Lennox Montebello MDLX40IN-PV User manual

MODELS
This appliance may be installed in an aftermarket permanently located, manufactured home (USA only) or mobile
home, where not prohibited by local codes. This appliance is only for use with the type of gas indicated on the rating
plate. This appliance is not convertible for use with other gases.
INSTALLATION INSTRUCTIONS
Montebello®DLX Power Vent
Direct-Vent Gas Fireplaces
MDLX40IN-PV MDLX45IN-PV
ELECTRONIC:
P/N 506023-16 Rev. NC 08/2012
This manual is one of a set of two supporting this product.
Refer to P/N 506025-08 for Care and Operation Instructions.
Ce manuel est disponible en francais, simplement
en faire la demande. Numéro de la pièce 506223-49.
INSTALLER: Leave this manual with the appliance.
CONSUMER: Retain this manual for future reference.
INSTALLATEUR : Laissez cette notice avec l'appareil.
CONSOMMATEUR : Conservez cette notice pour
consultation ultérieure.
AVERTISSEMENT : Assurez-vous de bien suivre les
instructions données dans cette notice pour réduire au
minimum le risque d’incindie ou d’explosion ou pour
éviter tout dommage matériel, toute blessure ou la mort.
WARNING: If the information in these instructions
is not followed exactly, a fire or explosion may
result, causing property damage, personal injury,
or death.
WARNING/AVERTISSEMENT/AVISO
• HOT GLASS WILL CAUSE
BURNS.
• DO NOT TOUCH GLASS
UNTIL COOLED.
• NEVER ALLOW CHILDREN
TO TOUCH GLASS.
• UNE SURFACE VITRÉE CHAUDE
PEUT CAUSER DES BRÛLURES.
• LAISSER REFROIDIR LA SURFACE
VITRÉE AVANT D'Y TOUCHER.
• NE PERMETTEZ JAMAIS À UN ENFANT
DE TOUCHER LA SURFACE VITRÉE.
• EL VIDRIO CALIENTE
CAUSARÁ QUEMADURAS.
• USTED DEBE NUNCA
TOCAR EL VIDRIO CALIENTE.
• LOS NIÑOS DEBEN NUNCA
TOCAR EL VIDRIO.
- Do not store or use gasoline or other flammable
vapors and liquids in the vicinity of this or any other
appliance.
- WHAT TO DO IF YOU SMELL GAS:
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any
phone in your building.
• Immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions.
• If you cannot reach your gas supplier, call the fire
department.
- Installation and service must be performed by a
qualified installer, service agency or the gas supplier.
- Ne pas entreposer ni utilizer d’essence ni d’autres vapeurs
ou liquides inflammables dans le voisinage de cet appareil
ou de tout autre appareil.
- QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ :
• Ne pas tenter d’allumer d’appareil.
• Ne touchez à aucan interrupteur. Ne pas vous servir des
téléphones se trouvant dans le bâtiment où vous trouvez.
• Appelez immédiatement votre fournisseur de gaz depuis
un voisin. Suivez les instructions du fournisseur.
• Si vous ne pouvez rejoindre le fournisseur de gaz,
appelez le service des incindies.
- L’installation et l’entretien doivent être assurés par un
installateur ou un service d’entretien qualifié ou par le
fournisseur de gaz.
Intertek Report No.
100513650PRT-001
®
Please read and understand these instructions
before starting installation.

2
WARNING
Young children should be
carefully supervised when they
are in the same room as the
appliance. Toddlers, young
children and others may be
susceptible to accidental contact
burns. A physical barrier is
recommended if there are at
risk individuals in the house.
To restrict access to a fireplace
or stove, install an adjustable
safety gate to keep toddlers,
young children and other at risk
individuals out of the room and
away from hot surfaces.
AVERTISSEMENT
Les jeunes enfants devraient
être surveillés étroitement
lorsqu’ils se trouvent dans la
même pièce que l’appareil.
Les tout petits, les jeunes
enfants ou les adultes
peuvent subir des brûlures
s’ils viennent en contact
avec la surface chaude. Il
est recommandé d’installer
une barrière physique si des
personnes à risques habitent
la maison. Pour empêcher
l’accès à un foyer ou à un
poêle, installez une barrière
de sécurité; cette mesure
empêchera les tout petits,
les jeunes enfants et toute
autre personne à risque
d’avoir accès à la pièce et aux
surfaces chaudes.
GENERAL INFORMATION
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
TABLE OF CONTENTS
Packaging .........................................Page 2
Introduction ......................................Page 2
General Information ..........................Page 2
Massachusetts Requirements...........Page 4
Cold Climate Insulation .....................Page 5
Manufactured Home Requirements ..Page 5
Location............................................Page 5
Vent Termination Clearances ............Page 6
Minimum Clearances to Combustibles Page 8
Pre-Installation Steps........................Page 9
Typical Installation Sequence ...........Page 9
Detailed Installation Steps.................Page 9
Step 1. Framing...............................Page 9
Fireplace and Framing Specifications Page 10
Step 2. Routing Gas Line ................Page 11
Proper Sizing of Gas Line..................Page 11
Step 3. Install the Vent System .......Page 12
General Vent Information..................Page 12
Power Vent Components...................Page 12
Vent Section Length Chart ................Page 13
Offset Installation..............................Page 13
Horizontal Termination System .........Page 16
Installing Power Vent Termination ....Page 16
Step 4. Field Wiring.........................Page 18
Step 5. Removing Glass Door
Frame Assembly ...............................Page 20
Step 6. Connecting Gas Line ...........Page 21
Step 7 Install Firebox Liner ............Page 21
Step 8. Verifying Appliance
Operation ..........................................Page 21
Step 9. Installing Logs ...................Page 22
Step 10. Install/Remove Glass
Door Assembly .................................Page 24
Step 11. Burner Adjustments............Page 24
Finishing Requirements ....................Page 26
Step 12. Attaching Safety-in-
Operation Warnings ................... Page 27
Installation Accessories ....................Page 28
PACKAGING
The assembled vented gas fireplace is packaged with:
BOX 1—Fireplace:
• Literature Kit (plastic bag shipped
inside rebox),
• Bags of Glowing Embers, Platinum Embers,
and Volcanic Stone
•Pull Screen
• Door Modesty Shield
• Adaptor with Probe Assembly
• (1) Remote Control Kit and Receiver Kit
BOX 2—Power Vent Components:
• (1) Power Vent Termination
• (1) Termination Adaptor
• (1) Horizontal Firestop Assembly
• (1) Vacuum Hose
• (1) 11/32 in. Hose Clamp
• (1) Strain Relief
• (1) Bushing
• (4) Insulated 1/4 in. Male Terminals
• (2) #10 Ring Terminals
REQUIRED ACCESSORIES
The following accessories are required:
• One of the following Firebox Liner Kits:
a. Ceramic Liner Kit—Buff Rustic
b. Ceramic Liner Kit—Red Rustic
c. Porcelain Liner Kit—Black
d. Ceramic Liner Kit—Red Herringbone
e. Ceramic Liner Kit—Buff Herringbone
NOTE: Porcelain kits include side and back
panels. Optional for use with log sets.
Required when using the contemporary
burner/floor kit.
• One of the following Floor Options:
a. Oak Log Set (For use with fireplace as
shipped from factory only. Not for use with
contemporary burner/floor kit.)
b. Contemporary Burner/Floor Kit
Contemporary Burner/Floor Kit requires
one of the following Media Kits:
i. Crushed Glass—Reective Black
ii. Crushed Glass—Platinum
iii. Crushed Glass—Reective Blue
iv. Crushed Glass—Goldfinger
v. Crushed Glass—Copper
NOTE: The Contemporary Burner/Floor Kit
installation instructions are provided
with the kit, and are not detailed in this
manual.
INTRODUCTION
These Electronic appliances are designed to
operate on natural gas and have an electronic
intermittent pilot ignition system. External
120 Volt AC electrical power is required to
operate these units.
These vented gas fireplaces are sealed
combustion gas replaces designed for
residential, manufactured home, and
commercial applications.
Use Only These Approved Vent Components
These replaces are designed, tested and
listed for operation and installation with, the
following (4 1/2 in. inner and 7 1/2 in. outer)
vent components only:
• Secure Vent®Direct-vent system
components manufactured by Security
Chimneys International.
These approved vent system components
are labeled for identication. Do NOT use any
other manufacturer’s vent components with
these appliances.
Children and adults should be alerted to the
hazards of high surface temperature and should
stay away to avoid burns or clothing ignition.
Les enfants et les adultes devraient être
infor-més des dangers que posent les
températures de surface élevées et se
tenir à distance afin d’éviter des brûlures
ou que leurs vêtements ne s’enflamment.
DO NOT ATTEMPT TO ALTER OR MODIFY
THE CONSTRUCTION OF THE APPLIANCE
OR ITS COMPONENTS. ANY MODIFICATION
OR ALTERATION MAY VOID THE
WARRANTY, CERTIFICATION AND LISTINGS
OF THIS UNIT.

