Heatcraft Refrigeration Products 25000102 Ventilation Requirements Indoor Units, Electrical

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Parallel Compressor Systems

Ventilation Requirements

Indoor Units

If compressors or condensing units are located in a machine room, adequate ventilation air must be provided to avoid an excessive temperature rise in the room. To allow for peak summer temperatures a 10°F temperature rise is recommended, although a 15°F rise might be acceptable.

With compressors with remote condensers, approximately 10% of the heat rejected is given off by the compressor casting and the discharge tubing. The correct formula for calculating the ventilation requirement of the Indoor Parallel unit is:

CFM = 10% of THR / hr

10° TD

The air intake should be positioned so that air passes over the units. All State, Local, and National codes should be followed.

Electrical

To insure the proper operation of equipment and reduce the possibility of interruption of refrigeration due to electrical power failure, the following precautions must be observed:

All electrical work must be done in accordance with the National Electrical Code and existing local codes

The power supply must be the same as specified on the unit data plate

An adequate power supply must be provided

Voltage fluctuations in excess of 10 percent must be corrected

Overload relays (Carrier compressors only) are selected in accordance with specified limits as determined by the motor-compressor manufacturer.They must not be changed in size or shorted-out

Control panels must be provided with a single phase, 60 Hertz supply. See the unit wiring diagram for the voltage requirement

Before starting up a parallel unit, insure that all fuses and motor-protective devices are in place and that all wiring is secure. A complete wiring diagram for troubleshooting the unit will be found inside the control panel cover

Refrigerant Piping

The system as supplied by Heatcraft, was thoroughly cleaned and dehydrated at the factory. Foreign matter may enter the system by way of the field piping required. Therefore, care must be used during installation of the piping to prevent introduction of foreign matter.

Install all refrigeration system components in accordance with all applicable local and national codes and in conformance with good practice required for the proper operation of the system.

Proper size refrigeration lines are essential to good refrigeration performance. Suction lines are more critical than liquid or

discharge lines. Oversized suction lines may prevent proper oil return to the compressor. Undersized lines can rob refrigeration capacity and increase operating cost. Consult the line sizing charts in this manual for proper pipe sizes.

The following procedures should be followed:

1.Do not leave dehydrated compressors or filter-driers open to the atmosphere

2.Use only refrigeration grade copper tubing, properly sealed against contamination

3.Suction lines should slope 1/4” per 10 feet towards the compressor

4.Discharge lines should slope 1/4” per 20 feet toward the condenser

Suction P-Traps

Provide P-Traps at the base of each suction riser of four (4) feet or more to enhance oil return to the compressor. Use a P-Trap for each 20 feet section of riser. See Figure 4 below:

Figure 4. P-Trap Requirements

*The P-Trap should be the same size as the horizontal line See Figure 5 below

Figure 5. P-Trap Construction

Parallel Compressor Systems Installation & Operations Manual, October 2004

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Contents Parallel Compressor Systems Table of Contents Model Definition IntroductionInspection Unit DesignationFloor & Foundation Requirements System WarrantyRigging Location Of Equipment Indoor ClearancesUnit Vibration Isolation Location of Equipment OutdoorGround Mounting Roof MountingUnits in Pits Unit AccessVertical Clearance Decorative FencesSuction P-Traps Ventilation Requirements Indoor UnitsElectrical Refrigerant PipingRefrigerant Line Support Refrigerant Line InsulationTable of Values for L Expansion LoopsRef. Line Amount of Expansion 20’ 25’ 30’ 40’ 50’ 75’ 100’ Pressure Loss of Liquid RefrigerantsEquivalent Feet of Pipe Liquid Line Rise in Feet Refrigerant 10’Suction Line at Suction Temperature Weight of Refrigerants in Copper Lines During OperationLine 40F 20F Recommended Line Sizes for R-404A/R-507 100’ 150’ 200’ 25’ Liquid Line SizeExpansion Valve LengthsSuction Line Size Recommended Line Sizes for R-22Capacity 40˚F 20˚F 10˚F 10˚F Liquid Line Size Suction TemperatureTotal Recommended Remote Condenser Line SizesNet 12 & R-134A 502 507 & R-404AEvacuation Leak Checking, Evacuation and Start-upStart-up Priority I Hot Gas Defrost Refrigerant DistributionOff-Cycle Electric DefrostEvaporator Superheat Electronic Control SystemSystem Balancing System SuperheatUnloader Factors CompressorsCopeland Compressors 4D/6D Solid State Modules Typical Voltage RangesCarlyle Compressors Oil Safety SwitchOil Charges Approved Copeland LubricantsPart Load Performance Multipliers Phase Voltage MonitorRequired Differential Pressure for Unloader Operation Sight Glass Safety Relief Devices Sight Glass & Moisture IndicatorDischarge Piping Table Henry Relief Valve Capacity RatingLevel Switch Table Auto Reset ModelsManual Reset Models Liquid Level SwitchOil Control Module ReplacementOil Separators Temprite Models Temprite Valve AdjustmentOil Level Regulators Sporlan Valve Co Troubleshooting Oil SystemAC&R Model Regulators Liquid Filter-Driers & Suction FiltersReplaceable Suction Filter CompressorMotorBurnoutCleanupProcedureSuction Filter Sporlan Valve CompanyType F Filter Type DF for cleanupType AFD for cleanup Superior Valve CompanyLiquid Drain Control Method Recommended Valve SettingsField Adjustment Hot Gas Bypass Regulator AdjustmentLow Pressure Switch Setting for Rmcc Control SettingsControl Settings for R-404A/R-507 Control Settings for R-22Quarterly General Maintenance ScheduleWeekly MonthlyUnit Short Symptom Cause Remedy CompressorTemperature Does Not RunLow Suction Symptom Cause Remedy LowSwitch Open High SuctionSystem Reference Data Service Record