Model YCUL Air-Cooled Scroll Compressor ... - Usair-eng.com

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Selection DataThe ratings shown on pages 14 through 25 are basedon unit operation in a well designed and properly pipedsystem.SELECTION RULES1. Capabilities are based on Refrigerant R-410A.2. Ratings may interpolated, but must not be extrapolated.3. Ratings shown are at saturated suction temperaturescorresponding to pressures at the compressor. Inactual practice, suction line pressure drop has theeffect of reducing compressor capacity, forcing thecompressor to operate at a lower suction pressureto maintain the desired evaporator temperature.For normal air conditioning applications, size the suctionline for a pressure drop of 3 PSI (0.2 bar), corresponding to2°F (1.1°C), for R-410A refrigerant. Thus, the evaporatortemperature will be approximately 2°F (1.1°C) higher thanthe compressor suction temperature. Line loss must betaken into consideration when selecting the evaporator.SELECTION PROCEDUREThe air-cooled condensing unit may be selected fromthe Ratings on pages 14 through 25, if the ambient airtemperature at the condenser and the saturated suctiontemperature at the compressor are known. The ambientair temperature is a known design parameter, but thesuction temperature at the compressor, in many cases,is known only within certain allowable limits. The actualcompressor operating suction temperature and the overallperformance of the system will depend directly uponthe choice of the evaporator. Starting with a preliminaryevaporator selection at a nominal evaporator temperatureand using data supplied by the evaporator manufacturer,enter the ratings tables and select a unit to meet therequired cooling load at a suction temperature at least2°F (1.1°C) below the evaporator temperature. The 2°F(1.1°C) allows for normal suction line loss.If more accurate selection is required, the evaporatorcapacity should be plotted against the condensing unitcapacity to determine the balanced system performance.Again, it is necessary to factor in the suction line loss.After the system balance point has been determined,the compressor KW input may be interpolated from theratings tables.SAMPLE SELECTIONSelect an R-410A Air-Cooled Condensing Unit with amatched central station air handling unit having the followingoperating conditions:Design Conditions1. An air handling unit with two large DX coils (one percircuit) having a total cooling load of 600 MBH (50tons).2. The coil suction temperature required 45°F.3. The design outdoor ambient temperature is 95°F.4. The power supply is 460V/3∅/60 hz.Selection1. Enter the YCUL0055EE Rating Table (page 12).2. The model YCUL0055EE will provide 51.6 tons with48.9 compressor KW input at 95°F ambient air and45°F suction pressure.3. Calculate the compressor Kw input for the specificdesign conditions of 50 tons and 95°F ambient air.KW =5051.6 Kwx 48.9 Kw = 47.4 KwThe YCUL0055EE is the suitable selection for the designcapacity.10JOHNSON CONTROLS
Selection Data - continuedFORM 150.68-EG1 (1109)Refrigerant PIPINGGeneral – When the unit has been located in its finalposition, the unit piping may be connected. Normal installationprecautions should be observed in order to receivemaximum operating efficiencies. System piping shouldconform to the York DX piping guide form 050.40-ES2 orASHRAE refrigeration handbook guidelines. All pipingdesign and installation is the responsibility of the user.JOHNSON CONTROLS ASSUMES NO WARRANTYRESPONSIBILITY FOR SYSTEM OPERATION ORFAILURES DUE TO IMPROPER PIPING OR PIPINGDESIGN.Filter driers and sight glasses are shipped loose for fieldinstallation on each refrigerant circuit. Field refrigerantpiping can be connected to the condensing unit.All expansion valves, liquid line solenoid valves, refrigerantand refrigerant piping are supplied and installed byothers.Table 4, pg 13, lists refrigerant line connections sizes perunit model number.REFRIGERANT LINE SIZINGRefrigerant piping systems must be designed to providepractical line sizes without excessive