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Error: Heater Control Type for WaterHeater:Stratified must be CYCLE?

asked 2020-04-02 19:57:07 -0500

bbrannon4's avatar

I've got this error:

   ** Severe  ** WaterHeater:HeatPump:WrappedCondenser = PLANTHEATPUMPWATERHEATER:
   **   ~~~   ** Heater Control Type for WaterHeater:Stratified = WATER HEATER TANK must be CYCLE.

on a fairly simple model, where I have I think completely copied the heat pump water heater components from the WaterHeaterHeatPumpWrappedCondensor example file (which has both a wrapped condenser heater and a stratified water heater tank, just like my model). This is why this error is confusing me, because it says the tank must have a cycle control, but that is only available in a WaterHeater:Mixed, not a WaterHeater:Stratefied - and somehow this combination is working fine int he example file. I wasn't able to find anything explaining the requirement in the documentation, so I'm at a bit of a loss. Any idea what might trigger this requirement in the heat pump settings or somewhere else? Just in case, here is my full text for those two objects:

    Water Heater Tank,       !- Name
    Water Heater,            !- End-Use Subcategory
    0.287691,                !- Tank Volume {m3}
    1.594,                   !- Tank Height {m}
    VerticalCylinder,        !- Tank Shape
    ,                        !- Tank Perimeter {m}
    100,                     !- Maximum Temperature Limit {C}
    Simultaneous,            !- Heater Priority Control
    WaterHeaterElec Setpoint Temp,  !- Heater 1 Setpoint Temperature Schedule Name
    18.5,                    !- Heater 1 Deadband Temperature Difference {deltaC}
    4500,                    !- Heater 1 Capacity {W}
    1.129,                   !- Heater 1 Height {m}
    WaterHeaterElec Setpoint Temp,  !- Heater 2 Setpoint Temperature Schedule Name
    18.5,                    !- Heater 2 Deadband Temperature Difference {deltaC}
    0,                       !- Heater 2 Capacity {W}
    0.266,                   !- Heater 2 Height {m}
    Electricity,             !- Heater Fuel Type
    1,                       !- Heater Thermal Efficiency
    8.3,                     !- Off Cycle Parasitic Fuel Consumption Rate {W}
    Electricity,             !- Off Cycle Parasitic Fuel Type
    0,                       !- Off Cycle Parasitic Heat Fraction to Tank
    1,                       !- Off Cycle Parasitic Height {m}
    8.3,                     !- On Cycle Parasitic Fuel Consumption Rate {W}
    Electricity,             !- On Cycle Parasitic Fuel Type
    0,                       !- On Cycle Parasitic Heat Fraction to Tank
    1,                       !- On Cycle Parasitic Height {m}
    Zone,                    !- Ambient Temperature Indicator
    ,                        !- Ambient Temperature Schedule Name
    CorridorFlr2 Thermal Zone,  !- Ambient Temperature Zone Name
    ,                        !- Ambient Temperature Outdoor Air Node Name
    0.7878,                  !- Uniform Skin Loss Coefficient per Unit Area to Ambient Temperature {W/m2-K}
    1,                       !- Skin Loss Fraction to Zone
    ,                        !- Off Cycle Flue Loss Coefficient to Ambient Temperature {W/K}
    1,                       !- Off Cycle Flue Loss Fraction to Zone
    ,                        !- Peak Use Flow Rate {m3/s}
    ,                        !- Use Flow Rate Fraction Schedule Name
    ,                        !- Cold Water Supply Temperature Schedule Name
    Water Heater Use Inlet Node,  !- Use Side Inlet Node Name
    Water Heater Use Outlet Node,  !- Use Side Outlet Node Name
    1,                       !- Use Side Effectiveness
    0,                       !- Use Side Inlet Height {m}
    autocalculate,           !- Use Side Outlet Height {m}
    ,                        !- Source Side Inlet Node Name
    ,                        !- Source Side Outlet Node Name
    ,                        !- Source Side Effectiveness
    ,                        !- Source Side Inlet Height {m}
    ,                        !- Source Side Outlet Height {m}
    Fixed,                   !- Inlet Mode
    autosize,                !- Use Side Design Flow Rate {m3/s}
    autosize,                !- Source Side Design Flow Rate {m3/s}
    1.5,                     !- Indirect Water Heating Recovery Time {hr}
    12;                      !- Number of Nodes

    PlantHeatPumpWaterHeater,!- Name
    ,                        !- Availability Schedule Name
    WaterHeaterGas Setpoint Temp,  !- Compressor Setpoint Temperature Schedule Name
    3.89,                    !- Dead Band Temperature Difference {deltaC ...
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answered 2020-04-03 10:03:13 -0500

Sure sounds like a bug to me. I suggest you post a bug report at

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Was afraid of that - will do

bbrannon4's avatar bbrannon4  ( 2020-04-03 13:51:19 -0500 )edit

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Asked: 2020-04-02 19:57:07 -0500

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Last updated: Apr 03 '20