Installation and Maintenance Manual IMM AGSDP-1 Group: Chiller Part Number: 331375801 Date: March 2009 Supersedes: October 2008 Air-Cooled Screw Compressor Chillers AGS 226DP through AGS 501DP 60 Hertz R-134a
Table of Contents Introduction ....................................... 3 Solid State Starters...........................40 General Description................................... 3 Nomenclature ............................................ 3 Inspection .................................................. 3 Component Location .......................48 Installation and Start-up..................... 4 Handling .................................................... 4 Location......................................
Introduction General Description McQuay AGS-DP air-cooled water chillers are complete, self-contained, automatic refrigerating units that include the latest in engineered components, arranged to provide a compact and highly efficient unit. Each unit is completely assembled, factory wired, evacuated, charged, tested and comes complete and ready for installation. Each unit consists of multiple air-cooled condenser sections with an integral subcooler section.
Installation and Start-up Note: Installation and maintenance are to be performed only by qualified personnel who are familiar with local codes and regulations, and experienced with this type of equipment. WARNING Sharp edges and coil surfaces are a potential injury hazard. Avoid contact with them. Start-up by McQuay Factory Service is included on all units sold for installation within the USA and Canada and must be performed by them to initiate the standard limited product warranty.
Location Locate the unit to provide proper airflow to the condenser. (See Figure 2 on page 6 for required clearances). Due to the shape of the condenser coils on the AGS-DP chillers, it is desirable to orient the unit so that prevailing winds blow parallel to the unit length, thus minimizing the wind effect on condensing pressure and performance.
Clearance Requirements Figure 2, Clearance Requirements, AGS 226DP – 501DP 5’-0” if open fence or 50% open wall 6’-0” if solid wall (see note 3 for pit) 5’-0” if open fence or 50% open wall 6’-0” if solid wall (see note 3 for pit) See notes 2 & 4 concerning wall height at unit sides. No obstructions. Recommended area required for unit operation, air flow and maintenance access. 10’-0” min.
Restricted Airflow General The clearances required for design operation of AGS air-cooled condensers are described in the previous section. Occasionally, these clearances cannot be maintained due to site restrictions such as units being too close together or a fence or wall restricting airflow, or both. The McQuay AGS chillers have several features that can mitigate the problems attributable to restricted airflow.
Case 1, Building or Wall on One Side of One Unit The existence of a screening wall, or the wall of a building, in close proximity to an air-cooled chiller is common in both rooftop and ground level applications. Hot air recirculation on the coils adjoining the wall will increase compressor discharge pressure, decreasing capacity and increasing power consumption. When close to a wall, it is desirable to place chillers on the north or east side of them.
Case 2, Two Units Side By Side Two or more units sited side by side are common. If spaced closer than 12 feet (3.7 meters) it is necessary to adjust the performance of each unit; circuits adjoining each other are affected. If one of the two units also has a wall adjoining it, see Case 1. Add the two adjustment factors together and apply to the unit located between the wall and the other unit. Mounting units end to end will not necessitate adjusting performance.
Case 3, Three or More Units Side By Side When three or more units are side by side, the outside units (chillers 1 and 3 in this case) are influenced by the middle unit only on their inside circuits. Their adjustment factors will be the same as Case 2. All inside units (only chiller 2 in this case) are influenced on both sides and must be adjusted by the factors shown below. Figure 8, Three or More Units Chiller 1 Chiller 2 Chiller 3 Figure 9, Adjustment Factor 4.0 8.0 3.0 6.0 2.0 4.0 1.0 2.
Case 3, Open Screening Walls Decorative screening walls are often used to help conceal a unit either on grade or on a rooftop. These walls should be designed such that the combination of their open area and distance from the unit do not require performance adjustment. It is assumed that the wall height is equal to, or less than the unit height when mounted on its base support. This is usually satisfactory for concealment. If the wall height is greater than the unit height, see Case 4, Pit Installation.
Case 4, Pit/Solid Wall Installation Pit installations can cause operating problems and great care should be exercised if they are to be used on an installation. Recirculation and restriction can both occur. A solid wall surrounding a unit is substantially the same as a pit and the data presented in this case should be used. Steel grating is sometimes used to cover a pit to prevent accidental falls or trips into the pit.
