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1 HVACR317 - Refrigeration Commercial Refrigeration Diagrams

1 HVACR317 - Refrigeration Commercial Refrigeration Diagrams

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  • Slide 1
  • 1 HVACR317 - Refrigeration Commercial Refrigeration Diagrams
  • Slide 2
  • 2 TIMER MOTOR 2 NONO HGS NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC DIAGRAM A 1 COMPRESSOR
  • Slide 3
  • 3 The first diagram represents a typical self- contained reach-in box. It is a low temp system using hot gas defrost. The compressor is CSIR. The LAC (Low Ambient Control) would be used if the condensing unit is installed outdoors. The Run cap is optional. The first diagram represents a typical self- contained reach-in box. It is a low temp system using hot gas defrost. The compressor is CSIR. The LAC (Low Ambient Control) would be used if the condensing unit is installed outdoors. The Run cap is optional.
  • Slide 4
  • 4 TIMER MOTOR 2 NONO HGS NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC POWER SWITCH CLOSED 2
  • Slide 5
  • 5 Like any system, fan, fan, and compressor will sequence in parallel. The start cap will provide the required torque to the start winding. Like any system, fan, fan, and compressor will sequence in parallel. The start cap will provide the required torque to the start winding.
  • Slide 6
  • 6 TIMER MOTOR 2 NONO HGS NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 3
  • Slide 7
  • 7 The BEMF energizes the relay and drops out the start cap. The system will cycle normally on the (Honeywell/White Rogers/Johnson Controls) remote bulb thermostat. The BEMF energizes the relay and drops out the start cap. The system will cycle normally on the (Honeywell/White Rogers/Johnson Controls) remote bulb thermostat.
  • Slide 8
  • 8 TIMER MOTOR 2 NONO HGS NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 4
  • Slide 9
  • 9 When the box temperature reaches 0 10 F (typical setting), the thermostat opens. EFM and TM continue to run.
  • Slide 10
  • 10 TIMER MOTOR 2 NONO HGS NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC
  • Slide 11
  • 11 TIMER MOTOR 2 NONO HGS NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 5
  • Slide 12
  • 12 When the timer switches to defrost, compressor stays on, and HGS energizes. The EFM is de-energized in defrost. When the timer switches to defrost, compressor stays on, and HGS energizes. The EFM is de-energized in defrost.
  • Slide 13
  • 13 HOT GAS DEFROST (PIPING) REMINDER.NORMAL OPERATION.. C MD CONDENSERCONDENSER EVAPORATOREVAPORATOR OFF
  • Slide 14
  • 14 C MD CONDENSERCONDENSER EVAPORATOREVAPORATOR EFM SHUTS OFF ON
  • Slide 15
  • 15 TIMER MOTOR 2 NONO DH NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 6 COMPRESSOR N 3 4 X DTT LIMIT
  • Slide 16
  • 16 This system is also low temp, but using electric defrost. This type of system has an evap fan delay sequence. It uses two DTT type controls. It also has the ability to disengage the timer out of defrost. STEP BY STEP SEQUENCE IS COMING UP This system is also low temp, but using electric defrost. This type of system has an evap fan delay sequence. It uses two DTT type controls. It also has the ability to disengage the timer out of defrost. STEP BY STEP SEQUENCE IS COMING UP
  • Slide 17
  • 17 TIMER MOTOR 2 NONO DH NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 7 COMPRESSOR N 3 4 X DTT LIMIT
  • Slide 18
  • 18 Just like the last system, fan, fan, compressor are running. The DTC timer is line-to-line, like the last system. A different type (or model) DTC is used. Notice the extra terminals on the timer. The device between 3 and X is a solenoid (more on that later). Just like the last system, fan, fan, compressor are running. The DTC timer is line-to-line, like the last system. A different type (or model) DTC is used. Notice the extra terminals on the timer. The device between 3 and X is a solenoid (more on that later).
  • Slide 19
  • 19 TIMER MOTOR 2 NONO DH NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 8 COMPRESSOR N 3 4 X DTT LIMIT
  • Slide 20
  • 20 The only path is through the heater and limit. All else is Off. The limit acts as a DTT (like the domestic units), but it has a higher temp (cut-out) rating than the domestic types. It is basically a high- temp safety. The actual DTT is the SPDT one just below the limit. The only path is through the heater and limit. All else is Off. The limit acts as a DTT (like the domestic units), but it has a higher temp (cut-out) rating than the domestic types. It is basically a high- temp safety. The actual DTT is the SPDT one just below the limit.
  • Slide 21
  • 21 TIMER MOTOR 2 NONO DH NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 9 COMPRESSOR N 3 4 X DTT LIMIT
  • Slide 22
  • 22 When the SPDT DTT senses that the evap coil is warm enough, it will switch up to the top circuit, completing a path to the clutch solenoid on the DTC. The solenoid will swap the contacts back into refrigeration mode (no waiting). When the SPDT DTT senses that the evap coil is warm enough, it will switch up to the top circuit, completing a path to the clutch solenoid on the DTC. The solenoid will swap the contacts back into refrigeration mode (no waiting).
