5
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT PLUS
®
B-VENT GAS FIREPLACES (MPB33/35/40/45) • INSTALLATION INSTRUCTIONS
Figure 3 - Typical Installations
When the unit is installed with one side flush with a
wall, the wall on the other side of the unit must not
extend beyond the front edge of the unit.
Offset
Venting
Vertical
Venting
Shown with Outside Air Kit
installed (model FOAK-4 or
FOAK-4LD)
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
Figure 4 - Vertical Vent Termination
Clearances
Roof Pitch is X/12
Minimum Height from Roof to
Lowest Discharge Opening
X
12
1“ (25 mm)
Minimum
2 ft.
(0.6m)
Minimum
Figure 5 - Multiple Terminations
If the fireplace is being installed on a cement
slab in cold climates, a sheet of plywood or
other raised platform can be placed underneath
to prevent conduction of cold transferring to
the fireplace and into the room. It also helps to
sheetrock inside surfaces and tape for maximum
air tightness and caulk firestops.
MANUFACTURED HOUSING
B-Vent Fireplaces are not approved for use in
OEM or aftermarket manufactured housing built
to HUD standards.
LOCATION
In selecting the location, the aesthetic and
functional use of the appliance are primary
concerns. However, vent system routing to
the exterior and access to the fuel supply are
also important.
Due to high temperatures, the appliance
should be located out of traffic and away from
furniture and draperies
(Figure 3)
.
En raison des températures élevées,
l’appareil devrait être installé dans un
endroit où il y a peu de circulation et loin
du mobilier et des tentures
(Figure 3)
.
The location should also be free of electrical,
plumbing or other heating/air conditioning
ducting.
Be aware that this is a heat producing ap-
pliance. Objects placed above the unit are
exposed to elevated temperatures.
Do not insulate the space between the ap-
pliance and the area above it
(see
Figure
10
on Page 8
).
The appliance must be mounted on a fully
supported base extending the full width
and depth of the unit. The appliance may be
located on or near conventional construction
materials. However, if installed on combustible
materials, such as carpeting, vinyl tile or other
combustible material other than wood flooring,
the appliance shall be installed on a metal or
wood panel extending the full width and depth
of the appliance
VENT TERMINATION CLEARANCES
Gas Vent Rule
- Gas vent caps are not per-
mitted within 8 feet (2.4 mm) of a vertical
wall or similar obstruction. Gas vent caps
that are located 8' or more from a portion
of a building which extends at an angle
greater than 45° upward from the horizontal
may terminate in accordance with
Figure 4
,
provided that in no case shall any discharge
opening on the cap be less than 2' (610 mm)
horizontally from the roof surface (National
Fuel Gas Code ANSI Z223.1 (NFPA 54) Gas
Vent Termination) (CAN/CGA B149.1).
MULTIPLE TERMINATIONS
These appliances may vent adjacent to and at
the same level with any other gas appliances
(including direct-vent appliances) provided that
there is at least 2 ft. (0.6m) between the proximal
edges of the vent caps. These appliances may
be vented adjacent to a chimney vent servicing
a solid fuel fireplace provided the B-vent cap
is at least 2 ft. (0.6m) away from the nearest
point of the chimney opening.