Vibration Isolators Vibration isolators are recommended for all roof-mounted installations or wherever vibration transmission is a consideration. The following section "Lifting and Mounting Weights" contains the location of unit lifting holes and the load at each location. Mounting holes dimensions and the bearing weight at each hole are also given. Isolator Installation Transfer the unit as indicated under “Moving the Unit.” In all cases, set the unit in place and level with a spirit level.
Table 2, AGS 351DP–501DP, Spring Isolator Locations and Kit Numbers, Aluminum Fins Model AGS 351DP AGS 391DP AGS 401DP AGS 451DP MOUNTING LOCATION, SEE FOOTPRINT DRAWINGS FIGURE 18, FIGURE 19 M1 M2 M3 M4 M5 M6 1D-3600 1D-3600 1D-3600 1D-3600 1D-3600 Green Green Green Green Green Green 1D-3600 1D-3600 1D-3600 1D-3600 1D-4800 1D-3600 Green Green Green Green Gray Green 1D-3600 1D-3600 1D-3600 1D-4800 1D-4800 1D-3600 Green Green Green Gray Gray Green 1D-3600 1D-3600 1D-360
Table 4, AGS 351DP–501DP, Spring Isolator Locations and Kit Numbers, Copper Fins MOUNTING LOCATION, SEE FOOTPRINT DRAWINGS FIGURE 18, FIGURE 19 M1 M2 M3 M4 M5 M6 Model AGS 351DP AGS 391DP 1D-3600 1D-3600 1D-3600 1D-3600 1D-3600 3600 Green Green Green Green Green Green 1D-3600 1D-3600 1D-3600 1D-3600 1D-4800 1D-3600 Green Green Green Green Gray Green 1D-3600 1D-3600 1D-4800 1D-4800 1D-3600 Green Green Gray Gray Green AGS 401DP AGS 451DP 1D-3600 AGS 501DP Green Model AGS
Lifting and Mounting Weights Figure 16, AGS 226DP – AGS 251DP Lifting and Mounting Locations AGS226 AGS251 AGS226 AGS251 AGS226 AGS251 Figure 17, AGS 276DP - AGS 301DP Lifting and Mounting Locations 88.0 (2235.2) 2 (51) Typical Spacing for Isolator Mounting (8) Table 7, AGS 226DP - AGS 301DP Lifting and Mounting Weights (Aluminum Fin) AGS Model 226DP 251DP 276DP 301DP Lbs. (kg) Lbs. (kg) Lbs. (kg) Lbs.
Table 8, AGS 226DP - AGS 301DP Lifting and Mounting Weights (Copper Fin) Lifting Weight for Each Point lb (kg) L1 L2 L3 L4 L5 L6 AGS Model 226DP 251DP 276DP 301DP Lbs. (kg) Lbs. (kg) Lbs. (kg) Lbs.
Table 9, AGS 351DP- AGS 501DP Lifting Weights (Aluminum Fin) AGS Model lbs (kg) lbs (kg) lbs (kg) lbs (kg) lbs (kg) 351DP 391DP 401DP 451Dp 501DP Lifting Weight for Each Point lb.
Chilled Water Pump It is required that the starter(s) for the chilled water pump be wired to and controlled by the chiller's microprocessor. The controller will energize the pump whenever at least one circuit on the chiller is enabled to run, whether there is a call for cooling or not. The pump will also be energized when the controller senses a near-freezing temperature at the chiller outlet sensor to assist in freeze protection. Connection points are shown in Figure 27 on page 39.
8. If the unit is used as a replacement chiller on a previously existing piping system, flush the system thoroughly prior to unit installation. Then regular chilled water analysis and chemical water treatment is recommended at equipment start-up. 9. In the event glycol is added to the water system as a late addition for freeze protection, recognize that the refrigerant suction pressure will be lower, cooling performance less, and water side pressure drop greater.
1. A power failure will prevent pumpdown and there is a potential for freezing outdoor equipment in systems using 100 percent water as the chilled fluid. 2. Unit shutdown due to a fault will cause immediate compressor shutdown without the pumpdown cycle. This situation can be remedied by correcting the fault, restarting the unit, and allowing it to go through its normal shutdown pumpdown. NOTE: The evaporator heaters come from the factory connected to the control power circuit.
