OWNER’S MANUAL

VENTING INSTALLATION

Continued

3.Lower the support box through the hole in the roof until the bottom of the box extends at least 2" below the ceiling (see Figure 23). Align the support box vertically and horizontally using a level. Temporarily tack the support box in place through the inside walls and into the roof sheathing.

4.Using tin snips, cut the support box from the top corners down to the roofline and fold the resulting flaps over the roof sheathing (see Figure 24). Apply a bead of non-hardening mastic around the top edges of the support box to make a seal between the box and the roof. Nail in place with roofing nails. Remove any combustible material that might be in- side of the support box.

5.Complete the cathedral ceiling instal- lation by following the same proce- dures outlined in steps 2 through 7 for Flat Ceiling Installation, page 12.

Level

Cathedral ceiling support box

2" minimum below finished ceiling

Vertical Termination Configurations

Figures 25 through 28 show four different configurations for vertical termination. All connections must be sealed with high temperature silicone sealant as specified in the second warning statement on page 7.

Venting with Two 90° Elbows

Vertical (V)

Horizontal (H1) +

 

Horizontal (H2)

5' min.

2' max.

6' min.

4' max.

7' min.

6' max.

8' min.

8' max.

20' max.

8' max.

Note: Install restrictor into 4" collar of fireplace as shown.

Figure 25 - Vertical Rigid Venting Configuration Using Two 90° Elbows with Two

Horizontal Runs

Cut hole 1/8" larger than support box when projected onto roofline

Figure 23 - Cathedral Ceiling Support Box Installation

Note: Install restrictor into 4" collar of fireplace as shown.

Venting with One 90° Elbow

Vertical (V)

Horizontal (H)

5' min.

2' max.

6' min.

4' max.

7' min.

6' max.

8' min.

8' max.

20' max.

8' max.

Non-hardening Mastic under all edges of support box before nailing

Figure 24 - Installed Cathedral Ceiling

Figure 26 - Vertical Rigid Venting Configuration Using One 90° Elbow

 

Support Box

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Desa BHDV37PC, BHDV41NC, BHDV41PC, BHDV37NC installation manual Vertical Termination Configurations, Venting with One 90 Elbow