Bryant 702B Manual de usuario descargar pdf (Pagina 10)

—10—

I Determine cooling and heating requirements at design

conditions:

Given:

Required Cooling Capacity (TC). . . . . . . . . . . 33,500 Btuh

Sensible Heat Capacity (SHC) . . . . . . . . . . . . 24,500 Btuh

Required Heating Capacity . . . . . . . . . . . . . . 15,000 Btuh

Condenser Entering Air Temperature . . . . . . . . . . . . 95°F

Indoor-Air Temperature . . . . . . . . . . . 80°F edb, 67°F ewb

Evaporator Air Quantity . . . . . . . . . . . . . . . . . . . .1200 cfm

External Static Pressure. . . . . . . . . . . . . . . . . . . 0.2 in. wg

Electrical Characteristics . . . . . . . . . . . . . . . . . . .230-1-60

II Select unit based on required cooling capacity.

Enter Cooling Capacities table at condenser entering

temperature of 95°F. The 702B036 unit at 1200 cfm and

67°F ewb (entering wet bulb) will provide a total capacity of

35,000 Btuh and a SHC of 26,000 Btuh. Calculate SHC

correction, if required, using Note 4 under Cooling

Capacities tables.

III Select electric heat.

The required heating capacity is 15,000 Btuh (given).

Determine the electric heat capacity in kW.

15,000 Btuh

3414 Btuh/kW

Enter the Electric Heater Packages table for 208/240,

single-phase, 702B036 unit. The 5-kW heater at 240v most

closely satisfies the heating required. To calculate kW at

208v, multiply the heater kW by multiplication factor 0.75

found in the Wattage Multiplication Factors table.

5 kW x 0.75 = 3.75 kW

3.75 kW x 3414 Btuh/kW = 12,802.50 Btuh

IV Determine fan speed and power requirements at design

conditions.

Before entering the air delivery tables, calculate the total

static pressure required. From the given, Filter Pressure

Drop table, and the Accessory Electric Heat Pressure Drop

table, find:

External static pressure 0.200 in. wg

Filter 0.130 in. wg

Total static pressure 0.330 in. wg

Enter the table for Wet Coil Air Delivery — (230 and 460 V.)

At 0.33 in. wg external static pressure and low speed, the

motor delivers 1228 cfm, and 440 watts.

V Select unit that corresponds to power source available.

The Electrical Data table shows that the unit is designed to

operate at 208/230-1-60.

= 4.4 kW of heat required

SELECTION PROCEDURE (WITH EXAMPLE)

Small Base Large Base

Model 50GL 024

030 036 042 048 060

Corner Weight #1 76 84 85 71 78 85

Corner Weight #2 49 60 60 55 56 66

Corner Weight #3 57 61 64 85 80 108

Corner Weight #4 88 86 90 110 112 140

Total Weight 270 291 299 321 326 399

702B Corner weights (In Pounds)

1 2 ... 5 6 7 8 9 10 11 12 13 14 15 ... 27 28

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Bryant 702B Manual de usuario Pagina 10

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