1. 2. These figures are examples only and cannot be appropriate to every situation. Generally, for an extended margin of protection, select a temperature at least 10°F lower than the expected lowest ambient temperature. Inhibitor levels should be adjusted for solutions less than 25% glycol. Glycol of less than 25% concentration is not recommended because of the potential for bacterial growth and subsequent loss of heat transfer efficiency, or add inhibitors.
Figure 20, Flow Switch Flow direction marked on switch 1" (25mm) NPT flow switch connection Tee 1 1/4" (32mm) pipe dia. min. before switch 1 1/4" (32mm) pipe dia. min. after switch Figure 21, Typical Field Water Piping Vent In Flow Switch Out Gate Valve Drain Valved Pressure Gauge Vibration Eliminator Water Strainer Vibration Eliminator Balancing Valve Protect All Field Piping Against Freezing Gate Valve Notes: 1.
1. Capacity - Cooling capacity is reduced from that with plain water. To find the reduced value, multiply the chiller’s water system tonnage by the capacity (Cap) correction factor to find the chiller’s capacity when using glycol. 2. Flow - To determine flow (or delta-T) knowing delta-T (or flow) and capacity: GPM = (24 ) (tons ) ( flow factor ) Delta − T (Water only, use Flow correction for glycols) 3.
Figure 22, Evaporator Pressure Drop, AGS 226DP - AGS 501DP Minimum/Nominal/Maximum Flow Rates AGS Unit Size IMM AGS-DP-1 Minimum Flow Flow ∆P gpm ft. Nominal Flow Flow ∆P gpm ft. Maximum Flow gpm ∆P ft 37.0 226DP 331 6.0 529 14.3 882 251DP 366 7.1 585 17.0 976 43.0 276DP 406 4.0 649 9.5 1082 26.5 301DP 454 4.8 727 12.2 1211 33.3 351DP 510 4.6 816 11.4 1360 30.0 391DP 576 5.0 922 12.6 1537 34.0 401DP 613 6.2 981 15.4 1635 40.0 451DP 661 7.0 1057 17.
Physical Data Table 17, Physical Data, AGS 226DP – AGS 27DP DATA 226DP Ckt 1 Ckt 2 AGS MODEL NUMBER 251DP Ckt 1 Ckt 2 BASIC DATA Unit Cap. @ ARI Conditions, tons 220.5 (774) 243.9 (856) (kW) Unit Operating Charge lbs (kg) 298 (135) 298 (135) 298 (135) 321 (145) Cabinet Dimensions 278 x 88 x 100 317 x 88 x 100 L x W x H, in. (mm) (7087 x 2235 x 2550) (8052 x 2235 x 2550) Unit Operating Weight (1), lbs.
Table 19, Physical Data, AGS 351Dp – AGS 401DP DATA Ckt. 1 351DP Ckt. 2 Ckt. 3 AGS MODEL NUMBER 391DP Ckt. 1 Ckt. 2 Ckt. 3 Ckt. 1 401DP Ckt. 2 Ckt. 3 BASIC DATA Unit Cap. @ ARI, tons (kW) Unit Operating Charge, lbs (kg) 340.1 (1196) 384.3 (1349) 408.8 (1435) 285 (129) 312 (141) 312 (141) 312 (141) 312 (141) 312 (141) 335 (152) 335 (152) 335 (152) 434 x 88 x 100 510 x 88 x 100 548 x 88 x 100 Cabinet Dim., L x W x H, in.
Dimensional Data Figure 23, Dimensions, AGS 226DP – AGS 301DP Note: 1. 2. See page 16 for lifting locations, mounting locations, weights and mounting loads. Allow one-inch manufacturing tolerance. 5.5 (139.7) SINGLE POINT POWER ENTRY "D" INLET SINGLE POINT POWER BOX OPTION POWER ENTRY POINT 0.875 (22.2) KNOCK-OUT FIELD CONTROL CONNECTION CONTROL PANEL CIRCUIT #1 51.1 (1297.9) 36.9 (937.3) CONTROL PANEL CIRCUIT #2 OUTLET E POWER ENTRY POINT 0.875 (22.
