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Combustible
Projection
extending up
to 2.5 inches
Combustible
Projection
extending more
than 2.5 inches
Horizontal Vent Termination Clearances
Side Elevation View
Ventilated or Unventilated Soffit
3 in
(76 mm)
24 in
(610 mm)
Horizontal Termination Kit
6
Horizontal Vent Termination Clearances
The horizontal vent termination must have a minimum of 3 in (76 mm) clearance to any overhead
combustible projection of 2-1/2 in (64 mm) or less (see Figure 4). For projections exceeding
2-1/2 in (64 mm), see Figure 4. For additional vent location restrictions refer to Figure 5 on Page 7.
Figure 4
For recess allowances of square horizontal termination into exterior walls,
see Figure 30 on Page 20.
Termination Heights for Vents
Above Flat or Sloped Roofs
(Ref. NFPA 54 / ANSI Z223.1)
Roof Pitch *Feet *Meters
Flat to 6/12 1.0 0.3
6/12 to 7/12 1.25 0.38
7/12 to 8/12 1.5 0.46
8/12 to 9/12 2.0 0.61
9/12 to 10/12 2.5 0.76
10/12 to 11/12 3.25 0.99
11/12 to 12/12 4.0 1.22
12/12 to 14/12 5.0 1.52
14/12 to 16/12 6.0 1.83
16/12 to 18/12 7.0 2.13
18/12 to 20/12 7.5 2.29
20/12 to 21/12 8.0 2.44
Vent/air intake termination clearances
above the high side of an angled roof
are listed in the table below.
Figure 3B: Vertical Vent Termination Clearances
12
X
Roof Pitch is X/12
2 FT
MIN.
2 FT MIN.
Lowest
Discharge
Opening
H*
*H = MINIMUM HEIGHT FROM ROOF TO
LOWEST DISCHARGE OPENING OF VENT
TERMINATION HEIGHTS FOR VENTS ABOVE
FLAT OR SLOPED ROOFS
Horizontal Overhang
Vertical
Wall
Vent
Termination
Storm Collar
Concentric
Vent Pipe
Flashing
1 inch (25.4 mm) Minimum
Clearance to Combustibles
LENNOX HEARTH PRODUCTS • MONTEBELLO
®
SEE-THROUGH DIRECT-VENT GAS FIREPLACES (LSM40ST-N / LSM40ST-P) • INSTALLATION INSTRUCTIONS
VENT TERMINATION
CLEARANCES
These instructions should be used as a guide-
line and do not supersede local codes in any
way. Install venting according to local codes,
these instructions, the current National Fuel
Gas Code (ANSI-Z223.1) in the USA or the cur-
rent standards of CAN/CSA-B149.1 in Canada.
Vertical Vent Termination Clearances
Terminate multiple vent terminations accord-
ing to the installation codes listed above. Also
see Figure 3A.
Terminate single vent caps relative to building
components as shown in Figure 3B.
12 in
(305 mm)
minimum
Figure 3A : Multiple Terminations
*H = minimum height from roof to lowest
discharge opening of vent.