Carrier 30GTN Service And Troubleshooting Manual

Also see for 30GTN: Product data Installation instructions Installation instructions

Carrier 30GTN Service And Troubleshooting Manual Manual pdf 66 page image

Consult application data section in the Product Data lit-erature and job design requirements to determine flow raterequirements for a particular installation.Table 34 — Nominal and Minimum CoolerFluid Flow Rates30GTN,RUNITSIZENOMINAL FLOWRATE* MINIMUM FLOWRATE (See Notes)Gpm L/s Gpm L/s040 86 5.43 36.8 2.32045 101 6.37 37.7 2.38050 123 7.76 37.7 2.38060 151 9.53 47.5 3.00070 173 10.91 47.5 3.00080,230B 192 12.11 66.7 4.20090,245B 216 13.62 59.5 3.75100,255B,270B 240 15.14 84.1 5.30110,290B,315B 264 16.65 84.1 5.30130 300 18.9 110 6.9150,230A-255A 348 21.9 110 6.9170,270A,330A/B,360B (50 Hz) 384 24.2 120 7.5190,290A,360A/B (60 Hz),360A (50 Hz),390B 432 27.2 120 7.5210,315A,390A,420A/B 480 30.2 148 9.3LEGENDARI — Air Conditioning and Refrigeration InstituteGpm — Gallons per minute (U.S.)L/s — Liters per secondN — Liters per kWV — Gallons per ton*Nominal flow rates required at ARI conditions are 44 F (6.7 C) leaving-fluid temperature, 54 F (12.2 C) entering-fluid temperature, 95 F(35 C) ambient. Fouling factor is .00001 ft2 • hr • F/Btu (.000018 m2• K/W).NOTES:1. Minimum flow based on 1.0 fps (0.30 m/s) velocity in cooler with-out special cooler baffling.2. Minimum Loop Volumes:Gallons = V x ARI Cap. in tonsLiters = N x ARI Cap. in kWAPPLICATION V NNormal Air Conditioning 3 3.25Process Type Cooling 6 to 10 6.5 to 10.8Low Ambient Unit Operation 6 to 10 6.5 to 10.8Operation Sequence — During unit off cycle, crank-case heaters are energized. If ambient temperature is below36 F (2 C), cooler heaters (if equipped) are energized.The unit is started by putting the ENABLE/OFF/REMOTECONTACT switch in ENABLE or REMOTE position. Whenthe unit receives a call for cooling (either from the internalcontrol or CCN network command or remote contact clo-sure), the unit stages up in capacity to maintain the coolerfluid set point. The first compressor starts 11 ⁄2 to 3 minutesafter the call for cooling.The lead circuit can be specifically designated or ran-domly selected by the controls, depending on how the unitis field configured (for 040-070 sizes, Circuit A leads unlessan accessory unloader is installed on Circuit B). A field con-figuration is also available to determine if the unit shouldstage up both circuits equally or load one circuit completelybefore bringing on the other.When the lead circuit compressor starts, the unit starts witha pumpout routine. On units with the electronic expansionvalve (EXV), compressor starts and continues to run withthe EXV at minimum position for 10 seconds to purge therefrigerant lines and cooler of refrigerant. The EXV then movesto 23% and the compressor superheat control routine takesover, modulating the valve to feed refrigerant into the cooler.On units with thermostatic expansion valve (TXV)(30GTN,R040,045 units with brine option), head pressurecontrol is based on set point control. When the lead com-pressor starts, the liquid line solenoid valve (LLSV) is keptclosed for 15 seconds by a time delay relay. The micro-processor stages fans to maintain the set point temperaturespecified by the controller. There is no pumpout sequenceduring shutdown of TXV controlled chillers.On all other units (EXV units), the head pressure is con-trolled by fan cycling. The desired head pressure set point isentered, and is controlled by EXV position or saturated con-densing temperature measurement (T3 and T4). For properoperation, maintain set point of 113 F (45 C) as shipped fromfactory. The default head pressure control method is set pointcontrol. The head pressure control can also be set to EXVcontrol or a combination of the 2 methods between circuits.For all units, if temperature reset is being used, the unitcontrols to a higher leaving-fluid temperature as the build-ing load reduces. If demand limit is used, the unit may tem-porarily be unable to maintain the desired leaving-fluid tem-perature because of imposed power limitations.On EXV units, when the occupied period ends, or whenthe building load drops low enough, the lag compressors shutdown. The lead compressors continue to run as the EXV closes,and until the conditions of pumpout are satisfied. If a faultcondition is signaled requiring immediate shutdown,pumpout is omitted.Loading sequence for compressors is shown in Tables 5Aand 5B.66