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A bug report about chilled water pumps. 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. Pump Control Type is set to Intermittent.

Since I can't find an ExampleFile which meets the coditions above, I reproduced the bug using HVACTemplate-5ZoneVAVWaterCooled.idf. I quickly revised the idf and expid files to meet the conditions above. The waterside schematic is shown below.

The bug is easy to spot on 7 and 8 May in the charts below. Chiller2 to 4 do not operate but all the chilled water pumps operate on those days.

The idf file is here. The version is V24-2-0.

A bug report about chilled water pumps. 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. Pump Control Type is set to Intermittent.

Since I can't find an ExampleFile which meets the coditions above, I reproduced the bug using HVACTemplate-5ZoneVAVWaterCooled.idf. I quickly revised the idf and expid files to meet the conditions above. The waterside schematic is shown below.

The bug is easy to spot on 7 and 8 May in the charts below. Chiller2 to 4 do not operate but all the chilled water pumps operate on those days.

The idf file is here. The version is V24-2-0.