3
NOTE: Installation and repair should be
done by a qualified service person. The
appliance should be inspected before use
and at least annually by a professional
service person. More frequent cleaning
may be required due to excessive lint from
carpeting, bedding material, etcetera. It
is imperative that control compartments,
burners and circulating air passageways of
the appliance be kept clean.
Remarque : L’installation et la
réparation devrait être confiées à un
technicien qualifié. L’appareil devrait
faire l’objet d’une inspection par un
technicien professionnel avant d’être
utilisé et au moins une fois l’an par la
suite. Des nettoyages plus fréquents
peuvent être nécessaires si les tapis,
la literie, et cetera produisent une
quantité importante de pous-sière. Il
est essentiel que les compartiments
abritant les commandes, les brûleurs
et les conduits de circulation d’air de
l’appareil soient tenus propres.
Do not use these appliances if any part
has been under water. Immediately call a
qualified, professional 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 utiliser cet appareil s’il a été
plongé, même partiellement, dans
l’eau. Appeler un technicien qualifié
pour inspecter l’appareil et remplacer
toute partie du système de commande
et toute commande qui a été plongée
dans l’eau.
Only trim kit(s) supplied by the
manufacturer shall be used in the
installation of this appliance.
Seules les trousses de garniture
fournies par le fabricant doivent
être utilisées pour l’installation de
cet appareil.
WARNING
Failure to position the parts in
accordance with these diagrams
orfailure touse onlyparts specifi-
callyapprovedwiththisappliance
may result in property damage or
personal injury.
AVERTISSEMENT
Risque de dommages ou de
blessures si les pièces ne sont
pas installées conformément à
ces schémas et ou si des pièces
autres que celles spécifiquement
approuvéesaveccetappareilsont
utilisées.
WARNING
Clothing or other flammable
material should not be placed
on or near the appliance.
AVERTISSEMENT
On ne devrait pas placer de
vêtements ni d’autres matières
inflammables sur l’appareil ni à
proximité.
WARNING
Improper installation or use
of this appliance can cause
serious injury or death from
fire, burns, explosion or
carbon monoxide poisoning.
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
WARNING
Improper installation,
adjustment, alteration, service
or maintenance can cause
injury or property damage.
Refer to this manual. For
assistance or additional
information consult a qualified
installer, service agency or the
gas supplier.
WARNING
Failure to comply with these
installation instructions will
result in an improperly installed
and operating appliance,
voiding its warranty. Any change
to this appliance and/or its
operating controls is dangerous.
WARNING
Any safety screen or guard
removed for servicing the
appliance must be replaced
prior to operating the appliance.
AVERTISSEMENT
Tout écran ou protecteur retiré
pour permettre l’entretien
de l’appareil doit être remis
en place avant de mettre
l’appareil en marche.
Codes and Standards
These appliances comply with National
Safety Standards and are tested and listed
by Intertek (Report No. 100513650) to
Z21.50b-2009 (in Canada, CSA-2.22b-2009),
and CAN/CGA-2.17-M91 (R2009) in both
USA and Canada, as vented gas replaces.
These appliances are listed by Intertek for
installation in bedrooms and manufactured
(mobile) homes.
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-B149.1 installation code).
The appliance, when installed, must be
electrically grounded in accordance with local
codes or, in the absence of local codes, with
the National Electrical Code, ANSI/NFPA 70—
latest edition, or the Canadian Electrical Code,
CSA C22.1—latest edition.
Provide adequate clearances around
air openings and adequate accessibility
clearance for service and proper operation.
Never obstruct the front openings of
the appliance.
These appliances are designed to operate
on natural gas. The use of other fuels
or combination of fuels will degrade the
performance of this system and may
be dangerous.
These appliances must not be connected to a
chimney or flue serving a separate solid fuel
burning appliance.
These electronic appliances are remotely
controlled and feature an electronic
intermittent pilot ignition system. External
electrical power is required to operate
these units.
These electronic models come standard
with a remotely-modulated gas valve; flame
appearance and heat output cannot be
controlled at the gas valve. The BTU Input
for these appliances is shown in Table 1.
Model No. Input (BTU/Hr)
MDLX40IN-PV 26,500–42,000
MDLX45IN-PV 35,000–48,000
Table 1: Input (BTU/HR), Natural Gas

4
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
In Canada - CAN/CGA-2.17-M91 (R2009)
(high altitude):
THE CONVERSION SHALL BE CARRIED OUT
BY A MANUFACTURER’S AUTHORIZED
REPRESENTATIVE, IN ACCORDANCE
WITH THE REQUIREMENTS OF THE
MANUFACTURER, PROVINCIAL OR
TERRITORIAL AUTHORITIES HAVING
JURISDICTION AND IN ACCORDANCE
WITH THE REQUIREMENTS OF THE
CAN/CGA-B149.1 OR CAN/CGA-B149.2
INSTALLATION CODES.
REQUIREMENTS FOR THE
COMMONWEALTH OF MASSACHUSETTS
These fireplaces are approved for installation
in the US state of Massachusetts if the
following additional requirements are met:
• Install this appliance in accordance with
Massachusetts Rules and Regulations
248 C.M.R.
• Installation and repair must be done by
a plumber or gas tter licensed in the
Commonwealth of Massachusetts.
• The exible gas line connector used shall
not exceed 36 in. (92 centimeters) in
length.
• The individual manual shut-off must be a
T-handle type valve.
Massachusetts Horizontal Vent Requirements
In the Commonwealth of Massachusetts,
horizontal terminations installed less than
seven (7) feet above the finished grade
must comply with the following additional
requirements:
• A hard wired carbon monoxide detector
with an alarm and battery back-up must
be installed on the oor level where the
gas replace is installed. The carbon
monoxide detector must comply with
NFPA 720, be ANSI/UL 2034 listed and be
ISA certified.
• A metal or plastic identication plate must
be permanently mounted to the exterior
of the building at a minimum height of
eight (8) feet above grade and be directly
in line with the horizontal termination.
The sign must read, in print size no less
than one-half (1/2) inch in size, GAS VENT
DIRECTLY BELOW. KEEP CLEAR OF ALL
OBSTRUCTIONS.
Gas Valve Diagram
See Figure 1 for gas valve diagram.
Figure 1: SIT Electronic Gas Valve
Wire
(From DFC Wire
Harness)
Pressure
Regulator
Tower
Yellow Ground Wire
(From DFC Wire
Harness)
Green Wire
(From DFC Wire
Harness)
Inlet (In) Test Port
Manifold (Out)
Test Port
Connect GTMS
Wire Harness
Main Gas Inlet
3/8 in. NPT
Test gauge connections are provided on the
front of the gas control valve; identified IN
for the inlet and OUT for the manifold side
(see Figure 1).
Orifice Sizes—Sea Level To High Altitude
These appliances are tested and approved
for installation at elevations of 0–4500 ft
(0–1370 m) above sea level, using the
standard burner orice sizes (marked with an
"*" in Table 4). For elevations above 4500 ft,
contact your gas supplier or qualied service
technician.
Deration—At higher elevations, the amount
of BTU fuel value delivered must be reduced
by either:
• Using gas that has been derated by the
gas company.
• Changing the burner orice to a smaller
size as regulated by the local Authorities
Having Jurisdiction and by the (USA)
National Fuel Gas Code NFPA 54/ANSI
Z223.1—latest edition, or in Canada, the
CAN/CGA-B149.1 code—latest edition.
Install the appliance according to the
regulations of the local authorities having
jurisdiction, and the (USA) National Fuel Gas
Code NFPA 54 / ANSI Z223.1—latest edition,
or (Canada) CAN/CSA-B149.1—latest edition.
NOTE: Flame appearance will diminish 4%
per one thousand feet of altitude.
Model Orifice Size / Catalog Number
MDLX40IN-PV 0.125 in. (1/8 in.) * H7924 •
MDLX45IN-PV 0.136 in. (#29) * H8141 •
* Standard size installed at factory
• Part /Cat. Number
Table 4: Burner Orifice Size
Elevation 0–4500 ft (0–1370 m)
The appliance and its appliance main gas
valve must be disconnected from the gas
supply piping system during any pressure
testing of that system at test pressures in
excess of 1/2 psi (3.5 kPa).
The appliance must be isolated from
the gas supply piping system by closing
its equipment shutoff valve during any
pressure testing of the gas supply piping
system at test pressures equal to or less
than 1/2 psi (3.5 kPa).
PURGE CYCLE
This is a power vented fireplace
that requires household electrical
power to operate. It will not operate
during a power failure. When the
fireplace is turned off, the exhaust
blower will continue to operate for
approximately fifteen (15) seconds
after shutdown to expel the exhaust
gases from the venting system.
LENNOX HEARTH PRODUCTS • MONTEBELLO® POWER VENT DV GAS FIREPLACES (LSM40/45EN-PV) • INSTALLATION INSTRUCTIONS
Gas Pressure—All Models
Tables 2 and 3 show the appliance inlet and
manifold gas pressure requirements.
Minimum Maximum
5.5 in. WC
(1.37 kPa)
10.5 in. WC
(2.62 kPa)
Table 2: Inlet Gas Supply Pressure
Low High
1.6 in. WC
(.40 kPa)
3.5 in. WC
(.87 kPa)
Table 3: Manifold Gas Supply Pressure

