The vent and combustion air intake systems must be sufficiently supported along
vertical and horizontal sections.
At minimum, it is recommended that a support is placed
along the vent or air intake piping every 4 feet. For horizontal systems, the first support shall
be located immediately adjacent to the first 90-deg. elbow following the vertical section
connected to the water heater. The support method should act to isolate the vent and
combustion air intake piping from floor joists or other structural members to reduce transmis-
sion of noise and vibration.
NOTE: Do not support, pin, or secure the vent and combustion air intake pipe in a
way that restricts the normal thermal expansion and contraction of the venting
material.
For replacement installations, thoroughly inspect the existing vent and combustion air intake
systems prior to installing the new water heater. The following steps shall be taken to properly
inspect the existing vent system:
• Verify that the materials as specified in this manual have been used.
• Verify the maximum and minimum vent and combustion air intake equivalent lengths and
terminal clearances meet the specifications in this manual.
• Inspect the vent and combustion air intake systems for cracking. Pay close attention to joints
between elbows and straight pipe.
• Inspect the system for misalignment of components. This may lead to sagging and unwanted
stresses in the joints.
If any corrections are required they must be computed before installing the replacement water
heater.
Horizontal Venting, Direct Vent 2-pipe termination
This water heater may be vented horizontally (through a sidewall) with a two-pipe
termination. Two holes through an exterior wall are required for the vent and
combustion air intake pipes. Minimum clearances between the terminals must be met as
specified in Figure 3. All clearances must comply with local codes or the latest edition of
NFPA 54/ANSI Z223.1 or CSA B149. See Figure 2 and Table 8 for terminal clearances.
Page 13
SECTION IV: INSTALLATION (cont .)
VENT & COMBUSTION AIR INTAKE (cont.)
Figure 2:
Terminal Clearances
