Bryant 569J manual Selection Procedure, Controls, Operating sequences

SELECTION PROCEDURE

Combination ratings for 569J* units matched with 524J Series air handlers are in this book. If unit is used with an air handler, use the Bryant Electronic Catalog AHU (Air-Handling Unit) selection program to obtain combined ratings.

I. Determine cooling load, evaporator-air temperature, and quantity.

Given:

Total Cooling Capacity

Required (TC) . . . . . . . . . . . . . . . . . . . 121,000 Btuh

Sensible Heat Capacity

Required (SHC) . . . . . . . . . . . . . . . . . . . 95,000 Btuh Compressor Type . . . . . . . . . . . . . . . . . . . . . . . . . Scroll

Temperature Air Entering

Condenser (Edb) . . . . . . . . . . . . . . . . . . . . . . . . . 95_F

Temperature Air Entering

Evaporator (db/wb) . . . . . . . . . . . . 80_F db, 67_F wb Evaporator Air Quantity . . . . . . . . . . . . . . . . . 4,000 cfm External Static Pressure . . . . . . . . . . . . . . . . . 0.4 in. wg

Length of Interconnecting

Refrigerant Piping . . . . . . . . . . . . . . . . . 25 ft (Linear) Power Supply (V-Ph-Hz) . . . . . . . . . . . . . 208/230-3-60

II.Select condensing unit air-handler combination.

For this example, select a 569J*12 matched with a 524J012 coil. This 569J*12/524J12 condensing unit air-handler combination provides 122,000 Btuh of total cooling capacity and 97,200 Btuh of sensible capacity at the given conditions. If other temperatures or airflow values are required, interpolate the values from the combination ratings.

III. Determine sizes of liquid and suction lines.

Enter Refrigerant Piping Sizes table. The sizes shown are based on an equivalent length of pipe. This equivalent length is equal to the linear length of pipe indicated at the top of each sizing column, plus a 50% allowance for fitting losses. (For a more accurate determination of actual equivalent length in place of using the estimated 50% value, refer to Bryant System Design Manual.) For this example, note in the linear length column that the proper pipe size is 1/2 in. for the liquid line and 13/8 in. for the suction line.

For extended line lengths over 100 feet, contact your Bryant representative or application engineer.

IV. Determine fan rpm and bhp (brake horsepower).

Refer to the 524J Air Handler Catalog - Fan Performance table. Enter the Air Handler Fan Performance table at 524J12 at 4000 cfm and move to the External Static Pressure (ESP) column. Note that the conditions require 803 rpm at 1.77 bhp.

V.Determine motor and drive.

Enter the Fan Motor Data tables and find the standard motor for 524J12 unit rated at 2.4 Hp. Since the bhp required is 1.77, a standard motor satisfies the requirement and should be used.

Next, find the type of drive that satisfies the 803 rpm requirement in the Drive Data tables. For the 524J012 unit, the Standard Drive table shows an rpm range of 666-863. Since the rpm required is 803, the standard drive satisfies the requirement and should be used.

CONTROLS

Operating sequences

When the wall thermostat calls for cooling, terminals G and Y1 are energized. As a result, the indoor fan contactor (IFC) and the compressor contactor (C1) are energized, causing the indoor fan motor (IFM), compressor #1, and outdoor fans (OFM) to start. The field-supplied and field-installed liquid line valve also opens, allowing the system to function in Cooling mode.

If the unit has 2 stages of cooling, the wall thermostat will additionally energize Y2. The Y2 signal will energize compressor contactor #2 (C2), causing compressor #2 to start.

Regardless of the number of stages, the field-supplied liquid line valve shall opens and the outdoor fan motors(OFM) runs continuously while unit is cooling.

When cooling demand decrease, the thermostat will de-energize Y2. Y2 signal will de-energize compressor contactor #2 (C2), causing compressor #2 to stop.

When cooling demand has been satisfied, the thermostat will de-energize Y1, and G terminals. Y1 and G signal will de-energize compressor contactor #1 (C1), causing compressor #1 to stop. If the wall thermostat is set to continuous (CONT), the indoor fan motor will continue to operate. Otherwise, the indoor fan motor will stop.

The outdoor fan motors (OFM) will turn off and field-supplied liquid line valve shall close , minimizing the potential for refrigerant migration.

569J

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