Bock Water heaters OT300-A Installation And Operation Instruction Manual page 14

SECTION IV: INSTALLATION (cont.)
VENT & COMBUSTION AIR INTAKE (cont.)
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.
Condensate Elbow Assembly
Prior to connecting the exhaust vent pipe, the condensate elbow assembly (supplied, but
not factory installed) must be connected to the exhaust pipe on the water heater.
The free end of the 3 x 3 x 1.5 PVC reducing tee slip fits over the 3" exhaust pipe on the
water heater. For maximum durability and sealing, use a high heat silicone sealant
appropriate for direct vent appliances (rated for at least 150° F). Apply a bead of silicone
around the inside of the free end of the reducing tee. Do the same around the end of the
exhaust pipe on the heater. Push the end of the reducing tee onto the exhaust pipe as far
as the tee allows. The orientation of the condensate elbow assembly is critical for
proper venting of gas and drainage of condensate. See Figure 5 for proper final
orientation of the assembly.
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Figure 5: Condensate Elbow Assembly Installation
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