pressure drops,prevent compressor oil from being “trapped” in the refrigerantpiping, and ensure proper flow of liquid refrigerantto the thermal expansion valve. Considerations shouldbe given to:1) Suction line pressure drop due to refrigerant flow.2) Suction line refrigerant velocity for oil return.3) Liquid line pressure drop due to refrigerant flow.4) Liquid line pressure drop (or gain) due to vertical riseof the liquid line.Table 5 provides the pressure drops for given pipe sizes forboth liquid and suction lines. The pressure drops given areper 100 equivalent ft. (30.5 m) of refrigerant piping. Thesefriction losses do not include any allowances for strainer,filter drier, solenoid valve, isolation valve or fittingsNominal pressure drop for solenoids, sight glass, anddriers are shown in Table 2, pg 12.Table 1, pg 12, includes approximate equivalent lengthsfor copper fittings.To ensure a solid column of liquid refrigerant to the expansionvalve, the total liquid line pressure drop should neverexceed 50 psi (3.4 bar). Refrigerant vapor in the liquid linewill measurably reduce valve capacity and poor systemperformance can be expected.To allow adequate oil return to the compressor, suctionrisers should be sized for a minimum of 1000 FPM (5.08m/s) while the system is operating at minimum capacityto ensure oil return up the suction riser.Evaporator Below Condensing UnitOn a system where the evaporator is located below thecondensing unit, the suction line must be sized for bothpressure drop and oil return. In some cases a double suctionriser must be installed to ensure reliable oil return atreduced loads. Table 3, pg 12, indicates when a doublesuction riser should be used for listed pipe sizes to provideadequate oil return at reduced loads. The calculatedinformation was based on maintaining a minimum of 1000fpm (5.08 m/s) refrigerant vapor velocity.Condenser Below EvaporatorWhen the condensing unit is located below the evaporator,the liquid line must be designed for both friction loss andstatic head loss due the vertical rise. The value of statichead loss of 5 PSI/ft (3.4 kPa/30 cm) must be added tothe friction loss pressure drop in addition to all pressuredrops due to driers, valves, etc.OIL TRAPSAll horizontal suction lines should be pitched at least 1/4"per foot (2 cm/m) in the direction of the refrigerant flow toaid in the return of oil to the compressor. All suction lineswith a vertical rise exceeding 3 feet (.91 meters) shouldhave a “P” trap at the bottom and top of the riser. Suctionlines with a vertical rise exceeding 25 feet (7.6 meters)should be trapped every 15 feet (4.6 meters).REFRIGERANT CHARGEThe condensing unit is charged with a dry nitrogen holdingcharge. The remaining operating charge for the condensingunit, evaporator coil, and refrigerant piping must beweighed in after all refrigerant piping is installed, leakchecked, and evacuated. Final adjustment of refrigerantcharge should be verified by subcooling values (refer tosection on Pre-Startup for checking subcooling).REFRIGERANT PIPING REFERENCEFor more details, refer to ASHRAE Refrigeration Handbook,Chapter 2.JOHNSON CONTROLS 11
Page 1 and 2: FORM 150.68-EG1 (1109)Model YCUL Ai
Page 3 and 4: IntroductionFORM 150.68-EG1 (1109)M
Page 5 and 6: MicroComputer Control CenterFORM 15
Page 7 and 8: Options and AccessoriesFORM 150.68-
Page 9: Unit NomenclatureFORM 150.68-EG1 (1
Page 13 and 14: FORM 150.68-EG1 (1109)TABLE 4 - REF
Page 15 and 16: FORM 150.68-EG1 (1109)MODEL: YCUL00
Page 31 and 32: FORM 150.68-EG1 (1109)50HzModel No.
Page 33 and 34: FORM 150.68-EG1 (1109)All dimension
Page 35 and 36: FORM 150.68-EG1 (1109)All dimension
Page 37 and 38: FORM 150.68-EG1 (1109)NEOPRENE ISOL
Page 39 and 40: Electrical Data - 50 & 60HzFORM 150
Page 41 and 42: Electrical NotesFORM 150.68-EG1 (11
Page 43 and 44: Application DataFORM 150.68-EG1 (11
Page 45 and 46: FORM 150.68-EG1 (1109)1. Coils: Int
Page 47 and 48: FORM 150.68-EG1 (1109)per system. T

Model YCUL Air-Cooled Scroll Compressor ... - Usair-eng.com

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