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