York Predator DM090 Installation Instruction

Also see for PREDATOR DM 090: Installation manual Technical guide Installation manual Installation manual Technical guide

035-17311-000 REV A (1200))Unitary Products Group 29COOLING OPERATION INSTRUCTIONSCOOLING SYSTEM PRELIMINARY OPERATIONNOTE: Prior to each cooling season, the crankcase heatersmust be energized at least 10 hours before the system is putinto operation.TURN ON THE POWER TO THE UNIT1. Set the room thermostat setting to lower than the roomtemperature.2. First stage compressors will energize after the built-intime delay (five minutes)3. The second stage of the thermostat will energize secondstage compressor if needed.POST START CHECK LISTVERIFY PROPER SYSTEM PRESSURES FOR BOTH CIR-CUITS1. Check the unit air flower (CFM). See “CHECKING AIRQUANTITY” on page 25.2. Measure the temperature drop across the evaporatorcoil.3. Check the voltage input.4. Measure the system Amperage draw across all legs of 3phase power wires.5. Measure the condenser fan amps draw.6. Measure evaporator fan motor’s amp draw.SHUT DOWN1. Set the thermostat to highest temperature setting.2. Turn off the electrical power to the unit.SEQUENCE OF OPERATIONSOVERVIEWFor the Predator series of units, the thermostat makes a cir-cuit between “R” and “Y1” for the first stage of cooling.The call is passed to the unit control board (UCB), which thendetermines whether the requested operation is available and,if so, which components to energize.For electric heat units, the UCB passes the call to the electricheater. When the “W1” call is sensed, the indoor air blower isenergized following a specified heating delay.If at any time a call for both heating and cooling are present,the heating operation will be performed. If operating, thecooling system is halted as with a completion of a call forcooling. Heating always takes priority.SAFETY CONTROLSThe Predator unit control board monitors the followinginputs for each cooling system:1. A suction line freezestat to protect against low evapora-tor temperatures due to a low airflow or a low return airtemperature, (opens at 26 ± 5 °F and resets at 38 ± 5°F).2. A high-pressure switch to protect against excessive dis-charge pressures due to a blocked condenser coil or acondenser motor failure, (opens at 405 ± 10 psig andresets at 300 ± 10 psig).3. A low-pressure switch to protect against loss of refriger-ant charge, (opens at 7 ± 3 psig and resets at 22 ± 5psig).The above pressure switches are hard-soldered to the unit.The refrigeration systems are independently monitored andcontrolled. On any fault, only the associated system will beeffected by any safety/preventive action. The other refriger-ant system will continue in operation unless it is effected bythe fault as well.TABLE 29: MOTOR SHEAVE DATUM DIAMETERS1VM50x7/8(1-1/2, 2 & 3 HP Motor)1VP56x1-1/8(5 HP Motor)Turns Open DatumDiameter Turns Open DatumDiameter0 4.4 1 5.31/2 4.3 1-1/2 5.21 4.2 2 5.11-1/2 4.1 2-1/2 5.02 4.0 3 4.92-1/2 3.9 3-1/2 4.83 3.8 4 4.73-1/2 3.7 4-1/2 4.64 3.6 5 4.54-1/2 3.5 5-1/2 4.45 3.4 6 4.3After installation has been completed, energize thecrankcase heaters for at least four hours beforeoperating unit. After this initial warm-up, the com-pressors should be given three false starts (ener-gized just long enough to make a few revolutions)with 5-7 minutes of delay between each startbefore being put into full time service.