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
5
COLD CLIMATE INSULATION
For cold climate installations, seal all cracks
around your appliance with noncombustible
material and wherever cold air could enter the
room. It is especially important to insulate
outside chase cavity between studs and
under oor on which appliance rests, if oor
is above ground level. Gas line holes and
other openings should be caulked or stuffed
with unfaced berglass insulation.
If the replace is being installed on a cement
slab in cold climates, a sheet of plywood
or other raised platform can be placed
underneath to prevent cold transfer to the
fireplace and into the room. It also helps
to sheetrock inside surfaces and tape for
maximum air tightness and caulk restops.
MANUFACTURED HOME
REQUIREMENTS
This appliance may be installed in
an aftermarket permanently located,
manufactured home and must be installed
in accordance with the manufacturer's
instructions.
Cet appareil peut être installé cómme
du matéri-el d'origine dans une maison
préfabriquée (É.U. seulement) ou mobile
et doit être installé selon les instructions
du fabricant.
This appliance is only for use with the type
of gas indicated on the rating plate. This
appliance is not convertible for use with
other gases.
Cet appareil doit être utilisé uniquement
avec le type de gaz indiqué sur la plaque
signalétique. Cet appareil ne peut être
converti à d'autres gaz.
CAUTION: Ensure that the cross
members are not cut or weakened
during installation. The structural
integrity of the manufactured home
floor, wall, and ceiling/roof must
be maintained.
CAUTION: This appliance must
be grounded to the chassis of the
manufactured home in accordance with
local codes or in the absence of local
codes, with the National Electrical
Code ANSI / NFPA 70—latest edition.
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 2).
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 2).
The location should also be free of
electrical, plumbing or other heating/air
conditioning ducting.
Recessed
Application
Cross Corner
Application
Flat
Application
Flat on Wall
Application
Room Divider
Application
Island
Application
Figure 2: Typical Installation
Top of Fireplace
Opening
Drywall
Noncombustible
Horizontal
Termination
Fireplace
Be aware that this is a heat producing
appliance. Objects placed above the unit
are exposed to elevated temperatures.
Do not insulate the space between the
appliance and the area above it.
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 ooring, the appliance shall be
installed on a metal or wood panel extending
the full width and depth of the appliance.
NOTE: When the unit is installed with one
sideflushwith awall, the wallon theother
sideof theunit mustnot extendbeyondthe
front edge of the unit.
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS

6
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
VENT TERMINATION CLEARANCES
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, and the
current (USA) National Fuel Gas Code
ANSI-Z223.1 / NFPA 54, or (Canada) CAN/
CSA-B149.1 standards.
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 3).
For projections exceeding 2 1/2 in. (64 mm),
see Figure 4. For additional vent location
restrictions refer to Figure 4 and Table 5 on
Page 7.
LENNOX HEARTH PRODUCTS • MONTEBELLO® POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
See Figure 19 on Page 17 for the re-
cess allowances,into exteriorwalls,
of the power vent terminations.
Combustible Projection
2 1/2 in. or less in length
Combustible Projection
Greater than 2 1/2 in. in length
Ventilated or
Unventilated Soffit
3 in.
(76 mm)
24 in.
(610 mm)
Power Vent Termination
Side Elevation View
Figure 3: Horizontal Vent Termination Clearances
Combustible
18 in.
(457 mm)

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
7
Minimum Clearances Canadian Installation * US Installation **
AClearance above grade, veranda, porch, deck
or balcony. 12 in. (30 cm) * 12 in. (30 cm) **
BClearance to window or door that may be opened.
6 in. (15.2 cm) for appliances < 10,000 BTU/hr (3kW),
12 in. (30 cm) for appliances > 10,000 BTU/hr (3kW)
and < 100,000 BTU/hr (30kW),
36 in. (91 cm) for appliances > 100,000 BTU/hr
(30kW)*
6 in. (15.2 cm) for appliances < 10,000 BTU/hr (3kW),
9 in. (23 cm) for appliances > 10,000 BTU/hr (3kW)
and < 50,000 BTU/hr (15kW),
12 in. (30 cm) for appliances > 50,000 BTU/hr
(15kW)*
CClearance to permanently closed window 12 in. (305 mm) recommended to prevent
window condensation
9 in. (229 mm) recommended to prevent
window condensation
D
Vertical clearance to ventilated soft located above
the terminal within a horizontal distance of 36 in.
(91.4cm) from the center line of the terminal 24 in. (61.0 cm) 24 in. (61.0 cm)
EClearance to unventilated soffit 24 in. (61.0 cm) 24 in. (61.0 cm)
FClearance to outside corner 5 in. (12.7 cm) 5 in. (12.7 cm)
GClearance to inside corner 36 in. (91.4 cm) 24 in. (61.0 cm)
HClearance to each inside of center line extended
above meter / regulator assembly 3 ft (91 cm) within a height of 15 ft above the meter / regulator assembly * 3 ft (91 cm) within a height of 15 ft above the meter / regulator assembly **
IClearance to service regulator vent outlet 3 ft (91 cm) * 3 ft (91 cm) **
J
Clearance to non-mechanical air supply inlet to
building or the combustion air inlet to any other
appliance
6 in. (15.2 cm) for appliances < 10,000 BTU/hr (3kW),
12 in. (30 cm) for appliances > 10,000 BTU/hr (3kW)
and < 100,000 BTU/hr (30kW),
36 in. (91 cm) for appliances > 100,000 BTU/hr
(30kW)*
6 in. (15.2 cm) for appliances < 10,000 BTU/hr (3kW),
9 in. (23 cm) for appliances > 10,000 BTU/hr (3kW)
and < 50,000 BTU/hr (15kW),
12 in. (30 cm) for appliances > 50,000 BTU/hr
(15kW)*
KClearance to mechanical air supply inlet 6 ft (1.83 m) * 3 ft (91 cm) above, if within 10 ft (3 m) horizontally**
LClearance above paved sidewalk or paved
driveway located on public property 7 ft (2.13 m) ‡ 7 ft (2.13 m) ‡
M Clearance under veranda, porch, deck or balcony 18 in. (46.0 cm) * ‡ 18 in. (46.0 cm) ** ‡
Table 5: Exterior Horizontal Vent Termination Clearance Requirements
* In accordance with the current CAN/CGA-B149.1 National Gas and B149.2 Propane Installation Code—Latest Editions.
** In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Gas Code—Latest Edition.
‡ A vent shall not terminate directly above a sidewalk or paved driveway which is located between two single family dwellings and serves both dwellings.
*‡ Only permitted if veranda, porch, deck or balcony is fully open on a minimum 2 sides beneath the oor.
NOTE: Local Codes Or Regulations May Require
Different Clearances.
NOTE: Location Of The Vent Termination Must Not
Interfere With Access To The Electrical Service.
V
V V
V
V
F
C
B
B
A
B
H
M
I
X V
D
V
A A
A
V
L
B
J
X E
V
A
G
*18”
18”
B
C
C
C
K
X



* See Item D in the Text Below.
Center Line
of Termination
Exterior Wall
Horizontal
Termination
Ventilated Soffit
Inside Corner
DETAIL D
Inside
Corner Detail
Operable
Window
Fixed
Closed
Window
= 9 in. in U.S.
=12 in. in Canada
3 ft.
3 ft.
= Air Supply Inlet = Vent Terminal = Area where Terminal is NOT permitted
24 in.
36 in.
Figure 4: Exterior Horizontal Vent Termination Clearance Requirements
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS

