Empire Comfort Systems DVLXG75BP90N-1 Installer's Manual page 36

Locate and mark the center point of the vent pipe on the
underside of the roof. Drive a nail through the center point. Mark
the outline of the roof hole around this center point.
NOTICE: Size of the roof hole dimensions depend on the pitch
of the roof. There must be a 1 inch (25 mm) minimum clearance
to the vertical pipe sections. Maintain this clearance to all
combustible material.
To keep out debris, cover the opening of the vent pipe before you
cut and frame the roof opening. Use lumber the same size as the
roof rafters to frame the opening. Securely attach the flashing
to frame to withstand high winds. Place the storm collar over
this joint to make a water-tight seal. Seal the flashing with non
hardening sealant.
Determining Minimum Vent Height Above the Roof.
Major U.S. building codes specify minimum chimney and vent
height above the roof top. These minimum heights ensure safe
operation of the fireplace.
Vent Cap
Gas Vent
NOTICE: For steep roof pitches, the vent height must be
increased. In high wind conditions, nearby trees, adjoining roof
lines, steep pitched roofs, and other similar factors can result in
poor draft, or down-drafting. In these cases, increasing the vent
height may solve this problem.
Installing the Vent System in a Chase
A chase is a vertical box-like structure built to enclose the gas
fireplace and/or its vent system. Vertical vent runs on the outside
of a building may be, but are not required to be, installed inside
a chase.
36
VERTICAL TERMINATION
WARNING
24"
24"
More than
10 feet
Treatment of firestop spacers and construction of the chase may
vary with the type of building. Check local building codes to
determine the requirements for these steps.
NOTICE: Build the chase large enough to maintain the
minimum clearance of combustible materials (including
insulation) to the vent system. When installing the vent system
in a chase, insulate the chase as you would the outside walls
of your home. This is especially important in cold climates.
Upon completion of chase framing, install the vent system by
following the instructions in this manual.
The vertical termination cap for this fireplace must not be any
closer than 24 inches to combustible materials.
If two vertical terminations are run near each other, they may
be placed a minimum of 12 inches between them if they are at
the same height. If two vent terminations are not at the same
height, they must be positioned at least 24 inches apart to
minimize draft issues between them.
CAUTION
24" Minimum
Clearance to combustibles
Natural or man-made
40' (12.9m) Max
12" Min.