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INSTALLATION INSTRUCTIONS
Venting for Direct-Vent Water Heater (cont.)
The system will not operate if there is excessive
restriction (pressure drop) in the venting system. Use
the chart above to calculate the maximum pipe run
length with the required number of elbows.
The vent termination does not count as part of the
straight pipe equivalent when determining the total vent
length.
Minimum Vent Length:
Exhaust
Air Intake
All intake and exhaust common venting components
must have the same diameter size. DO NOT use
a different size on the intake and exhaust common
venting.
The unit may be vented horizontally through a wall
or vertically through the roof. Pipe runs must be
adequately supported along both vertical and horizontal
runs. Maximum unsupported span is recommended
to be no more than 39" (1 m) horizontally or 78" (2 m)
vertically. It is imperative that the first hanger be located
on the horizontal runs immediately adjacent to the
first 87-degree elbow from the vertical rise. Only use
support isolation hanging bands. DO NOT use wire to
support pipe runs.
Stress levels in the pipe and fittings can be significantly
increased by improper installation. If rigid pipe clamps
are used to hold the pipe in place, or if the pipe cannot
move freely through a wall penetration, the pipe may
be directly stressed, or high thermal stresses may be
formed when the pipe heats up and expands. Install
accordingly to minimize such stresses.
14
8" Common
Vent
One 87 Degree Elbow +
Termination
One 87 Degree Elbow
Preexisting Venting Notes:
If the water heater is being installed as a replacement
for an existing water heater, a thorough inspection of
the existing venting and air intake system must be
performed prior to any installation work. Verify that the
correct materials, vent lengths, and terminal locations
as described in this manual have been met. Carefully
inspect the entire venting and air intake system for
any signs of cracks or fractures, particularly at the
joints between elbows or other fittings and the straight
runs of vent pipe. Check the system for signs of
sagging or other stresses in the joints as a result of
misalignment of any components in the system. If any
of these conditions are found, they must be corrected in
accordance with the venting instructions in this manual
before completing the installation and putting the water
heater into service.
NOTICES:
• It is required that the exhaust common venting pipe have
a 5/8" per foot (5.6 cm per meter) upward slope toward the
outdoors.
• A clearance of 0 in. (0 cm) is allowed between the
exhaust common vent pipe or the air intake common vent
pipe and combustible material.
• Use proper support for the exhaust common vent pipe and
the air intake common vent pipe.
• It is recommended the support method used isolates the
vent pipe from floor joists or other structural members. This
helps prevent transmission of noise and vibration.
• DO NOT support, pin, or otherwise secure the common
venting system in a way that restricts the normal thermal
expansion and contraction of the chosen venting material.
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