Specifications

14
Nondirect Vent Applications
Refer to the following tables for applicable length, elbows and pipe diameter for construction of the vent/flue pipe systems of a
nondirect vent (single pipe) installation. In addition to the vent/flue pipe, a single 90º elbow should be secured to the combustion air
intake to avoid inadvertent blockage. The tee used in the vent/flue termination must be included when determining the number of
elbows in the piping system.
NOTES:
■ One 90º elbow should be secured to the combustion air
intake connection.
■ Minimum length of each vent/flue pipe is 5 ft (1.5 m) and one
elbow/tee.
■ Tee used in the vent/flue termination must be included when
determining the number of elbows in the piping system.
■ 2¹⁄₂" (6.4 cm) or 3" (7.6 cm) diameter pipe can be used in
place of 2" (5.1 cm) diameter pipe.
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.
Nondirect Vent (Single Pipe) Maximum Allowable Length of Vent/Flue Pipe—ft (m)
Number of Elbows
Models (kBtu_Tons) Pipe Size—in. (cm) 2 3 4 5 6 7 8
045_3 2 or 2¹⁄₂ (5.12 or 6.4) 68 (20.7) 65 (19.8) 62 (18.9) 59 (18) 56 (17.1) 53 (16.2) 50 (15.2)
070_3 2 or 2¹⁄₂ (5.12 or 6.4) 68 (20.7) 65 (19.8) 62 (18.9) 59 (18) 56 (17.1) 53 (16.2) 50 (15.2)
070_4 2 or 2¹⁄₂ (5.12 or 6.4) 46 (14) 43 (13.1) 40 (12.2)
Not Recommended
070_4 3 (7.6) 68 (20.7) 65 (19.8) 62 (18.9) 59 (18) 56 (17.1) 53 (16.2) 50 (15.2)
090$ 2 or 2¹⁄₂ (5.12 or 6.4) 16 (4.9) 13 (4) 10 (3)
Not Recommended
3 (7.6) 68 (20.7) 65 (19.8) 62 (18.9) 59 (18) 56 (17.1) 53 (16.2) 50 (15.2)
090_5 3 (7.6) 68 (20.7) 65 (19.8) 62 (18.9) 59 (18) 56 (17.1) 53 (16.2) 50 (15.2)
115_5 3 (7.6) 68 (20.7) 65 (19.8) 62 (18.9) 59 (18) 56 (17.1) 53 (16.2) 50 (15.2)