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Rated capacity of chiller in the E+ tabular report

Two Rated capacities of the same chiller is reported in the E+ tabular report. image description

Note the Reference capacity is slightly different from Rated Capacity.

However, the 2nd one under [The same Report] / chillers shows the same value.

image description

The chiller reference capacity is autosized.

I tried to find out how is Rated Capacity calculated by E+, but failed. (The source code is quite complex) Anyway, we may focused on the Reference Capacity, which is well explained by the Input Output Reference. If some could explain how the 1st Rated Capacity is calculated, it is helpful.

The results before the question was edited was from a big idf. I created a small project for test and the phenomenon is the same. I'm not able to use online drives, but I upload the idf, results and epw files to the github. The EnergyPlus version I use is 23.2.0.

Mwaltre's avatar
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Mwaltre
asked 2024-10-23 20:02:34 -0500, updated 2024-10-30 01:50:05 -0500
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Can you upload your IDF to something like Google Drive or Dropbox? Also, you may be able to edit the post and add an image now.

shorowit's avatar shorowit (2024-10-29 08:54:38 -0500) edit
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Thank you very much. The results before the question was edited was from a big idf. I created a small project for test and the phenomenon is the same. I'm not able to use online drives, but I upload the idf, results and epw files to the github. The EnergyPlus version I use is 23.2.0.

Mwaltre's avatar Mwaltre (2024-10-30 01:51:52 -0500) edit
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1 Answer

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The table Equipment Summary / For Facility / Chillers should list both Reference and Rated Temperatures (Entering Condenser Temperature, Leaving Evaporator Temperature). The Reference Temperatures are inputs in the Chiller:Electric:EIR object. If the Reference temps are the same as the Rated temps, the Reference Capacity will be equivalent to the Rated Capacity. If the temperatures are different, the rated/ref capacities will be different.

ericmartinpe's avatar
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ericmartinpe
answered 2024-10-29 10:35:38 -0500
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Thank you. In the Chillers table, Reference temps are the same as the Rated temps so that the same values are reported. However, in the Equipment summary / For Facility / Central Plant table, the two capacities are slightly different, which is the point that I do not understand. I upload a test project to github, you can check the file if necessary.

Mwaltre's avatar Mwaltre (2024-10-30 00:58:34 -0500) edit
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