Assessments - 2, GPA: 5
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Five (5) wires should be run from thermostat subbase to the 24V terminal board in the unit. A five conductor, 18 gauge copper, color-coded thermostat cable is recommended. The connection points are shown in Figure 8: TABLE 3 THERMOSTAT WIRE SIZE Maximum Transformer Distance VA FLA Wire Gauge In Feet 55 2.3 20 gauge 18 gauge 16 gauge 14 guage 12 guage 45 60 100 160 250 TABLE 4 WALL THERMOSTAT AND SUBBASE COMBINATIONS Thermostat Subbase Predominate Features 8403-002 T87F3111 8404-003 Q539A1220 1 stage heat, 1 stage cool System: heat-off-cool Fan: auto-on 8403-041 T8034C --1 stage heat, 1 stage cool System: heat-off-cool Fan: auto-on 8403-019 T874C1760 8404-012 Q674A1001 1 stage cool, 2 stage heat System: heat-auto-cool Fan: auto-on 8403-021 T874D1934 8404-012 Q674A1001 2 stage cool, 2 stage heat System: heat-auto-cool Fan: auto-on 8403-035 1F95-80 --2 stage cool, 2 stage heat 7 day programmingElectronic 8403-043 CM-200 --1 stage heat, 1 stage cool auto-onFan:System: heat-off-cool Manual 2100-218 Page 12 Manual 2100-218 Page 13 FIGURE 8 UNIT 24V TERMINAL BOARD MIS-1373 START UP IMPORTANT INSTALLER NOTE For improved start up performance wash the indoor coil with a dish washing detergent. CRANKCASE HEATERS WA421 units are provided with compressor crankcase heat. WA602 and WA482 units are not provided with crankcase heat. These units utilize scroll compressors which do not require crankcase heat in this application. The WA421 models have an insertion well-type heater located in the lower section of the compressor housing. This is a self-regulating type heater that draws only enough power to maintani the compressor at a safe termperature on these units. Some form of crankcase heat is essential to prevent liquid refrigerant from migating to the compressor causing oil pump out on compressor start up and possible valve failure due to compressing a liquid. The decal in Figure 9 is affixed to all WA421 units detailing start up procedure. This is very important. Please read carefully. HIGH PRESSURE SWITCH The WA482 and WA602 models are supplied with a remote reset high pressure switch. If tripped, this pressure switch may be reset by turning the themostat off then back on again. THREE PHASE SCROLL COMPRESSOR START UP INFORMATION Scroll compressors, like several other types of compressors, will only compress in one rotational direction. Direction of rotation is not an issue with single phase compressors since they will always start and run in the proper direction. However, three phase compressors will rotate in either direction depending upon phasing of the power. Since there is a 50-50 chance of connecting power in such a way as to cause rotation in the reverse direction, verification of proper rotation must be made. Verification of proper rotation direction is made by observing that suction pressure drops and discharge pressure rises when the compressor is energized. Reverse rotation also results in an elevated sound level over that with correct rotation, as well as, substantially reduced current draw compared to tabulated values. Verification of proper rotation must be made at the time the equipment is put into service. If improper rotation is corrected at this time there will be no negative impact on the durability of the compressor. However, reverse operation for over one hour may have a negative impact on the bearing due to oil pump out. FIGURE 9 STARTING PROCEDURE IMPORTANT THESE PROCEDURES MUST BE FOLLOWED AT INITIAL START UP AND AT ANY TIME POWER HAS BEEN REMOVED FOR 12 HOURS OR LONGER. To prevent compressor damage which may result from the presence of liquid refrigerant in the compressor crankcase. 1. Make certain the room thermostat is in the “off” position (the compressor is not to operate). 2. Apply power by closing the system disconnect switch. This energizes the compressor heater which evaporates the liquid refrigerant in the crankcase. 3. Allow 4 hours or 60 minutes per pound of refrigerant in the system as noted on the unit rating plate, which ever is greater. 4. After properly elapsed time, the thermostat may be set to operate the compressor. 5. Except as required for safety while servicing, Do not open system disconnect switch. 7961-061 NOTE: If compressor is allowed to run in reverse rotation for several minutes, the compressor’s internal protector will trip. All three phase ZR3 compressors are wired identically internally. As a result, once the correct phasing is determined for a specific system or installation, connecting properly phased power leads to the same Fusite terminal should maintain proper rotation direction. The direction of rotation of the compressor may be changed by reversing any two line connections to the unit. CONDENSER FAN OPERATION The condenser fan motor on 230/208 volt, one and three phase, 60 HZ units is a two speed motor that comes factory wired on high speed for peak performance. If ambient conditions permit, it can be reconnected to low speed (red wire) for lower sound level...
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