5894307-UIM-B-0920
Johnson Controls Ducted Systems
15
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 can 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 is determined by the furnace model, the total
length of pipe required, and the number of elbows required.
Table 5 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 7.
Note:
The equivalent length of the vent system is the total length of
straight pipe plus the equivalent length of all of the elbows.
Adhere to the following rules:
• Drain, waste, and vent (DWV) elbows with a long radius (sweep)
are recommended. Standard DWV elbows can be used, but
because they have a longer equivalent length, they reduce the
total length of pipe that is allowed. Short radius (plumbing or pres-
sure) elbows are not allowed for venting. The standard dimen-
sions of the acceptable elbows are shown in Figure 18.
• The maximum equivalent length listed in Table 5 is for the vent
piping and the air intake piping separately. For example, if the
table allows 65 equivalent ft for a particular model, the vent can
have 65 equivalent ft of pipe, and the combustion air intake can
have another 65 equivalent ft of pipe.
• Three vent terminal elbows (two for the vent and one for the com-
bustion air intake) are already accounted for and do not need to
be included in the equivalent length calculation.
• 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 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 venting or air intake.
• 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.
• All models are supplied with 2 in. (5.1 cm) vent connections.
When the pipe must be increased to 3 in. (7.6 cm) diameter, the
transition from 2 in. to 3 in. must be done as close to the furnace
as possible. The 2 in. to 3 in. increase must be installed in the
vertical position to avoid creating an area that pools water.
• In Canada, vents must be certified to ULC S636, Standard for
Type BH Gas Venting Systems.
• In Canada, the first 3 ft (91.4 cm) of the vent must be readily
accessible for inspection.
• For single-pipe systems, it is best practice to install the combus-
tion air coupling provided and install approximately 18 in. (46 cm)
of PVC pipe on the furnace.
• The minimum vent length for all models is 5 ft (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 in. - 2PF-HCT
• Horizontal concentric termination - 3 in. - 3PF-HCT
• Locking band - PF-LB
Consult the Polyflue installation instructions for assembly details. For
other Polyflue pipe and fitting part numbers, visit
www.polyflue.com
.
Duravent Polypro part numbers
• Adapter to air intake coupling - 2PPS-ADL
• Adapter connector - PPS-PAC
• Twin pipe horizontal termination - 2 in. - 2PPS-HTPL
• Twin pipe horizontal termination - 3 in. - 3PPS-HTPL
Consult the Polypro installation instructions for assembly details. For
other Polypro pipe and fitting part numbers, visit
www.duravent.com
.
Centrotherm Innoflue part numbers
• Adapter to air intake coupling - ISAGL0202
• Adapter to draft inducer blower - ISAAL0202
• Low profile wall termination - 2 in. - ISLPT0202
• Low profile wall termination - 3 in. - ISLPT0303
Consult the Innoflue installation instructions for assembly details.
For other Innoflue pipe and fitting part numbers, visit
www.centrotherm.us.com
.
IMPORTANT:
The vent system must be installed as specified in
these instructions 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 2 ft 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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