A.O. Smith 317443-000 instruction manual Venting, Vent Pipe Termination, Planning the Vent System

VENTING

Never operate the water heater unless it is vented to the outdoors.

The instructions in this section of the manual must be followed to avoid choked combustion or recirculation of flue gases. Such conditions cause sooting of the combustion chamber, burners and flue tubes and creates a risk of asphyxiation.

VENT PIPE TERMINATION

The first step is to determine where the vent pipe will terminate. See Figures 15, 16, and 17. The vent may terminate through a sidewall as shown in Figures 15 and 16 or through the roof as shown in Figures 17 and 18.

The vent system must terminate so that proper clearances are maintained as cited in local codes or the current edition of the National Fuel Gas Code, (ANSI Z223.1, 12.9.1 through 12.9.4). See Figures 13 and 14.

Instructions on proper installation through a sidewall are provided in Figures 15A, 15B, 15C, and 16.

Plan the vent system layout so that proper clearances are maintained from plumbing and wiring.

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 Facts to Consider About Location and INSTALLING THE WATER HEATER, and with the National Fuel Gas Code and local codes.

PLANNING THE VENT SYSTEM

Plan the route of the vent system from the exhaust elbow to the

planned location of the vent terminal.

1.Layout total vent system to use a minimum of vent pipe and elbows.

2.This water heater is capable of venting flue gases equivalent to 45’ (13.7 m) of 2” pipe, 128’ (39 m) of 3” pipe as listed in Table 2.

Table 2

Number of	2” Maximum	3” Maximum
90° Elbows	Pipe - ft. (m)	Pipe - ft. (m)
1	40 (12.19)	120 (36.57)
2	35 (10.66)	115 (35.05)
3	30 (9.14)	110 (33.52)
4	25 (7.62)	105 (32)
5	20 (6.09)	100 (30.48)
6	15 (4.57)	95 (28.95)

The minimum vent length for each pipe size is one 90° plus 2’ (61 cm) of straight pipe and the appropriate termination.

NOTE: The equivalent feet (m) of pipe listed above are exclusive of the termination. That is, the termination, with an installed screen, is assumed to be in the system and the remainder of the system must not exceed the lengths discussed above.

3.The exhaust elbow assembly is designed to accept only straight sections of 2” pipe. To start, a minimum 2” (5.1cm) maximum

6” long of 2” pipe must be inserted and glued to the exhaust elbow assembly if utilizing 3” vent pipe. Use the same method with the blower inlet if a direct vent configuration is utilized.

If using 2” inch vent pipe:

A minimum of 2” (5.1cm) diameter vent pipe must be attached to the exhaust elbow assembly. The total system cannot exceed the lengths discussed above, where each elbow is equal to 5 equivalent feet (1.5m) of straight pipe.

If using 3” inch vent pipe:

Two inches (5.1cm) of 2” pipe must be attached to the exhaust elbow assembly before adding a reducer to acquire the desired pipe diameter. An appropriately sized 45 degree elbow (supplied locally-a schedule 40 DWV) vent terminal must be obtained with an equivalent screen (supplied in vent kit). The total system cannot exceed the equivalent pipe lengths discussed above where each elbow is equal to 5 feet (1.5m) of straight pipe (3” vent pipe).

NOTE: This unit can be vented with PVC pipe materials (DWV ASTM-D2665 or CSA B181.2; Schedule 40, 80, 120 ASTM-D1785 or CSA B137.3; or SDR Series ASTM-D2241 or CSA B137.3), CPVC pipe materials (CPVC41 ASTM-D2846 or CSA B137.6; Schedule 40, 80 ASTM-F441 or CSA B137.6; or SDR Series ASTM-F442), ABS pipe materials (Schedule 40 DWV ASTM-D2661 or CSA B181.1. The fittings, other than the TERMINATION should be equivalent to PVC-DWV fittings meeting ASTM D-2665 (Use CPVC fittings, ASTM F-438 for CPVC pipe and ABS fittings, ASTM D-2661/3311 for ABS pipe). If CPVC or ABS pipe and fittings are used, then proper cement must be used for all joints, including joining the pipe to Termination (PVC Material). If local codes do not allow the use of the PVC termination when a material other than PVC is used for venting, then an equivalent fitting of that material may be substituted if the screen in the PVC terminal is removed and inserted into the new fitting.

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