Carrier 48HG014-028 Specifications download pdf (Page 16)

START-UP

Use the following information and Start-Up Checklist on

page CL-1 to check out unit PRIOR to start-up.

Unit Preparation —

Check that unit has been installed in

accordance with these installation instructions and all applica-

ble codes.

Compressor Mounting —

Compressors are internally

spring mounted. Do not loosen or remove compressor hold-

down bolts.

Refrigerant Service Ports —

Each refrigerant sys-

tem has a total of 3 Schrader-type service gage ports per circuit.

One port is located on the suction line, one on the compressor

discharge line, and one on the liquid line. Be sure that caps on

the ports are tight.

Crankcase Heater(s) —

Crankcase heaters are ener-

gized as long as there is power to the unit and the compressor is

not operating.

Compressor Rotation

It is important to be certain the compressors are rotating in

the proper direction. To determine whether or not compressors

are rotating in the proper direction perform the following

procedure:

1. Use the Service Test feature to energize a compressor (see

Controls and Troubleshooting literature for details).

2. If the compressor is rotating in the wrong direction, the

control will stop the compressor and an alarm will be

displayed.

NOTE: The evaporator fan is probably also rotating in the

wrong direction.

3. Turn off power to the unit and lock out the power.

4. Reverse any two of the incoming power leads.

5. Turn on power to the unit.

6. Repeat the procedure to energize each compressor and

check the evaporator fan rotation.

Internal Wiring —

Check all electrical connections in

unit control boxes; tighten as required.

Evaporator Fan —

Fan belt and variable pulleys are

factory-installed. Remove tape from the fan pulley. See

Tables 3-23 for Fan Performance Data. Be sure that fans rotate

in the proper direction. See Table 24 for air quantity limits. See

Table 25 and 26 for Evaporator Fan Motor Specifications. See

Table 27 for fan rpm at various motor pulley settings. To alter

fan performance, see Evaporator Fan Performance Adjustment

section on page 42.

Condenser-Fans and Motors —

Condenser fans and

motors are factory set. Refer to Condenser-Fan Adjustment

section (page 42) as required.

Return-Air Filters —

Check that correct filters are in-

stalled in filter tracks (see Table 1). Do not operate unit without

return-air filters.

Outdoor-Air Inlet Screens —

Outdoor-air inlet screens

must be in place before operating unit.

Gas Heat —

Verify gas pressures before turning on heat as

follows:

1. Turn off manual gas stop.

2. Connect pressure gage to supply gas pressure tap (see

Fig. 14).

3. Connect pressure gage to manifold pressure tap on gas

valve.

4. Turn on manual gas stop and set thermostat to HEAT

position. After the unit has run for several minutes, verify

that incoming pressure is 5.5 in. wg to 13.0 in. wg, and

that the manifold pressure is 2.95 in. wg. on horizontal

discharge applications and 3.00 in. wg on vertical dis-

charge applications. If manifold pressure must be adjust-

ed, refer to Gas Valve Adjustment section on page 43.

5. After unit has been in operation for 5 minutes, check tem-

perature rise across the heat exchangers. See unit infor-

mative plate for correct rise limits of the heat supplied.

Air quantities may need to be adjusted to bring the actual

rise to within the allowable limits.

IMPORTANT: Unit power must be on for 24 hours prior

to start-up. Otherwise, damage to compressor may

result.

Improper wiring will cause compressor stoppage and

alarm. Correct wiring by switching leads at contactor.

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Carrier 48HG014-028 Specifications Page 16

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