Multiple SwimmingPool:Indoor objects do not work
A bug report. Two or more SwimmingPool:Indoor objects do not work properly.
Let me explain using ExampleFIle: 5ZoneSwimmingPool.idf. Oroginally, the examle file has one SwimmingPool:Indoor object, so it works properly. When I added 4 SwimmingPool:Indoor objects (all 5 zones have SwimmingPool:Indoor objects), only "Test Pool5" met the pool setpoint temperature of 27ºC.

The order of the objects matter. When I changed the order as shown below, only "Test Pool" met the pool setpoint temperature.

But the problem is more complicated. I explain using the revised example file with 2 SwimmingPool:Indoor objects just because 5 pools are too much to explain. The hot water plant loop is as shown below. When there are 2 SwimmingPool:Indoor objects,
HW SUPPLY OUTLET NODE:System Node Temperaturedoes not meet the Setpoint of 82ºC.HW SUPPLY OUTLET NODE:System Node TemperatureandHW DEMAND INLET NODE:System Node Temperatureare inconsistent.TEST POOL:Indoor Pool Inlet Water TemperatureandPOOL WATER INLET NODE:System Node Temperatureare inconsistent.TEST POOL2:Indoor Pool Water Temperaturemeet the Setpoint of 27ºC even ifTEST POOL2:Indoor Pool Inlet Water Temperatureis lower than 27ºC.

It's a mess. The bug extends beyond SwimmingPool:Indoor objects to the entire hot water loop, so that zones cannot meet the heating temperature setpoint.
The idf files are here (V22-2-0). You can reproduce the bug.
Personally, I have a few projects with multiple swimming pools, and I don't have time to wait for the future EnergyPlus version to fix the bug... Please let me know if anyone has been able to force multiple SwimmingPool:Indoor objects to work using EMS or other means.



One makeshift I came up with:
SwimmingPool:Indoorobject.SwimmingPool:Indoor.SwimmingPool:Indoorobjects.SwimmingPool:Indoorobjects withLoadProfile:Plantobjects for the final idf file.I don't need to know the water use of the swimming pools. This makeshift may be the most accurate to know the annual energy use at the moment although it cannot simulate the water evaporation and the pool surface temperature.