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NOTE: DIAGRAMS & ILLUSTRATIONS NOT TO SCALE.
2
CONGRATULATIONS!
In selecting this LENNOX B-Vent Gas Appliance you have chosen the fi nest and most
dependable fi replace to be found anywhere. Its 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 carefully read and 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.
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.)
GENERAL INFORMATION
Note: Installation and repair should be per-
formed 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.
TABLE OF CONTENTS
Introduction .......................................page 2
General Information ...........................page 2
Gas Controls/Control Compartment,
Access .............................................page 4
Operation/Care of Your Appliance ......page 4
Variable Flame Adjustment .................page 5
Venting Action and (spill switch) .......page 5
Outside Combustion Air Control ........page 6
Maintenance .......................................page 6
Front Glass Enclosure Panel,
Removal and Installation ..................page 7
Logs, Vermiculite & Ember Placement page 8
Burner Adjustments ...........................page 10
Maintenance Schedule .......................page 11
Troubleshooting Guide – Millivolt ......page 12
Troubleshooting Guide – Electronic ...page 12
Millivolt Appliance Checkout ..............page 14
Electronic Appliance Checkout ...........page 14
Wiring Diagrams ................................page 14
Warranty ............................................page 14
Product Reference Information ..........page 14
Accessory Components .....................page 15
Lighting Instructions – Millivolt .........page 18
Lighting Instructions – Electronic ......page 19
Replacement Parts List ......................page 20
Electronic Models -
Electronic models have a fi xed rate gas valve.
Input of electronic models is shown in the
following table:
INTRODUCTION
The millivolt appliances have a millivolt gas
control valve witha piezo ignition system which
provides safe, effi cient operation.
The electronic appliances have an electronic
intermittent pilot system provides safe, effi cient
operation. External electrical power is required
to operate these units.
LISTING AS FOLLOWS:
These appliances comply with National Safety
Standards and are tested and listed by Omni-
Test Laboratories (Report No. 116-F-27-5)
to ANSI Z21.50 - 2000 (in Canada, CSA 2.22
- 2000), and CAN/CGA-2.17-M91 in both USA
and Canada, as vented gas fi replaces.
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.
These appliances are designed to operate on
natural or propane gas only. The use of other
fuels or combination of fuels will degrade
the performance of this system and may be
dangerous.
Millivolt Models - BTU Input
Millivolt models come standard with the manu-
ally-modulated gas valve; fl ame appearance and
heat output can be controlled at the gas valve.
Input of for these models is shown in the fol-
lowing table:
Gas Pressure -
Tables 3, 4 and 5 show the appliances' gas
pressure requirements.
Inlet Gas Supply Pressure
(all models)
Fuel # Minimum Maximum
Natural Gas
5.0" WC
(1.24 kPa)
10.5" WC
(2.61 kPa)
Propane
11.0" WC
(2.74 kPa)
13.0" WC
(3.23 kPa)
Table 3
Manifold Gas Supply Pressure
(electronic models)
Fuel # Fixed
Natural Gas
3.5" WC
(.87 kPa)
Propane
10.0" WC
(2.49 kPa)
Table 5
Input (BTU) - Fixed Rate
(electronic models)
Models Fuel
Type
Input Rate
(BTU / HR)
MPB35ST-NE Nat. Gas 30,000
MPB35ST-PE
(if fi eld converted)
Pro. Gas 28,000
Table 2
Manifold Gas Supply Pressure
(millivolt models)
Fuel # Low High
Natural
Gas
(Lo) 2.2" WC
(.55 kPa)
(Hi) 3.5" WC
(.87 kPa)
Propane
(Lo) 6.3" WC
(1.57 kPa)
(Hi) 10.0" WC
(2.49 kPa)
Table 4
Input (BTU) Manually-Modulated Gas
Valves (millivolt models)
Models Fuel
Type
Input Rate
(BTU / HR)
MPB35ST-NM Nat. Gas
30,000 high
23,000 low
MPB35ST-PM Propane
28,000 high
22,000 low
Table 1
IMPORTANT
It is imperative that the control
compartment, burners and
circulating air passage ways
of the appliance be kept clean.
See Maintenance instructions
on Pagex 6.