Lennox DT3025 Installation Instructions Manual page 16

Horizontal Overhang
2 FT MIN.
Termination
Storm Collar
Flashing
12
Detailed steps for installation of the vertical vent at
and above the roof:
1 - Determine the location of the vent's penetration of
the roof.
2 - Cover the openings of the concentric vent and cut the
hole in the roof large enough in order to provide a
minimum of one inch (25.4mm) clearance to roof
combustible material.
3 - Frame the vent hole (with material of at least the
same dimensions as the roof rafters) in order to pro-
vide adequate nailing support for the roof-to-vent
flashing. (Note - Vent assembly above the roof may
be subjected to high winds).
4 - Install the remaining vent sections and the vent ter-
mination. See figure 22 for minimum allowable ter-
mination heights above the roof and minimum allow-
able clearances to obstacles above the roof.
5 - Use both flashing and a storm collar at the point
where the vent pipe exits the roof. Seal flashing to
roof, and storm collar to vent with non-hardening
caulking compound.
Horizontal Venting Through a Side Wall
This Lennox gas fireplace is for use only with Lennox
approved concentric vent pipe; either rigid or flexible
vent pipe may be used when horizontally venting the
fireplace through a side wall.
DT/DTH Applications - See figures 23, 24, or 25 for vent
length requirements using concentric vent pipe.
DR/DRH Applications - See figures 26, 27, or 28 for vent
length requirements using concentric vent pipe.
Also, see figure 4 for venting in a corner installation.
TERMINATION HEIGHTS FOR VENTS ABOVE
FLAT OR SLOPED ROOFS
2 FT MIN.
Vent
Lowest
Discharge
Opening
H*
*H = MINIMUM HEIGHT FROM ROOF
TO LOWEST DISCHARGE OPENING
Concentric Vent Pipe
X
Roof Pitch is X/12
Vertical
Wall
OF VENT
FIGURE 22
General guidelines for horizontal vent installations:
1 - Provide a firestop / spacer any time vent pipe must
pass through a combustible floor, ceiling or wall. See
figure 14. Refer to listing on page 26 for catalog num-
bers of Lennox firestop spacers.
2 - Horizontal sections of the vent pipe run should be
sloped upward a minimum of 1/4 in. per foot of hori-
zontal vent in the direction away from the fireplace.
In addition, horizontal sections of pipe must be sup-
ported using metal straps spaced every 2 ft.
3 - Maintain proper clearances any time vent pipe must
pass through insulated spaces. Use insulation shield
when vent pipe passes through any insulation.
4 - Two 45 elbows may be used in place of one 90
_
bow. This can only occur once in the entire venting
system.
One 45 elbow may be substituted for one 90
_
at any point in the venting system.
The same rise to run ratios as shown in the venting
figures must be followed if 45
5 - The longest length of flexible vent pipe available is 48
inches, measured when in its compressed form. Flex-
ible vent pipe may not be applicable in every venting
configuration depicted in figures 23, 24, 25, 27, and
28, depending on the total vent length required.
Under no circumstances, may separate sections of
concentric flexible vent pipe be joined together.
P a g e 1 6
H - FT
ROOF PITCH
FLAT TO 6/12
1.0
6/12 TO 7/12
1.25
7/12 TO 8/12
1.5
8/12 TO 9/12
2.0
9/12 TO 10/12
2.5
10/12 TO 11/12
3.25
11/12 TO 12/12
4.0
12/12 TO 14/12
5.0
14/12 TO 16/12
6.0
16/12 TO 18/12
7.0
18/12 TO 20 /12
7.5
20/12 TO 21/12
8.0
elbows are used.
_
IMPORTANT
el-
_
elbow
_