SetpointManager:WarmestTemperatureFlow interferes with proper autosizing in WinterDesignDay

[keigo-nomura]

Issue overview

Indicated in the title. Please refer to the Unmethours link below for mroe details on the issue.

Details

Some additional details for this issue (if relevant):

• Version of EnergyPlus: V22-2-0
• Unmethours link: SetpointManager:WarmestTemperatureFlow interferes with proper autosizing in WinterDesignDay

Checklist

Add to this list or remove from it as applicable. This is a simple templated set of guidelines.

• [ ] Defect file added (list location of defect file here)
• [ ] Ticket added to Pivotal for defect (development team task)
• [ ] Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)

[mjwitte]

The heating supply temperature is inconsistent with the setpoint manager.

  Sizing:System,
    16.7,                    !- Central Heating Design Supply Air Temperature {C}

  SetpointManager:WarmestTemperatureFlow,
    11.2,                    !- Minimum Setpoint Temperature {C}
    16.,                     !- Maximum Setpoint Temperature {C}

So, the reheat coil is sizing for an inlet air temperature of 16.7C but the max supply temperature is only 16.0C. Fixing this helps a little bit, but not much.

The bigger problem is that the reheat coil sizing is assuming full airflow. From the eio output:

 Component Sizing Information, AirTerminal:SingleDuct:ConstantVolume:Reheat, SPACE1-1 CAV REHEAT, Design Size Maximum Air Flow Rate [m3/s], 0.28813
 Component Sizing Information, AirTerminal:SingleDuct:ConstantVolume:Reheat, SPACE1-1 CAV REHEAT, Design Size Maximum Reheat Water Flow Rate [m3/s], 1.25103E-004
 Component Sizing Information, AirTerminal:SingleDuct:ConstantVolume:Reheat, SPACE1-1 CAV REHEAT, Design Size Reheat Coil Sizing Air Volume Flow Rate [m3/s], 0.28813
 Component Sizing Information, AirTerminal:SingleDuct:ConstantVolume:Reheat, SPACE1-1 CAV REHEAT, Design Size Reheat Coil Sizing Inlet Air Temperature [C], 16.70000
 Component Sizing Information, AirTerminal:SingleDuct:ConstantVolume:Reheat, SPACE1-1 CAV REHEAT, Design Size Reheat Coil Sizing Inlet Air Humidity Ratio [kgWater/kgDryAir], 8.00000E-003
 Component Sizing Information, Coil:Heating:Water, SPACE1-1 ZONE COIL, Design Size Rated Capacity [W], 5662.38342
 Component Sizing Information, Coil:Heating:Water, SPACE1-1 ZONE COIL, Design Size Maximum Water Flow Rate [m3/s], 1.25103E-004
 Component Sizing Information, Coil:Heating:Water, SPACE1-1 ZONE COIL, Design Size U-Factor Times Area Value [W/K], 114.61180

But the system is not operating at full air flow during heating when SetpointManager:WarmestTemperatureFlow is used. It has a Minimum Turndown Ratio of 0.3, and the Sizing:System Central Heating Maximum System Air Flow Ratio is set to 0.3, but this is used only for sizing the central heating coil.

I tried setting the Sizing:Zone heating design air flow to DesignDayWithLimits with a 0.3 fraction, but that didn't change the reheat coil sizing for AirTerminal:SingleDuct:ConstantVolume:Reheat.