Venting Through A Roof; Vent Pipe Preparation - A.O. Smith Power Direct ventedGasModels Instruction Manual

If this concentric termination, through the wall type of venting system is
preferred, the concentric vent kit can be ordered from the Service Parts
Department under kit #9002749. Installation instructions are provided
with the kit.

ventInG throuGh a roof

Two 3" inlet and outlet PVC Schedule 40 - 45° vent caps are supplied.
A 5' (1.5 m) section of 3" CPVC Schedule 40 outlet vent pipe is
supplied with 75 gallon models and a 5' (1.5 m) section of 3" ABS
Schedule 40 outlet vent pipe is supplied with 50 gallon 65,000 Btu/
Hr models. More may be required and must be purchased locally.
1. The water heater requires its own (separate) venting system.
2. Only 3" ABS Schedule 40 piping and fittings are acceptable
materials on the first five feet of the outlet vent system on the
50 gallon 65,000 BTU/HR models and 3" CPVC Schedule 40
piping and Schedule 80 fittings are acceptable materials on the
first five feet of the outlet vent system on 75 gallon models.
3. 3" PVC, ABS, or CPVC Schedule 40 piping and fittings are
acceptable materials for the inlet vent system and for the outlet
vent system after the first five feet (1.5 m).
4. The unit cannot be connected to existing vent piping or chimney.
5. Venting must terminate vertically to the outdoors.
6. The total vertical and horizontal vent runs cannot exceed the
maximum length with a maximum number of 90° elbows as
specified in the table below. If more elbows are required, the
venting distance must be reduced 5 feet for every 90° elbow.
The number of 90° elbows shown in the table is for both the intake
air and vent pipes. IE: The vent pipe can contain three 90° elbows,
the intake air pipe can also contain three 90° elbows.
3" dIa. vents MaX.
lenGth (ft.)
45
40
35
*NOTE: Two 45° elbows are equivalent to one 90° elbow. One 90°
elbow equals 5 feet (1.5 m) of equivalent vent length.
fIGure 30.
nuMBer of 90°
elBows*
1
2
3
20

vent pIpe preparatIon

1. InItIal preparatIon
A. Make sure the solvent cement you are planning to use is
designed for the specific application you are attempting.
B. Know the physical and chemical characteristics and
limitations of the PVC, ABS and CPVC piping materials that
you are about to use.
C. Know the reputation of your manufacturer and their products.
D. Know your own qualifications or those of your contractor. The
solvent welding technique of joining PVC, ABS and CPVC pipe
is a specialized skill just as any other pipe fitting technique.
E. Closely supervise the installation and inspect the finished
job before start-up.
F. Contact the manufacturer, supplier, or competent consulting
agency if you have any questions about the application or
installation of PVC, ABS and CPVC pipe.
G. Take the time and effort to do a professional job. Shortcuts
will only cause you problems and delays in start-up. By far,
the majority of failures in PVC, ABS and CPVC systems are
the result of shortcuts and/or improper joining techniques.
2. selectIon of MaterIals
• Cutting Device - Saw or Pipe Cutter
• Deburring Tool, Knife, File, or Beveling Machine (2" [5 cm] and above)
• Brush - Pure Bristle
• Rag - Cotton (Not Synthetic)
• Primer and Cleaner
• Solvent Cement - PVC for PVC Components and CPVC for
CPVC Components and ABS for ABS components.
• Containers - Metal or Glass to hold Primer and Cement. Select
the type of PVC, ABS or CPVC materials to be used on the basis
of their application with respect to chemical resistance, pressure
rating, temperature characteristics, etc.
• Insertion Tool - Helpful for larger diameter pipe and fittings 6
inches (15.2 cm) and above.