Figure 24, Dimensions, AGS 351DP –501DP Note: 1. 2. See page 17 for lifting locations, mounting locations, weights and mounting loads. Allow one-inch manufacturing tolerance. SINGLE POINT POWER ENTRY "D" INLET POWER ENTRY POINT FIELD CONTROL CONNECTION 5.5 (139.7) SINGLE POINT POWER BOX OPTION 0.875 (22.2) KNOCK-OUT CONTROL PANEL CIRCUIT #1 51.1 (1297.9) 36.9 (937.2) CONTROL PANEL CONTROL PANEL CIRCUIT #3 CIRCUIT #2 OUTLET POWER ENTRY POINT 0.875 (22.2) KNOCK-OUT POWER ENTRY POINT 0.875 (22.
Wind Baffles and Hail Guards Wind Baffles/Hail Guards are a field installed option that are used to stabilize unit operation in high wind areas and to assist in operation at low ambient temperatures. Figure 25 shows a typical panel assembly on an AGS unit. The actual number of panels and parts will vary by model size. The parts are shown in the table below and referenced by balloon numbers. The baffles extend out 20 inches from each side.
Table 21, Packing List Description Vertical Support Rib Top Cover Front Panel ¼ - 20 x ½” Screw (Place in Poly Bag) Part Number 074758501 330409401 330409501 046093807 Bubble Number 1 2 3 Figure 26, Components TOP REAR (AGAINST UNIT) VERTICAL SUPPORT RIB TOP COVER FRONT PANEL Top Panel, Install Last Overlap the Front panel Front Panel, Install Second Rib, Install First IMM AGS-DP-1 31
BAS/McQuay Remote Panel Interface BAS Interface Connection to the chiller for all building automation systems (BAS) protocols is at the unit controller. An optional interface module, depending on the protocol being used, may have been factory-installed in the unit controller (or it can be field installed).
Electrical Data Field Wiring General Wiring must comply with all applicable codes and ordinances. Damage to the equipment caused by wiring not complying with specifications is not covered under warranty. An open fuse or circuit breaker indicates a short, ground, or overload. Before replacing a fuse or restarting a compressor or fan motor, the trouble must be found and corrected. Copper wire is required for all power lead terminations at the unit and copper must be used for all other wiring to the unit.
Table 22, AGS 226DP – AGS 501DP, Electrical Data, Optional Single-Point AGS UNIT SIZE 226DP 251DP 276DP 301DP 351DP 391DP 401DP 451DP 501DP VOLTS 460 575 460 575 460 575 460 575 460 575 460 575 460 575 460 575 460 575 HZ POWER SUPPLY MINIMUM CIRCUIT AMPACITY (MCA) QTY 475 418 519 447 555 471 611 516 688 605 768 658 804 683 860 728 885 748 6 6 6 6 6 6 6 6 12 12 12 12 12 12 12 12 12 12 60 60 60 60 60 60 60 60 60 FIELD WIRE WIRE GAUGE 250 4/0 300 4/0 300 250 350 300 4/0 3/0 250 4/0 250 4/0 300 4/0 30
Table 24, AGS 340B–AGS 475B, Electrical Data, Standard Multiple-Point, Circuits # 1 & 2 AGS UNIT SIZE 351DP 391DP 401DP 451DP 501DP ELECTRICAL CIRCUIT 1 (COMP 1) ELECTRICAL CIRCUIT 2 (COMP 2) FIELD FIELD POWER SUPPLY POWER SUPPLY FUSING FUSING MIN.