8
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
* 3 in. (75 mm) above any horizontal/inclined vent component.
** See Page 9, Step 1 for clearance requirements to the nailing
flange located at each side of the unit and any screw heads adjacent
to it.
Wall Finishes / Surrounds / Mantels
NOTE: Combustible wall finish materials and/or surround materials
must not be allowed to encroach the area defined by the appliance
front face (black sheet metal). Never allow combustible materials
to be positioned in front of or overlapping the appliance face. See
Figure 6 and Figure 44 on Page 26.
Noncombustible materials, such as surrounds and other appliance
trim, may be installed on the appliance front face with these
exceptions: they must not cover any portion of the removable glass
panel.
Vertical installation clearances to combustible mantels vary according
to the depth of the mantel (see Figure 5). Mantels constructed of
noncombustible materials may be installed at any height above the
appliance. Minimum clearance requirements include any projections
such as shelves, window sills, mantels, etc. above the appliance.
NOTE: We recommend the use of high temperature paint (rated
175 °F or higher) on the underside of the mantel.
MINIMUM CLEARANCES TO COMBUSTIBLES
Appliance And Vent Clearances
The appliance is approved with zero clearance to combustible materials
on all sides. Refer to Table 6 for minimum clearance values. For typical
installations, see Figure 2 on Page 5.
Figure 6: Minimum Distance to Unprotected Side Wall
Figure 5: Minimum Mantel Clearances
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
Sides 1/2 in. (13 mm)
0 in. (0 mm) Spacers **
Top Spacers 0 in. (0 mm)
Floor 0 in. (0 mm)
Back 1/2 in. (13 mm)
0 in. (0 mm) Spacers
Bottom of Appliance To Ceiling 64 in. (1626 mm)
Vent 3 in. (76 mm) Top*
1 in. (25.4 mm) Sides & Bottom
Table 6: Appliance Minimum Clearances
Front 3 ft (0.9 m)
Table 7: Appliance Service Clearances
3 1/2 in.
(89 mm)
Top View of
Fireplace
Combustiblematerials
may project beyond
either side of the
fireplace opening as
long as they are kept
within the shaded
“Safe Zone” area.
At 0 in. minimum
side wall clearance,
one combustible
wall can project to
any length.
45o
Mantel Leg,
Trim, or Wall
12 (305) MANTEL
10 (254) MANTEL
8 (203) MANTEL
6 (152) MANTEL
4 (102) MANTEL
4
(102)
14
(356) 12
(305) 10
(254) 2 (51) MANTEL
TOP OF
APPLIANCE
6
(152)
NOTE: Hood shown as positioned in louvered
front model. The hood position in the flush
faced front model is lower than shown.
8
(203)
MANTEL CLEARANCES
Inches (mm)

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
9
PRE-INSTALLATION STEPS
The appliance is shipped with all gas controls
and components installed and pre-wired.
Before installing the appliance, follow these steps:
1. Remove the shipping carton.
2. Remove the shipping pad, exposing the
front glass door.
3. Using a Phillips screwdriver, unfasten the
two (2) screws located at the top of the glass
frame (see Figure 40 on Page 24). Tilt the
top of the glass frame away from the unit.
Lift it carefully off the bottom door track
and set the door aside, protecting it from
inadvertent damage.
4. Remove the embers and volcanic stone
from the control compartment.
TYPICAL INSTALLATION SEQUENCE
The typical sequence of installation is
outlined below. However, each installation
is unique and may result in variations to the
steps described.
See the page numbers references in the
following steps for detailed procedures.
Step 1. (Page 9) Construct the appliance
framing. Position the appliance
within the framing and secure with
nailing brackets.
Step 2. (Page 11) Route gas supply line to
the right side.
Step 3. (Page 12)Install the vent system and
exterior termination.
Step 4. (Page 18) Field Wiring
Connect 120 VAC electrical power to
the appliance receptacle.
Step 5. (Page 20)Remove glass door
assembly.
Step 6. (Page 21) Make connection to gas
supply.
Step 7. (Page 21) Install rebox liner kit.
Step 8. (Page 21)Verify appliance operation.
Step 9. (Page 22) Install volcanic stone,
glowing embers, and logs.
Step 10. (Page 24)Install glass door
assembly.
Step 11. (Page 24) Adjust burner to ensure
proper flame appearance.
Step 12.(Page 27) Attach Safety-in-
Operation Warnings.
Unit Being Secured by Its Nailing
Flanges to the Framing
Note: The nailing flanges, combustible members
and screw heads located in areas directly adjacent
to the nailing flanges, are EXEMPT from the 1/2 in.
clearance to combustible requirements for the
firebox outer wrapper. Combustible framing may be
in direct contact with the nailing flanges and may
be located closer than 1/2 in. from screw heads and
the firebox wrapper in areas adjacent to the nailing
flanges. Frame the opening to the exact dimensions
specified in the framing details of this manual.
Use Top Flange For
1/2 in. Thick Drywall
Use Bottom Flange For
5/8 in. Thick Drywall
Front Of
Fireplace
Use Center Flange
For Flush Mount
Left Side Front Corner of Fireplace Shown
(Right Side Requirements the Same)
Unit Being Secured By Its Nailing Flanges
To The Framing
Note: The nailing flanges, combustible members
and screw heads located in areas directly adjacent
to the nailing flanges, are EXEMPT from the 1/2 in.
clearance to combustible requirements for the
firebox outer wrapper. Combustible framing may be
in direct contact with the nailing flanges and may
be located closer than 1/2 in. from screw heads and
the firebox wrapper in areas adjacent to the nailing
flanges. Frame the opening to the exact dimensions
specified in the framing details of this manual.
Left Side Front Corner of Fireplace Shown
(Right Side Requirements the Same).
Figure 7: Unit Secured by Nailing
Flanges to the Framing
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
DETAILED INSTALLATION STEPS
Step 1. FRAMING
Frame these appliances as illustrated in
Figure 8 on Page 10, unless the appliance is
to be installed in a corner. See Figure 9 on
Page 11 for corner framing installations. All
framing details must allow for a minimum
clearance to combustible framing members
as shown in Table 6 on Page 8.
If the appliance is to be elevated above oor
level, a solid continuous platform must be
constructed below the appliance.
Headers may be in direct contact with
the appliance top spacers but must not
be supported by them or notched to t
around them.
The replace should be secured to the side
framing members using the unit nailing
anges—one top and bottom on each side
of the fireplace front (see Figure 7). Use 8d
nails or their equivalent.

10
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Vent Size
Co-axial DV
Vent Size
4 1/2 in. Inner
7 1/2 in. Outer
E
A
B
D
Top View
Front View
5 3/32 in. (129)
Right Side View
14 1/8 in.
8 1/2 in.
(216)
5 1/4 in.
(133)
(359) 26 15/32 in.
(672)
C
25 29/32 in.
(658)
25 1/2 in.
(648)
7 in.
2 1/2 in. (64)
(178)
19 5/8 in.
(498)
Gas Inlet
(This
Side
Only)
Electrical
Inlet
8 3/8 in.
(213)
F
G
H
J
8 / 11 in.
Vent / Intake
Notes
Diagrams, illustrations andphotographs
are not to scale – consult installation
instructions. Product designs, materi-
als, dimensions, specifications, colors
and prices are subject to change or
discontinuance without notice.
* C = Adaptor Plus 4 ft Vertical Vent (min.) and 90° Elbow
Model
No. A B C D E F G H J
MDLX40IN-PV in. 50 5/8 37 1/4 42 7/8 25 5/16 34 37 5/8 33 3/32 29 9/32 34 3/4
mm 1286 946 1089 643 864 956 840 744 883
MDLX45IN-PV in. 56 11/16 42 1/4 47 7/8 28 3/8 40 1/8 43 5/8 38 3/32 34 1/2 40 59/64
mm 1440 1073 1216 721 1019 1108 968 876 1039
Table 9: Fireplace Dimensions
Figure 8: Fireplace and Framing Specifications
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
FIREPLACE AND FRAMING SPECIFICATIONS
A
BC
VENT FRAMING
TOP VENT WITH 2 FEET
VERTICAL VENT AND
ONE 90° ELBOW
Framing should be constructed
of 2x4 or larger lumber.
Inches (mm)
(641)
25 1/4 in.
1/2 A
10 1/2 in.
(267)
7 in.
(178)
5 1/8 in.
(130) 12 1/8 in.
(308)
Model No. A B C *
MDLX40IN-PV in. 50 3/4 43 139 1/8
mm 1289 1092 3534
MDLX45IN-PV in. 56 7/8 48 144 1/8
mm 1445 1219 3661
Table 8: Framing Dimensions
Adaptor Plus 4 ft
Vertical
Vent (min.)
and 90° Elbow

