Commercial Refrigeration for Air Conditioning Technicians

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