Mechanical (cont'd), 2 venting (cont'd), 2 venting requirements (cont'd) – Reznor B Unit Installation Manual User Manual
Page 18: Figure 16 - venting arrangement without vent run, Vent run length table

Form I-F/B, P/N 98126 R21, Page 18
Reznor Vent Cap
24 (610mm)
Minimum
3 ft (1M)
Minimum
Double-wall or
single-wall pipe
Roof jack
Double-wall
pipe
Tee or elbow
(cap lower
run of tee if
used)
Slope at least
1/4 per foot
(6mm per
305mm)
upward
Double-wall or
single-wall pipe
Reznor Vent Cap
24 (610mm)
Minimum
3 ft (1M)
Minimum
Roof jack
Single-wall pipe
Use thimble
through
the ceiling.
Double-wall or
single-wall pipe
Slope at least
1/4 per foot
(6mm per
305mm) upward
Tee or elbow
(cap lower run
of tee if used)
FIGURE 15 - Venting Arrangement with Vent
Run (no ceiling)
FIGURE 14 - Venting Arrangement with Vent Run
and through a Ceiling
Reznor Vent Cap
3ft (1M)
Minimum
24 (610mm)
Minimum
Double-wall
pipe
Roof jack
Double-wall or
single-wall pipe
FIGURE 16 - Venting Arrangement
without Vent Run
9. If the unit heater is installed in a space served by a large exhaust fan, be sure that
the exhaust fan does not affect the operation of the heater or the satisfactory vent-
ing of its products of combustion.
If a negative pressure exists, as evidenced by a downdraft, a factory-designed
mechanical motor driven venter (Option CA) should be installed. (The addition of
a power venter allows for horizontal venting and alters the venting requirements
including the vent pipe size and length. For additional installation information on an
optional power venter, refer to Paragraph
6.2.4. Complete information is included
in the venter package.)
In severe negative pressure conditions, makeup air equipment may be necessary.
6.2.2 Venting
Requirements (cont'd)
6. Mechanical
(cont'd)
6.2 Venting (cont'd)
Model Sizes
25/50
75
100
125
165/200
250/300
400
Vertical
Height of Vent
Vent Diameter
4"
5"
6"
7"
8"
10"
12"
Maximum Horizontal Run Length using Double Wall Type B Connector and Double-Wall Type B Vent
7 ft (2.1M)
2 ft
.6M
6 ft
1.8M
6 ft
1.8M
6 ft
1.8M
6 ft
1.8M
6 ft
1.8M
6 ft
1.8M
9 ft (2.7M)
6 ft 1.8M
6 ft
1.8M
7 ft
2.1M 16 ft 4.9M 16 ft 4.9M 16 ft 4.9M 16 ft 4.9M
10 ft (3M)
8 ft 2.4M 10 ft
3M
16 ft 4.9M 20 ft 6.1M 20 ft 6.1M 20 ft 6.1M 20 ft 6.1M
15 ft (4.6M)
12 ft 3.7M 16 ft 4.9M 16 ft 4.9M 30 ft 9.1M 30 ft 9.1M 30 ft 9.1M 30 ft 9.1M
20 ft (6.1M)
16 ft 4.9M 20 ft 6.1M 30 ft 9.1M 30 ft 9.1M 30 ft 9.1M 30 ft 9.1M 30 ft 9.1M
30 ft (9.1M)
18 ft 5.5M 20 ft 6.1M 40 ft 12.2M 40 ft 12.2M 40 ft 12.2M 40 ft 12.2M 40 ft 12.2M
Maximum Horizontal Run Length using Single Wall Metal Pipe
6 ft (1.8M
2 ft
.6M
2 ft
.6M
2 ft
.6M
2 ft
.6M
2 ft
.6M
2 ft
.6M
2 ft
.6M
8 ft (2.4M)
2 ft
.6M
5 ft
1.5M
5 ft
1.5M 10 ft
3M
10 ft
3M
10 ft
3M
10 ft
3M
10 ft (3M)
2 ft
.6M
5 ft
1.5M 10 ft
3M
15 ft 4.6M 15 ft 4.6M 15 ft 4.6M 15 ft 4.6M
15 ft (4.6M)
2 ft
.6M
5 ft
1.5M 10 ft
3M
15 ft 4.6M 20 ft 6.1M 20 ft 6.1M 20 ft 6.1M
20 ft (6.1M)
N.R.
10 ft
3M
15 ft 4.6M 20 ft 6.1M 20 ft 6.1M 20 ft 6.1M
Vent Run Length Table