The vent system must terminate so that proper clearances are maintained as cited in local codes or the latest edition of the National Fuel Gas Code, ANSI Z223.1.73.4e and 7.8a, b as follows:
1.Do not terminate near soffit vents or crawl space or other area where condensate or vapor could create a nuisance or hazard or cause property damage.
2.Do not terminate the exhaust vent terminal where condensate or vapor could cause damage or could be detrimental to the operation of regulators, relief valves, or other equipment.
3.Do not terminate the exhaust vent terminal over public area or walkways where condensate or vapor can cause nuisance or hazard.
4.The vent shall terminate a minimum of 12 inches above expected snowfall level to prevent blockage of vent termination.
5.The manufacturer requires the centerline distances between the air intake and exhaust vent terminals to be a minimum of 36 inches (91.4 cm) apart and the exhaust terminal must extend 6 inches (15.2 cm) past the air intake terminal.
Vent pipes serving power vented appliances are classified by building codes as “vent connectors”. Required clearances from combustible materials must be provided in accordance with information in this manual under LOCATION OF WATER HEATER and CLEARANCES, and with National Fuel Gas Code and local codes.
All vent pipes and terminals are to have a 1” minimum clearance to combustibles. DO NOT use the placement of insulation or other materials in the required clearance spaces surrounding the venting to combustible material unless otherwise specified.
Horizontal Installation:
In a horizontal application, it is important that condensate not be allowed to buildup in the exhaust vent pipe. To prevent this from happening, the pipe should be installed with a slight upward slope so the condensate will run back toward the water heater. The vent system must be supported every 5 feet of vertical run and every 3 feet of horizontal run of vent pipe length.
CAUTION
Failure to properly support the vent piping with hangers and clamps may result in damage to the water heater or venting system.
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.
Follow the following procedure for direct venting through the wall:
1.Cut two 2 ½ inch (6.4 cm) diameter holes for 2 inch (5.1 cm) diameter pipe, two 3 ½ inch (8.9 cm) diameter holes (for 3 inch (7.6 cm) diameter pipe), or two 4 ½ inch (11.4 cm) diameter holes (for 4 inch (10.2 cm) diameter pipe) in the wall with the centerline hole distances at least 36 inches (91.4 cm) apart in the location where the exhaust vent and air intake terminals will exit the outside wall if vented on the same wall.
2.Use the proper cement to secure the exhaust vent and air intake terminals provided with the water heater to the pipes. The distance between the back edge of the exhaust vent terminal and the exterior wall (see Figure 12) must be 6 inches (12.7 cm) more for the exhaust vent terminal than the air intake terminal. Use the proper cement or sealant and assembly procedures to secure the vent connector joints between the terminal and the blower outlet. Provide support brackets for every 3 feet (.91 m) of horizontal vent beyond the intake terminal.
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