Coil:Cooling:DX:VariableSpeed does not run on latent only load

[TiejunWu]

Issue overview

In the attached IDF files, I have a simple DOAS air loop with 3 components (Supply Fan, DX Cooling Coil, Dehumidification Reheat Coil). The DOAS has a cooling temperature setpoint of 26.7 C and a Maximum Humidity Ratio setpoint of 0.0089 kg water/kg dry air.

In the "CoilSystem:Cooling:DX" object that wraps the DX cooling coil, I set the "Run on Latent Load" to Yes, which means the coil should run if there is a latent load, even if there is no sensible load.

When the DX Cooling Coil is a "Coil:Cooling:DX:SingleSpeed" object, the DX coil runs ok to maintain the cooling coil outlet maximum humidity ratio setpoint.

However, when the DX cooling coil is a "Coil:Cooling:DX:VariableSpeed" object, the DX cooling coil will only run when there is a sensible load. The coil remains off for the time period with only latent load but no sensible load.

Based on this results, I think there is either a bug in the "CoilSystem:Cooling:DX" object or the "Coil:Cooling:DX:VariableSpeed" object.

Details

Some additional details for this issue (if relevant):

• Platform (WIndows 11, 64bit)

• Version of EnergyPlus (24.2)

• Unmethours link or helpdesk ticket number

• Defect files

  DOAS_SingleSpdCoil.idf.zip
  DOAS_VariableSpdCoil.idf.zip

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 EnergyPlus Defect Complexity (Github Project)
• Pull request created (the pull request will have additional tasks related to reviewing changes that fix this defect)