[EnergyPlus_Support] Problem with UpdateZoneSizing: Heating supply air temperature [2 Attachments]

[<m.aldegheri@xxxxxxxxx>]

Dear all,

I'm having some trouble with a simulation.

In my idf, the HVAC system is composed of 2 different entities: a radiant low temperature heating system and a mechanical ventilation system which should provide only a defined air change in my zones. Each of them works only during winter time.

I upload the .svg to show how the system is realized. In particolar, my mec vent system is not properly a heating system, it provides an only airflow but with a control on the temperature. Just before the entrance of the air flux in a zone, there is a heating coil which should increase the incoming air temperature until 18°C, if the outside air temperature is less than 18°C. If the outside air temperature is >18°C the air flux is not heated by this coil. I should have set this using SetpointManager:OutdoorAirReset,

SetpointManager:OutdoorAirReset,
    Air Loop Setpoint Manager,  !- Name
    Temperature,             !- Control Variable
    18.00,                   !- Setpoint at Outdoor Low Temperature {C}
    -20.00,                  !- Outdoor Low Temperature {C}
    18.00,                   !- Setpoint at Outdoor High Temperature {C}
    18.00,                   !- Outdoor High Temperature {C}
    Air Loop Setpoint Manager Node List;  !- Setpoint Node or NodeList Namet;

I would like to ask you if do you mind how to fix this error. I have many severe errors like this one, one error for each thermal zone.

   ** Severe  ** UpdateZoneSizing: Heating supply air temperature (calculated) within 2C of zone temperature
   **   ~~~   ** ...check zone thermostat set point and design supply air temperatures
   **   ~~~   ** ...zone name = P0:P0%A1ZN4B
   **   ~~~   ** ...design heating load         = 0.00 W
   **   ~~~   ** ...thermostat set piont temp   = 0.000 C
   **   ~~~   ** ...zone temperature            = 17.898 C
   **   ~~~   ** ...supply air temperature      = 18.000 C
   **   ~~~   ** ...temperature difference      = 0.10230 C
   **   ~~~   ** ...calculated volume flow rate = 8253.19807 m3/s
   **   ~~~   ** ...calculated mass flow rate   = 9723.31707 kg/s


Maybe the problem is in the design supply air temperatures, which I set to 18°C but I don't understand exaclty what's wrong...



!-   ===========  ALL OBJECTS IN CLASS: SIZING:ZONE ===========

Sizing:Zone,
    P0:P0%A1Zn5i,            !- Zone or ZoneList Name
    SupplyAirTemperature,    !- Zone Cooling Design Supply Air Temperature Input Method
    14.00,                   !- Zone Cooling Design Supply Air Temperature {C}
    5.00,                    !- Zone Cooling Design Supply Air Temperature Difference {deltaC}
    SupplyAirTemperature,    !- Zone Heating Design Supply Air Temperature Input Method
    18,                      !- Zone Heating Design Supply Air Temperature {C}
    15.00,                   !- Zone Heating Design Supply Air Temperature Difference {deltaC}
    0.0090,                  !- Zone Cooling Design Supply Air Humidity Ratio {kgWater/kgDryAir}
    0.0040,                  !- Zone Heating Design Supply Air Humidity Ratio {kgWater/kgDryAir}
    P0:P0%A1Zn5i Design Specification Outdoor Air Object,  !- Design Specification Outdoor Air Object Name
    1.25,                    !- Zone Heating Sizing Factor
    1.15,                    !- Zone Cooling Sizing Factor
    DesignDay,               !- Cooling Design Air Flow Method
    0.000000,                !- Cooling Design Air Flow Rate {m3/s}
    0.000760,                !- Cooling Minimum Air Flow per Zone Floor Area {m3/s-m2}
    0.000000,                !- Cooling Minimum Air Flow {m3/s}
    0.00,                    !- Cooling Minimum Air Flow Fraction
    DesignDay,               !- Heating Design Air Flow Method
    0.000000,                !- Heating Design Air Flow Rate {m3/s}
    0.002030,                !- Heating Maximum Air Flow per Zone Floor Area {m3/s-m2}
    0.141580,                !- Heating Maximum Air Flow {m3/s}
    0.30,                    !- Heating Maximum Air Flow Fraction
    P0:P0%A1Zn5i Design Specification Zone Air Distribution Object;  !- Design Specification Zone Air Distribution Object Name


Thank you all,

Marco





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