10
50JX Corner weights ( In Pounds)
I Determine cooling and heating requirements at design
conditions:
Given:
Required Cooling Capacity (TC) . . . . . . . . . . 28,000 Btuh
Sensible Heat Capacity (SHC). . . . . . . . . . . . 20,500 Btuh
Required Heating Capacity . . . . . . . . . . . . . . 28,550 Btuh
Outdoor Entering Air Temperature . . . . . . . . . . . . . . 95°F
Outdoor-Air Winter Design Temperature . . . . . . . . . 20°F
Indoor-Air Winter Design Temperature . . . . . . . . . . 70°F
Indoor Entering-Air Temperature . . . . . . . . . . . .80°F edb
67°F ewb
Indoor-Air Quantity . . . . . . . . . . . . . . . . . . . . . . 1125 cfm
External Static Pressure . . . . . . . . . . . . . . . . . . 0.20 in. wg
Electrical Characteristics (V-Ph-Hz) . . . . . . . . . .230-1-60
edb — entering dry bulb
ewb — entering wet bulb
II Select unit based on required cooling capacity.
Enter Cooling Extended Performance table at outdoor
entering-air temperature of 95°F, indoor air entering at
1125 cfm and 67°F ewb (entering wet bulb). The unit will
provide a total cooling capacity of 30,900 Btuh and a
sensible heat capacity of 24,800 Btuh.
For indoor-air temperature other than 80°F edb (entering
dry bulb), calculate sensible heat capacity correction, as
required, using the formula found in Note 3 following the
cooling capacities tables. NOTE: Unit ratings are net
capacities.
III Select electric heat.
Enter the unit Heating Extended Performance table at 1125
cfm. At 70°F return indoor air and 20°F air entering
outdoor coil, the integrated heating capacity is 16,200 Btuh.
(Select integrated heating capacity value since deductions
for outdoor-coil frost and defrosting have already been
made. No correction is required.)
The required heating capacity is 28,550 Btuh. Therefore,
12,350 Btuh (28,550 – 16,200) additional electric heat is
required.
Determine additional electric heat capacity in kW.
12,350 Btuh
3414 Btuh/kW
Enter the Electric Heater table on page 5 for 208/230 v,
single-phase, unit. The 5-kW heater at 240 v most closely
satisfies the heating required. To calculate kW at 230 v,
multiply the heater kW by multiplication factor 0.92 found
in the Multiplication Factors table on page 17.
5 kW x 0.92 = 4.6 kW
4.6 kW x 3414 = 15,704 Btuh
Total unit heating capacity is 31,900 Btuh (16,200 +
15,704).
IV Determine fan speed and power requirements at design
conditions.
Before entering the air delivery tables, calculate the total
static pressure required.
= 3.6 kW of heat required
Selection Procedure (with example)
1
2
4
3
x
y
CORNER WEIGHTS (Small Cabinet)
CORNER WEIGHTS (Large Cabinet)
Unit
24
30
36
—
—
Unit
42
48
60
Total Weight (lbs.)
299
320
328
—
—
Total Weight (lbs.)
350
375
428
Corner Weight 1
63
63
64
—
—
Corner Weight 1
75
81
92
Corner Weight 2
62
74
76
—
—
Corner Weight 2
49
52
60
Corner Weight 3
56
56
58
—
—
Corner Weight 3
95
102
116
Corner Weight 4
118
127
130
—
—
Corner Weight 4
131
140
160
Model 50JX
