Venting INSTALLATION

Continued

This appliance may be vented through a manufactured chimney system or a masonry chimney using a B-vent adapter or a chimney liner system if all are listed, inspected and approved by local codes and/or building authorities.

The examples shown in Figure 9 are typical of most B-vent installations and codes practices.

Example 1: Shows the minimum allowable system height and lateral offset for a 60° or greater inclination. Code specifies that offsets at 60° or greater are considered horizontal and must follow the 75% rule for lateral to total vertical system height. Codes also allows only one offset in the total system when at 60° or greater. The total vertical height in this example represents the minimum height of 8 feet and therefore the allowable lateral is 6 feet when the 75% rule applies. If the lateral length must exceed 75% then the system must be sized in accordance with the Category I venting tables.

Example 2: Shows a multiple offset each at 45° of inclination. Multiple offsets are permitted if they do not exceed 45° of inclination. The total lengths of the two offsets are not required to meet the 75% allowable rule.

Example 3: Shows a single offset at 45° of inclination and therefore the lateral length at 10 feet of offset does not have to meet the 75% rule.

In each case the offsets must be supported and firestops must be positioned wherever the vent must pass through a sub-floor, ceiling joist or an attic overhang. The vent pipe must terminate vertically into a listed type vent cap and extend a sufficient height through an approved roof flashing, roof jack or a roof thimble. At all points the listed clearances must be maintained.

Vent terminations must be located in accordance with height and proximity rules of NFPA No. 54. These rules apply to vents at 12" diameter or less and require a minimum height in accordance with the roof pitch and a minimum of 8 feet distance from a vertical wall or obstruction (see Figure 10, page 10).

If venting horizontally through a side wall becomes necessary, a listed thimble approved for use with B-type vent must be used. Check with your local codes before venting through a side wall.

Some codes areas allow the use of existing B- type vent systems if the system is at or above the recommended diameter of the flue.

The flue connection must be made using listed B-type connectors and the existing system must be code inspected for damage and proper installation.

 

Listed

 

 

 

 

 

Vent Cap

 

Listed

Listed

 

 

 

 

 

 

Vent Cap

 

 

 

Vent Cap

 

 

 

 

Maintain

 

Maintain

 

 

 

Listed

 

Listed

 

 

 

Clearance

 

Clearance

 

 

Maintain

 

 

Support Each

Maintain

 

Listed

 

 

Lateral At

Listed

 

Clearance

 

60°

Least Every

45°Clearance

 

 

8' Position

 

6 Feet

12' Min.

45°

10'

6'

 

Position

12' Min. Firestop

Position

Firestop

 

12' Min.

 

 

 

 

Firestop

45°

 

 

 

 

 

 

 

 

Maintain

 

Maintain

 

Maintain

 

Listed

 

Listed

 

Listed

 

Clearance

Clearance

 

Clearance

EXAMPLE 1

EXAMPLE 2

EXAMPLE 3

 

Figure 9 - Typical B-Vent Configuration

 

108794-01G

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