Central Heat Pump Modeling Options

Working on modeling a central heat pump that will be providing heating and cooling for the building. Thanks to @MingboPeng 's excellent template pictured below, we were able utilize the CentralHeatPump successfully model it.

One thing that we learned that I wanted to document here in case it helps others using this template is that initially the heating was only working at certain times, leading to a lot of unmet heating hours. Changing the hardcoded capacity here as well as adding more modules allowed us to meet the hot water loop set point and eliminate all but a few of the unmet hours. The issue with autosizing not allowing the heating to work correctly is documented here:

But the question that I wanted to ask here was about how to use these two loop components, the HeatPumpWatertoWaterEquationFittingHeating and HeatPumpWatertoWaterEquationFittingCooling. How are they different from the central HP system above and what does the HP output get connected to? We tried a few configurations of how to use them but got an error each time about unconnected inlet and outlet nodes.


Will appreciate any insight that can be provided

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Hi @Elliot_Glassman, these WaterToWater heat pumps are used between plant loops. E+ has a nice diagram explaining this. HP should be connected to the first plant loop’s demand side and “toSupplySide” is connected to the second loop’s supply side where they supply hot/cold water.

Group – Plant Equipment: Input Output Reference — EnergyPlus 9.2 (bigladdersoftware.com)