Lochinvar 399 Prepare roof penetrations, 2Vertical Terminations with Multiple Boilers

Installation & Operation Manual

5Vertical direct venting (continued)

Vent/air termination – vertical

Prepare roof penetrations

1.Air pipe penetration:

a.Cut a hole for the air pipe. Size the air pipe hole as close as desired to the air pipe outside diameter.

2.Vent pipe penetration:

a.Cut a hole for the vent pipe. For either combustible or noncombustible construction, size the vent pipe hole with at least a 1/2 inch clearance around the vent pipe outer diameter:

•5½ inch hole (140 mm) hole for 4 inch (102 mm) vent pipe

•7½ inch hole (191 mm) hole for 6 inch (152 mm) vent pipe

b.Insert a galvanized metal thimble in the vent pipe hole (when required by local codes).

3.Space the air and vent holes to provide the minimum spacing shown in FIG.’s 5-1A and 5-1B, page 30.

4.Follow all local codes for isolation of vent pipe when passing through floors, ceilings, and roofs.

5.Provide flashing and sealing boots sized for the vent pipe and air pipe.

Termination and fittings

1.Prepare the vent termination coupling and the air termination elbow (FIG.’s 5-1A and 5-1B) by inserting bird screens. Bird screens should be obtained locally.

2.The air piping must terminate in a down-turned 180° return bend as shown in FIG.’s 5-1A and 5-1B. Locate the air inlet pipe no further than 2 feet (.6 m) from the center of the vent pipe. This placement avoids recirculation of flue products into the combustion air stream.

3.The vent piping must terminate in an up-turned coupling as shown in FIG. 5-1A. The top of the coupling must be at least 1 foot (.3 m) above the air intake. When the vent termination uses a rain cap as illustrated in FIG. 5-1B maintain at least 36" (914 mm) above the air inlet. The air inlet pipe and vent pipe can be located in any desired position on the roof, but must always be no further than 2 feet (.6 m) apart and with the vent termination at least 1 foot (.3 m) above the air intake.

4.Maintain the required dimensions of the finished termination piping as shown in FIG.’s 5-1A and 5-1B.

5.Do not extend exposed vent pipe outside of building more than shown in this document. Condensate could freeze and block vent pipe.

Multiple vent/air terminations

1.When terminating multiple Knight XL boilers, terminate each vent/air connection as described in this manual (FIG. 5-2).

Terminate all vent pipes at the same height ￿ WARNING and all air pipes at the same height to

avoid recirculation of flue products and the possibility of severe personal injury, death, or substantial property damage.

2. Place roof penetrations to obtain minimum clearance of 12 inches (305 mm) between edge of air intake elbow and adjacent vent pipe of another boiler for U.S. installations (see FIG. 5-2). For Canadian installations, provide clearances required by CSA B149.1 Installation Code.

3. The air inlet of a Knight XL boiler is part of a direct vent connection. It is not classified as a forced air intake with regard to spacing from adjacent boiler vents.

Figure 5-2Vertical Terminations with Multiple Boilers

12" (305 MM) MINIMUM VERTICALLY FROM VENT OUTLET TO ANY AIR INLET

	VENT
	AIR
	12" (305 MM) MINIMUM FROM EDGE
VENT	OF AIR INTAKE PIPE TO ADJACENT
AIR	VENT PIPE FROM ANOTHER BOILER

Figure 5-3Alternate Vertical Terminations with Multiple Boilers

VENT

VENT

12" (305 MM) MINIMUM VERTICALLY FROM VENT OUTLET TO ANY AIR INLET

AIR

AIR

31