Carrier EW, 48EJ, EK, EY024-048 installation instructions GND Ð Ground, Terminal Block

IMPORTANT: THE VAV (variable air volume) units use variable frequency drives, which generate, use and can radiate radio frequency energy. If units are not in- stalled and used in accordance with these instructions, they may cause radio interference. They have been tested and found to comply with limits of a Class A com- puting device as de®ned by FCC (Federal Communi- cations Commission) regulations, Subpart J of Part 15, which are designed to provide reasonable protection against such interference when operated in a commer- cial environment.

The unit must be electrically grounded in accordance with local codes and NEC ANSI/NFPA 70 (National Fire Protection Association).

Affix crankcase heater sticker (located in the installers packet) to unit disconnect switch.

Voltage to compressor terminals during compressor op- eration must be within the voltage range indicated on the unit nameplate. On 3-phase units, phases must be balanced within 2%. Contact local power company for correction of improper voltage or phase imbalance. Unit failure due to op- eration of unit on improper line voltage or with excessive phase imbalance constitutes abuse and may cause damage to unit electrical components.

On 208/230-v units, transformer no. 1 is wired for 230-v. If 208/230-v unit is to be run with 208-v power supply, the transformer must be rewired as follows:

1.Remove cap from red (208 v) wire.

2.Remove cap from spliced orange (230 v) wire. Discon- nect orange wire from black unit power wire.

3.Cap orange wire.

4.Splice red wire and black unit power wire. Cap wires.

IMPORTANT: BE CERTAIN UNUSED WIRES ARE CAPPED. Failure to do so may damage the transformers.

FIELD CONTROL WIRING Ð The unit can use either a Carrier-approved thermostat or a CCN (Carrier Comfort Network) compatible temperature sensor. Thermostats are used on CV (constant volume) units only. Control box diagrams are shown in Fig. 18 and 19.

Thermostat Wiring (CV Only) Ð Install a Carrier-approved accessory thermostat assembly (per current price pages) ac- cording to the installation instructions included with the ac- cessory or these instructions. Locate the thermostat on a solid interior wall in the conditioned space to sense the average temperature.

Route the thermostat cable or equivalent single leads of colored wire from the subbase terminals to the low-voltage connection as shown on unit label wiring diagram and in Fig. 20.

NOTE: For wire runs up to 50 ft, use no. 18 AWG (American Wire Gage) insulated wire (35 C minimum). For 50 to 75 ft, use no. 16 AWG insulated wire (35 C minimum). For over 75 ft, use no. 14 AWG insulated wire (35 C mini- mum). All wire larger than no. 18 AWG cannot be directly connected at the thermostat and will require a junction box and splice at the thermostat.

Set heat anticipators to 0.1 for all voltages.

Sensor Wiring (CV or VAV) Ð The temperature sensor is wired into the unit control board. See Fig. 21.

The unit is controlled with a T-55 or T-56 (CV only) zone sensor. Terminal TH (T-56) or T1 (T-55) on the sensor is connected to T1 of the base module board. Terminal COM (T-56) or T2 (T-55) on the sensor is connected to T2 on the base module board. If a T-56 set point override sensor is used, the override connection SW on the sensor is connected to T3 on the base module board.

If more than sensor is being used and averaged, sensors must be wired in multiples of 4 or 9. See Fig. 22.

Heat Interlock Relay Ð VAV units require a ®eld-supplied heat interlock relay (HIR) to drive the air terminal wide open when in heat mode. Heat Interlock relay part number is HN61KK041.

	LEGEND
GND Ð Ground
NEC	Ð National Electrical Code
TB	Ð Terminal Block

NOTE: Maximum wire size for TB1 is 500 MCM.

Fig. 17 Ð Field Power Wiring Connections

		LEGEND
C	Ð	Compressor/Contactor	IF	Ð	Indoor Fan
CB	Ð Circuit Breaker		OF	Ð Outdoor Fan
DIP	Ð	Dual In-Line Package	PEC	Ð	Power Exhaust Controller
FU	Ð	Fuse	TB	Ð	Terminal Block
HR	Ð	Heater Relay	TRAN Ð		Transformer

Fig. 18 Ð Control Box Diagram (Sizes 024-034)

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