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
11
Model No. A B C D
MDLX40IN-PV in. 50 5/8 83 5/8 59 1/8 41 7/8
mm 1286 2124 1502 1064
MDLX45IN-PV in. 56 3/4 89 7/8 63 1/2 44 7/8
mm 1441 2283 1613 1140
Table 10: Dimensions for Corner Framing with Power Vent Terminations
C
Back wall of chase/enclosure
(including any finishing materials)
D
A
B
Figure 9: Corner Framing with Power Vent Termination
Gas lines must be routed, constructed
and made of materials that are in strict
accordance with local codes and regulations.
We recommend hiring a qualied plumber
or gas fitter to correctly size and route the
gas supply line to the appliance. Installing a
gas supply line from the fuel supply to the
appliance involves numerous considerations
of materials, protection, sizing, locations,
controls, pressure, sediment, and more. Only
a qualied installer should attempt sizing or
installing gas pipe.
Notes:
• All appliances are factory-equipped with
a exible gas line connector and 1/2 in.
shutoff valve (see Figure 30 on Page 21).
• See Massachusetts Requirements on
Page 4 for additional requirements for
installations in the state of Massachusetts
in the USA.
• The gas supply line should Not be
connected to the appliance until Step 6
(Page 21).
• A pipe joint compound rated for gas
should be used on the threaded joints. Be
very careful that the pipe compound does
not get inside the pipe.
• Installing a sediment trap in the supply
line as close as possible to the appliance
is recommended.
• Check with local building ofcial for local
code requirements.
Length Inside Diameter
0–10 ft (0–3.1 m) 1/2 in. (12.7 mm)
10–40 ft (3.1–12.2 m) 1/2 in. (12.7 mm)
40–100 ft (12.2–30.5 m) 1/2 in. (12.7 mm)
100–150 ft (30.5–45.7 m) 3/4 in. (19.1 mm)
150–200 ft (45.7–61.0 m) 3/4 in. (19.1 mm)
Table 11: Schedule 40 Black Iron Pipe
Inside Diameter
6 1/4 in.
(159 mm)
19 5/8 in.
(498 mm)
Figure 10: Right-Front Corner of
Fireplace Framing
Step 2. ROUTING GAS LINE
Route a 1/2 in. (13 mm) gas line along the
inside of the right side framing as shown
in Figure 10. Gas lines must be routed,
constructed and made of materials that are
in strict accordance with local codes and
regulations.
All appliances are factory-equipped with a
exible gas line connector and 1/2 in. shutoff
valve. (see Step 6 on Page 21).
Proper Sizing of Gas Line
Properly size and route the gas supply
line from the supply regulator to the area
where the appliance is to be installed per
requirements outlined in the (USA) National
Fuel Gas Code, ANSI Z223.1/NFPA 54—latest
edition, or (Canada) CAN/CSA-B149.1—
latest edition.
Never use galvanized or plastic pipe. Refer to
Table 11 for proper sizing of the gas supply
line, if black iron pipe is being used.
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS

12
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Power Vent Components
Locate the replace as instructed in this manual. Make the following modications to add the
components used with the Power Vent Kit. This kit may only be used in conjunction with Direct-
Vent series electronic versions of Lennox Hearth Products Fireplaces. This installation must
conform with local codes, or, in the absence of local codes, with the (USA) National Fuel Gas
Code, ANSI Z223.1/NFPA 54—latest edition, or (Canada) CAN/CGA-B149.1—latest edition.
CAUTION: This power vent kit cannot be used with millivolt appliances. Use the kit only
with the electronically controlled fireplaces listed for its use as shown in this document.
Item No. Part
Number Description Qty.
1604187-01 Adaptor Assembly With Probe 1
2601970-01 Vacuum Hose 1
3601451-01 Termination Assembly 1
474L61 SV Termination Adaptor (SV4.5RCH) 1
5102010-01 Strain Relief—3/8 in. 1
6H2246 Firestop Assembly (Horizontal) 1
7102022-01 Hose Clamp—11/32 in. 2
8P-8-7102 Snap Bushing 1
9 — Ring Terminal—#10 2
10 —Insulated 1/4 in. Male Terminal 4
Table 12: Power Vent Kit Components
Step 3. INSTALL THE VENT SYSTEM
General Information
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, and
the (USA) National Fuel Gas Code, ANSI
Z223.1/NFPA 54—latest edition, or
(Canada) CAN/CSA-B149.1—latest edition.
These fireplaces are designed, tested and
listed for operation and installation only
with Secure Vent®(SV4.5) and Secure Flex®
Direct-Vent System Components,
manufactured by Security Chimneys
International. These approved vent system
components are labeled for identification.
DO NOT use any other manufacturer's vent
components with these appliances.
Ensure clearances are in accordance
with local installation codes and the
requirements of the gas supplier.
Dégagement conforme aux codes
d'installation locaux et aux exigences du
foumisseunde gaz.
Use only approved venting components.
See Approved Vent Components on Page 2.
These fireplaces must be vented
directly to the outside.
The vent system may not service multiple
appliances, and must never be connected to
a ue serving a separate solid fuel burning
appliance. The vent pipe is tested to be run
inside an enclosed wall (such as a chase).
There is no requirement for inspection
openings in the enclosing wall at any of the
joints in the vent pipe.
Venting System
With the appliance secured in framing,
determine vent routing and identify the
exterior termination location. The following
sections describe horizontal (exterior wall)
vent applications. A list of approved venting
components is shown on Page 28.
2
13
46
5
7
8
Figure 11: Power Vent Kit Components
89
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
13
Note: Convert inches into metric equivalent
measurement, as follows:
Millimeters (mm) = Inches x 25.4
Centimeters (cm) = Inches x 2.54
Meters (m) = Inches x .0254
Model Effective Length
SV4.5L6 4 1/2 in.
SV4.5L12 10 1/2 in.
SV4.5L24 22 1/2 in.
SV4.5L36 34 1/2 in.
SV4.5L48 46 1/2 in.
Table 13: Effective Vent Length
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5.712 521.81 0 1 0 6 0 7
5.922 521.91 0 0 1 6 0 7
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5.142 521.02 0 0 0 7 0 7
642 5.02 1 0 0 7 0 8
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5.865 573.74 0 1 0 0 21 31
375 57.74 1 1 0 0 21 41
5.085 573.84 0 0 1 0 21 31
5.985 521.94 0 1 2 2 01 51
5.595 526.94 1 1 1 0 21 51
5.406 573.05 0 0 0 0 31 31
516 52.15 0 1 0 0 31 41
5.526 521.25 0 2 0 0 31 51
5.136 526.25 1 0 1 0 31 51
5.736 521.35 0 1 1 0 31 51
156 52.45 0 0 0 0 41 41
5.556 526.45 1 0 0 0 41 51
276 65 0 2 0 0 41 61
876 5.65 1 0 1 0 41 61
5.886 573.75 1 1 1 0 41 71
5.796 521.85 0 0 0 0 51 51
207 5.85 1 0 0 0 51 61
5.217 573.95 1 1 0 0 51 71
027 06 0 0 1 0 51 61
Table 14: Vent Section Length
LENNOX HEARTH PRODUCTS • MONTEBELLO® POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
VENT SECTION LENGTHS
Determine the number of straight vent
sections required. 4 1/2 in. (114 mm),
10 1/2 in. (267 mm), 22 1/2 in. (572 mm),
34 1/2 in. (876 mm) and 46 1/2 in.
(1181 mm) net section lengths are available
(see Table 14).
Offset Installation
Analyze the vent routing and determine
the quantities of vent sections and number
of elbows required. Refer to Figures 16
and 17 on Page 15 showing vent run
requirements to aid in selecting the type of
vertical installation desired. Vent sections are
available in net lengths of 4 1/2 in. (114 mm),
10 1/2 in. (267 mm), 22 1/2 in. (572 mm),
34 1/2 in. (876 mm) and 46 1/2 in.
(1181 mm). Refer to the Vent Section
Length Chart for an aid in selecting length
combinations. Elbows are available in 90°
and 45° congurations. Refer to Figure 15
on Page 14 for the SV4.5 E45 and SV4.5 E90
elbow dimensional specications.
Where required, a telescopic vent section
(SV4.5LA) may be used to provide the
installer with an option in installing in tight
and confined spaces or where the vent run
made up of xed length pieces develops a
joint in a undesirable location, or will not
build up to the required length. The SV4.5LA
Telescopic Vent Section has an effective
length of from 1 1/2 in. (38 mm) to 6 3/4 in.
(171 mm). The SV4.5LA is tted with a
dimpled end (identical to a normal vent
section component) and a plain end with 3
pilot holes. Slip the dimpled end over the
locking channel end of a standard SV4.5 vent
component the required distance and secure
with three screws.
Maintain a minimum 1 in. (25 mm)
clearance to combustible materials for
all vertical elements. Clearances for all
horizontal elements are 3 in. (76 mm)
on top, 1 in. (25 mm) on sides and 1 in.
(25 mm) on the bottom.

