Module 2
1 week (8 hours)

Refrigeration

Part of the HVAC Technician training program

Overview

Deep dive into refrigeration systems — the heart of all cooling equipment. Learn refrigerant chemistry, refrigeration cycle analysis, system components, and the skills needed to install, charge, and maintain refrigeration systems of all sizes.

Sub-topics

Refrigerant Chemistry & Types

2 hours

Study the properties and applications of R-22, R-410A, R-404A, R-454B, R-32, and other refrigerants. Understand ozone depletion potential (ODP), global warming potential (GWP), and the transition to next-generation low-GWP refrigerants mandated by environmental regulations.

Lessons

Refrigerant Nomenclature

Understand R-number naming convention. Learn that R-22 means Refrigerant-22, with “22” indicating molecular structure. Recognize H (hydrogen), C (carbon), C (chlorine), B (bromine) designations.

Ozone Depletion Potential (ODP)

Study how refrigerants affect the ozone layer. Understand that CFCs (R-11, R-12) have high ODP, while HFCs (R-134a, R-410A) have zero ODP.

Global Warming Potential (GWP)

Learn GWP as a measure of climate impact over 100 years. Compare R-22 (GWP 1810) vs. R-410A (GWP 2088) vs. R-454B (GWP 466).

Low-GWP Refrigerant Transition

Understand the shift to R-32, R-454B, and R-466A. Learn new handling requirements and compatibility with existing equipment.

A2L Refrigerants

Study mildly flammable A2L refrigerants. Understand safety requirements including charge limits, ventilation, and explosion-proof electrical equipment.

Practical Exercises

  • Identify refrigerant type from nameplate and R-number
  • Compare GWP values for common refrigerants using reference chart
  • Select appropriate refrigerant for given application
  • Explain ODP differences between R-22 and R-134a

Safety Checklist

  • Verify refrigerant type before connection
  • Check for proper recovery before service
  • Ensure adequate ventilation in work area
  • Wear chemical-resistant gloves
  • Store cylinders upright and secure
  • Never mix different refrigerant types

Refrigeration Cycle Analysis

2 hours

Analyze the vapor-compression refrigeration cycle using pressure-enthalpy charts. Calculate system efficiency, understand saturation points, and master superheat/subcooling diagnostics. Learn to identify common cycle failures including restricted metering devices and non-condensables.

Lessons

Vapor-Compression Cycle Overview

Study the four main components: compressor, condenser, metering device, and evaporator. Understand the phase changes and energy transfers in each.

Pressure-Enthalpy (P-H) Charts

Learn to read P-H diagrams for refrigeration cycles. Understand isobaric compression, isenthalpic expansion, and heat transfer processes.

Superheat Measurement

Calculate superheat: Superheat = Suction Line Temperature - Saturation Temperature. Understand proper measurement points and why superheat matters.

Subcooling Measurement

Calculate subcooling: Subcooling = Saturated Liquid Temperature - Liquid Line Temperature. Learn why adequate subcooling prevents flood-back.

Common Cycle Problems

Identify symptoms of overcharged, undercharged, non-condensing, and non-boiling conditions. Learn diagnostic procedures for each.

Practical Exercises

  • Calculate superheat for R-410A system (suction temp 65°F, head 120 psi)
  • Determine subcooling from liquid line temp and pressure
  • Plot cycle on P-H diagram from system data
  • Diagnose undercharged system symptoms
  • Check for non-condensables using temperature-pressure plot

Key Formulas

Superheat = Suction Temp - Saturation TempSubcooling = Sat Liquid Temp - Liquid Line TempCompression Ratio = Discharge Pressure / Suction Pressure

Refrigerant Recovery & Recycling

2 hours

Practice proper refrigerant recovery procedures using EPA-compliant equipment. Learn recycling vs. reclamation processes, cylinder storage requirements, and documentation procedures. Master leak detection techniques using electronic detectors, bubble solution, and ultrasonic tools.

Lessons

EPA Recovery Requirements

Understand when recovery is required (service, maintenance, disposal). Learn that 80% of refrigerant must be recovered before opening system.

Recovery Equipment Types

Compare recovery cylinders, recovery pumps, and catalytic destroyers. Understand UL-listed equipment requirements.

Recovery Procedures

Learn push-pull recovery method. Understand when to recover liquid vs. vapor. Know proper cylinder positioning.

Recycling vs. Reclamation

Understand that recycling cleans refrigerant on-site, while reclamation sends to special facility. Know equipment vs. service center distinction.

Leak Detection Methods

Study electronic leak detectors, UV dyes, and soap bubble solutions. Learn sensitivity levels and false positive avoidance.

Practical Exercises

  • Demonstrate proper recovery cylinder connection
  • Perform recovery on simulated system to 0.5 lb residual
  • Use electronic leak detector to find simulated leak
  • Check recovery equipment for proper operation
  • Document recovery amount and method

Safety Checklist

  • Verify recovery equipment is properly grounded
  • Check cylinder for damage before use
  • Ensure adequate ventilation during recovery
  • Monitor recovery pressure to prevent overfilling
  • Record recovered amount in service log
  • Inspect hoses for cracks or wear

Refrigeration System Components

2 hours

Study scroll, screw, and reciprocating compressors; air-cooled and water-cooled condensers; evaporative and DX evaporators; and various metering devices including TXV, piston, and electronic expansion valves. Understand capacity control methods and system sequencing.

Lessons

Compressor Types

Compare scroll (quiet, efficient), screw (high capacity), and reciprocating (robust, serviceable) compressors. Understand application suitability.

Air-Cooled Condensers

Study finned coil designs and fan control. Learn about airflow requirements and approach temperature.

Water-Cooled Condensers

Understand closed-loop cooling with cooling towers. Learn about water flow rates and heat rejection calculations.

Expansion Devices

Compare fixed orifice, TXV, and electronic expansion valves. Understand superheat control and capacity modulation.

Evaporator Types

Study finned coil, tube-fin, and shell-and-tube evaporators. Learn about airflow and refrigerant flow distribution.

Practical Exercises

  • Identify compressor type from cutaway view
  • Check condenser airflow and fan operation
  • Test TXV operation with superheat measurement
  • Inspect evaporator fins for restriction or damage
  • Measure approach temperature on water-cooled system

Required Tools

Manifold gauge set with R-410A adaptersThermometer with clamp-on probeFlashlight for component inspectionCleanable bore scope for internal inspectionPressure gauges with Schrader fitting accessInsulation penetration thermometer

Learning Objectives

  • Explain the phase-change refrigeration cycle and identify each component's function
  • Select appropriate refrigerant for a given application based on P-T charts and environmental regulations
  • Properly recover, recycle, and document refrigerant handling per EPA requirements
  • Diagnose common refrigeration cycle faults using pressure-temperature readings
  • Calculate and verify proper superheat and subcooling for optimal system performance
  • Replace and charge compressors and metering devices on operating systems

Previous Module

Module 1: Fundamentals

Next Module

Module 3: Installations

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