Lennox DT3025 Installation Instructions Manual page 13

Vertical Venting Through the Roof
This Lennox gas fireplace is for use only with Lennox
approved concentric vent pipe; only rigid vent pipe may
be used when vertically venting the fireplace through
the roof.
DT/DTH Applications - See figures 16, 17, or 18 for vent
length requirements using concentric vent pipe.
DR/DRH Applications - See figures 19, 20, or 21 for vent
length requirements using concentric vent pipe.
DT/DTH and DR/DRH Applications -
Figure 15 provides a detail of the vertical vent termination.
Figure 22 shows the minimum vent termination height re-
quirements above a flat or sloped roof.
General guidelines for vertical vent installations:
1 - DT/DTH Models -
Install a vent restrictor (provided) in the flue outlet as
shown in figure 13.
VENT RESTRICTOR INSTALLATION
(DT/DTH UNITS ONLY)
RESTRICTOR
CABINET TOP
TOP FLUE OUTLET
WHEN USING THE TOP FLUE OUTLET IN VERTICAL VENTING
APPLICATIONS, INSTALL RESTRICTOR FLUSH WITH FLUE
COLLAR OUTLET.
FIGURE 13
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.
INNER
COLLAR
RESTRICTOR
FLUSH
SIDE VIEW
2 - Horizontal sections of the vent pipe run should
be sloped upward a minimum of 1/4 in. per foot of
horizontal vent in the direction away from the
fireplace. In addition, horizontal sections of pipe
must be supported 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
bow. This can only occur once in the entire venting
system.
One 45
at any point in the venting system.
The same rise to run ratios as shown in the venting
figures must be followed if 45
OUTER
COLLAR
LENNOX MILL-PAC
TEMPERATURE
(Catalog Number 10K81)
P a g e 1 3
elbows may be used in place of one 90
_
elbow may be substituted for one 90
_
FIRESTOP / SPACER
(Vertical Applications Shown)
plications require 3 inch
(76mm) clearance above
FIGURE 14
VERTICAL TERMINATION DETAIL
BLACK HIGH
SEALANT
RIGID VENT
FIGURE 15
el-
_
elbow
_
elbows are used.
_
NOTE - Horizontal ap-
top of vent.