14
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Figure 12: Framing Ceiling Opening
A. Frame ceiling opening—Use a plumb line
from the ceiling above the appliance to locate
center of the vertical run. Cut and/or frame
an opening, 10 1/2 in. x 10 1/2 in. (267 mm x
267 mm) inside dimensions, about this center
mark (Figure 12).
Figure 13: Attaching the Vent Adaptor
Align the dimple (four places) of the
upper vent section with the opening
of the locking incline channel on
the lower vent section or appliance
collar. Twist vent component
clockwise to engage and seal until
arrow and dimple align.
Dimple
Locking Incline
Channel
Connected Vent
Sections Arrow
Arrow
Adaptor on Appliance Collar
or Vent Section
B. Attach adaptor (with probe) to appliance
collar—Secure Vent® SV4.5 direct-vent
system components are unitized concentric
pipe components featuring positive twist lock
connections (see Figure 13).
All of the appliances covered in this
document are fitted with collars having
locking inclined channels. The dimpled end
of the adaptor fits over the appliance collar to
create the positive twist lock connection.
10 1/2 in. min.
(267 mm)
Ceiling Framing
Plumb Bob
10 1/2 in. min.
(267 mm)
To attach a vent component to the adaptor
on appliance collar, align the dimpled end
over the adaptor collar, adjusting the radial
alignment until the four locking dimples are
aligned with the inlet of the four inclined
channels on the collar (refer to Figure 13).
Push the vent component against the
collar until it fully engages, then twist the
component clockwise, running the dimples
down and along the incline channels until
they seat at the end of the channels.
Support the vertical portion of the venting
system every eight feet (2.4 m) above the
fireplace vent outlet. One method of support
is by utilizing eld provided support straps
(conventional plumber's tape). Secure the
plumber's tape to the framing members
with nails or screws. Strap the tape around
the vent, securing the ends of the tape to
the framing. If desired, sheet metal screws
#6 x 1/2 in. length may be used to secure the
support straps to the vent pipe.
F. Change vent direction to horizontal/
inclined run—At transition from or to a
horizontal/inclined run, install the SV4.5E45
and SV4.5E90 elbows in the same manner as
the straight vent sections. The elbows feature
a twist section to allow them to be routed
about the center axis of their initial collar
section to align with the required direction
of the next vent run element. Twist elbow
sections in a clockwise direction only so as
to avoid the possibility of unlocking any of
the previously connected vent sections (see
Figures 13 and 15).
The unitized design of the Secure Vent®
components will engage and seal both the inner
and outer pipe without the need for sealant or
screws. If desired a #6 x 1/2 in. screw may be
used at the joint, but it is not required as the
pipe will securely lock when twisted.
C. Attach vent components to each other—
Other vent sections may be added to the
previously installed section in accordance
with the requirements shown in Figures 16
and 17 on Page 15.
To add another vent component to a length
of vent run, align the dimpled end over
the inclined channel end of the previously
installed section, adjusting the radial
alignment until the four locking dimples are
aligned with the inlets of the four incline
channels of the previous section.
Push the vent component against the
previous section until it fully engages, then
twist the component clockwise running the
dimples down and along the incline channels
until they seat at the end of the channels.
This seating position is indicated by the
alignment of the arrow and dimple as
shown in Figure 13.
D. Install firestop/spacer at ceiling—When
using Secure Vent, use SV4.5VF restop/
spacer at ceiling joists. If there is living space
above the ceiling level, the restop/spacer
must be installed on the bottom side of the
ceiling. If attic space is above the ceiling,
the restop/spacer must be installed on the
top side of the joist. Route the vent sections
through the framed opening and secure
the firestop/spacer with 8d nails or other
appropriate fasteners at each corner.
Maintain 1 in. (25 mm) clearance to
combustibles, framing members, and attic
or ceiling insulation when running vertical
chimney sections. Attic insulation shield
(H3907) may be used to obtain the required
clearances indicated here. See installation
accessories on Page 28. The gap between
the vent pipe and a vertical firestop may be
sealed with noncombustible caulking.
E. Support the vertical vent run sections -
8 1/8 in.
(206 mm)
4 13/16 in.
(122 mm)
Swivel Joint
(360° swivel)
SV4.5E45
45° Elbow)
Swivel Joint
(360° swivel)
SV4.5E90
90° Elbow)
G. Continue installation of horizontal/
inclined sections—Continue with the
installation of the straight vent sections in
horizontal/inclined run as described in Step
C. Install support straps every three feet
(914 mm) along horizontal/inclined vent runs
using conventional plumber’s tape (Figure 16
on Page 15).
NOTE: Maintain the horizontal/inclined
run in a straight, slightly elevated plane—
approximately 1/4 in. per foot (20 mm
per meter)—in a direction away from
the fireplace. Smaller rise per foot run
ratios are acceptable, down to at or near
level. Use a carpenter’s level to measure
from a constant surface and adjust the
support straps as necessary.
NOTE: Maintain the required clearances to
combustibles: 1 in. (25 mm) at all sides
for all vertical runs; and 3 in. (76 mm) at
the top, 1 in. (25 mm) at sides, and 1 in.
(25 mm) at the bottom for all horizontal/
inclined runs.
Blocking
Support Straps
(Plumber's
tape)
8 ft (2.4 m)
Maximum
1/2 in. (13 mm)
minimum
clearance to
combustibles
Figure 14: Supporting Vertical Vents
Figure 15: Vent Elbow Sections
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
15
Power Vent
Termination
Horizontal / Inclined Run Support
Brackets Building
Support
Framing
SV4.5E90
Elbow
Ceiling
Minimum
Vent Run
Horizontal
10 ft
Exterior
Wall
Power Vent
Termination
Probe Adaptor
(required)
Probe Adaptor
(required)
Fireplace
Floor
Maximum Horizontal
Venting 110 ft
Up to 6 Elbows
Firestop / Spacer
Exterior
Wall
SV4.5L 6 / 12 / 24 / 36 / 48
Vent Sections Vertical Rise
66 ft max.
4 ft min.
Figure 16: Typical Power Vent Routing
Venting Can Run Up To
3 ft Below Unit
VENT FIGURES
Notes:
• Secure Vent®components (rigid vent pipe and terminal) are shown.
• Two 45° elbows may be used in place of one 90° elbow.
• SV4.5VF (Secure Vent) firestop/spacer must be used anytime vent pipe passes through a combustible floor or ceiling. SV4.5HF (Secure Vent)
firestop/spacer must be used anytime vent pipe passes through a combustible wall.
• Maintain the horizontal/inclined run in a straight, slightly elevated plane—approximately 1/4 in. per foot (20 mm per meter)—in a direction
away from the fireplace. Smaller rise per foot run ratios are acceptable, down to at or near level. Use a carpenter’s level to measure from a
constant surface and adjust the support straps as necessary.
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
Maximum Number Of Elbows — 6
Maximum Feet Of Run A + B 110 ft
Minimum Horizontal Run B10 ft
Minimum Vertical Run AAdaptor Plus 4 ft Vertical Vent
(min.) and 90° Elbow
Maximum Vertical Rise A66 ft
Table 15: Power Venting
Vertical Vent Pipe 1.0 in. (25.4 mm)
Horizontal Vent Pipe
Top—3 in. (76.2 mm)
Sides—1 in. (25.4 mm)
Bottom—1 in. (25.4 mm)
Table 16: Minimum Clearance to Combustibles
Probe Adaptor
(Required)
A
(See Chart)
B
Figure 17: Power Vent Routing with Probe Adaptor

