5715184-BIM-A-0519
Johnson Controls Ducted Systems
17
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 or MH application. It may be installed without modification to the
condensate system in a basement, garage, equipment room, alcove,
attic or any other indoor location where all required clearance to com-
bustibles and other restrictions are met. The combustion air and the
venting system must be installed in accordance with Section 5.3, Air for
Combustion 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 provi-
sions 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 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 reduce the total length of
pipe that is allowed. Short radius (plumbing or pressure) elbows are
not allowed for venting. The standard dimensions of the acceptable
elbows are shown in Figure 21.
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 ft for a particular model, then the vent can
have 65 equivalent ft of pipe, AND the combustion air intake can
have another 65 equivalent ft 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 combustion air and vent pipe must conform to American
National Standards Institute (ANSI) and American Society for Test-
ing 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 venting 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
temperature. Flexible connectors are also allowed in the combus-
tion air pipe.
6.
All models are supplied with 2 in. vent connections. When the pipe
must be increased to 3 in. 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 a vertical position to avoid creating an
area that pools water.
7.
In Canada, vents shall be certified to ULC S636, Standard for Type
BH Gas Venting Systems.
8.
In Canada, the first 3 ft (900 mm) of the vent must be readily acces-
sible for inspection.
9.
For single pipe systems it is recommended to install the combustion
air coupling provided and install approximately 18 in. of PVC pipe
on the furnace.
10. Minimum vent length for all models is 5 ft.
IMPORTANT:
The VENT SYSTEM must be installed as specified in
these instructions for Manufactured (Mobile) Home and Modular
Homes. The sealed combustion air/vent system is the only configu-
ration that can be installed in a Manufactured (Mobile) Home.
WARNING
Vertical vent termination must be secured for transit.
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 sep-
arate 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 must be
insulated with 1/2 in. Armaflex or other heat resistant type insulation
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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