[EnergyPlus_Support] DX system ratings and max total coil load

["Willis" <willis.nessle@xxxxxxxxx>]

Have a couple questions really basic questions about the hourly results and standard output summaries for DX Unitary systems (PSZ).  Hoping somebody can clear things up for me.  

The model I have is set to "auto-size".

The Equipment Summary report includes both a "Cooling Coil" and a "DX Cooling Coil" Report.  The first one give "Nominal Capacity" and "Nominal COP";  the second one gives "Rated Net Capacity" and "Rated SEER, EER, IEER".

If the system is auto-sized, what is the difference b/t "nominal" and "rated"?  My hunch is that it reflects the affects of bldg loads, climate, performance curve adjustments, etc.

Second, I need to calculate the equivalent full load hours (EFLH) of each PSZ.  If I divide "Total Load at that timestep" by "Rated Net Capacity", it indicates Part Load.  Then, if I add the Part Load values for each hour of the year, isn't that equivalent to Full Load Hours per year? (e.g., if it ran at 10% every hour of the year, the EFLH = 876, correct?)

Finally, I'm having terrible difficulty identifying Max Total Load met by the DX Coil.  When I make an RVI hourly report for Total Cooling Coil Rate (export to Excel) the MAX value does not match the Monthly Table Maximum presented the Standard DX Coil Monthly Report.  They're different by quite a lot.  In fact, when I make my own custom Monthly Table, using the same Total Cooling Coil Rate variable, the max value doesn't match the max hourly value.  The hourly max values are all much lower than the monthly max values.

I can't think of any explanation for this. 

Any insights are greatly appreciated. Thanks,
Will






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