Air Cooled Packaged Module - Multistack

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AIR COOLED PACKAGED MODULE Operations 1. CHILLER IDENTIFICATION More model numbers for related modules are available on page 5 of this manual. The new model numbers will be effective for any new module ordered after July 1, 2011. Any existing orders will not change. Existing ASP 30 X 1 H 1 A 0 R410A New ASP 030 X C/N 1 1 H 1 A L 1 A A 1 S -410A Refrigerant Fan Configuration 6 Series Power Connection (1 - Direct Connect, 2 - Multiple Module Connections) Voltage 2 Frame Designation 1 - 32 x 58, 2 - 36 x 72, 3 - 36 x 84, 4 - 72 x 84, 5 - other3 - 36 x 84, 4 - 72 x 84, 5 - other) No. of Refrigerant Circuits ( 1 - single , 2 - dual, 4 - four) AHRI Certified (C - certified, N - Not certified) Compressor Type 1 Module Nominal Capacity (10-75 tons, needs 3 digits) Condenser Coating 5 Condenser 4 Evaporator 3 Ambient ( L - Low, S - Standard, H - high, C - low & high) Voltage (H - 460/3/60, C for 575/3/60, E for 400/3/50) Application (A - Air Cooled, D - Cond Unit, H - Heat Recovery, R - Heat Pump) 1 B - Bristol, C - Trane Cornerstone, R - Bitzer Screw, S - Trane Scroll, T - Danfoss Turbocor, Z - Copeland scroll (old elec), X - Copeland Scroll (ZP), A - Copeland Scroll (ZR) 2 A - 208/3/60, L - 230/3/60, H - 460/3/60, C - 575/3/60, D - 200/3/50, E - 400/3/50, F - 380/3/60, S - 220/230/1/60, V - Other 3 A - Brazed SS, B - Brazed SMO, C- S&T copper, D - S&T cu-Ni, Z - Other 4 A - Cu tube Al fin, B - Cu tube Cu fin, C- Microchannel, V - Other 5 A - None, B - Bronzeglow, H - Heresite, E - Electrofin, V - Other 6 S - Standard, H - High static, L -Low sound, V -Other 2. THEORY OF OPERATION The Airstack ASP chiller provides chilled water to an external load based on the return water temperature as measured by the ASP master control. When the temperature of the returning water rises above the set point as calculated by the upper set point, the lower set point and the VSP the master controller starts compressors, one at a time, to produce chilled water. The number of compressors that will start is determined by the program in the master controller based on the temperature being returned. When the return chill water approaches the correct set point the master controller starts to turn off compressors as needed. When the return chilled water reaches the set point or a little below, the master controller will have turned off all the compressors. During operation of the compressors, the controller will cycle on one or both of the condenser fans in a module according to the refrigerant high pressure. Some systems have a large heat exchanger which uses a main chiller to chill the return water/glycol. When the chilled water from the main system is cold enough, the heat exchanger valves open and chill the return water/glycol through the smaller chiller enough that the compressors will not run. If the Heat Exchanger does not chill the return water/glycol enough, the 3 heat exchanger valves close and the compressors will start and chill the discharge water to the set-point. 3. Fail to Run Airstack ASP systems designed for critical needs have a design that will allow individual modules to run in the event that the master module fails or goes offline or if certain System Faults occur that would otherwise disable the entire chiller. Each module must be in the Auto mode of operation in order for this OVERRIDE condition to occur. If the Master Control comes back online and all System Faults are cleared then the control of the compressors will automatically shift back to the master control.
AIR COOLED PACKAGED MODULE Operations 4. Pressure readings The operating suction and discharge pressures in the modules are directly related to the temperature of the water flow, condenser temperatures, the ambient temperature and the cleanliness of the system. If a module is faulting on a High Pressure (HP) fault, you should first check to see that the fans are operating. If both fans are working check the cleanliness of the condenser coil. All ASP modules have both, a high pressure and low pressure (LP) cut out setting. Each module will cut out on HP or LP when the programmed limit in the master control is met. In addition a back up manual HP cut out switch is installed on each module. A LP fault is an indication of low refrigerant charge in the system. If a module is going out on a LP fault, check the static pressure of the system while the module is in the off mode. It will be necessary to wait for the system to warm up before checking the pressures by the gauge. If pressures are low, check the circuit for possible leaks. Call the Multistack service department for leak testing procedures. A further possible cause of a low suction temperature fault could be insufficient water flow. The strainers, filters and pump and valve settings should be checked. 5. Strainer Cleaning All ASP modules have a 30 mesh filter cartridge in the chilled water inlet header. The purpose of the filter cartridge is to keep debris from entering the heat exchanger. An external “Y” or basket type strainer should also be installed as a pre-filter to the factory supplied strainers. There is no set time for cleaning the filter cartridges. The factory recommendation is that the internal filters be removed and cleaned once per year. Sometimes the filter must be removed more often if the water in the closed loop system has particulates. A good indicator that the strainers need to be cleaned is a “low leaving water temperature” fault in the module(s) near the discharge side of the chiller. a. In order to remove the in-line strainers the following steps must be performed. b. Shut down the chiller and stop the chill water pump c. Close the inlet and outlet water valves to the chiller d. Drain the water-glycol from the system and dispose properly. When the water/glycol level is below the top header the system can be safely opened. e. Remove the 4” Victaulic end cap on the last module on the discharge side. On systems with 2 banks of modules, the upper crossover pipe will also have to be removed to access the strainer in the second bank of modules. Care should be taken to close the isolation valve for that header. f. Remove the strainers and clean immediately. A hooked tool may be required to remove the strainers further in the system. This tool can be manufactured on site. g. Slowly open the bottom water isolation valve and fill the unit from the bottom up to prevent air from being trapped in the headers. Care should be taken to check for leaks. h. Restart the chill water pump and again check for possible leaks, bleed any trapped air from the system and start the chiller. 6. Refrigerant charge / Evacuation All ASP modules come from the factory charged with the recommended refrigerant volume. Prior to charging, each unit is evacuated to a maximum of 150 microns and held 15 minutes. The proper refrigerant charge for each module can be found on the module data plate. On air cooled machines the proper charging procedure is by a calculated weigh-in method. Charging to a full sight glass on air cooled machines will likely result in over charging as the elbows in the liquid line as well as the liquid line solenoid valve still produce some flashing even with the correct charge. As fans are cycling the sight glass will also display some bubbling. 7. Superheat / Sub cooling All ASP modules use a mechanical type expansion valve. By turning the valve adjustment clockwise superheat is increased. On each module, superheat is set at the factory during the run test. Superheat is set for 10-12°F during the test run. No further adjustments should be necessary after the module is shipped. Sub cooling is necessary in the system to prevent flash gas as the refrigerant enters the expansion valve. ASP condensers are sized and charged so that sub cooling of the liquid refrigerant will take place with no separate sub-cooler being needed. The range of sub cooling is 7-15° F. 23
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Air Cooled Packaged Module - Multistack

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