Carrier GZ024 Installation Instructions Manual

Carrier GZ024 Installation Instructions Manual Manual pdf 20 page image

20SYSTEM FUNCTIONS AND SEQUENCEOF OPERATIONGZ models utilize either a Communicating Wall Control or astandard 2--stage heat pump thermostat.With a call for first stage cooling/heating, the low stage isenergized. If low--stage cannot satisfy the cooling/heating demand,high stage is energized by the second stage of indoor thermostat.After second stage is satisfied, the unit returns to low--stageoperation until the first stage is satisfied or until second stage isrequired again.When both first and second stage cooling are satisfied, thecompressor will shut off. When a 2--stage unit is operating atlow--stage, system vapor (suction) pressure will be higher than astandard single--stage system or high--stage system.Communicating Sequence: The UPM board controls allfunctions. See Fig. 22.Non--Communicating Sequence: The reversing valve is energizedto cool.Cooling -- The first stage of cooling powers Y1 and O. Thesecond stage of cooling powers Y1, Y2 and O.Heating -- The first stage of heating powers Y1, and the secondstage of heating powers Y1 and Y2.Communication and Status Function LightsA green LED (COMM light) on the UPM (see Fig. 22) indicatessuccessful communication with the other system products. Thegreen LED will remain OFF until communication is established.Once a valid command is received, the green LED will turn ONcontinuously. If no communication is received within 2 minutes,the LED will be turned OFF until the next valid communication.Amber Status Light -- An amber colored STATUS light is used todisplay the operation mode and fault codes as specified in thetroubleshooting section. See Table 15 for codes and definitions.NOTE: Only one code will be displayed on the UPM board (themost recent, with the highest priority).Time DelaysUnit time delays include:S Five minute time delay to start cooling or heating operation whenthere is a call from the thermostat or user interface. To bypass thisfeature, momentarily short and release Timer Speed--Up pins.S Five minute compressor re--cycle delay on return from abrown--out condition.S Two minute time delay to return to standby operation from lastvalid communication (with UI only).S There is no delay between staging from low to high and from highto low capacity. The compressor will change from low to highand from high to low capacity “on the fly” to meet the demand.Compressor OperationThe basic scroll design has been modified with the addition of aninternal unloading mechanism that opens a by--pass port in the firstcompression pocket, effectively reducing the displacement of thescroll. The opening and closing of the by--pass port is controlled byan internal electrically operated solenoid.The modulated scroll uses a single step of unloading to go fromfull capacity to approximately 67% capacity. A single speed, highefficiency motor continues to run while the scroll modulatesbetween the two capacity steps. Modulation is achieved by ventinga portion of the gas in the first suction pocket back to the low sideof the compressor, thereby reducing the effective displacement ofthe compressor.Full capacity is achieved by blocking these vents, thus increasingthe displacement to 100%. A DC solenoid in the compressorcontrolled by a rectified 24 volt AC signal in the external solenoidplug moves the slider ring that covers and uncovers these vents.The vent covers are arranged in such a manner that the compressoroperates at approximately 67% capacity when the solenoid is notenergized and 100% capacity when the solenoid is energized. Theloading and unloading of the two step scroll is done ”on the fly”without shutting off the motor between steps.NOTE: 67% compressor capacity translates to approximately75% cooling or heating capacity at the indoor coil. Thecompressor will always start unloaded and stay unloaded for fiveseconds even when the thermostat is calling for high stage capacity.Safety Devices and UPM Board3124 5689101211131415161718 1971. PL2 LPS Low pressure switch 11. C W 1 Y 1 Y2 0: Standard tstatconnection2. PL3 HPS: High pressure switch 12. J2 Speed Up Timer: Test jumper3. SEC1 and SEC2: Transformer 13. S1: DIP Switches4. VS: Start circuit high volt. 14. PL8 Model: Model plug conn.5. L2 and L1: Contactor and highvoltage15. PL6 FRZ1: Water coil freeze sen-sor6. PWM1 and PWM2: N/A 16. PL6 OPT: N/A7. F1: 3 amp fuse 17. PL1 RVS: Reversing valve plug8. PL5: Compressor plug 18. LED1 COMM: Comm status light9. PL7: ABCD comm. stat conn. 19. LED2 STATUS: Status and faultcode light10. COND: Condensate overflowA150170Fig. 22 -- UPM BoardThe UPM Board includes the following features:S LOW PRESSURE SWITCH: The low pressure switch safety isdesigned to shut down the compressor in th event of loss ofcharge. Cut in 60 +/-- 15 psig and cut out 40 +/-- psig.S HIGH PRESSURE SWITCH: The high pressure switch safetyis designed to shut down the compressor if it exceeds limits. Cutin 420 +/-- 15 psig and cut out 600 +/-- psig.Pressure Switch Protection: The split geothermal unit isequipped with high-- and low--pressure switches. If the controlsenses the opening of a high-- or low--pressure switch, it willrespond as follows:1. De--energize the compressor contactor.2. Display the appropriate fault code (see Table 15).3. After a 15 minute delay, if there is a call for cooling or heat-ing and LPS or HPS is reset, the compressor contactor isenergized.4. If the open switch closes anytime after the 15 minute delay,then resume operation with a call for cooling or heating.5. If LPS or HPS trips 2--4 consecutive cycles per the dipswitch lockout setting or UI setting (Communicating only),the unit operation is locked out for 4 hours.6. In the event of a high--pressure switch trip or high--pressurelockout, check the refrigerant charge, and the coax coil (incooling) for water issues, or indoor airflow in heating.7. In the event of a low--pressure switch trip or low--pressurelockout, check the refrigerant charge and indoor airflow(cooling) and coax coil water pressure and flow in heating.S LOW PRESSURE BYPASS TIMER: If the compressor isrunning and the low pressure switch opens, the board will keepthe compressor ON for 120 seconds. After 2 minutes, if the lowpressure switch remains open, the board will shut down thecompressor and enter a soft lockout. The compressor will not be