Table 25, AGS 226DP–AGS 475B, Compressor and Condenser Fan Motor Amp Draw AGS UNIT SIZE 226DP 251DP 276DP 301DP 351DP 391DP 401DP 451DP 501DP RATED LOAD AMPS VOLTS 460 575 460 575 460 575 460 575 460 575 460 575 460 575 460 575 460 575 HZ 60 60 60 60 60 60 60 60 60 NO OF FAN CIRCUIT CIRCUIT CIRCUIT MOTORS #1 #2 #3 195 171 195 171 225 190 250 210 195 171 195 171 225 190 225 190 250 210 195 171 225 190 225 190 250 210 195 171 225 190 225 190 250 210 250 210 195 171 225 190 225 190 250 210 250 210 12 1
Table 27, AGS 226DP–AGS 475B, Wiring Information with Multiple-Point AGS UNIT SIZE 226DP 251DP 276DP 301DP 351DP 391DP 401DP 451DP 501DP VOLTS HZ 460 575 460 575 460 575 460 575 460 575 460 575 460 575 460 575 460 575 TERMINAL SIZE (AMPS) CKT 1 CKT 2 CKT 3 WIRING TO UNIT POWER BLOCK CONNECTOR WIRE RANGE PER PHASE (COPPER WIRE ONLY) CKT 1 CKT 2 CKT 3 60 400 400 -- #6-350 #6-350 -- 60 400 400 -- #6-350 #6-350 -- 60 400 400 -- #6-350 #6-350 -- 60 400 400 -- #6-350 #6-350 -- 60
Electrical Data Notes 1. Allowable voltage limits Unit nameplate 460V/60Hz/3Ph: 414V to 506V Unit nameplate 575V/60Hz/3Ph: 518V to 632V 2. Unit wire size ampacity (MCA) is equal to 125% of the largest compressor-motor RLA plus 100% of RLA of all other loads in the circuit. 3. Single point power supply requires a single disconnect to supply electrical power to the unit. This power must be fused. 4. All field wiring to unit power block or optional nonfused disconnect switch must be copper. 5.
Field Wiring Diagram Figure 27, Typical Field Wiring Diagram, Circuit #1 Control Box Note: Field-wired control connections are made in the control panel for circuit 1 only. UNIT MAIN TERMINAL BLOCK DISCONNECT (BY OTHERS) GND LUG 3 PHASE TO COMPRESSOR(S) AND FAN MOTORS POWER SUPPLY FUSED CONTROL CIRCUIT TRANSFORMER 120 VAC NOTE: ALL FIELD WIRING TO BE TB1 (115 VAC) INSTALLED AS NEC CLASS 1 TB1-2 WIRING SYSTEM WITH CONDUCTOR 1 RATED 600 VOLTS 120 VAC 82 CHW PUMP RELAY #1 (BY OTHERS) 120 VAC 1.
Solid State Starters Solid state starters are standard on all AGS units. A solid state starter uses a silicon-controlled rectifier (SCR) power section to allow a motor to be brought to full speed with a reduced initial voltage that increases to full line voltage over a given time. The McQuay motor starter, custom designed for this specific application, is microprocessor controlled. Along with this starting technique, the motor starter also provides protection for the motor and monitors its load conditions.
OL OL will alternately blink with the normal display on the LED display when motor thermal overload content has reached 90% to 99% of its capacity. OLL The motor thermal overload content has reached 100%, and the motor has stopped. The motor cannot be restarted until the overloaded motor has cooled and OLt is displayed. OLt The motor thermal overload content has been reduced to 60% or less, and the motor can be restarted. ena Passcode protection is enabled. dis Passcode is disabled.
Number Description Controlled Stop Auto Reset 37 Current Imbalance Y Y 38 Ground Fault Y N 39 No Current At Run N Y 40 Shorted/Open SCR N N 41 Current While Stopped N N 47 Stack Protection Fault N Y 48 Bypass Contactor Fault (on STOP input) Y N 50 Control Power Low N Y 51 Current Sensor Offset Error -- N 52 Burden Switch Error N N 60 Thermistor Trip N N 61 Stack OT Switch Trip N N 71 Analog Input Trip Y Y 82 Modbus Time-out Y Y 94 CPU Error – Soft
Figure 28, Trouble Shooting Guide Start 3 Yes Low or Missing Line? No 4 1 No Fuses OK? Yes Replace Fuses No Yes Phase Order Fault No 2 Circuit Breaker OK? 5 Swap Any 2 Power Leads Yes Thermal Trip? Yes No 6 Replace Circuit Breaker Yes No In-Line OK? Interlock Open? No Yes 7 Correct Inline Fault Correct Power Source Problem 8 No No High Ambient? Wiring OK? Yes Yes 9 Replace Control Card Correct and Wait to Cool Yes Bad Air Circulation? No Correct Interlock State No Return T
From Previous Page 11 Current Imbalance Fault? No Yes 7 No Fuses Blown or Breaker Tripped? Wiring Good? Yes Yes 12 Motor Winding Short? Correct Wiring No Yes Replace Fuse or Reset Breaker No 13 No 12 No SCRs OK? Motor Problem? Yes Replace Defective SCRs 14 All Gate Pulses Present? Yes 15 Yes CT Burden Switches Set Correctly? Repair or Replace Motor No Replace Control Card Return to Normal Operation No Yes Contact Benshaw For Assistance Replace Control Card No Check Jumpers P
FLOW CHART DETAILS: 1. Fuses Determine if power line fuses have been installed, and if they are operating properly. 2. Circuit Breaker Determine if the circuit breaker is off, or has tripped and disconnected the line from the starter. 3. Power Line Voltage Verify that line voltage is present, and is the correct voltage. 4. Phase Order Fault If Fault Codes F1 or F2 are displayed on the control card LED display, exchange any two incoming power line cable connections. 5.
