Carrier 50HQP072-120 specifications Pre-Start-Up

PRE-START-UP

System Checkout — When the installation is complete, follow the system checkout procedure outlined below before starting up the system. Be sure:

1.Voltage is within the utilization range specifications of the unit compressor and fan motor and voltage is balanced for 3-phase units.

2.Fuses, breakers and wire are correct size.

3.Low voltage wiring is complete.

4.Piping and system flushing is complete.

5.Air is purged from closed loop system.

6.System is balanced as required. Monitor if necessary.

7.Isolation valves are open.

8.Water control valves or loop pumps are wired.

9.Condensate line is open and correctly pitched.

10.Transformer switched to lower voltage tap if necessary.

11.Blower rotates freely — shipping support is removed.

12.Blower speed is on correct setting.

13.Air filter is clean and in position.

14.Service/access panels are in place.

15.Return-air temperature is 4.4 to 26.7 C for heating and 10.0 to 43.3 C for cooling.

16.Air coil is clean.

17.Control field selected settings are correct.

AIR COIL — To obtain maximum performance, the air coil should be cleaned before starting the unit. A ten percent solution of dishwasher detergent and water is recommended for both sides of the coil. Rinse thoroughly with water.

Airflow and External Static Pressure — The 50HQP units are available with standard, low, and high-staticfactory-installed options. These options will substitute a differ- ent blower drive sheave for each static range. In addition, cer- tain static ranges may require the optional large fan motor.

SHEAVE ADJUSTMENT — The 50HQP units are supplied with a variable sheave drive on the fan motor to adjust for dif- fering airflows at various ESP (external static pressure) condi- tions. See Tables 5-7 for unit airflows. When fully closed, the sheave will produce the highest static capability (higher rpm).

To adjust sheave position, follow the procedure outlined below:

1.Loosen belt tension and remove belt.

2.Loosen set screw on fan motor.

3.Open sheave to desired position.

4.Retighten set screw and replace belt. NOTE: Set belt tension as outlined below.

BELT TENSION ADJUSTMENT — An overly loose belt will, upon starting motor, produce a slippage “squeal” and cause premature belt failure and or intermittent airflow. An overly tight belt can cause premature motor or blower bear- ing failure. To adjust the belt tension, follow the procedure outlined below:

1.Remove belt from motor sheave.

2.Lift motor assembly.

3.Loosen the 5/16-in. hex nuts on the grommet motor adjust- ment bolts (2 per bolt). To increase the belt tension loosen the top hex nut. To decrease the belt tension loosen the bottom hex nut.

4.Turn the bolts by hand to the desired position then tighten the 5/16-in. hex nuts (2 per bolt).

5.Lower the motor assembly.

6.Install the belt.

7.The belt tension can be adjusted by using one of the fol- lowing methods:

a.Tighten until belt deflects approximately 13 mm with very firm finger pressure.

b.Grasp belt midway between two pulleys and twist for a 90-degree rotation.

NOTE: Adjusting less than 90 degrees will over- tighten the belt and adjusting more than 90 degrees will loosen belt.

c.Set proper belt tension to 32 to 36 kg.

NOTE: The motor position should not need adjustment. Motor sheave position is at mid position of each sheave. For example, the motor sheave is 2.5 turns open on a 5-turn sheave. The belt tension adjustment can also be accomplished by turning the 5/16-in. hex nuts to the desired position.

NOTE: Available airflows for all units are shown in Tables 5-7.

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