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Installation and Operation
Manual
Bulletin No. H-IM-PCS October 2004 Part Number 25000102
(Replaces H-IM-72B, October 2004)
Parallel
Compressor
Systems
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Installation and Operations Manual Table of Contents Introduction .............................................................................................................. 3 Table 14. Oil Safety Switch ..................................................................................... 22 Inspection Table 15. Part Load Performance Multipliers Unit Designation Table 16. Required Differential Pressure Model Definition Three-Phase Voltage Monitor System Warranty ............
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Parallel Compressor Systems Introduction Model Definition: Parallel Compressor systems are central refrigeration units 1st digit - Brand (B, C, H, or L) employing 2 to 8 parallel piped compressors, a control panel, 2nd digit - Compressor Type and receiver mounted on one common base frame. The system H - Hermetic may be designed for either Indoor or Outdoor use. The Outdoor R - Reciprocating design may include the condenser mounted and piped. S - Screw O - Open The selection and design
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Installation and Operations Manual means of cables at the four corners of the base. If cables are System Warranty used, the lifting cables should be prevented from contacting This equipment is designed to operate properly and produce any of the unit piping or electrical components. the rated capacity when installed in accordance with good refrigeration practice. Location Of Equipment - Indoor The following conditions should be adhered to when installing Clearances this unit to maintain the
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Parallel Compressor Systems absorbing spring mounts (optional equipment) must be placed Compressor Spring Vibration Isolators under the base frame of each unit. See Figure 1 for view of On units with this option, the compressors are secured rigidly Spring Isolator. The spring mounts are placed under the unit to make sure there is no transit damage. Before operating the and the unit carefully lowered on to the mounts. Note that no unit, it is necessary to follow these steps: other mounting
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Installation and Operations Manual Unit Access Always provide sufficient clearance for unit maintenance and service. Minimum clearances for most situations are described below (except 60 Inches of free space is required in front of the control panel). Please note that these are minimums and more clearance may be required by local codes. Vertical Clearance Overhead obstructions are not permitted. Vertical air discharge from the condenser must have no obstructions that can cause the discharg
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Parallel Compressor Systems discharge lines. Oversized suction lines may prevent proper oil Ventilation Requirements return to the compressor. Undersized lines can rob refrigeration Indoor Units capacity and increase operating cost. Consult the line sizing If compressors or condensing units are located in a machine charts in this manual for proper pipe sizes. room, adequate ventilation air must be provided to avoid The following procedures should be followed: an excessive temperature ri
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Installation and Operations Manual • In systems equipped with capacity control compressors, • When brazing refrigerant lines, an inert gas should or where multiple compressors are used with one or more be passed through the line at low pressure to prevent compressors cycled off for capacity control, double suction scaling and oxidation inside the tubing. Dry nitrogen is risers should be installed. See Figure 6 below. The two preferred. lines should be sized so that the total cross-section are
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Parallel Compressor Systems Expansion Loops In order to compensate for the expansion of the tubing, it Suction, liquid and remote condenser lines are subject to is necessary to estimate the amount of expansion and then expansion and contraction and proper piping techniques provide offsets or loops in the refrigerant piping. Normally the must be employed (especially on hot gas lines) to prevent line area to be most concerned with is the straight line distance breakage. This is critical on
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Installation and Operations Manual Table 2. Pressure Loss of Liquid Refrigerants (In Liquid Line Risers - Expressed in Pressure Drop, PSIG, and Subcooling Loss, °F) Liquid Line Rise in Feet 10’ 15’ 20’ 25’ 30’ 40’ 50’ 75’ 100’ Refrigerant PSIG °F PSIG °F PSIG °F PSIG °F PSIG °F PSIG °F PSIG °F PSIG °F PSIG °F R-12 5.4 2.8 8.1 4.2 10.7 5.4 13.4 6.9 16.1 8.3 21.5 11.3 26.9 14.3 40.3 22.4 53.7 31.0 R-22 4.8 1.6 7.3 2.3 9.7 3.1 12.1 3.8 14.5 4.7 19.4 6.2 24.2 8.0 36.3 12.1 48.4 16.5 R-502 4.9 1.5 7.
