Form I-UDB, P/N 202658 R10, Page 18
6.3 Unit Discharge
(cont’d)
6.0 Mechanical
(cont’d)
Size CFM at 60°F
Temp Rise
Polytube
Diameter
(inches)
Approximate
Free Area
(square inches)
Suggested Hole Sizes and Locations by Length
Polytube
Holes
Length of Polytube
50 Ft
75 Ft 100 Ft 125 Ft 150 Ft
75*
960
18
115
Quantity
75 pairs 75 pairs 75 pairs 75 pairs 75 pairs
Diameter
1"
1"
1"
1"
1"
Spacing
8"
12"
16"
20"
24"
100*
1345
18
160
Quantity
48 pairs 48 pairs 48 pairs 48 pairs 48 pairs
Diameter
1-1/2"
1-1/2"
1-1/2"
1-1/2"
1-1/2"
Spacing
12-1/2" 18-3/4"
25"
31-1/4" 37-1/2"
125*
1540
18
185
Quantity
50 pairs 50 pairs 50 pairs 50 pairs 50 pairs
Diameter
1-1/2"
1-1/2"
1-1/2"
1-1/2"
1-1/2"
Spacing
12"
18"
24"
30"
36"
150
1920
24
230
Quantity
40 pairs 40 pairs 40 pairs 40 pairs 45 pairs
Diameter
2"
2"
2"
2"
1-7/8"
Spacing
15"
22-1/2"
30"
37-1/2"
40"
175
2240
24
270
Quantity
50 pairs 50 pairs 80 pairs 80 pairs 80 pairs
Diameter
1-7/8"
1-7/8"
1-1/2"
1-1/2"
1-1/2"
Spacing
12"
18"
15"
18-3/4" 22-1/2"
200
2560
24
300
Quantity
50 pairs 50 pairs 50 pairs 50 pairs 50 pairs
Diameter
2"
2"
2"
2"
2"
Spacing
12"
18"
24"
30"
36"
225
2880
24
340
Quantity
42 pairs 42 pairs 42 pairs 42 pairs 42 pairs
Diameter
2-1/4"
2-1/4"
2-1/4"
2-1/4"
2-1/4"
Spacing
14"
21"
28"
35"
42"
250
3200
24
380
Quantity
50 pairs 50 pairs 50 pairs 60 pairs 60 pairs
Diameter
2-1/4"
2-1/4"
2-1/4"
2"
2"
Spacing
12"
18"
24"
25"
30"
300
3840
24
460
Quantity
60 pairs 60 pairs 75 pairs 75 pairs 75 pairs
Diameter
2-1/4"
2-1/4"
2"
2"
2"
Spacing
10"
15"
16"
20"
24"
350
4480
24
540
Quantity
50 pairs 50 pairs 50 pairs 50 pairs 50 pairs
Diameter
2-1/2"
2-1/2"
2-1/2"
2-1/2"
2-1/2"
Spacing
12"
18"
24"
30"
36"
400
5120
24
600
Quantity
60 pairs 60 pairs 75 pairs 75 pairs 75 pairs
Diameter
2-1/2"
2-1/2"
2-1/4"
2-1/4"
2-1/4"
Spacing
10"
15"
16"
20"
24"
6.4 Blowers, Belts,
and Drives
Blower Model
Sizes 30-125
are equipped with a direct drive motor. Blower Model
Sizes 150-400
have an adjustable belt drive.
Size 150-400 units are equipped with Power Twist Plus
®
blower belts. These belts are
designed in link sections allowing for easy sizing and adjustment. The belt is sized
at the factory for the proper tension. If the belt needs adjustment, the recommended
method of adjusting the belt length is to count the number of links and remove one
link for every 24. (A link is made up of two joining sections of belt. For easier removal
of links, turn the belt inside out. But be sure to turn it back before installing.) The belt
tension should be checked after the first 24 hours of running at full load and at regular
maintenance inspections. Proper belt tension is important to the long life of the belt
and motor.
The blower speed may be adjusted to achieve the desired outlet temperature, as long
as the adjustment is within the temperature rise and the static pressure limits shown on
the heater rating plate.
Direct drive
motors
are factory set as indicated in the chart on
page 19.
Belt drive motors
are factory set at the nominal temperature rise specified
for that unit.
6.4.1 Belt
6.4.2 Adjusting
Blower Speed
FIGURE 13 (cont’d) - Requirements for field-supplied Polytube Duct
