9
In the event that the pipe length is in between the lengths listed in
the Vent Table, use the next larger length listed. For example, if a
length of pipe needed to install the furnace is 27 ft (8.2 m), use
the diameter values for the 30 ft (9.1 m) row in the tables.
For direct vent installations, if the vent and air intake pipe are not
equal in length and number of elbows, then determine the
minimum pipe diameter for both the vent and air intake. If the
results indicate different diameters, use the larger of the two for
both the vent and air intake.
NOTE: Under no circumstances should the vent and air intake
pipe size be different in diameter. See “Plan Vent System” for the
furnace model and type of installation.
Determine Vent Pipe Direction
The vent system of the furnace must be self-supporting and must not apply any weight load to the combustion blower.
Combustion Air Sources
There are 2 sources for combustion air:
1. From outside the building (Direct Vent)
2. From inside the building (Nondirect Vent)
Please read the information provided here about Vertical and
Horizontal Venting, then find and follow the instructions for your
venting configuration.
Vertical Venting
A vertical vent should extend through the roof a minimum of 24"
(5.1 cm) and not be obstructed a minimum of 10 ft (3 m) in any
direction.
Horizontal Venting
The vent terminal location shall comply with the National Fuel
Gas Code (ANSI Z223.1) or local requirements. For informational
purposes, the side wall terminal vent clearances are shown in the
Sidewall Vent Terminal Clearances tables.
Vent Table—90,000 to 100,000 Btu/h Models
Vent Pipe Length—ft (m) Minimum Pipe Diameter—in. (cm)
5 (1.5)
NR
2 (5.1)
2 (5.1)
2 (5.1)
2 (5.1)
2 (5.1)
2 (5.1)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
10 (3)
2 (5.1)
2 (5.1)
2 (5.1)
2 (5.1)
2 (5.1)
2 (5.1)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
20 (6.1)
2 (5.1)
2 (5.1)
2 (5.1)
2 (5.1)
2 (5.1)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
3" (7.6)
30 (9.1)
2 (5.1)
2 (5.1)
2 (5.1)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
3 (7.6)
3 (7.6)
3 (7.6)
40 (12.2)
2 (5.1)
2 (5.1)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
50 (15.2)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
NR
60 (18.3)
2
¹⁄₂
(6.4)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
NR
NR
NR
70 (21.3)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
3 (7.6)
NR
NR
NR
NR
NR
80 (24.4)
3 (7.6)
3 (7.6)
3 (7.6)
NR
NR
NR
NR
NR
NR
NR
90 (27.4)
3 (7.6)
3 (7.6)
NR
NR
NR
NR
NR
NR
NR
NR
Number of 90° Elbows
0
1
2
3
4
5
6
7
8
9
NR = Not Recommended
Vent Table—112,000 to 125,000 Btu/h Models
Vent Pipe Length—ft (m) Minimum Pipe Diameter—in. (cm)
5 (1.5)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
10 (3)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
3 (7.6)
20 (6.1)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
3 (7.6)
3 (7.6)
NR
30 (9.1)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
3 (7.6)
3 (7.6)
NR
NR
NR
40 (12.2)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
2
¹⁄₂
(6.4)
3 (7.6)
NR
NR
NR
NR
NR
50 (15.2)
2
¹⁄₂
(6.4)
3 (7.6)
3 (7.6)
NR
NR
NR
NR
NR
NR
NR
60 (18.3)
3 (7.6)
3 (7.6)
NR
NR
NR
NR
NR
NR
NR
NR
Number of 90° Elbows
0
1
2
3
4
5
6
7
8
9
NR = Not Recommended
Summary of Contents for WFCT
Page 31: ...31 Notes ...
