York SUNLINE 2000 D3CE 036 Installation Instruction

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York SUNLINE 2000 D3CE 036 Installation Instruction Manual pdf 13 page image

Two-Stage Cooling:A two-stage cooling thermostat may be used if the unit has aneconomizer. First-stage cooling is provided by the economizerif the outdoor air enthalpy is acceptable, and second-stagecooling is provided by the compressor. Jumper wire J1 mustbe removed. Refer to unit wiring diagram.After the thermostat is satisfied and opens, the blowercontinues to run for a short time. All other components stop.SAFETY CONTROLSThe refrigerant system is equipped with the following safetycontrols:1. A Suction Line Freezestat to protect against low evaporatortemperatures due to a low air flow or a low return airtemperature.2. A High Pressure Cutout Switch to protect against excessivedischarge pressures due to a blocked condenser coil or acondenser motor failure.3. A Low Pressure Switch to protect against loss of refrigerantcharge.If any of the above safety controls opens, the refrigerant systemis locked out. The lock out of the system can be reset byopening the 24V circuit either at the room thermostat or at theunit disconnect.HEATING SEQUENCE OF OPERATIONThe following sequence of operation is based on using astandard single-stage or two-stage heating thermostat.WITH POWER TO UNIT AND THERMOSTAT IN THEHEATING MODESingle-Stage Heating:a. If the fan switch is in the “ON” position, the evaporatorblower motor relay (BR) will be energized through terminalG to provide continuous blower operation. If the fan switchis in the “AUTO” position, the blower operates only whenthere is a call for heating by the thermostat.b. Upon a call for heat by the thermostat, the first stage of heatis energized. Sequencer 1S (or contactor 2M) is always thefirst and last to complete its timing cycle and controls powerto the evaporator blower motor.c. The thermostat cycles the electric heat to satisfy the heat-ing requirements of the conditioned space.Two-Stage Heating:a. If the fan switch is in the “ON” position, the evaporatorblower motor relay (BR) is energized through terminal Gto provide continuous blower operation. If the fan switch isin the “AUTO” position, the blower operates only when thereis a call for heating by the thermostat.b. Upon a call for first-stage heat by the thermostat, the firststage of heat is energized.If the thermostat calls for the second stage of heat, thesecond stage of heat is energized.As before, sequencer 1S (or contactor 2M) maintainscontrol of the evaporator blower.c. The thermostat cycles the electric heat to satisfy theheating requirements of the conditioned space.CONTINUOUS BLOWER - Continuous blower operation ispossible by closing the R to G circuit on the thermostat.HEAT ANTICIPATOR SETPOINTSIt is important that the anticipator setpoint be correct. Too higha setting results in longer heat cycles and a greatertemperature swing in the conditioned space. Reducing thevalue below the correct setpoint causes shorter “ON” cyclesand may result in the lowering of the temperature within theconditioned space. Refer to Table 8 for the required heatanticipator setting.CHECKING SUPPLY AIRFLOWThe speed of the supply air blower depends on the requiredairflow, the unit accessories and the static resistances of boththe supply and the return air duct systems. With thisinformation, the speed for the supply air blower can bedetermined from the static resistance and blower performancedata on Tables 3, 4 and 5.Knowing the required blower RPM and the blower motor HP,the speed setting for the direct-drive supply air motor can bedetermined.The setting (turns open) for the optional belt-drive supply airmotor pulley can be determined from Table 9.OPTIONAL BELT-DRIVE BLOWERAll units with belt-drive blowers have single-speed motors. Thevariable pitch pulley on the blower motor can be adjusted toobtain the desired supply air airflow. Refer to Table 6 for blowermotor and drive data.Start the supply air blower motor. Adjust the resistances in boththe supply and the return air duct systems to balance the airdistribution throughout the conditioned space. The jobspecifications may require that this balancing be done bysomeone other than the equipment installer.To check the supply airflow after the initial balancing has beencompleted:1. Remove the dot plugs from the holes in the filter access andblower access panels. See Figure 5 for location of plugs.2. Insert at least 203mm (8 in.) of 6mm (1⁄4 in.) tubing into eachof these holes for sufficient penetration into the air flow onboth sides of the evaporator coil.NOMINALHEATERSIZEKWVOLTAGESETTING, AMPSTH1 TH2710152030380/415-3-500.350.350.350.370.37---0.290.29TABLE 8 - HEAT ANTICIPATOR SETTINGTURNS OPEN* BLOWER DRIVE RANGE (RPM)MODEL 060 MODEL 0765 850 9004 916 9603 982 10202 1048 10801 1114 11400 1180 1200* Pulley can be adjusted in half-turn increments.TABLE 9 - BELT-DRIVE SUPPLY AIRMOTOR PULLEY ADJUSTMENT530.26-N1YIUnitary Products Group 13

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