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[EnergyPlus_Support] water tank that is heated by an air-to-water heat pump





Iâ??m trying to model a water tank that is heated by an air-to-water heat pump. I tried to change the setpoint temperatures, but in both cases it doesnâ??t work.

 

1)

 

WaterHeater:Mixed,

    Aux HW Loop HP Water Heater Water Heater,  !- Name

    0.265000,                !- Tank Volume {m3}

    55C,                     !- Setpoint Temperature Schedule Name

    3,                       !- Deadband Temperature Difference {deltaC}

    90.00,                   !- Maximum Temperature Limit {C}

    Cycle,                   !- Heater Control Type

    0,                       !- Heater Maximum Capacity {W}

    0,                       !- Heater Minimum Capacity {W}

    0.000000,                !- Heater Ignition Minimum Flow Rate {m3/s}

    0.0,                     !- Heater Ignition Delay {s}

    Electricity,             !- Heater Fuel Type

    1.00,                    !- Heater Thermal Efficiency

    100% efficient,          !- Part Load Factor Curve Name

    0.000,                   !- Off Cycle Parasitic Fuel Consumption Rate {W}

    Electricity,             !- Off Cycle Parasitic Fuel Type

    0.00,                    !- Off Cycle Parasitic Heat Fraction to Tank

    36.000,                  !- On Cycle Parasitic Fuel Consumption Rate {W}

    Electricity,             !- On Cycle Parasitic Fuel Type

    0.50,                    !- On Cycle Parasitic Heat Fraction to Tank

    Zone,                    !- Ambient Temperature Indicator

    Water heater ambient temperature schedule: Always 20.00,  !- Ambient Temperature Schedule Name

    0:RXserve/Buanderie,     !- Ambient Temperature Zone Name

    Aux HW Loop HP Water Heater Water Heater Outdoor Air Node,  !- Ambient Temperature Outdoor Air Node Name

    0.8900,                  !- Off Cycle Loss Coefficient to Ambient Temperature {W/K}

    1.00,                    !- Off Cycle Loss Fraction to Zone

    0.8900,                  !- On Cycle Loss Coefficient to Ambient Temperature {W/K}

    1.00,                    !- On Cycle Loss Fraction to Zone

    0.000000,                !- Peak Use Flow Rate {m3/s}

    ,                        !- Use Flow Rate Fraction Schedule Name

    ,                        !- Cold Water Supply Temperature Schedule Name

    Aux HW Loop HP Water Heater Water Heater DHW Inlet Node,  !- Use Side Inlet Node Name

    Aux HW Loop HP Water Heater Water Heater DHW Outlet Node,  !- Use Side Outlet Node Name

    1.00,                    !- Use Side Effectiveness

    Aux HW Loop HP Water Heater Water Outlet Node,  !- Source Side Inlet Node Name

    Aux HW Loop HP Water Heater Water Inlet Node,  !- Source Side Outlet Node Name

    1.00,                    !- Source Side Effectiveness

    autosize,                !- Use Side Design Flow Rate {m3/s}

    autosize,                !- Source Side Design Flow Rate {m3/s}

    1.500000,                !- Indirect Water Heating Recovery Time {hr}

    StorageTank;             !- Source Side Flow Control Mode

 

WaterHeater:HeatPump:PumpedCondenser,

    Aux HW Loop HP Water Heater,  !- Name

    On 24/7,                 !- Availability Schedule Name

    52C,                     !- Compressor Setpoint Temperature Schedule Name

    2,                       !- Dead Band Temperature Difference {deltaC}

    Aux HW Loop HP Water Heater Water Inlet Node,  !- Condenser Water Inlet Node Name

    Aux HW Loop HP Water Heater Water Outlet Node,  !- Condenser Water Outlet Node Name

    autocalculate,           !- Condenser Water Flow Rate {m3/s}

    autocalculate,           !- Evaporator Air Flow Rate {m3/s}

    OutdoorAirOnly,          !- Inlet Air Configuration

    ,                        !- Air Inlet Node Name

    ,                        !- Air Outlet Node Name

    Aux HW Loop HP Water Heater Outdoor Air Node,  !- Outdoor Air Node Name

    Aux HW Loop HP Water Heater Exhaust Air Node,  !- Exhaust Air Node Name

    ,                        !- Inlet Air Temperature Schedule Name

    ,                        !- Inlet Air Humidity Schedule Name

    ,                        !- Inlet Air Zone Name

    WaterHeater:Mixed,       !- Tank Object Type

    Aux HW Loop HP Water Heater Water Heater,  !- Tank Name

    Aux HW Loop HP Water Heater Water Heater DHW Inlet Node,  !- Tank Use Side Inlet Node Name

    Aux HW Loop HP Water Heater Water Heater DHW Outlet Node,  !- Tank Use Side Outlet Node Name

    COIL:WATERHEATING:AIRTOWATERHEATPUMP:PUMPED,  !- DX Coil Object Type

    Aux HW Loop HP Water Heater HP Water Heating Coil,  !- DX Coil Name

    -5.0000,                 !- Minimum Inlet Air Temperature for Compressor Operation {C}

