1083163-UIM-J-0918
Johnson Controls Unitary Products
19
SECTION VII: COMBUSTION AIR AND
VENT SYSTEM
COMBUSTION AIR AND VENT SAFETY
This Category IV, dual certified direct vent furnace is designed for resi-
dential application. It may be installed without modification to the con-
densate system in a basement, garage, equipment room, alcove, attic
or any other indoor location where all required clearance to combusti-
bles and other restrictions are met. The combustion air and the venting
system must be installed in accordance with Section 5.3, Air for Com-
bustion and Ventilation, of the National Fuel Gas Code Z223.1/NFPA 54
(latest edition), or Sections 7.2, 7.3 or 7.4 of CSA B149.1, National Gas
and Propane Codes (latest edition) or applicable provisions of the local
building code and these instructions.
COMBUSTION AIR/VENT PIPE SIZING
The size of pipe required will be determined by the furnace model, the
total length of pipe required and the number of elbows required.
Table 6 lists the maximum equivalent length of pipe allowed for each
model of furnace. The equivalent length of pipe for each elbow installed
is listed in Table 9. The equivalent length of the vent system is the total
length of straight pipe PLUS the equivalent length of all of the elbows.
The following rules must also be followed:
1. Drain, waste, and vent (DWV) elbows with a long radius (sweep)
are recommended. Standard DWV elbows may be used, but since
they have a longer equivalent length, they will reduce the total
length of pipe that will be allowed. Short radius (plumbing or pres-
sure) elbows are not allowed for venting. The standard dimensions
of the acceptable elbows are shown in Figure 20.
2. The maximum equivalent length listed in Table 6 is for the vent pip-
ing and the air intake piping separately. For example, if the table
allows 65 equivalent feet for a particular model, then the vent can
have 65 equivalent feet of pipe, AND the combustion air intake can
have another 65 equivalent feet of pipe.
3. Three vent terminal elbows (two for the vent and one for the com-
bustion air intake) are already accounted for and need not be
included in the equivalent length calculation.
4. All PVC or ABS combustion air and vent pipe must conform to
American National Standards Institute (ANSI) and American Soci-
ety for Testing and Materials (ASTM) standards D1785 (Schedule
40 PVC), D2665 (PVC-DWV), F891 (PVC-DWV Cellular Core),
D2261 (ABS-DWV) or F628 (Schedule 40 ABS). Pipe cement and
primer must conform to ASTM Standard D2546 (PVC) or D2235
(ABS). If ABS pipe is to be used, any joint where ABS pipe is joined
to PVC pipe must be glued with cement that is approved for use
with BOTH materials. Metallic materials must not be used for vent-
ing or air intake.
5. If a flexible connector is used in the vent system, it must be made of
a material that is resistant to acidic exposure and to at least 225°F
(107°C) temperature. Flexible connectors are also allowed in the
combustion air pipe.
6. All models are supplied with 2" (5.1 cm) vent connections. When
the pipe must be increased to 3" (7.6 cm) diameter, the transition
from 2" to 3" must be done as close to the furnace as possible. The
2” to 3” increase should be installed in the vertical position as to not
create an area that will pool water.
7. In Canada, vents shall be certified to ULC S636, Standard for Type
BH Gas Venting Systems.
8. In Canada, the first three feet (91.4 cm) of the vent must be readily
accessible for inspection.
9. For single pipe systems it is recommended to install the combustion
air coupling provided and install approximately 18” (46 cm) of PVC
pipe on the furnace.
10. Minimum vent length for all models is 5 feet (1.5 m).
POLYPROPYLENE VENT/INTAKE PIPING
The ULC S636 approved polypropylene (PP) vent piping materials
listed below have been tested and approved for use with this furnace.
DO NOT mix parts made by different manufacturers. The entire vent/air
intake system must be made from pipe, fittings and termination made
by the same manufacturer. Only single-wall rigid polypropylene pipe is
approved for these furnaces. Use of flexible polypropylene pipe is not
allowed.
Selkirk Polyflue (Hart & Cooley) part numbers
• Horizontal concentric termination - 2" - 2PF-HCT
• Horizontal concentric termination - 3" - 3PF-HCT
• Locking band - PF-LB
Consult the Polyflue installation instructions for assembly details.
For other Polyflue pipe and fitting part numbers, visit website
www.polyflue.com
Duravent Polypro part numbers
• Adapter to air intake coupling - 2PPS-ADL
• Adapter connector - PPS-PAC
• Twin pipe horizontal termination - 2" - 2PPS-HTPL
• Twin pipe horizontal termination - 3" - 3PPS-HTPL
Consult the Polypro installation instructions for assembly details.
For other Polypro pipe and fitting part numbers, visit website
www.duravent.com
Centrotherm Innoflue
• Adapter to air intake coupling - ISAGL0202
• Adapter to draft inducer blower - ISAAL0202
• Low profile wall termination - 2" - ISLPT0202
• Low profile wall termination - 3" - ISLPT0303
Consult the Innoflue installation instructions for assembly details.
For other Innoflue pipe and fitting part numbers, visit website
www.centrotherm.us.com
IMPORTANT
The “VENT SYSTEM” must be installed as specified in these instruc-
tions for Residential and non-HUD Modular Homes. The direct vent
system is the only configuration that can be installed in a non-HUD
Modular Home.
WARNING
This furnace may not be common vented with any other appliance,
since it requires separate, properly sized air intake and vent lines.
The furnace shall not be connected to any type of B, BW or L vent or
vent connector, and not connected to any portion of a factory-built or
masonry chimney.
The furnace shall not be connected to a chimney flue serving a sepa-
rate appliance designed to burn solid fuel.
CAUTION
When combustion air pipe is installed above a suspended ceiling or
when it passes through a warm and humid space, the pipe may need
insulated if two feet or more of pipe is exposed.
Vent piping must be insulated if it will be subjected to freezing tem-
peratures such as routing through unheated areas or through an
unused chimney.
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