Cathedral Ceiling Installation 1. Remove shingles or other roof covering as necessary to cut the rectangular hole for the support box. Mark the outline of the cathedral ceiling support box on the roof sheathing using the locating hole as a center point. 2. Cut the hole 1/8" larger than the support box outline (see Figure 27). 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 27). 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 28). 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 inside of the support box. 5. Complete the cathedral ceiling installation by following the same procedures outlined in steps 2 through 7 for Flat Ceiling Installation, page 16. Venting Installation Instructions Continued Level Cathedral ceiling support box 2" minimum below finished ceiling Cut hole 1/8" larger than support box when projected onto roofline Figure 27 - Cathedral Ceiling Support Box Installation Non-hardening Mastic under all edges of support box before nailing Figure 28 - Installed Cathedral Ceiling Support Box Vertical Termination Configurations Figures 29 through 32 show four different configurations for vertical termination. These minimum vertical rises are based on horizontal runs with a minimum of 1/4" upwards pitch per foot ad do not reflect constraints on a vertical system with 45° or greater offset. Any offset pitch of 45° or less must be considered horizontal and sized within the maximum allowable lengths listed in the following examples. All connections must be sealed with high temperature silicone sealant as specified in the second warning statement on page 11. 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. Venting Installation Instructions Continued 45° Starter Elbow Note: Install restrictor into inner collar of fireplace as shown. 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. Figure 30 - Vertical Rigid Venting Configuration Using One 90° Elbow 45° Starter Elbow Note: Install restrictor into inner collar of fireplace as shown. Note: Install restrictor into inner collar of fireplace as shown. Figure 29 - Vertical Rigid Venting Configuration Using Two 90° Elbows with Two Horizontal Runs 45° Starter Elbow Venting with Two 90° Elbows Vertical (V1) Horizontal (H) 5' min. 6' max. 6' min. 12' max. 7' min. 18' max. 8' min. 20' max. Figure 31 - Vertical Rigid Venting Configuration Using Two 90° Elbows High altitude installation Your DESA direct-vent fireplace has been tested and approved for elevations from 0-2,000 feet (USA) and elevations from 0-4,500 feet (Canada) Fireplaces for High Altitude (models ending in -HA) are for installation above 4,000 feet only. These fireplaces are equipped with parts specific for higher altitudes. IMPORTANT: These fireplaces can NOT be converted to propane/LP gas. When installing a non-high altitude fireplace at an elevation above 2,000 feet (USA), you may need to decrease the input rating by changing the existing burner orifice to a smaller size. Reduce input 4% for each 1,000 feet above sea level. Check with your local gas company for proper orifice size identification. When installing this fireplace at an elevation above 4,500 feet (Canada), check with local authorities. IMPORTANT: For horizontal installations above 2,000 feet, it is recommened that a 12" extension pipe be added before starter elbow (see Figure 33). Venting Installation Instructions Continued 45° Starter Elbow 12" Extension Vertical Venting V = 40' max. Figure 33 - Recommended 12" Extension for High Altitude Installation 45° Starter Elbow parts list for DESA venting kits and components DESA (5"/8") Pipe & Vent Kits Number Description VKR-58 Roof Vent Kit, Galvanized (Includes: 45° Elbow, 7"-12" Adjustable Pipe, Flue Restrictor, Vertical High Wind Termination, 2' Pipe, 4' Pipe, Wall Firestop, Storm Collar, Roof Flashing [0/12 - 6/12], 26 Screws) VKB-58 Basement Vent Kit, Galvanized (Includes: 45° Elbow, 7"-12" Adjustable Pipe, Wall Firestop, Horizontal Square Termination, 4' Pipe, 90° Elbow, 20 Screws) VKS-58 Snorkel Vent Kit, Galvanized (Includes: 45° Elbow, 7"-12" Adjustable Pipe, Wall Firestop, 36" Snorkel Termination, 4' Pipe, 1' Pipe, 90° Elbow, 26 Screws) VKG-58 Ground Floor Vent Kit, Galvanized (Includes: 45° Elbow, 7"-12" Adjustable Pipe, Wall Firestop, Horizontal Square Termination, 16 Screws) P58-48 48" Section Double Wa...