Bryant 702B - Manual (Page 10)

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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
4 3
x
y