Type
    NO LOCKOUT,              !- Economizer Lockout
    ,                        !- Economizer Upper Temperature Limit {C}
    ,                        !- Economizer Lower Temperature Limit {C}
    ,                        !- Economizer Upper Enthalpy Limit {J/kg}
    ,                        !- Supply Plenum Name
    ,                        !- Return Plenum Name
    Draw Through,            !- Supply Fan Placement
    Inlet Vane Dampers,      !- Supply Fan Part-Load Power Coefficients
    Stay Off,                !- Night Cycle Control
    ,                        !- Night Cycle Control Zone Name
    None,                    !- Heat Recovery Type
    0.7,                     !- Sensible Heat Recovery Effectiveness
    0.65,                    !- Latent Heat Recovery Effectiveness
    None,                    !- Cooling Coil Setpoint Reset Type
    None,                    !- Heating Coil Setpoint Reset Type
    None,                    !- Dehumidification Control Type
    ,                        !- Dehumidification Control Zone Name
    60,                      !- Dehumidification Setpoint {percent}
    None,                    !- Humidifier Type
    ,                        !- Humidifier Availability Schedule
    0.000001,                !- Humidifier Rated Capacity {m3/s}
    2690,                    !- Humidifier Rated Electric Power {W}
    ,                        !- Humidifier Control Zone Name
    30;                      !- Humidifier Setpoint {percent}




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