Carrier 48TM016-028 Installation, Start-up And Service Instructions Manual

Also see for 48TM016: User's information manual

Contents

23DIFFERENTIAL ENTHALPY CONTROL (Fig. 30) —Differential enthalpy control requires both an enthalpy switch/receiver (33CSENTHSW) and an enthalpy sensor(33CSENTSEN). The enthalpy switch/receiver is mounted inthe outdoor air inlet and calculates outdoor air enthalpy. Theenthalpy sensor is mounted in the return airstream and calcu-lates the enthalpy of the indoor air.The enthalpy switch/receiver energizes the HI Enthalpyrelay output when the outdoor enthalpy is greater than theindoor enthalpy. The LOW Enthalpy terminal is energizedwhen the outdoor enthalpy is lower than the indoor enthalpy.The relay output is wired to the unit economizer which willopen or close depending on the output of the switch.NOTE: The enthalpy calculation is done using an averagealtitude of 1000 ft above sea level.Mounting — Mount the enthalpy switch/receiver in a locationwhere the outdoor air can be sampled (such as the outdoor airintake). The enthalpy switch/receiver is not a NEMA 4 enclo-sure and should be mounted in a location that is not exposed tooutdoor elements such as rain, snow, or direct sunlight. Usetwo field-supplied no. 8 x 3/4-in. TEK screws. Insert the screwsthrough the holes in the sides of the enthalpy switch/receiver.Mount the enthalpy sensor in a location where the indoor aircan be sampled (such as the return air duct). The enthalpysensor is not a NEMA 4 enclosure and should be mounted in alocation that is not exposed to outdoor elements such as rain orsnow. Use two field-supplied no. 8 x 3/4-in. TEK screws. Insertthe screws through the holes in the sides of the enthalpy sensor.Wiring — Carrier recommends the use of 18 to 22 AWGtwisted pair or shielded cable for all wiring. All connectionsmust be made with 1/4-in. female spade connectors.The PremierLink™ board provides 24-vac to power theenthalpy switch/receiver. Connect the GND and 24 VACterminals on the enthalpy switch/receiver to the terminals onthe transformer. On some applications, the power from theeconomizer harness can be used to power the enthalpy switch/receiver. To power the enthalpy switch/receiver from the econ-omizer harness, connect power of the enthalpy switch/receiverto the red and brown wires (1 and 4) on the economizerharness.Connect the LOW Enthalpy terminal on the enthalpyswitch/receiver to J4 — pin 2 of the PremierLink control on theHVAC unit. The switch can be powered through the Premier-Link control board if desired. Wire the 24VAC terminal on theenthalpy switch/receiver to J4 — pin 1 on the PremierLinkcontrol. Wire the GND terminal on the enthalpy switch/receiver to J1 — pin 2 on the PremierLink control. The HIEnthalpy terminal is not used. See Fig. 29.Connect the 4-20 mA IN terminal on the enthalpy switch/receiver to the 4-20 mA OUT terminal on the return airenthalpy sensor. Connect the 24-36 VDC OUT terminal on theenthalpy switch/receiver to the 24-36 VDC IN terminal on thereturn air enthalpy sensor. See Fig. 30.Enthalpy Switch/Receiver Jumper Settings — There are twojumpers. One jumper determines the mode of the enthalpyswitch/receiver. The other jumper is not used. To access thejumpers, remove the 4 screws holding the cover on theenthalpy switch/receiver and then remove the cover. Thefactory settings for the jumpers are M1 and OFF.The mode jumper should be set to M2 for differentialenthalpy control. The factory test jumper should remain onOFF or the enthalpy switch/receiver will not calculate enthalpy.Enthalpy Sensor Jumper Settings — There are two jumpers.One jumper determines the mode of the enthalpy sensor. Theother jumper is not used. To access the jumpers, remove the4 screws holding the cover on the enthalpy sensor and thenremove the cover. The factory settings for the jumpers are M3and OFF.Fig. 30 — Differential Enthalpy Control Wiring24 VAC OUTPUT FROM N/C CONTACT WHEN THEOUTDOOR ENTHALPY IS LESS THAN THEINDOOR ENTHALPY(ENABLE ECONOMIZER)24 VAC OUTPUT FROM N/O CONTACT WHEN THEINDOOR ENTHALPY IS GREATER THAN THEOUTDOOR ENTHALPY24 VACSECONDARYHI LOW GND 24VACENTHALPY 4-20mAIN24-36VDCOUTJUMPER SETTINGS FOR 33CSENTHSWM1M2M30%50%100%OFF33CSENTHSWJUMPER SETTINGS FOR 33CSENTSENM1M2M30%50%100%OFF33CSENTSEN24-36VDCINORN120 VACLINE VOLTAGE4-20mAOUTLEGENDN/C — Normally ClosedN/O — Normally Open