Variable Speed Primary Chilled Water Pumps Operate Unexpectedly

[keigo-nomura]

Issue overview

The bug is reported in detail on UnmetHours. Below is an extract from UnmetHours.

The bug occurs when the following conditions are met.

1. There are multiple chiller objects e.g.Chiller:Electric:EIR.
2. Each chiller has a primary chilled water pump.
3. The primary chilled water pumps are Pump:VariableSpeed, and Chiller Flow Mode of Chiller:Electric:EIR is set to LeavingSetpointModulated.
4. Design Minimum FLow Rate of Pump:Variable:Speed is not 0.
5. Load Distribution Scheme of Plant Loop is SequentialUniformPLR, SequentialLoad or Optimal.

I expect that each chilled water pump is interlocked with each dedicated chiller, but actually all chilled water pumps operate when there is a cooling load even if the load is small enough to be handled by one chiller. That's the bug.

Operating System (Multiple choices)

Windows

Operating System Version

11

Version of EnergyPlus

24.2.0

Unmethours link or helpdesk ticket number

https://unmethours.com/question/101057/variable-speed-primary-chilled-water-pumps-operate-unexpectedly/

Defect file

Please find the defect file in the following link.

https://drive.google.com/drive/folders/1q4Km9ixacxopFaIweUVQ7nKBHSq6yzR8?usp=drive_link