Monessen Hearth BDV300 Installation And Operating Instructions Manual page 25

VENt INStALLAtION
3. Cut a hole in the roof using the locating hole as a center point. (Cover any exposed open vent
pipes before cutting hole in roof). The 9
on the horizontal. Actual length may be larger depending on the pitch of the roof. There must
be a 1" minimum clearance from the vent pipe to combustible materials. (Insulation should be
considered a combustible material).
4. Connect a section of pipe and extend up through the hole.
NOTE: If an offset is needed to avoid obstructions, you
must support the vent pipe every three (3) feet. Use
wall straps for this purpose. Refer to Figure 28, page
23. Whenever possible, use 45° elbows instead of 90°
elbows. The 45° elbow offers less restriction to the flow
of the flue gases and intake air.
5. Place the flashing over the pipe section(s) extending
through the roof. Secure the base of the flashing to
the roof and framing with roofing nails. Be sure roofing
material overlaps the top edge of the flashing. There
must be a 1" clearance from the vent pipe to combustible
materials.
6. Continue to add pipe sections until the height of the vent
cap meets the minimum building code requirements.
NOTE: You must increase vent height for steep roof
pitches. Nearby trees, adjoining roof lines, steep pitched
roofs, and other similar factors may cause poor draft or
down-drafting in high winds. Increasing the vent height
may solve this problem.
NOTE: If the vent pipe passes through any occupied
areas above the first floor, including storage spaces
and closets, you must enclose pipe. You may frame
and sheetrock the enclosure with standard construction material. Make sure
to meet the minimum allowable clearances to combustibles. Do not fill any of
the required clearance spaces with insulation.
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. Figure 32
3. Lower the support box through the hole in the roof until the bottom of the box
extends at least 2" below the ceiling. 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 sheeting.
4. Using tin snips, cut the support box from the top corners down to the roof line and fold the result-
ing flaps over the roof sheeting. Figure 33. 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 the support box.
5. Complete the cathedral ceiling installation by following the same procedures outlines in steps 2
through 6 for Flat Ceiling Installation.
54D0700
1 1/ 
/ "x9 " (241 mm x 241 mm) hole must be measured

Termination
Vent
Storm Collar
Flashing
Concentric
Vent Pipe
Figure 33 - Minimum Chimney Clearance
BDV Series Gas Fireplace
Horizontal Overhang
2 ft.
2 ft. Min.
Min.
Lowest
Discharge
Opening
H*
1" Minimum Clearance to
Combustibles
Roof Pitch
FP1971
Flat to 6/1
Min chimney clearance
Over 6/1 to 7/1
Over 7/1 to 8/1
Over 8/1 to 9/1
Over 9/1 to 10/1
Over 10/1 to 11/1
Over 11/1 to 1/1
*H - Minimum height from roof to
lowest discharge opening of vent
Vertical Wall
12
X
FP1971
H (feet)
1.0
1.5
1.5
.0
.5
3.5
4.0
5