Daikin Pathfinder AWV Series Installation, Operation And Maintenance Manual

Daikin Pathfinder AWV Series Installation, Operation And Maintenance Manual Manual pdf 15 page image

InsTallaTIon and applICaTIon ConsIderaTIonswww.DaikinApplied.com 15 IOM 1242-2 • PATHFINDER® MODEL AWV CHILLERS• Thermometers at the inlet and outlet connections of theevaporator.• Water pressure gauge connection taps and gauges atthe inlet and outlet connections of the evaporator formeasuring water pressure drop.• Shutoff valves to isolate the unit from the piping duringunit servicing.• Minimum bends and changes in elevation to minimizepressure drop.• An expansion tank and regulating valve to maintainadequate water pressure. Tank becomes requiredfor closed loop systems based on water volume andtemperature ranges.• Vibration eliminators in both the supply and return waterlines to reduce transmissions to the building.• Flushing the system water piping thoroughly beforemaking connections to the unit evaporator.• Piping insulation, including a vapor barrier, helps preventcondensation and reduces heat loss.• Regular water analysis and chemical water treatmentfor the evaporator loop is recommended immediately atequipment startup.WARNINGDaikin Applied recommends against the use of PVC andCPVC piping for chilled water systems. In the event the pipeis exposed to POE oil used in the refrigerant system, the pipecan be chemically damaged and pipe failure can occur.Inlet Strainer GuidelinesAn inlet water strainer kit must be installed in the chilled waterpiping within 5 feet of the evaporator inlet. Two paths areavailable to meet this requirement:1. A field-installed kit shipped loose with the unit is availablefor all unit sizes and consists of:• Y-type area strainer with 304 stainless steel perforatedbasket, Grooved pipe connections and strainer cap— a strainer with perforations no larger than 0.063”(1/16”, 1.6 mm) diameter for AWV models with abraze plate evaporator— a strainer with perforations no larger than 0.125”(1/8”, 3.2 mm) diameter for AWV models with a directexpansion evaporator• Extension pipe with two couplings that may be usedfor gauges and sensors. The pipe provides sufficientclearance from the evaporator for strainer basketremoval.• ½-inch blowdown valve• Two grooved clampsThe strainer is sized per Table 2 and has the pressure dropshown in the Strainer Pressure Drop graph. Connection sizesare given in the Pressure Drop Data section on page 39.2. A field-supplied strainer that meets specification andinstallation requirements of this manual.Table 2: Strainer Sizing DataStrainerSize (in.)Maximum Perforation Sizein. (mm)Strainer Weight(lbs)6 0.063” (1/16”, 1.6 mm) 12060.125” (1/8”, 3.2mm)1208 22010 514Figure 26: Strainer Pressure DropInstalling Inlet Strainer (Field-installed Kit)The extension pipe is located adjacent to the evaporator withthe strainer then mounted to it. The strainer must be mountedper manufacturer’s instruction with the arrows in the directionof flow; inlet and outlet are noted along with the arrows.Use one grooved clamp to mount the extension pipe to theevaporator and the second to mount the strainer to the pipe.The clamps to mount the field piping to the strainer are fieldsupplied. The piping and strainer must be supported to preventany stress on the evaporator nozzle.System Water VolumeAll chilled water systems need adequate time to recognize aload change, respond to that load change and stabilize, withoutundesirable short cycling of the compressors or loss of control.In air conditioning systems, the potential for short cyclingusually exists when the building load falls below the minimumchiller plant capacity or on close-coupled systems with verysmall water volumes. Some of the things the designer shouldconsider when looking at water volume are the minimumcooling load, the minimum chiller plant capacity during the lowload period and the desired cycle time for the compressors.Assuming that there are no sudden load changes and thatthe chiller plant has reasonable turndown, a rule of thumb of“gallons of water volume equal to two to three times the chilledwater gpm flow rate” is often used. A storage tank may haveto be added to the system to reach the recommended system