  • Slide 23
  • 23 TIMER MOTOR 2 NONO DH NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 10 COMPRESSOR N 3 4 X DTT LIMIT
  • Slide 24
  • 24 The evap fan has not come on yet due to the warm evap coil. When the DTT cools back down, the switch will drop back in, and the evap fan will restart. The purpose of this control (and sequence) is to prevent a hot pull-down situation after each defrost cycle. The evap fan has not come on yet due to the warm evap coil. When the DTT cools back down, the switch will drop back in, and the evap fan will restart. The purpose of this control (and sequence) is to prevent a hot pull-down situation after each defrost cycle.
  • Slide 25
  • 25 HOT PULL DOWN EXAMPLE: PRESENTLY THE SYSTEM IS RUNNING NORMAL (R134a). THE SYSTEM PRESSURES WILL GENERALLY RUN 5 TO 20 PSIG C MD CONDENSERCONDENSER EVAPORATOREVAPORATOR 5 150
  • Slide 26
  • 26 WHEN THE SYSTEM GOES INTO DEFROST THE EVAP COIL HEATS UP AND THE PRESSURES ARE BASICALLY EQUALIZED OFF MD CONDENSERCONDENSER EVAPORATOREVAPORATOR 100 HEATERS ON
  • Slide 27
  • 27 WHEN DEFROST IS TERMINATED, THE EXTREME HEAT LOAD ON THE COIL COULD CAUSE AN OVERLOAD ON THE ELECTRICAL CIRCUIT AND TRIP A BREAKER. C MD CONDENSERCONDENSER EVAPORATOREVAPORATOR 50 170 DELAYING THE EFM IS ONE WAY TO KEEP THE PRESSURES DOWN AT INITIAL START UP TOO HIGH
  • Slide 28
  • 28 TIMER MOTOR 2 NONO DH NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 11 COMPRESSOR N 3 4 X DTT LIMIT
  • Slide 29
  • 29 TIMER MOTOR 2 NONO DH NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 11 COMPRESSOR N 3 4 X DTT LIMIT
  • Slide 30
  • 30 Like all (domestic or commercial) automatic defrost system,s this defrost circuit can be terminated by time and / or temperature. The main advantage of using this type of timer is that the refrigeration mode can be brought back instantly if the DTT duration exceeded a few minutes. Like all (domestic or commercial) automatic defrost system,s this defrost circuit can be terminated by time and / or temperature. The main advantage of using this type of timer is that the refrigeration mode can be brought back instantly if the DTT duration exceeded a few minutes.
  • Slide 31
  • 31 TIMER MOTOR 2 NONO DH NCNC EFM TS LPS HPS LAC CFM RC S 1 2 5 SC 12 COMPRESSOR N 3 4 X DTT LIMIT
  • Slide 32
  • 32 If the SPDT DTT should fail, the limit will provide a lockout condition if an overheating situation should occur.
  • Slide 33
  • 33 ELECTRIC DEFROST REMINDERSTHE ELEMENT IS EITHER ON OR BELOW THE EVAP COILDTT AND LIMIT ARE BOTH LOCATED ON EVAP COIL C MD CONDENSERCONDENSER EVAPORATOREVAPORATOR
  • Slide 34
  • 34 LPS CFM RC S 1 2 5 SC 13 COMPRESSOR EFM TM X 4 N
  • Slide 35
  • 35 This system is a medium temp application (EFM is line-to-line). The defrost cycle simply shuts down the compressor circuit (sometimes done in the late evening hours). A simple timer is used. The LP switch is used as a temperature control (not the best way to go, but it is common). This system is a medium temp application (EFM is line-to-line). The defrost cycle simply shuts down the compressor circuit (sometimes done in the late evening hours). A simple timer is used. The LP switch is used as a temperature control (not the best way to go, but it is common).
  • Slide 36
  • 36 LPS LAC CFM RC S 1 2 5 SC 14 COMPRESSOR EFM TM X 4 N
  • Slide 37
  • 37 Using an LP switch as a thermostat: Set the LP switch to its recommended settings (C.I. & C.O.). Attach gauges. Place a thermometer in the box and close the door. When the box reaches the desired temp (e.g., 35 F), set the C.O. of the LP switch to the low side pressure shown on the gauge. Using an LP switch as a thermostat: Set the LP switch to its recommended settings (C.I. & C.O.). Attach gauges. Place a thermometer in the box and close the door. When the box reaches the desired temp (e.g., 35 F), set the C.O. of the LP switch to the low side pressure shown on the gauge.
  • Slide 38
  • 38 LPS CFM RC S 1 2 5 SC 15 COMPRESSOR EFM R134A: 30 # DIFF. CI:50 psig CO: 20 psig
  • Slide 39
  • 39 High or medium temp system: Uses Off Cycle Defrost Off cycle defrost can be set up by adjusting the LP switch differential higher than normal. The 30 psig differential allows sufficient time for defrost. High or medium temp system: Uses Off Cycle Defrost Off cycle defrost can be set up by adjusting the LP switch differential higher than normal. The 30 psig differential allows sufficient time for defrost.