Carrier OMNIZONE 50XJ064-104 Operating And Troubleshooting Manual

Also see for OMNIZONE 50BV020: Installation and service instructions

6by the freeze condition. Unit reset is automatic when thecontacts on the freeze protection switch close again. Thecontacts on the freeze protection switch open below 37 F.TOWER SUMP TEMPERATURE SENSOR (50XJPCB3) — This sensor is used for monitoring (only) the towersump temperature.LEAVING WATER TEMPERATURE SENSOR (50XJPCB3) — This sensor is used for monitoring (only) the leav-ing water temperature.BUILDING STATIC PRESSURE SENSOR (50XJPCB3) — This sensor is used to control both the speed of thebuilding exhaust fan and the building static pressure.INDOOR AIR QUALITY (CO 2 ) SENSOR (50XJPCB3) — This sensor monitors CO2 levels.INDOOR RELATIVE HUMIDITY SENSOR (50XJPCB3) — This sensor monitors and controls the humiditycontrol relay.OUTDOOR AIR TEMPERATURE SENSOR (50XJPCB3) — This sensor is used to monitor outdoor air andbroadcast the value over the Carrier Comfort Network (CCN).STAGE HEAT RELAYS (50XJ PCB3) — These relays con-trol up to four stages of electric heat, or other heating methods.PUMP REQUEST RELAY (50XJ PCB3) — This relay turnson a tower pump when requested.TOWER REQUEST/CONTROL RELAY (50XJ PCB3) —This relay is used to activate a tower fan.BUILDING EXHAUST FAN SPEED CONTROL (50XJPCB3) — This output controls building exhaust fan speed.HUMIDITY CONTROL RELAY (50XJ PCB3) — This relaycontrols a humidifier or dehumidification device.Wiring Control Devices — Standard controls for the50XJ require no field-wiring. Standard 50XJ controls include:Supply Air Temperature (SAT), Duct Static Pressure (DSP),Duct High Static Limit Switch (DHS), Filter Status Switch(FLTS), Entering Water Temperature (EWT), Compressor Sta-tus (CSMUX), Supply Fan Start/Stop (SF), Supply Fan Speed(SPEED), and Mixed/Air Return/Air sensor (MA_RA).NOTE: The MA_RA sensor will be located in the return airsteam if the unit does not have a water economizer, and inthe mixed airstream if the unit is equipped with a watereconomizer.For the 50BV unit, standard controls include: Duct StaticPressure (DSP), Duct High Static Limit Switch (DHS), Com-pressor Status (CSMUX), Supply Fan Start/Stop (SF), andSupply Fan Speed (SPEED).For the 50XJ unit, optional controls will be wired to thefield terminal blocks (TB5 and TB6) provided. Refer toFig. 2A and the descriptions below.For the 50BV unit, optional controls are wired to fieldterminal block TB2 as shown in Fig. 2B.EXTERNAL 0 TO 10 VOLT DC RESET SIGNAL (RESET)(50XJ PCB2) — This field-supplied 0 to 10 vdc signal is usedto reset the 50XJ supply-air temperature. The controller willscale the signal to provide 0 reset at 0 volts and 20 degrees ofreset at 10 volts. Wire the positive of the signal to the RESETterminal and the negative to the C or common terminal.SUPPLY AIR RESET (50BV) — Use a 5k ohm sensorinstalled at the Entering Water Temperature sensor (EWT)location on PCB1. For space temperature averaging, two 10kohm Space Temperature Sensors (SPT) can be wired in parallel.SPACE TEMPERATURE SENSOR (50XJ PCB2) — Thespace temperature sensor (33ZCT55SPT) is used in the follow-ing cases:• When using the optional water economizer and not usingCarrier’s ComfortID™ System.• To determine the average temperature of the space beingserved.• To determine supply-air temperature reset, occupiedheating, unoccupied heating and cooling (refer toSequence of Operation in the Start-Up section.).To wire the sensor, perform the following (see Fig. 3).Identify which cable is for the sensor wiring.1. Strip back the jacket from the cable for at least3 inches. Strip 1/4-in. of insulation from each conduc-tor. Cut the shield and drain wire from the sensor endof the cable.2. Wire the sensor to the SPT and C terminals on the fieldterminal block (TB5). A typical 10K thermistor suchas the 33ZCT55SPT sensor may be used. If the SPTsensor is not installed and the MA_RA (mixed air/return air) sensor is configured for return air, the 50XJunit will use this sensor to control supply air reset,occupied heat, and unoccupied heating and coolingSee Fig. 4 for space temperature sensor averaging.HOT WATER OR STEAM VALVE (HWV) (50XJPCB2) — The HWV terminal supplies the positive signal tocontrol a 4 to 20 mA hot water or steam valve for occupied andunoccupied heat. Connect the common side of the valve to theC terminal or an equipment ground.Fig. 2A — Field Terminal Blocks for 50XJ UnitFig. 2B — Field Terminal Block for 50BV Unit