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HVAC School - For Techs, By Techs

Jun 27, 2024

This episode focuses on understanding and effectively utilizing various refrigeration system charts and measurements for troubleshooting and diagnostics. Joey Henderson, an HVAC veteran and trainer, shares his wealth of knowledge and experience on this topic.

Joey starts by discussing the challenges he faced early in his career when trying to make sense of the confusing charts with arrows indicating high, low, high head, low head, etc. He emphasizes the importance of knowing the "supposed to be" values before attempting any measurements or referencing charts. Without this baseline understanding, the measurements become meaningless.

He then delves into specific measurements like subcooling, superheat, evaporator temperature/suction saturation, condenser split, and compressor amperage. For each measurement, Joey explains the ideal range, how to interpret deviations, and how different factors like humidity, airflow, and refrigerant type can affect these values. He also highlights the differences in approaches for fixed metering devices versus TXV/EEV systems.

Topics covered in the podcast:

  • Understanding refrigeration system charts and their limitations
  • Importance of knowing "supposed to be" values for meaningful diagnostics
  • Measuring and interpreting subcooling
  • Measuring and interpreting superheat
  • Determining evaporator temperature/suction saturation
  • Calculating and understanding condenser split
  • Evaluating compressor amperage
  • Differences in charging fixed metering devices vs. TXV/EEV systems
  • Impact of humidity, airflow, and refrigerant type on measurements
  • Using psychrometers and measuring wet bulb temperatures accurately
  • Calculating and interpreting Delta T (wet bulb/dry bulb split)
  • Resources like the Efficient Comfort website and Dick Wirz's RefTech app


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