16
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
D. Attach vent components to appliance—
To attach a vent component to the
appliance collar, align the dimpled end
over the collar, adjusting the radial
alignment until the four locking dimples
are aligned with the inlets of the four
incline channels on the collar (refer to
Figure 13 on Page 14).
Push the vent component against the
collar until it fully engages, then twist the
component clockwise, running the dimples
down and along the incline channels
until they seat at the end of the channels.
The unitized design of the Secure Vent
components will engage and seal both the
inner and outer pipe elements with the same
procedure. Sealant and securing screws are
not required.
E. Attach vent components to each other—
Other vent sections may be added to the
previously installed section in accordance
with the requirements of the vent tables.
To add another vent component to a
length of vent run, align the dimpled
end of the component over the inclined
channel end of the previously installed
section, adjusting the radial alignment
until the four locking dimples are aligned
with the inlets of the four incline channels
of the previous section. Push the vent
component against the previous section
until it fully engages, then twist the
component clockwise running the dimples
down and along the incline channels
until they seat at the end of the channels.
This seating position is indicated by the
alignment of the arrow and dimple as
shown in Figure 13 on Page 14.
F. Install firestop/spacer at ceiling—
When using Secure Vent, use SV4.5VF
restop/spacer at ceiling joists. If there
is living space above the ceiling level, the
restop/ spacer must be installed on the
bottom side of the ceiling. If attic space
is above the ceiling, the restop/ spacer
must be installed on the top side of the
joist. Route the vent sections through the
framed opening and secure the firestop/
spacer with 8d nails or other appropriate
fasteners at each corner. The gap between
the vent pipe and a restop can be sealed
with noncombustible caulking.
Maintain 1 in. (25 mm) clearance to
combustibles, framing members, and
attic or ceiling insulation when running
vertical chimney sections.
G. Support the vertical run sections—
On the vertical run, support the venting
system every eight feet (2.4 m) above the
fireplace vent outlet with field provided
support straps (Plumber's tape). Attach
the straps to the vent pipe and secure to
the framing members with nails or screws.
H.Change vent direction—At transitions
from or to a horizontal/inclined run, install
the SV4.5E45 and SV4.5E90 elbows in
the same manner as the straight vent
sections. The elbows feature a twist
section to allow them to be routed about
the center axis of their initial collar section
to align with the required direction of
the next vent run element. Twist elbow
sections in a clockwise direction only so
as to avoid the possibility of unlocking
any of the previously connected vent
sections (see Figure 13 on Page 14).
I. Continue installation of horizontal/
inclined sections—Continue with the
installation of the straight vent sections
in horizontal/inclined run as described
in Step E. Install support straps every
three feet (1914 mm) along horizontal/
inclined vent runs using conventional
plumber’s tape (see Figure 16 on
Page 15).
NOTE: Maintain the horizontal/inclined
run in a straight, slightly elevated
plane—approximately 1/4 in. per foot
(20 mm per meter)—in a direction away
from the fireplace. Smaller rise per foot
run ratios are acceptable, down to at or
near level. Use a carpenter’s level to
measure from a constant surface and
adjust the support straps as necessary.
Installing Power Vent Termination
J. Assemble vent run to exterior wall—If
not previously measured, locate the
center of the vent on the exterior wall.
Prepare an opening as described in this
manual. Assemble the vent system to
a point where the terminus of the last
section is within 8 in. of the outside wall
surface where the power vent is to be
mounted (see Figure 18 on Page 17).
If the terminus of the last section is not
within this distance, use the telescopic
vent section SV4.5LA, as the last vent
section. For wall thicknesses greater than
that shown in Figure 19 on Page 17, refer
to Table 17 on Page 17 for the additional
venting components needed (in addition
to the termination and adaptor) for a
particular range of wall thicknesses.
K. Attach termination adaptor—Attach
the adaptor (SV4.5RCH—provided with
the power vent kit) to the vent section
telescoping vent section, or elbow, as
shown in Figures 18 and 19 on Page 17
in the same manner as any SV4.5
vent component.
HORIZONTAL (OUTSIDE WALL)
TERMINATION SYSTEM
See Figures 16 and 17 on Page 15
illustrating the various horizontal venting
congurations that are possible for use
with these appliances. Table 15 on Page 15
shows each system’s minimum and
maximum vertical and horizontal length
values that can be used to design and
install the vent components in a variety
of applications.
The horizontal vent system terminates
through an outside wall. Building codes
limit or prohibit terminating in specic
areas. Refer to Figure 4 on Page 7 for
location guidelines.
Secure Vent® SV4.5 direct-vent system
components are unitized concentric pipe
components featuring positive twist
lock connection, (refer to Figure 13 on
Page 14). All of the appliances covered in
this document are fitted with collars having
locking inclined channels. The dimpled
end of the vent components fit over the
appliance collar to create the positive twist
lock connection.
A. Plan the vent run—
Analyze the vent routing and determine
the types and quantities of sections
required 4 1/2 in. (114 mm), 10 1/2 in.
(267 mm), 22 1/2 in. (572 mm), 34 1/2 in.
(876 mm) and 46 1/2 in. (1181 mm)
net section lengths are available. Make
allowances for elbows as indicated in
Figure 15 on Page 14.
Maintain a minimum 1 in. (25 mm)
clearance to combustibles on the
vertical sections. Clearances for the
horizontal runs are: 3 in. (76 mm) on
top, 1 in. (25 mm) on sides, and 1 in.
(25 mm) at the bottom.
B. Frame exterior wall opening—
Locate the center of the vent outlet on the
exterior wall according to the dimensions
shown in Figure 8 on Page 10.
Cut and/or frame an opening, 10 1/2 in.
x 12 1/8 in. (267 mm x 308 mm) inside
dimensions, about this center.
C. Frame ceiling opening—If the vertical
route is to penetrate a ceiling, use a
plumb line to locate the center above the
appliance. Cut and/or frame an opening,
10 1/2 in. x 10 1/2 in.(267 mm x 267 mm)
inside dimensions, about this center (see
Figure 12 on Page 14).

17
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
L. Install Firestop/Spacer at exterior wall—
Install SV4.5HF Firestop/Spacer, provided
with the power vent kit, over the opening
at the exterior side of the framing, long
side up, with the 3 in. spacer clearance
at the top as shown in Figure 18, and
nail into place. The Firestop/Spacer may
also be installed over the opening at
the interior side of the framing. The gap
between the vent pipe and a restop can
be sealed with noncombustible caulking.
(The Firestop/Spacer may also be installed
over the opening at the interior side of the
framing).
M.Install the Power Vent termination—
From outside the exterior wall, slide
the collars of the termination onto the
adaptor until the termination seats against
the exterior wall surface to which it
will be attached. Orient the housing of
the termination with the arrow pointed
upwards. Secure the termination to the
exterior wall. The termination must not
be recessed into the exterior wall or
siding by more that the 1 1/4 in. (32 mm)
as shown in Figure 19.
Siding
Stucco
1 1/4 in. Maximum Recess of
the Square Termination into
Exterior Finishing Material
Exterior Surface of
Framing
6 in. to 9 1/4 in.
(152 to 235 mm)**
Exterior Surface of Siding
Interior Surface of
Finished Wall
Maximum wall thickness
9 1/4 in.(235 mm)**
Power Vent
Termination
Maximum Extent of Vent Run
Sections Relative to Exterior
Surface of Framing
Last Vent Section.
Use Telescopic Vent
Section (SV4.5LA),
If Necessary
Adaptor
SV4.5RCH
Venting Connection and Exterior Wall Recessing
of the Power Vent Horizontal Termination
*Use silicone caulking to
seal the top and sides of
the termination, up to the
underlayment, stucco, or
masonry wall surface.
Power Vent
Termination
*Caulk
*Caulk
To help minimize water infiltration
it is recommended that the Firestop/Spacer (SV4.5HF)
be installed on the exterior side of the wall.
Power Vent
Termination
7 in.
(178)
5 1/8 in.
(130 mm)
12 1/8 in.
(308 mm)
Note: Centerline of Vent Piping is
NOT the Same as the Centerline of
the Frame Opening.
6 to 48 in. Vent Section,
Telescopic vent section,
Elbow or Appliance Collar Base of Appliance
3 in.
(76 mm)
1 in.
(25.4 mm)
Adaptor
SV4.5RCH
10 1/2 in.
(267 mm)
The Power Vent termination has been
designed to perform in a wide range of
weather conditions. Terminations meet
or exceed industry standards.
When selecting the location of
termination, do not place the
termination where water from eaves
and adjoining roof lines may create
a heavy flow of cascading water onto
the termination. If the termination
must be placed where the possibility
of cascading water exists, it is the
responsibility of the builder to direct the
water away from the termination cap by
using gutters or other means.
Carefully follow the Installation
Instructions for the termination,
including the use of silicone caulking
where required.
WARNING: The vent termination
is hot while in operation and for a
period of time following the use of
the fireplace. Young children should
be carefully supervised when in the
same area as a hot termination.
Figure 18: Installing Power Vent Horizontal Termination
Figure 19: Venting Connection and Exterior Wall Recessing of the Power Vent
Horizontal Termination
Vent Components Required Exterior Wall Thickness
Termination Kit Only 6–9 1/4 in.(152–235 mm)
Termination Kit and 6 in. Vent Section (SV4.5L6) 10 3/4–14 in. (273–356 mm)
Termination Kit and 12 in. Vent Section (SV4.5L12) 16 3/4–20 in. (426–508 mm)
Termination Kit and Telescopic Section (SV4.5L12) 11 3/4–20 in. (299–508 mm)
Table 17: Venting Components Required for Various Exterior Wall Thicknesses—
when Using the Power Vent Termination
See Table 17 as an aid in venting component
selection for a particular range of exterior
wall thicknesses.
See Figure 8 on Page 10 for Minimum
Distance to Base of Appliance
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
**For thicknesses greater
than 9 1/4 in., see Table 17

