10
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT PLUS
®
B-VENT GAS FIREPLACES (MPB33/35/40/45) • INSTALLATION INSTRUCTIONS
IMPORTANT: If propane is used, be aware that
if tank size is too small (i.e. under 100-lbs, if
this is the only gas appliance in the dwelling.
Ref. NPFA 58), there may be loss of pressure,
resulting in insufficient fuel delivery (which
can result in sooting, severe delayed ignition
or other malfunctions). Any damage resulting
from an improper installation, such as this,
is not covered under the limited warranty.
STEP 3. INSTALLING VENT SYSTEM
These instructions should be used as a
guideline 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 current standards of CAN/CGA-B149.1
in Canada.
Ensure clearances are in accordance with
local installation codes and the requirements
of the gas supplier.
Dégagement conforme aux codes d'installa-
tion locaux et aux exigences du foumis-
seunde gaz.
Use only approved vent components (see
Approved Vent Components
on
Page 2).
These fireplaces must be vented vertically to
the outside.
Refer to
Figure 14,
and slip the first section
of B-Vent over the fireplace flue outlet and
secure with sheet metal screws (# 8 or larger),
then install the remainder of the B-Vent vertically
to the outside. Minimum overall height of the
vent system and appliance must be 10' (2.54
m) vertical with no offset, or 12' (3.7 m) when
an offset up to 45 degrees from the vertical is
used; or 15' (4.6 m) when an offset is greater
than 45 degrees and up to 60 degrees (see
Figure 17
).
The offset may start at the fireplace flue collar.
The maximum overall height of the vent system
and appliance should not exceed 40 feet.
Install the B-vent system in accordance with
the vent manufacturer's instructions.
Required Pipe Diameter:
MPB33 series:
Requires 4" (102 mm)
MPB35 series:
Requires 5" (127 mm)
MPB40 series:
Requires 5" (127 mm)
MPB45 series:
Requires 6" (152 mm)
Figure 14 - Initial B-Vent Installation
Type B-Vent - 4" (102 mm) for MPB33 Models,
5" (127 mm) for MPB35 / 40 Models or 6"
(152 mm) for MPB45 Models
Securing
Screws
Flue Outlet
Collar
Refer to the vent manufacturers installation
instructions for variations of venting techniques.
If common venting of several units is contem-
plated, it should be discussed with an architect
and the local Building Department.
Do not place insulation materials within 1" of
the gas vent system.
Back View
Of Appliance
10 ft.
Minimum
Back View
Of Appliance
*12 ft. Min.
**15 ft. Min.
*with an offset up to 45 degrees
** with an offset greater than 45
degrees and up to 60 degrees
Vertical
Installations
Back View
Of Appliance
10 ft.
Minimum
Back View
Of Appliance
*12 ft. Min.
**15 ft. Min.
*with an offset up to 45 degrees
** with an offset greater than 45
degrees and up to 60 degrees
Offset
Installations
The maximum overall height of the vent system
and appliance should not exceed 40 feet.
Figure 17 - Vent System Installation
CAUTION
This appliance cannot be vented
horizontally.
USE ONLY APPROVED B-VENT DIAMETER
MPB33, MPB35, MPB40 and MPB45 series
fireplaces must be vertically vented using
listed type-B, double-walled vent pipe with
the proper diameter as listed below and a
listed vent termination.