Chilled water cooling coil has water deltaT with no airflow or air deltaT across coil

[matthew-larson]

Issue overview

The screenshot below shows the inlet and outlet flow rates and temperatures of the air and water across a chilled water cooling coil. From 24:00 to 5:00, there is no air flow across the coil and no change in air temperature from the inlet and outlet, yet there is chilled water flow through the coil with a temperature increase of 3-4C. Even with water flow through the coil, there shouldn't be an increase in chilled water temperature through the coil if there is no air flow. The Cooling Coil Total Cooling Energy output does report 0 energy consumption during this period.

Details

Some additional details for this issue (if relevant):

• EnergyPlus v9.3

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]

@matthew-larson Just curious, if you increase the minimum number of plant iterations (ConvergenceLimits), do you see the same result?

[matthew-larson]

I increased the minimum number of plant iterations to 4 from the default of 2 and still got the same result.

[matthew-larson]

Coming back to this one and found the source of the problem. The InletWaterTemp and OutletWaterTemp are equal and greater than 6.67C and at line 2246, the InletWaterTemp gets set to the splitter outlet temperature of 6.67C, but the OutletWaterTemp never gets updated to match the 6.67C. Need to figure out why the InletWaterTemp and OutletWaterTemp are above 6.67 to begin with or do the node temperatures need to be updated after the UpdatePlantSplitter function.