Figure 24. PVC/CPVC VENTING - VERTICAL
VENTING SUPPORTS
Care must be taken in the installation of the venting system that adequate support is maintained throughout the installation process. When extending more than 10 feet (3.0 m) vertically, vertical support kits are required once every 10 feet (3.0 m) of vertical run. Vertical support is also required immediately after any transition (elbow, tee, etc.) to vertical of over 10 feet (3.0 m) of run and after any offset in the vertical run.
The support brackets (supplied in the Vertical Support Kit) are to be securely fastened to a solid vertical member of the building using the appropriate fasteners; i.e., wood screws for wood framing, machine or tapping screws for structural steel or masonry anchors for solid masonry. The bracket should be located so that it will not interfere with any joints of the venting system. The bottom most support bracket should be located directly above the first transition from horizontal to vertical.
If a means of support for the brackets is not available and horizontal vent sections are present, install hanger straps (made from non-combustible material) as close to the points of transition as possible. If the horizontal portions of the vent and/or vent connector are longer than 6 feet (2.0 m), then install hanger straps every 6 feet (2.0 m) to support the connector.
Do not rivet or screw the straps to the conduit or otherwise puncture the conduit wall. Instead, wrap an extra loop of strap around the conduit to hold it in position, or attach the strap to the center screw of the double wall AL 29-4C®vent coupling, if applicable.
VERTICAL INSTALLATION REQUIREMENTS
1.The vent system must terminate at least 3 feet (1.0 m) and no more than 6 feet (2.0 m) above the roof line and no closer than 10 feet (3.0 m) from any wall or vertical structure. If the exhaust vent terminal is within 10 feet (3.0 m) of a wall or parapet, it must extend a minimum of 2 feet (610 mm) above the wall or parapet, see Figure 25 on Page 28 and Figure
28 on Page 29.
2.For direct vent installations, the total distance of the vent system from the boiler vent connector to the vertical vent termination should not exceed 100 equivalent feet
(30.5 m). A maximum of three 90° elbows can be used. Minimum vertical vent is 7 equivalent feet (2.1 m) for direct vent installations. Standard minimum vertical vent length is 7 feet (2.1 m). See Figure 25, Figure 28 thru Figure 30 for differences between standard and direct vent installations.
3.An AL 29-4C®Vent Vertical Vent Terminal must be used at the termination.
4.Maintain a minimum of 6 feet (2.0 m) separation between the air intake and the exhaust terminals.
HORIZONTAL INSTALLATION REQUIREMENTS
1.The vent system must terminate with the Through-the-Wall Termination (TWT) kits. Do not locate the terminal within 8 feet (2.5 m) of an inside corner of a building or adjacent to outside walls, shrubs or other such objects that may cause adverse wind conditions in the immediate area.
2.The TWT should be located not less than 12 inches (305
mm)above grade or, in geographical areas where snow accumulates, no less than 12 inches (305 mm) above antici pated snow line. Ensure that TWT is protected against blockage which may occur during ice buildup or snowstorms. The TWT should terminate at least 3 feet (1.0 m) above any forced air inlet within 10 feet (3.0 m), except when the forced air inlet is the combustion air intake of a direct vent appliance. The TWT should terminate at least 4 feet (1.2 m) below, 4 feet (1.2 m) horizontally from or 1 foot (305 mm) above any door, window or gravity air inlet into any building as provided in the current edition of the national fuel gas code ANSI Z223.1. In addition, a minimum clearance of 4 feet (1.2 m) horizontally from, and in no case above or below, unless the 4 feet (1.2
m)of horizontal distance is maintained from electric meters, gas meters, regulators and relief equipment.
3.This horizontal exhaust vent system must pitch upward toward the termination at 1/4 inch per foot (21 mm per meter).
4.The TWT is designed such that the building is protected from degradation by flue gas and condensate. However, if additional protection is desired, install against the wall a non-corrosive metal sheet under the TWT.
5.Due to the normal formation of water vapor in the combustion process, horizontal terminations must not be located over areas of pedestrian or vehicular traffic, (i.e., public walkways or over areas where condensate could create a nuisance or hazard). This is especially true in colder climates where ice buildup is likely to occur. A.O. Smith Corporation will not be held liable for any personal injury or property damage due to any dislodging of ice.
DIRECT VENT INSTALLATION REQUIREMENTS
The labels in the Direct Vent Kit must be affixed to the boiler in locations specified by the instruction sheet provided in the kit. The following are requirements for the Air-Intake Terminal (AIT):
1.The Air-Intake System (AIS) must terminate with the venting equipment provided with the boiler.
2.The AIT should not be located less than 3 feet (1.0 m) below any exhaust vent within 10 feet (3.0 m).
3.The total horizontal distance of the AIS from the boiler’s Blower Adapter to the outside of the “AIT” should not be greater than 100 equivalent feet (30.5 m) of vent pipe nor less than 3 feet (1.0 m), excluding elbows. A maximum of 3 elbows, equivalent to 10 feet (3.0 m) each of pipe may be used.
