Table 1 — Specifications
BASE UNIT 551B
036
048
060
072
NOMINAL CAPACITY (tons)
3
4
5
6
OPERATING WEIGHT (lb)
Unit
435
445
465
520
With Varislide™ Economizer
469
479
499
554
With PARABLADE Economizer
477
487
507
562
Roof Curb
115
115
115
115
COMPRESSOR
Scroll
Quantity
1
1
1
1
Oil (oz)
42
53
50
60
REFRIGERANT TYPE
R-22
Operating Charge (lb-oz)
5-8
8-6
10-0
9-10
CONDENSER FAN
Propeller Type
Qty...Diameter (in.)
1...22.0
1...22.0
1...22.0
1...22.0
Nominal Cfm
3000
3000
4000
4000
Motor Hp...Rpm
1
⁄
8
...825
1
⁄
8
...825
1
⁄
4
...1100
1
⁄
4
...1100
Watts Input (Total)
450
450
450
450
CONDENSER COIL
High-Efficiency Enhanced Copper Tubes, Lanced Aluminum Fins
Rows...Fins/in.
1...17
2...17
2...17
2...17
Total Face Area (sq ft)
14.58
16.53
16.53
16.53
EVAPORATOR FAN
Centrifugal Type, Belt Drive
Qty...Size (in.)
1...10 x 10
1...10 x 10
1...10 x 10
1...10 x 10
Nominal Cfm
1200
1600
2000
2400
Maximum Continuous Bhp
1.20
1.20
1.80
2.40
Motor Frame
48
48
56
56
Fan Rpm Range (Nominal)
760-1090
840-1185
1020-1460
1120-1585
Motor Bearing Type
Ball
Ball
Ball
Ball
Maximum Fan Rpm
2100
2100
2100
2100
Motor Pulley Pitch Diameter A/B (in.)
1.9/2.9
1.9/2.9
2.4/3.4
2.4/3.4
Nominal Motor Shaft Diameter (in.)
1
⁄
2
1
⁄
2
1
⁄
2
5
⁄
8
Fan Pulley Pitch Diameter (in.)
4.5
4.0
4.0
3.7
Belt, Qty...Type...Length (in.)
1...A...33
1...A...36
1...A...40
1...A...38
Pulley Center Line Distance (in.)
10.0-12.4
10.0-12.4
14.7-15.5
14.7-15.5
Speed Change per Full Turn of
Movable Pulley Flange (rpm)
65
70
75
93
Movable Pulley Maximum Full Turns
From Closed Position
5
5
6
5
Factory Setting — Full Turns Open
3
3
3
3
Factory Speed Setting (rpm)
890
980
1240
1305
Fan Shaft Diameter at Pulley (in.)
5
⁄
8
5
⁄
8
5
⁄
8
5
⁄
8
EVAPORATOR COIL
High-Efficiency Enhanced Copper Tubes, Aluminum Double-Wavy Fins,
Acutrol™ Feed Device
Rows...Fins/in.
2...15
2...15
4...15
4...15
Total Face Area (sq ft)
5.5
5.5
5.5
5.5
HIGH-PRESSURE SWITCH (psig)
Standard Compressor Internal Relief (Differential)
450 ± 50
Cutout
428
Reset (Auto.)
320
LOSS-OF-CHARGE/LOW-PRESSURE
SWITCH (Liquid Line)(psig)
Cutout
7 ± 3
Reset (Auto.)
22 ± 7
FREEZE-PROTECTION THERMOSTAT
Opens (F)
30
Closes (F)
45
OUTDOOR-AIR INLET SCREENS
Cleanable
Qty...Size (in.)
1...20 x 24 x 1
RETURN-AIR FILTERS
Throwaway
Qty...Size (in.)
2...16 x 25 x 2
LEGEND
Bhp — Brake Horsepower
—6—
Summary of Contents for 551B Series
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