Lennox Hearth MPD-40 Series Framing Dimensions for Roof Pitch, 12/12, 10-1/2 267 mm 305 mm, Elbow

One method of support is by utilizing field provided support straps (conventional plumber's tape). Secure the plumber's tape to the framing members with nails or screws. Loop the tape around the vent, securing the ends of the tape to the framing. If desired, sheet metal screws #6 x 1/2" length may be used to secure the support straps to the vent pipe. Refer to Figure 20.

F. Change vent direction to horizontal/in- clined run - At transition from or to a horizon- tal/inclined run, install the SV4.5E45 and SV4.5E90 elbows in the same manner as the straight vent sections. The elbows feature a twist section to allow them to be routed about the center axis of their initial collar section to align with the required direction of the next vent run element. Twist elbow sections in a clockwise direction only so as to avoid the possiblity of unlocking any of the previously connected vent sections. See Figure 21.

4-13/16"	8-1/8"
	(206 mm)
(122 mm)

Swivel Joint	Swivel Joint
(360° swivel)
	(360° swivel)
SV4.5E45	SV4.5E90
(45° Elbow)	(90° Elbow)

Figure 21

G. Continue installation of horizontal/inclined sections - Continue with the installation of the straight vent sections in horizontal/inclined run as described in Step C. Install support straps every 5 ft. (1.52 m) along horizontal/ inclined vent runs using conventional plumber’s tape. See page 16, Figure 31. It is very important that the horizontal/inclined run be maintained in a straight (no dips) and recommended to be in a slightly elevated plane, in a direction away from the fireplace of 1/4" rise per foot (20 mm per meter) which is ideal, though rise per foot run ratios that are smaller are acceptable all the way down to at or near level. Use a carpenter’s level to measure from a constant surface and adjust the support straps as necessary.

It is important to maintain the required clear- ances to combustibles: 1" (25 mm) at all sides for all vertical runs; and 3" (76 mm) at the top, 1" (25 mm) at sides, and 1" (25 mm) at the bottom for all horizontal/inclined runs.

H. Frame roof opening - Identify location for vent at the roof. Cut and/or frame opening per Roof Framing Chart and Figure 22.

C

D

Framing Dimensions for Roof

Pitch	C	D
0/12	10-1/2 in.	10-1/2 in.
	(267 mm)	(267 mm)
6/12	10-1/2 in.	12 in.
	(267 mm)	(305 mm)
12/12	10-1/2 in.	17-3/4 in.
	(267 mm)	(451 mm)

Figure 22

I. Install the roof flashing - Extend the vent sections through the roof structure. Install the roof flashing over the vent section and position such that the vent column rises vertically (use carpenters level) (Figure 23 ). Nail along pe- rimeter to secure flashing or adjust roofing to overlap the flashing edges at top and sides only and trim where necessary. Seal the top and both sides of the flashing with waterproof caulking.

Figure 23

J. Install the storm collar - Install the storm collar, supplied with the flashing, over the vent/flashing joint. See Figure 24. Loosen the storm collar screw. Slide collar down until it meets the top of the flashing. Tighten the adjusting screw. Apply non-combustible caulk- ing or mastic around the circumference of the joint to provide a water tight seal.

NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.

Storm

Collar

Figure 24

K. Install the vertical termination - The final step involves installation of the SV4.5CGV-1 Vertical Termination. Extend the vent sec- tions to the height as shown in the "Vertical vent termination section" on page 5. The SV4.5CGV-1 Vertical Termination (Figure 25) can be installed in the exact same fashion as any other Secure Vent section. Align the termination over the end of the previously installed section, adjusting the radial align- ment until the four locking dimples of the termination are aligned with the inlets of the four incline channels of the last vent section. Push the termination down until it fully en- gages, then twist the termination clockwise running the dimples down and along the incline channels until they are seated at the end of the channels.

Figure 25

If the vent system extends more than 5' (1.5 m) above the roof flashing, stabilizers may be nec- essary. Additional screws may be used at section joints for added stability. Guide wires may be attached to the joint for additional support on multiple joint configurations.

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