Commercial Refrigeration for Air Conditioning Technicians

Description

Technicians trained on air conditioning systems are often required to apply their skills to the servicing of commercial refrigeration equipment. This book provides a solid foundation in comfort cooling that can be readily transferred to a broad understanding of medium and low temperature refrigeration equipment such as walk-ins, reach-ins, refrigerated cases, and ice machines. Coverage specific to refrigeration in the food service industry is emphasized, with scores of practical tips that technicians can use right away in the installation and service of commercial equipment. Helpful tips and sound advice from the experienced author and his employees add a personal touch to the comprehensive coverage, increasing interest in, and retention of, key concepts. This book will improve technicians' knowledge, efficiency, and effectiveness in commercial refrigeration and can serve as a permanent addition to the reference library in any truck or shop. Front Cover......Page 1 Title Page......Page 4 Copyright......Page 5 Contents......Page 6 Preface......Page 16 CHAPTER 1: Refrigeration......Page 24 The Refrigeration Cycle......Page 25 How Is Heat Absorbed into the Evaporator?......Page 26 Comparing Commercial Refrigeration with AC......Page 27 Newer Refrigerants in Commercial Refrigeration......Page 29 Evaporator......Page 30 Summary......Page 31 CHAPTER 2: Evaporators......Page 36 Temperature Difference......Page 37 Humidity and TD......Page 38 Reach-in TD and Humidity......Page 39 Using TROT for TD and Troubleshooting......Page 40 Heat Exchange Efficiency......Page 42 Types of Evaporators......Page 43 Measuring Superheat......Page 45 Flooding and Starving Evaporators......Page 46 Medium-Temperature Evaporator Air Defrost......Page 47 When to Defrost......Page 49 Defrost Operation of Freezers......Page 50 Summary......Page 60 CHAPTER 3: Condensers......Page 64 Condenser Operation......Page 65 Condensing Phase......Page 66 Using Subcooling to Prevent Flash Gas......Page 67 Condenser Split......Page 69 Cleaning and Maintaining Air-Cooled Condensers......Page 70 Coil Cleaners......Page 71 Low-Ambient Controls for Air-Cooled Condensers......Page 72 Fan Cycle Controls......Page 73 Condenser Flooding......Page 74 Troubleshooting HPR Valves......Page 76 Water-Cooled Condensers......Page 77 Water-Regulating Valves......Page 78 Cooling Towers......Page 79 Service and Maintenance of Water-Cooled Equipment......Page 80 Cleaning Water-Cooled Condensers......Page 82 Summary......Page 84 CHAPTER 4: Compressors......Page 90 How a Reciprocating Compressor Operates......Page 91 Hermetic Compressors......Page 93 Semihermetic Compressors......Page 94 Compressor Lubrication......Page 95 Compressor Problems and Failures......Page 96 Slugging......Page 99 Compressor Capacity Control......Page 102 Two-Stage Compound Systems......Page 109 Scroll Compressors......Page 113 Variable Frequency Drives......Page 115 Summary......Page 116 CHAPTER 5: Metering Devices......Page 122 Functions of a Metering Device......Page 123 What Is the Proper Superheat?......Page 125 How a TEV Operates......Page 127 TEV Body Styles......Page 128 Equalized Valves, Internal and External......Page 129 TEV Bulb Placement......Page 131 How the System Affects TEVs......Page 134 TEV Sizing......Page 135 Reading an Expansion Valve......Page 137 TEV Hunting......Page 138 Capillary Tube Metering Devices......Page 139 How a Cap Tube Works......Page 141 How Cap Tubes Respond to System Conditions......Page 143 Troubleshooting Cap Tubes......Page 144 Automatic Expansion Valves......Page 145 Electric Expansion Valves......Page 146 Summary......Page 150 CHAPTER 6: Controls and Accessories......Page 156 Temperature Controls......Page 157 Compressor Service Valves......Page 161 Solenoid Valves for Pump-down and Hot Gas Bypass......Page 164 Hot Gas Bypass Valves......Page 166 Crankcase Pressure Regulators......Page 167 Evaporator Pressure Regulators......Page 169 Low-Pressure Controls......Page 171 High-Pressure Controls......Page 173 Oil Separators......Page 174 Oil Safety Controls......Page 175 Receivers......Page 179 Filter Driers......Page 180 Sight Glass......Page 183 Heat Exchangers......Page 184 Summary......Page 185 CHAPTER 7: Refrigeration System Troubleshooting......Page 192 Review and Preview......Page 193 Compressor......Page 195 How Fixed Metering Devices React to System Conditions......Page 196 How a TEV System Reacts to System