A.O. Smith FPSH - 75 owner manual Venting, Vent Pipe Termination, Planning the Vent System

BETWEEN THE RELIEF VALVE AND TANK. DO NOT PLUG THE RELIEF VALVE.

The drain line connected to this valve must not contain a reducing coupling or other restriction and must terminate near a suitable drain to prevent water damage during valve operation. The discharge line shall be installed in a manner to allow complete drainage of both the valve and line. DO NOT THREAD, PLUG OR CAP THE END OF THE DRAIN LINE.

VENTING

WARNING

NEVER OPERATE THE HEATER UNLESS IT IS VENTED TO THE OUTDOORS AND HAS ADEQUATE AIR SUPPLY TO AVOID RISKS OF IMPROPER OPERATION, FIRE, EXPLOSION OR ASPHYXIATION.

VENT PIPE TERMINATION

The first step is to determine where the vent pipe will terminate. See Figures 3, 8 and 9. The vent may terminate through the roof as shown in Figure 9 or through a sidewall as shown in Figure 8.

IMPORTANT

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, 7.3.4e and 7.8a, b.

For your convenience instructions on proper installation through a sidewall are provide in Figure 3 and the numbered points below:

1.The exit terminals of a mechanical vent system shall be not less than 7 feet above grade when located adjacent to public walkways.

2.A venting system shall terminate at least 3 feet above any forced air inlet located within 10 feet.

3.The venting system shall terminate at least 4 feet below, 4 feet horizontally from or, 1 foot above any door, window or gravity air inlet into any building.

4.The manufacturer also recommends that the vent system termination not be installed closer than 3 feet from an inside corner of an L shaped structure and not be less than 1 foot above grade. The vent shall terminate a minimum of 12'' above expected snowfall level to prevent blockage of vent termination.

5.The vent termination shall not be mounted directly above or within 3 feet horizontally from an oil tank vent or gas meter to avoid potential freeze-up from condensation.

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 LOCATION OF HEATER and INSTALLATION OF VENT SYSTEM, and with the National Fuel Gas Code and local codes.

PLANNING THE VENT SYSTEM

Plan the route of the vent system from the discharge of the blower to the planned location of the vent terminal.

1.Layout the total vent system to use a minimum of vent pipe and elbows. Take into consideration that an elbow will be necessary to make the first vent pipe connection to the power venter outlet (see Figure 6).

2.This water heater is capable of venting the flue gases the equivalent of thirty (30) feet of 3 inch pipe or eighty-five (85) feet of 4 inch pipe as listed in Table 1.

TABLE 1

Number of	3" Maximum	4" Maximum
90° Elbows	Pipe (Feet)	Pipe Feet
ONE (1)	25	80
TWO (2)	20	75
THREE(3)	15	70
FOUR (4)	10	65
FIVE (5)	- - -	60

Minimum of 7 equivalent feet (one {1} elbow and 2 feet) must be installed for 3" and 4" pipe.

NOTE: The equivalent feet of pipe listed above are exclusive of the "Tee" termination. That is, the termination "Tee", with installed screens, is assumed to be in the system and the remainder of the system must not exceed the thirty (30) equivalent feet of 3 inch pipe or eighty five (85) equivalent feet of 4 inch pipe.

3.The blower discharge adapter is made to accept only straight sections of 3" pipe. To start a minimum of 2 inches of 3" pipe must be attached to the blower discharge (See figure 6).

If using 3 inch vent pipe:

A minimum of 2 inches, maximum of 4 feet of 3" pipe must be attached to the blower before the first 3-inch elbow. After the first elbow add the additional venting required for the installation. The total system cannot exceed 30 equivalent feet of venting, where each elbow is equal to 5 feet of straight pipe.

If using 4 inch vent pipe:

Two inches of 3" pipe must be attached to the blower discharge. A 4" x 3" reducer is added and then up to maximum 4 feet of 4 inch pipe added before the first elbow. An additional 4" x 3" reducer and (1) foot of 3" pipe must be added to the end of the vent system before terminating into the 3" tee. The total system cannot exceed 85 equivalent feet of 4" venting, where each elbow is equal to 5 feet of straight pipe.

FIGURE4

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