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LDAP-IOM (01-22) 207733-A
Table 10. Vent Pipe Diameters and Lengths
Unit Size
Venter Outlet
Diameter
Vent Pipe
Diameter
Maximum Vent
Length
*
Equivalent Straight Length
**
Venter Outlet
Connection
***
90-Degree Elbow 45-Degree Elbow
Inches (mm)
Feet (Meters)
Inches (mm)
400
6 (152)
6 (152)
45 (13 .7)
15 (4 .6)
7 .5 (2 .3)
—
7 (178)
60 (18 .3)
8 (2 .4)
4 (1 .2)
6–7 (152–178)
800
8 (203)
8 (203)
50 (15 .2)
15 (4 .6)
7 .5 (2 .3)
—
10 (254)
45 (13 .7)
5 (1 .5)
2 .5 (0 .8)
8–10 (203–254)
1200
8 (203)
8 (203)
50 (15 .2)
15 (4 .6)
7 .5 (2 .3)
—
10 (254)
45 (13 .7)
5 (1 .5)
2 .5 (0 .8)
8–10 (203–254)
*
Includes one 90° elbow at venter outlet .
**
Add all straight sections and equivalent lengths for elbows—the total combined length must not exceed the maximum vent length .
***
Field-supplied taper-type increaser connection required at the venter outlet .
Vent Pipe Type
The type of vent pipe is determined by whether the vent is horizontal or vertical:
• Horizontal:
approved for Category III appliance or appropriately sealed 26-gauge or heavier galvanized steel or
equivalent single-wall pipe
• Vertical:
approved for Category III appliance, appropriately sealed 26-gauge or heavier galvanized steel or equivalent
single-wall pipe, or if at least 75% of equivalent length of vent run is vertical, double-wall (Type B) vent pipe
Vent Pipe Size
•
Use only one diameter of vent pipe on an installation .
•
The minimum vent length is 3 feet (1 meter) .
•
A minimum of 1 foot (0 .3 meter) of vertical vent is required on the venter outlet before installing an elbow .
•
Vent pipe diameters and maximum vent lengths in
apply to both horizontal and vertical vents .
Vent System Sealing
Vent system joints depend on the type of pipe being used:
• Category III pipe:
follow manufacturer’s instructions for joining pipe sections—connect venter outlet or the vent
cap using secure, sealed joints that follow a procedure best suited to the style of Category III pipe being used .
• Single-wall galvanized pipe (26-gauge or heavier):
secure slip-fit connections using sheet metal screws or
rivets—seal all joints and seams inside the building using tape such as option FA1 (PN 98266) or high-temperature
silicone sealant .
• Double-wall Type B vent pipe:
join pipe sections in accordance with the pipe manufacturer’s requirement—refer
to the illustrated instructions in
to connect double-wall pipe to the heater collar, single-wall pipe, and
vent cap . Work quickly to assemble components before sealant dries .
NOTE: A double-wall pipe run is allowed only if at least 75% of the vent length is vertical.