Table 30, Solid State Starter Settings No. P1 P2 P3 P4 P5 P6 P7 P8 Operating Parameter Motor Full Load Amps (FLA) Note 1 Motor Rated Load Amps (RLA) Note 2 Motor Service Factor Motor Overload cless Initial Motor Current Maximum Motor Current Ramp Time UTS Time Default 1A 1A 1.08 10 100 600 15 30 P9 Stop Mode CoS P10 P11 P12 P13 P14 P15 Decel Begin Level Decel End Level Decel Time Default Meter Display0 Overcurrent Trip level Overcurrent Trip Delay Time 40 20 15 0 to 19 Off 2.
Operation LED Display • View parameters, messages and faults • Shows software version on power-up Programming • • • • Press PARAM to enter the menu and then UP or DOWN to reach the desired parameter. Press ENTER to show the present value of the parameter. Press UP or Down to change the value of the parameter. Press ENTER to store the new value or PARAM to abandon the change. Quick Meters • • • Press DOWN to display the motor thermal overload content. Press UP to display the incoming line phase order.
Component Location Major Component Location Figure 29, Two-Compressor Unit Cutaway Control/Power Panel Circuit #1 Condenser Section Circuit #2 Two-Circuit Flooded Evaporator Compressor #1 Compressor #2 Control/Power Panel Circuit #2 Oil Separator #1 48 IMM AGS-DP-1
Figure 30, Piping Schematic AIR FLOW S02 S05 CHECK VALVE CHARGING VALVE SCHRADER VALVE RELIEF VALVE DISCHARGE TUBING SCHRADER (EACH DISCH HEADER) OIL SEPARATOR DISCHARGE TUBING ANGLE VALVE OIL FILTER SIGHT GLASS SIGHT GLASS CONDENSER ASSEMBLY CONDENSER ASSEMBLY AIR FLOW AIR FLOW S01 S04 S07 RELIEF VALVE (EVAP SHELL) TO REAR OF COMPRESSOR SUCTION AIR FLOW BUTTERFLY VALVE (OPTION) CHARGING VALVE SOLENOID VALVE LIQUID SHUT-OFF VALVE WATER OUT FILTER DRIER OIL RETURN SCHRADER S09 S08 SC
Power Panel Each compressor and its associated refrigerant circuit and controlled devices have a dedicated power and control system. They are contained in a duplex panel, the outer box containing the MicroTech II microprocessor with related accessories and the inner box containing the power components including the starter.
Control Panel The control panel for Circuit #1 is shown below. The panel for circuit #2 and #3 is similar but does not contain the Unit Controller. Distributed control architecture enhances unit reliability. Each compressor circuit has its own microprocessor controller so that if one controller is inoperative, the other compressor(s) will be allowed to run. EWHR, Evaporator Heater Relay T4, Load/ Unload Solenoid Transformer T3, Control Transformer MHPR, Mech.
Optional Features There are a number of options that may or may not be present on any specific unit. These options can affect unit control operation and how a unit is installed and wired. Controls Ice Storage The unit is equipped with control logic to handle the low temperatures associated with thermal storage applications. Additional evaporator insulation is recommended.
