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NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
CONGRATULATIONS!
In selecting this Lennox B-Vent Gas Appliance you have chosen the fi nest and most
dependable fi replace to be found anywhere. A beautiful, prestigious, alternative to a
wood burning fi replace. Welcome to a Family of tens of thousands of satisfi ed Lennox
Fireplace Owners.
Please read and carefully follow all of the instructions found in this manual. Please pay
special attention to the safety instructions provided in this manual. The Homeowner's
Care and Operation Instructions included here will assure that you have many years of
dependable and enjoyable service from your Lennox product.
INTRODUCTION
Installation must conform to local codes. In
the absence of local codes, installation must
comply with the current National Fuel Gas Code,
ANSI Z223.1 (NFPA 54). (In Canada, the current
CAN/CGA B149 installation code). Electrical
wiring must comply with local codes. In the
absence of local codes, installation must be in
accordance with the National Electrical Code,
NFPA 70 - (latest edition). (In Canada, the current
CSA C22.1 Canadian Electric Code).
TABLE OF CONTENTS
Safety & Warning Information ..........Page 2
Introduction ......................................Page 3
General Information ..........................Page 3
Operation/Care of Your Appliance .....Page 4
Variable Flame Adjustment ................Page 4
Outside Combustion Air Control .......Page 5
Manual Limit Switch .........................Page 6
Maintenance Schedule ......................Page 7
Maintenance ......................................Page 8
Front Glass Enclosure Panel,
Removal and Installation ...............Page 8
Burner Adjustments ..........................Page 9
Millivolt Appliance Checkout .............Page 9
Electronic Appliance Checkout ..........Page 9
Logs, Rockwool, Vermiculite &
Volcanic Stone Placement .............Page 10
Wiring Diagrams ...............................Page 15
Warranty ...........................................Page 15
Replacement Parts ............................Page 15
Product Reference Information .........Page 15
Accessory Components ....................Page 16
Lighting Instructions – Millivolt ........Page 20
Lighting Instructions – Electronic .....Page 22
Troubleshooting Guide – Millivolt .....Page 24
Troubleshooting Guide – Electronic ..Page 24
Replacement Parts List .....................Page 26
The millivolt appliances are designed to operate
on either natural or propane gas. A millivolt
gas control valve with piezo ignition system
provides safe, effi cient operation. External
electrical power is required to operate the
optional electrically powered components, if
installed. Electrical power must be wired during
appliance installation.
The electronic appliances are designed to
operate on either natural or propane gas. An
electronic intermittent pilot system provides
safe, effi cient operation. External electrical
power is required to operate these units.
These appliances comply with National Safety
Standards and are tested and listed by OMNI-
Test Laboratories, Inc. (Report No. 116-F-36-5)
to ANSI Z21.50 (in Canada, CSA 2.22), and
CAN/CGA-2.17-M91 in both USA and Canada,
as vented gas fi replaces.
GENERAL INFORMATION
Note: Installation and repair should be
performed by a qualifi ed service person. The
appliance should be inspected annually by a
qualifi ed professional service technician. More
frequent inspections and cleanings may be
required due to excessive lint from carpeting,
bedding material, etc. It is imperative that the
control compartment, burners and circulating air
passage ways of the appliance be kept clean.
S'assurer que le brùleur et le compartiment des
commandes sont propres. Voir les instructions
d'installation et d'utilisation qui accompagnent
l'appareil.
Provide adequate clearances around air open-
ings and adequate accessibility clearance for
service and proper operation. Never obstruct
the front openings of the appliance.
Due to high temperatures the appliance should
be located out of traffi c and away from furniture
and draperies. Locate furniture and window
coverings accordingly.
Millivolt Models with
Manually-Modulated Gas Valve
Natural Gas Propane Gas
Model Input Rate
(BTU/HR)
Input Rate
(BTU/HR)
MPB3328
13,500 to 17,500 13,500 to 17,500
MPB3530
16,000 to 20,000 16,500 to 20,000
MPB4035
24,000 to 30,000 22,300 to 28,000
MPB4540
24,750 to 31,000 23,000 to 29,000
Table 1
Electronic Models -
Electronic models have a fi xed rate gas valve.
Input of electronic models is shown in Table 2:
Electronic Models with
Fixed-Rate Gas Valve
Natural Gas Propane Gas
Model Input Rate
(BTU/HR)
Input Rate
(BTU/HR)
MPB3328
17,500 17,500
MPB3530
20,000 20,000
MPB4035
30,000 28,000
MPB4540
31,000 29,000
Table 2
These appliances are designed to operate on
natural or propane gas only.
Input of millivolt models is variable. These rates
are shown in Table 1:
Maximum manifold pressure is 3.5 in. w.c. (0.87
kPa) for natural gas and 10 in. w.c. (2.49 kPa)
for LP/Propane gas.
Do not use these appliances if any part has been
under water. Immediately call a qualifi ed, profes-
sional service technician to inspect the appliance
and to replace any parts of the control system and
any gas control which have been under water.
Ne pas se servir de cet appareil s'il a été plongé
dans l'eau, complètement ou en partie. Appeler
un technicien qualifi é pour inspecter l'appareil et
remplacer toute partie du système de contrôle et
toute commande qui ont été plongés dans l'leau.
Test gauge connections are provided on the front
of the millivolt gas control valve (identifi ed OUT
for the manifold side and IN for inlet pressure. A
1/8" NPT test gauge connection is provided on the
electronic gas control valve adjacent to the outlet
to the main burner.
Minimum inlet gas pressure to these appliances is
5.0 inches water column (1.24 kPa) for natural gas
and 11 inches water column (2.74 kPa) for propane
for the purpose of input adjustment.
Maximum inlet gas supply pressure to these appli-
ances is 10.5 inches water column (2.61 kPa) for
natural gas and 13.0 inches water column (3.23
kPa) for propane.
Table 3 shows the units' orifi ce size for the
elevations indicated.
Burner Orifi ce Sizes
Elevation 0-4500 feet ( 0-1372 meters)
Models
NaturalGas
drill size (inches)
Propane Gas
drill size (inches)
MPB-3328 #47 (.0785") *
39L66 •
1.2mm (.048")*
99K78 •
MPB-3530 #44 (.086")*
60J80 •
#55 (.052")*
19L52 •
MPB-4035 #37 (.104")*
24M10 •
1/16"
(.0625")*
21L01 •
MPB-4540 #36 (.1065")*
18L40 •
#52 (.0635")*
37G00 •
Table 3
* Standard size installed at factory
• Part /Cat. Number