SWHC049-09 CCH and Defrost Investigation

[yagi-solaris]

SWHC049-09 CCH and Defrost Investigation

• Parameterized crankcase and defrost parameters in "res-zone-hvac-combi.pxt" and defined parameters in cases files.
• Updated "Crankcase Heater Capacity" to 50W for both coils to align with "unitary.pxt" (Originally 40W for Single Speed, 0W for Multispeed).
• Updated "Defrost Time Period Fraction" to EnergyPlus default for Single Speed coil to match Multispeed value (0.058333).
• Updated "Defrost Control" to OnDemand for Multispeed coil to match Single Speed setting and due to EnergyPlus bug for ReverseCycle control strategy. (See link)

Main Contributor: Yasemin Agi (yagi@solaris-technical.com)

DEER Support Email: DeerSupport@guidehouse.com

PR Author

• Make sure the PR branch is up to date with main branch at the time of the PR submission
• Craft a succinct title that effectively encapsulates the essence of the pull request, providing a general overview of the proposed changes.
• Label the PR with at least one of the following: New Measure, Bug, or Feature.
• Provide a concise description of the measure, bug, or feature. Submit one PR per measure.
• For a new measure, attach a workbook named DEER_EnergyPlus_Modelkit_Measure_list_working.xlsx, containing only rows used for post-processing the measure.
• Add comments in the code when necessary to facilitate the review process.
• Add a comment before the added code, including the author's full name, company, and specifying if it's a bug fix, new measure, or feature.
• For a new feature or bug, demonstrate the impact on energy consumption for selected cases with justification using plots and descriptions.
• For a new measure, add a summary table showing total energy consumption per simulated case.

PR Reviewer

• Conduct a thorough code review.
• If the branch is behind the main, merge the branch locally to check for potential conflicts.
• If a bug, locally reproduce it and compare energy consumptions before and after.
• Explore creative ways to stress-test the code.
• Locally check the error file and other outputs.

[yagi-solaris]

The attached documentation provides more detail on the following changes/findings:

• Default values were parameterized for Single Speed and Multispeed and used values from unitary.pxt to align with the commercial prototype.
• CCH and defrost parameters were modified to be identical between Single Speed and Multispeed.
• Multispeed coils seem to require OnDemand control to recognize that the strategy is ReverseCycle. This issue is not present in the Single Speed coil object.

CCH and Defrost Analysis 2026-05-20.xlsx
Crankcase Heater and Defrost Modeling Investigation 2026-05-20.docx