Inconsistent Water Flow Rates in SwimmingPool:Indoor

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I want to model a swimming pool with a constant water flow rate. Normally, a hot water loop for a swimming pool has a constant flow because flitration system (which is not modelled for energy simulation) is in the loop and the pool water needs to be continuously filtered while the swimming pool is in operation.

Here is a sample model (V23-1-0). There are only hot water loops with SwimmingPool:Indoor and no air-conditioning system in the idf file. The water-side schematic is as follows. The secondary loop has Pump:ConstantSpeed.

The simulation runs successfully without error. The water flow in the secondary loop is constant when the loop is in operation from 6am to 11pm. System Node Mass Flow Rate of Pool Water Inlet Node also shows a constant flow. However, I found that Indoor Pool Inlet Water Mass Flow Rate has a variable flow. I think these two Output:Variables refer to the same Node. Why are these two flow rates different? Is this a bug?

Indoor Pool Inlet Water Mass Flow Rate is consistent with Indoor Pool Water Heating Rate, and SwimmingPool:Indoor seems to accept only the amount of hot water required to heat the pool water to a setpoint temperature. Indoor Pool Inlet Water Mass Flow Rate becomes 0kg/s when the pool water temperature reach the setpoint and it does not need to be heated, but that's not what I expect. I want keep the constant water flow even when the pool water temperature reaches the setpoint.

If both Indoor Pool Inlet Water Mass Flow Rate and System Node Mass Flow Rate of Pool Water Inlet Node are correct, then Indoor Pool Inlet should be inside the SwimmingPool:Indoor component separately from Pool Water Inlet Node, and a bypass pipe with 3 way valves should be also inside the SwimmingPool:Indoor component as shown below. Is my understanding correct?