    ,                        !- Maximum Inlet Air Temperature for Compressor Operation {C}

    Outdoors,                !- Compressor Location

    ,                        !- Compressor Ambient Temperature Schedule Name

    Fan:OnOff,               !- Fan Object Type

    Aux HW Loop HP Water Heater Supply Fan,  !- Fan Name

    DrawThrough,             !- Fan Placement

    0.0000,                  !- On Cycle Parasitic Electric Load {W}

    0.0000,                  !- Off Cycle Parasitic Electric Load {W}

    Outdoors;                !- Parasitic Heat Rejection Location

 

 

In this case I get the following warning and the heat pump is always off:

 

  ** Warning ** WaterHeater:HeatPump:PumpedCondenser "AUX HW LOOP HP WATER HEATER:  Water heater tank set point temperature is greater than or equal to the cut-in temperature of the heat pump water heater. Heat Pump will be disabled and simulation continues.

   **   ~~~   **  ...Heat Pump cut-in temperature=   50.0000000000000    

   **   ~~~   **  Environment=YEAR, at Simulation time=01/01 00:00 - 00:30

   ************* Simulation Error Summary *************

   ************* There are 1 unused objects in input.

   ************* Use Output:Diagnostics,DisplayUnusedObjects; to see them.

   ************* There are 22 unused schedules in input.

   ************* There are 5 unused week schedules in input.

   ************* There are 7 unused day schedules in input.

   ************* Use Output:Diagnostics,DisplayUnusedSchedules; to see them.

 

 

2) In order to avoid the previous problem I have decreased the setpoint temperature of the water heater:

 

WaterHeater:Mixed,

    Aux HW Loop HP Water Heater Water Heater,  !- Name

    0.265000,                !- Tank Volume {m3}

    48C,                     !- Setpoint Temperature Schedule Name

    3,                       !- Deadband Temperature Difference {deltaC}

    90.00,                   !- Maximum Temperature Limit {C}

    Cycle,                   !- Heater Control Type

    0,                       !- Heater Maximum Capacity {W}

    0,                       !- Heater Minimum Capacity {W}

    0.000000,                !- Heater Ignition Minimum Flow Rate {m3/s}

    0.0,                     !- Heater Ignition Delay {s}

    Electricity,             !- Heater Fuel Type

    1.00,                    !- Heater Thermal Efficiency

    100% efficient,          !- Part Load Factor Curve Name

    0.000,                   !- Off Cycle Parasitic Fuel Consumption Rate {W}

    Electricity,             !- Off Cycle Parasitic Fuel Type

    0.00,                    !- Off Cycle Parasitic Heat Fraction to Tank

    36.000,                  !- On Cycle Parasitic Fuel Consumption Rate {W}

    Electricity,             !- On Cycle Parasitic Fuel Type

    0.50,                    !- On Cycle Parasitic Heat Fraction to Tank

    Zone,                    !- Ambient Temperature Indicator

    Water heater ambient temperature schedule: Always 20.00,  !- Ambient Temperature Schedule Name

    0:RXserve/Buanderie,     !- Ambient Temperature Zone Name

    Aux HW Loop HP Water Heater Water Heater Outdoor Air Node,  !- Ambient Temperature Outdoor Air Node Name

    0.8900,                  !- Off Cycle Loss Coefficient to Ambient Temperature {W/K}

    1.00,                    !- Off Cycle Loss Fraction to Zone

    0.8900,                  !- On Cycle Loss Coefficient to Ambient Temperature {W/K}

    1.00,                    !- On Cycle Loss Fraction to Zone

    0.000000,                !- Peak Use Flow Rate {m3/s}

    ,                        !- Use Flow Rate Fraction Schedule Name

    ,                        !- Cold Water Supply Temperature Schedule Name

    Aux HW Loop HP Water Heater Water Heater DHW Inlet Node,  !- Use Side Inlet Node Name

    Aux HW Loop HP Water Heater Water Heater DHW Outlet Node,  !- Use Side Outlet Node Name

    1.00,                    !- Use Side Effectiveness

    Aux HW Loop HP Water Heater Water Outlet Node,  !- Source Side Inlet Node Name

    Aux HW Loop HP Water Heater Water Inlet Node,  !- Source Side Outlet Node Name

    1.00,                    !- Source Side Effectiveness

    autosize,                !- Use Side Design Flow Rate {m3/s}

    autosize,                !- Source Side Design Flow Rate {m3/s}

    1.500000,                !- Indirect Water Heating Recovery Time {hr}

    StorageTank;             !- Source Side Flow Control Mode

 

 

In that case I got a fatal error:

 

   **  Fatal  ** CalcDoe2DXCoil: Coil:WaterHeating:AirToWaterHeatPump:Pumped="AUX HW LOOP HP WATER HEATER HP WATER HEATING COIL" - Rated total cooling capacity is zero or less.

 

What should I do?

Best Regards




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Posted by: fpasserini.tn@xxxxxxxxx


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