Conditions......Page 198 Summary of How External Temperature Changes Affect the Refrigeration System......Page 199 Superheat and Subcooling......Page 200 Diagnosing Nine System Problems......Page 201 How an Undercharge Affects a Reach-in with Cap Tube System......Page 203 How an Undercharge Affects a TEV System......Page 204 How an Overcharge Affects a Cap Tube System......Page 205 How an Overcharge Affects a TEV System......Page 206 Condenser Problems on a TEV System......Page 207 Noncondensables......Page 209 Inefficient Compressor......Page 211 Partially Restricted Capillary Tube......Page 213 Partially Restricted TEV......Page 214 Restriction in the High Side Before the Receiver......Page 215 Evaporator Problems on a Cap Tube System......Page 216 Evaporator Problems on a TEV System......Page 217 Using a Diagnostic Chart......Page 218 Evaporator Oil Logging......Page 221 Troubleshooting without Gauges......Page 222 Summary......Page 224 CHAPTER 8: Compressor Motor Controls......Page 234 Contactors......Page 235 Single-Phase Motors......Page 237 Start Relays and Capacitors......Page 238 Current Relays......Page 239 Start Capacitors......Page 240 Run Capacitor......Page 242 PTCR......Page 244 Types of Motor Overloads......Page 245 No Sound......Page 246 Motor Tries to Start......Page 247 Checking Start Relays......Page 249 Summary......Page 251 CHAPTER 9: Retrofitting, Recovery, Evacuation, and Charging......Page 258 Refrigerant Efficiencies......Page 259 Oil Replacement......Page 260 Retrofit Refrigerants......Page 261 Retrofitting Cap Tube Systems......Page 262 Refrigerant Recovery Procedures......Page 263 Push–Pull Liquid Recovery......Page 264 Liquid Recovery with a Tank in a Vacuum......Page 265 Recovery Cylinders......Page 266 System Evacuation......Page 267 Triple Evacuation......Page 268 Vacuum Pump and Micron Gauge Operation and Maintenance Tips......Page 270 Start-up and System Charging......Page 271 How to Know the Charge Is Correct......Page 272 Charging for Low-Ambient Conditions......Page 274 Summary......Page 280 CHAPTER 10: Supermarket Refrigeration......Page 286 Parallel Rack Systems......Page 287 Parallel Rack System Controls......Page 289 Rack System Controllers......Page 291 Energy Efficiency......Page 292 Coil Defrosting......Page 294 Mechanical Subcooling......Page 297 Display Case Airflow......Page 298 Installation, Service, and Maintenance......Page 299 Refrigerant Leak Detection......Page 300 New Technology......Page 301 Summary......Page 307 CHAPTER 11: Walk-in Refrigerators and Freezers......Page 310 Walk-in Box Types and Sizes......Page 311 Walk-in Box Installation......Page 312 Walk-in Door Types and Adjustments......Page 314 Walk-in Box Applications......Page 317 Matching System Components for Proper Operation......Page 318 Matching Compressor Horsepower to Btuh......Page 319 System Capacity Based on Condensing Unit and Evaporator Matching......Page 320 Special TEV sizing......Page 321 Production, or Pull-down, Boxes......Page 322 Refrigeration Piping......Page 324 Discharge Line Piping and Suction Line Double Risers......Page 327 Drain Piping......Page 330 Troubleshooting Walk-in Problems......Page 331 Evaporator Airflow Problems......Page 332 Drain Problems......Page 333 Freezer Defrost Problems......Page 334 Glass Door Sweating Problems......Page 335 Summary......Page 336 CHAPTER 12: Ice Machines......Page 340 Basic Ice Machine Operation......Page 341 Installation-Related Service......Page 343 Ice Machine Maintenance and Cleaning......Page 346 Ice Machine Warranties......Page 349 Troubleshooting a “No Ice” Service Call......Page 350 Troubleshooting a “Slow Ice” or “Not Enough Ice” Service Call......Page 351 Additional Troubleshooting Tips......Page 352 Summary......Page 353 CHAPTER 13: Product Temperatures for Preservation and Health......Page 356 Problem Areas and Solutions......Page 357 Hinges, Handles, and Gaskets......Page 359 Refrigeration Maintenance Program......Page 360 Interesting Temperature and Health Facts......Page 361 Summary......Page 362 CHAPTER 14: Refrigeration Business Tips......Page 366 Starting and Staying in Business......Page 367 Records and Paperwork......Page 368 Pricing and Costs......Page 369 Customers......Page 371 Employees......Page 372 Maintenance Contracts......Page 373 Technicians as Salesmen......Page 375 Summary......Page 376 Summary of TROT......Page 380 Pressure Temperature (P/T) Chart......Page 382 Troubleshooting Charts......Page 384 Glossary......Page 386 Index......Page 392