High- Short Circuit Current Protection The control panels and single point connection box (if ordered) will have the high short circuit current rating as shown below. A high interrupt circuit breaker is included. 115 Volt Convenience Outlet A 10.0 amp, 115-volt convenience outlet mounted inside the control panel is available as an option on all units. The outlet is located in the #2 circuit control box.
Start-up and Shutdown NOTICE McQuayService personnel or factory authorized service agency must perform initial start-up in order to activate warranty. CAUTION Most relays and terminals in the unit control center are powered when S1 is closed and the control circuit disconnect is on. Therefore, do not close S1 until ready for start-up or the unit may start unintentionally. Switches There is a single unit on-off switch, S1, located in the control box for circuit #1.
CAUTION The unit has a one-time pumpdown operation. When the CS switches are in the Off position the unit will pump down once and not run again until the switches are moved to the On position. If the CS switches are in the On position and the load has been satisfied, the unit will do a one-time pumpdown and will remain off until the MicroTech II control senses a call for cooling and starts the circuit.
Start-up After Extended (Seasonal) Shutdown 1. With all electrical disconnects locked and tagged open, check all screw or lug-type electrical connections to be sure they are tight for good electrical contact. 2. Check the voltage of the unit power supply and see that it is within the ±10% tolerance that is allowed. Voltage unbalance between phases must be within ±2%. 3. See that all auxiliary control equipment is operative and that an adequate cooling load is available for start-up. 4.
System Maintenance General On initial start-up and periodically during operation, it will be necessary to perform certain routine service checks. Among these are checking the liquid line sight glasses, evaporator sight glasses, and oil separator sight glasses, plus taking a full set of refrigerant pressure and temperature readings. Through the MicroTech II keypad, check to see that the unit has normal superheat and subcooling readings.
Electrical Terminals DANGER Electric shock hazard and risk of personal injury or death exists. Turn off all power before continuing with following service. Periodically check electrical terminals for tightness and tighten as required. Condensers The condensers are air-cooled and constructed of 3/8" (9.5mm) OD internally finned copper tubes bonded in a staggered pattern into louvered aluminum (standard material) fins.
NOTE: Exceeding normal charge can result in abnormally high discharge pressure and relief valve discharge, or cause low discharge superheat resulting in oil loss into the system. An element inside the sight glass indicates the moisture condition corresponding to a given element color. The color code is printed on the edge of the sight glass. If the sight glass does not indicate a dry condition after about 12 hours of operation, the circuit should be pumped down and the filter-drier changed.
Preventative Maintenance Schedule PREVENTATIVE MAINTENANCE SCHEDULE OPERATION General Complete unit log and review (Note 3) Visually inspect unit for loose or damaged components and visible leaks Inspect thermal insulation for integrity Clean and paint as required WEEKLY Condenser (air-cooled) Clean condenser coils (Note 4) Check fan blades for tightness on shaft (Note 5) Check fans for loose rivets and cracks, check motor brackets Check coil fins for damage and straighten as necessary ANNUAL (Note 2) X
Service CAUTION 1. Service on this equipment is to be performed by qualified refrigeration personnel familiar with equipment operation, maintenance, correct servicing procedures, and the safety hazards inherent in this work. Causes for repeated tripping of equipment protection controls must be investigated and corrected. 2. Anyone servicing this equipment must comply with the requirements set forth by the EPA regarding refrigerant reclamation and venting.
1. On the circuit controller, under the "SET EXV SPs (2)", change the "Service Pumpdown" set point from "No" to "Yes". 2. If the circuit status is "Off:PumpDwnSw", move the circuit pumpdown switch from "Pumpdown and Stop" to "Auto". Also clear the anticycle timers through the MicroTech keypad. 3. Move the circuit switch to the OFF position. The compressor will unload to minimum slide position and the unit will pump down. 4.
Evaporator The evaporator is a flooded, shell-and-tube type with water flowing through the tubes and refrigerant flowing up the shell over the tubes. The tubes are internally enhanced to provide extended surface and turbulent flow of water through the tubes. Normally no service work is required on the evaporator other than cleaning the water (tube) side in the event of improper water treatment or contamination.