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Parallel Compressor Systems Table 4. Weight of Refrigerants in Copper Lines During Operation (Pounds per 100 Lineal Feet of Type “L” Tubing) Suction Line at Suction Temperature Line Size Liquid Hot Gas Refrigerant OD (in.) Line Line -40°F -20°F 0°F 20°F 40°F 12, 134A 4.0 .15 .01 .01 .02 .04 .06 3/8 22 3.9 .22 .02 .03 .04 .06 .08 R-507, 502, 404A 3.4 .31 .03 .04 .06 .09 .13 12, 134A 7.4 .30 .01 .03 .04 .07 .11 1/2 22 7.4 .41 .03 .05 .07 .11 .15 R-507, 502, 404A 6.4 .58 .04 .07 .13 .16 .24 12, 134
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Installation and Operations Manual Table 5A. Recommended Line Sizes for R-404A/R-507* Suction Line Size Suction Temperature System Capacity 20˚F 10˚F -10˚F -20˚F BTU/H Equivalent Lengths Equivalent Lengths Equivalent Lengths Equivalent 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 1,000 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 1/2 3/8 3/8 3/8 1/2 1/2 1/2 3/8 3/8 1/2 3,000 3/8 3/8 1/2 1/2 1/2 5/8 3/8 1/2 1/2 1/2 5/8 5/8 1/2 1/2 5/8 5/8 5/8 7/8 1/2
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Parallel Compressor Systems Table 5B. Recommended Line Sizes for R-404A/R-507 (continued)* Suction Line Size Liquid Line Size Suction Temperature Receiver to System Expansion Valve Capacity -20˚F -30˚F -40˚F Equivalent Lengths BTU/H Lengths Equivalent Lengths Equivalent Lengths 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 1/2 1/2 1/2 3/8 3/8 1/2 1/2 1/2 5/8 3/8 1/2 1/2 1/2 5/8 5/8 3/8 3/8 3/8 3/8 3/8 3/8 1,000 5/8 7/8 7/8 1/2 1/2 5/8 5/8 7/8 7
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Installation and Operations Manual Table 6A. Recommended Line Sizes for R-22* Suction Line Size Suction Temperature System Capacity 40˚F 20˚F 10˚F 0˚F BTU/H Equivalent Lengths Equivalent Lengths Equivalent Lengths Equivalent 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 1,000 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 1/2 3/8 3/8 3/8 3,000 3/8 3/8 3/8 1/2 1/2 1/2 3/8 1/2 1/2 1/2 5/8 5/8 3/8 1/2 1/2 1/2 5/8 5/8 1/2 1/2 1/2 4,
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Parallel Compressor Systems Table 6B. Recommended Line Sizes for R-22 (continued)* Suction Line Size Liquid Line Size Suction Temperature Receiver to System Expansion Valve Capacity 0˚F -10˚F -20˚F Equivalent Lengths BTU/H Lengths Equivalent Lengths Equivalent Lengths 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 25’ 50’ 75’ 100’ 150’ 200’ 3/8 1/2 1/2 3/8 3/8 3/8 3/8 1/2 1/2 3/8 3/8 3/8 1/2 1/2 1/2 3/8 3/8 3/8 3/8 3/8 3/8 1,000 5/8 5/8 5/8 1/2 1/2 1/2 5/8 5/8 5/8 1/2 1/2
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Installation and Operations Manual Table 7. Recommended Remote Condenser Line Sizes R-12 & R-134A R-22 R-502 R-507 & R-404A Liquid Line Liquid Line Liquid Line Liquid Line Net Total Discharge Discharge Discharge Discharge Cond. to Cond. to Cond. to Cond. to Evap. Equiv. Line Line Line Line Receiver Receiver Receiver Receiver Capacity Length (OD) (OD) (OD) (OD) (OD) (OD) (OD) (OD) 50 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3/8 3,000 100 1/2 3/8 3/8 3/8 3/8 3/8 3/8 3/8 50 1/2 3/8 3/8 3/8 3/8 3/8 1/2 3/8 6,000
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Parallel Compressor Systems Leak Checking, Evacuation and Start-up Warning: It is illegal to knowingly vent or discharge 4. With all compressor and control breakers and toggle any CFC’s and HCFC’s to the atmosphere. switches turned off, apply power to the unit. If the unit is ALL CFC’s and HCFC’s must be reclaimed using a phase monitor, the green light must come on before or recycled. going any further. (See instructions for phase protector elsewhere in this manual.) A red light indicates
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Installation and Operations Manual Refrigerant Distribution The distribution system is selected based upon the type of discharge gas will condense into liquid as it flows through the defrost for that particular system. For each set of liquid/suction cold evaporator. lines a distribution system must be selected. The liquid exits the coil at the distributor side-port, then flows Liquid solenoids are recommended to be installed at the through the liquid line by pass check valve into the drain
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Parallel Compressor Systems Electronic Control System The electronic controller has become the standard on Also, as the superheat increases, the suction pressure decreases resulting in reduced capacity. For maximum system capacity, parallel compressor systems. The increased capabilities of the controllers magnify the efficiency of the parallel compressor suction superheat should be kept as low as is practical. Heatcraft recommends that the superheat at the compressor be no lower system maki
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Installation and Operations Manual Compressors The majority of the Heatcraft Parallel systems incorporate the Many compressors are available with unloading for capacity Copeland compressor. Other brand compressors are available control. The unloading of a compressor adds many capacity upon customer request. The compressors are solid mounted steps to those normally available to an electronic controller. to a base frame or mounted on the refrigerant receiver. All Usually, the more steps availab