18
Step 4. FIELD WIRING
CAUTION: Label all wires prior to disconnection when
servicing controls. Wiring errors can cause improper and
dangerous operation.
ATTENTION: Au moment de l'entretien des commandes,
étiquetez tous les fils avant de les débrancher. Des erreurs
de cáblage peuvent entraîner un fonctionnement inadéquat
et dangereux.
Verify proper operation after servicing.
S'assurer que l'appareil fonctionne adéquatement une fois
l'entretien terminé.
CAUTION: Ground supply lead must be connected to the wire
attached to the green ground screw located on the outlet
box. See Figures 27 and 28 on Page 20. Failure to do so will
result in a potential safety hazard. The appliance must be
electrically grounded in accordance with local codes or, in the
absence of local codes, the (USA) National Electrical Code,
ANSI/NFPA 70—latest edition, or the Canadian Electrical
Code, CSA C22.1—latest edition.
Route Cable
NOTE: Electrical wiring must be performed by a qualified electrician.
• Install the strain relief in the hole provided on the right side of
fireplace for the electrical wiring (see Figure 20).
• Either use the intgrated junction box, or position an electrical
junction box (not provided) within reach of the termination wiring
pigtail (see Figure 23 on Page 19). Route the pigtail to the junction
box as the termination is installed.
• Route 14 gauge AWG grounded solid wire Romex® or equally-sized
stranded cable (e.g., SJOT) from the replace to the newly installed
junction box near the termination. Ensure the cable is safety
plated to prevent damage from framing nails and finish drywall
screws. Route it into the lower control compartment and cut to
length before installing the terminals. Install provided hardware on
the ends of the cable. Cable is not provided. The provided crimp
terminals are intended for use with stranded cable. If using Romex,
connect per National Electric Code or local code.
14 Gauge
Grounded
Romex or
similar
Stranded
Cable
Strain
Relief
Vacuum
Hose
Snap
Bushing
Wall Switch
Harness
Junction Box
Right Side
of Fireplace
Probe (1 *)
Hose Clamp (7 *)
Vacuum Hose (2 *)
* See Figure 11 on Page 12
Adaptor Assembly
Pressure Switch
Pressure Switch
Vacuum Hose
Firebox
Pressure switch is located
behind the panel on the right
side of firebox
Vacuum Hose
• Refer to Figure 25 on Page 19 and install the electrical hardware
on the ends of the cable. Male terminals on the Black and White
wires, and ring terminals on the ground wire.
• Using standard electrical practices and the terminals provided,
connect the three wires of the cable to the termination pigtail
within the Electrical junction box. Ensure ground.
• The replace end of the cable will be addressed in Connecting
The Power Vent To The Fireplace Control System.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Figure 20: Routing Wiring
Figure 21: Vacuum Hose Connection to Probe
Figure 22: Vacuum Hose Connection to Pressure Switch
NOTE: Pressure switch style may vary from that shown.
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
19
9
10
Wiring—Fireplace (See Figures 27 and 28 on Page 20)
NOTE: These electronic appliances must be connected to the
main power supply. The gas valve is set in place and pre-wired at
the factory.
1. Route a 3-wire 120 Vac 60 Hz 1ph power supply to the appliance
junction box.
2. Remove the electrical inlet cover plate from the side of the unit by
removing the plate securing screws (see Figure 8 on Page 10).
3. Remove the cover plate knockout and then feed the power supply
through the knockout opening and into the unit junction box.
4. Connect the black power supply to the power outlet red pigtail lead and
the white power supply to the common terminal of the outlet as shown
in Figures 27 and 28 on Page 20.
5. Connect the ground supply to the pigtail lead attached to outlet
green ground screw.
6. Wall-mounted ON/REMOTE/OFF burner control switch and remote
control kits may be used. Mount the switch in a convenient location
on a wall near the fireplace.
NOTE: One end of the supplied wire (15 ft) is factory-connected and
the other end is attached to the side of the unit.
CAUTION: Do Not connect the ON/REMOTE/OFF wall switch to a
120 V power supply.
8. Turn the wall-mounted ON/REMOTE/OFF burner control switch to
the OFF position.
9. After the wiring is complete, replace the cover plate.
Wiring—Power Vent Termination
Alternate Instructions (For use when access to the termination is easy
and a secondary electrical junction box installation is not desired).
• Remove the junction box cover from the termination by removing
the attaching screw (see Figure 23).
• Loosen the strain relief on the termination shown in Figure 25. Pull
the pigtail in and shorten it to t within the junction box cover.
WARNING: Crimp connectors may be used on stranded cables (such
as SJOT cable) only. Solid wire Romex must be connected per the
National Electric Code, NEC 70—latest version, or local codes.
• Route 14 gauge AWG grounded solid wire Romex or equally sized
stranded cable (e.g., SJOT) from the replace to the newly installed
junction box near the termination. Ensure the cable is safety
plated to prevent damage from framing nails and finish drywall
screws. Route it into the lower control compartment and cut to
length before installing the terminals. Install provided hardware on
the ends of the cable. Cable is not provided. The provided crimp
terminals are intended for use with stranded cable. If using Romex,
connect per National Electric Code or local code.
Attaching Screw
Pigtail Junction Box Cover
Cable
Black and White
Ground Wire
Strain Relief
Ground Cable to
The Termination
Pigtail Wires Cut
Off and Shortened
Wire Nuts
Strain Relief Holding Cable
• Refer to Figure 26 and install the electrical hardware on the fireplace
end of the cable. Male terminals (#10) on the Black and White
wires, and ring terminals (#9) on the ground. The termination end
of the cable will be connected to the termination with wire nuts
(not provided).
• Refer to Figure 26 to connect the three wires of the cable to the
termination. Ensure the ground ring terminal is grounded beneath
a structural screw as shown. Attach the junction box cover to the
termination with the screw previously removed.
• The replace end of the cable will be addressed in Connecting The
Power Vent To The Fireplace Control System.
Cable
Figure 23: Bottom of Termination
Figure 24: Cable Connections
Figure 25: Back of Termination
Figure 26: Junction Box Cover Removed
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS

20
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Step 5. REMOVE THE GLASS
DOOR ASSEMBLY
Refer to Figure 40 on Page 24 and remove
the front glass door assembly as follows:
To remove the rescreens, lift up the center
of the rod to disengage it from the center
bracket, bend down at center, hold left side
with hand until it disengages from left side,
being careful not to scratch the paint. Slowly
remove the rod from the right side.
Using a Phillips screwdriver, unfasten the
two (2) screws located at the top of the
glass door assembly.
Tilt the glass door assembly at the top away
from the unit. Lift it carefully off the bottom
door track and set the glass door assembly
aside, protecting it from inadvertent damage.
WARNING
•Handle this glass with
extreme care! Glass is
susceptible to damage—
Do not scratch or
handle roughly.
•Do not attempt to substitute
the materials used on this
door, or replace cracked
or broken glass with any
materials other than those
provided by the appliance
manufacturer.
•The glass door of this
appliance must only be
replaced as a complete
unit as provided by the
manufacturer. Do not attempt
to replace broken, cracked,
or chipped glass separately.
LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX POWER VENT DV GAS FIREPLACES (MDLX40/45IN-PV) • INSTALLATION INSTRUCTIONS
Factory Wired
Field Wired
Junction Box
Tab Intact
Tab
Intact
neerG-dnuorG
etihW-lar
t
ueN
120 VAC - Black
Green
Ground
Screw
White
Green
Neutral
Side
Hot
Side
Red
Black
Figure 28: Junction Box Wiring—
120 V, 60 hz, 1-phase
Figure 27: Electronic Wiring Diagram
580489-01
Pilot Tube
Spark
Electrode
Flame
Sensor
IPI Pilot
885 Valve
Optional
Split Flow
BL
W
Y
Y
BR
G
O
O
R
R
B
B
G
GR
R
B
BL
WH
BB
WG
Battery Holder w/Switch
ON/ Remote
/OFF
Battery Holder
Wire Harness
Reset Switch
(See instructions.)
Power Vent Blower
Power Vent
Models Only
Air Pressure Switch
Power Vent Only
Note: On models
without pressure
switch, these
connectors are
plugged together.
Main Wire
Harness
Main Power Cord
Control Module
GB
G
W
B
Fuse
ELECTRONIC WIRING DIAGRAM
Ground Y
B
Battery Holder with Switch
ON/Remote/OFF
(Schematic representation only)
COLOR CODE:
B = Black
BB = Brown w/Black Stripe
BG = Brown w/Green Stripe
BL = Blue
BR = Brown
G = Green
GY = Gray
O = Orange
R = Red
W = White
Y = Yellow