Evaporator Oil Return Line: In some applications, the evaporator oil return line can cause low discharge superheat and some oil loss into the system. It may be necessary to reduce the flow through the evaporator oil return line by incrementally closing down the ball valve. This can help maintain oil in the oil separator and higher DSH, if it is overfeeding and dropping the DSH too much.
Summary: At 100% slide position, in Subcool control, the DSH should be as high as possible with suction pressure at a operable value based on water/glycol mixture. At 100% load, in Subcool control, the DSH and suction pressure need to be balanced. Example: Running circuit 1 at 100% slide target, with water only in the loop, set the low evaporator pressure unload to 28psi (32°sat.) and the low evaporator pressure hold to 30psi. Run the suction pressure at approximately 32psi at full load.
Charging Oil The oil separator is equipped with two sight glasses that are used to indicate oil quantity. Oil charge determination must be done at, or near, full load. It may be normal to see the oil below the bottom sight glass while running at part load conditions due to oil laying in the compressor casting at low refrigerant flows. However, oil trips at part load indicate low oil level.
Evaporator entering water temperature - This sensor is located on the evaporator water inlet connection and is used for monitoring purposes and return water temperature reset control. Evaporator pressure transducer circuit #1, 2 (and 3) - This sensor is located on the suction side of the compressor and is used to determine saturated suction refrigerant pressure and temperature. It also provides low pressure freeze protection.
Although the high pressure switch will close again at 200 psig (1379 kPa), the control circuit will remain locked out and it must be reset through the MicroTech II control. The control is mounted in the control panel. Compressor motor protection The compressors are supplied with two types of motor protection. Solid state electronic overloads mounted in the control box sense motor current to within 2% of the operating amps. The MUST TRIP amps are equal to 140% of unit nameplate compressor RLA.
Fan Stages with VFD Option The VFD option must always be enabled. The first two fans are controlled by the fan VFD. This leaves 6 stages of fan control available with 8 fan circuits, and 4 stages available on 6 fan circuits. Although fans 5/6 and 7/8 are controlled by one contactor each, more stages are created by using virtual stages.
When a stage down occurs, or the saturated temperature rises back within the Stage Down deadband, the Stage Down Error Accumulator is reset to zero. The accumulator is also held at zero after startup until either the outside ambient temperature is less than, or equal to 75°F (23.9°C), or the saturated condenser temperature is greater than the condenser target, less the active stage down deadband.
Controls, Settings and Functions Table 35, Controls DESCRIPTION Compressor Heaters Compressor FUNCTION To provide heat to drive off liquid refrigerant when compressor is off. SYMBOL HTR1-COMPR SETTING On, when compressor is off. RESET N/A LOCATION On the Compressor On the Loads compressor LOAD N/A N/A Unloads the compressor UNLOAD N/A N/A Evaporator Heaters Help prevent evaporator freeze-up HTR-EVAP 38oF (3.
Troubleshooting Chart Table 36, Troubleshooting PROBLEM Compressor will not run. POSSIBLE CAUSES POSSIBLE CORRECTIVE STEPS 1. 2. 3. 4. 5. 6. Main power switch open. Unit S1 system switch open. Circuit switch, CS in pumpdown position. Chilled water flow switch not closed. Circuit breakers open. Fuse blown or circuit breakers tripped. 1. 2. 3. 4. 5. 6. 7. 8. Unit phase voltage monitor not satisfied. Compressor overload tripped. 7. 8. Close switch. Check unit status on MicroTech II display.
Periodic Maintenance Log Date of inspection: Address: Facility/job name: City/State: Unit model number: Physical location of unit: Unit serial number: Service technical (name): Software identification: Operating hours: Compressor #1 Compressor #2 Compressor #3 Number of starts Compressor #1 Compressor #2 Compressor #3 Follow up service required: Yes No General Actions to be Taken Upper part of report completed: Yes No Fill in above Compressor operation: Yes 1.
All McQuay equipment is sold pursuant to McQuay’s Standard Terms and Conditions of Sale and Limited Product Warranty. Consult your local McQuay Representative for warranty details. Refer to form 933-430285Y-00-A (09/08). To find your local representative, go to www.mcquay.com This document contains the most current product information as of this printing. For the most up-to-date product information, please go to www.mcquay.com. 2006 McQuay International • www.mcquay.
