Lennox Montebello DLX, Montebello MDLX40IN, Montebello MDLX40IP, Montebello MDLX45IN, Montebello MDLX45IP Installation Instructions Manual

INSTALLATION INSTRUCTIONS

Montebello® DLX
Direct Vent Gas Fireplaces

MODELS

P/N 506023-15 Rev. A 07/2012

This manual is one of a set of two supporting this product.
Refer to P/N 506025-07 for Care and Operation Instructions.

Ce manuel est disponible en francais, simplement
en faire la demande. Numéro de la pièce 506223-41.

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.

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 unless a certified kit is used.

Intertek Report No.

100513650

MDLX40IN
MDLX40IP

ELECTRONIC

MDLX45IN
MDLX45IP

®

WARNING /AVERTISSEMENT/AVISO

• HOT GLASS WILL CAUSE
BURNS.

• DO NOT TOUCH GLASS
UNTIL COOLED.

• NEVER ALLOW CHILDREN
TO TOUCH GLASS.

WARNING: If the information in these instructions
is not followed exactly, a fire or explosion may
result, causing property damage, personal injury,
or death.

- 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.

• 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.

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.

- 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.

• EL VIDRIO CALIENTE
CAUSARÁ QUEMADURAS.

• USTED DEBE NUNCA
TOCAR EL VIDRIO CALIENTE.

• LOS NIÑOS DEBEN NUNCA
TOCAR EL VIDRIO.

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

TABLE OF CONTENTS

Packaging ......................... 2

Introduction ........................ 2

General Information .................. 3

Massachusetts Requirements .......... 4

Cold Climate Insulation ............... 5

Manufactured Home Requirements ...... 5

Location . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Vent Termination Clearances ........... 6

Minimum Clearances to Combustibles ..... 8

Detailed Installation Steps ............. 9

Typical Installation Sequence .......... 9

Step 1. Framing .................... 9

Fireplace and Framing Specifications ...... 10

Step 2. Routing Gas Line ............. 11

Proper Sizing of Gas Line .............. 11

Step 3. Install the Vent System ........ 12

Vertical Termination Systems ........... 13

Vent Section Length Chart ............. 13

Vertical Vent Tables and Figures ......... 16

Horizontal Termination System ......... 17

Horizontal Vent Tables and Figures ...... 19

Step 4. Field Wiring ................. 21

Step 5. Removing Glass Door

Frame Assembly .................. 23

Step 6. Connecting Gas Line .......... 23

Step 7. Checking Appliance

Operation ........................ 23

Step 8. Installing Logs and Panels ...... 24

Step 9. Installing Glass Door .......... 26

Step 10. Burner Adjustments ........... 26

Finishing Requirements ............... 28

Step 11. Attaching Safety-in-

Operation Warnings ................ 29

Installation Accessories ............... 30

Gas Conversion Kits .................. 31

Please read and understand these
instructions before beginning your
installation.

PACKAGING

The assembled fireplace is packaged with the
following:

• Literature Kit (plastic bag shipped inside

rebox), containing Care and Operation

Instructions, Installation Instructions (this

manual), Safety-in-Operation Warning
Labels, and Warranty.

• One (1) bag Glowing Embers

• One (1) bag Platinum Embers

• One (1) bag Volcanic Stone

• Pull Screen Kit

• Remote Control and Wall Receiver

Switch Kit

• Door Modesty Shield

• Log Grate

Note: For use with fireplace as shipped

from factory only. Not for use with
Contemporary Burner/Floor Kit.

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 and operation instructions are
provided with the kit, and are not detailed
in this manual.

INTRODUCTION

The Montebello® DLX direct-vent, sealed­combustion gas fireplaces operate on natural
or propane gas. These appliances feature a
remotely controlled electronic intermittent
pilot ignition system (manual adjustment of

the gas valve settings is not possible).
The Montebello DLX is a decorative replace

and may not be installed and operated as the
primary heat source in a dwelling.

Electrical power (120 Vac line voltage) is
recommended to operate the fireplace;

however, four (4) "AA" batteries can be used

for full-time operation or as a backup in case
of a power outage.

Approved Vent Components

These fireplaces are designed, tested, and
listed for operation and installation with

Secure Vent® direct vent system components

(8 in. inner, 11 in. outer) manufactured by

Security Chimneys International.
These approved vent system components

are labeled for identification. USE ONLY

APPROVED VENT COMPONENTS. Do
NOT use any other manufacturer’s vent
components with these appliances.

Codes and Standards

These appliances comply with National
Safety Standards and are tested and listed by

Intertek (Report No. 100513650) to Z21.50
(in Canada, CSA-2.22), and CAN/CGA-

2.17-M91 in both USA and Canada, as vented

gas fireplaces.

These appliances are listed by Intertek
for installation in bedrooms and 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 (in Canada, the current
CAN/CSA-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).

2

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

GENERAL INFORMATION

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.

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 infor­més 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.

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

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

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.

WARNING

Improper installation or use of
this appliance can cause serious
injury or death from fire, burns,
explosion or carbon monoxide
poisoning.

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 se servir de cet appareil s'il a été
plongé dans l'eau, complètement ou en
partie. Appeler un technicien qualifié
pour inspecter l'appareil et remplacer
toute partie du système de contrôle et
toute commande qui ont été plongés
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.

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 or propane gas only. 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.

3

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

These electronic appliances are remotely
controlled and feature an electronic
intermittent pilot ignition system or standing

pilot. 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)

Natural Gas
MDLX40IN 32,000 to 50,000
MDLX45IN 38,500 to 60,000

Propane Gas
MDLX40IP 32,000 to 50,000
MDLX45IP 38,500 to 60,000

Table 1: Input (BTU/HrR)

Gas Pressure—All Models

Appliance inlet and manifold gas pressure
requirements are listed in Tables 2 and 3.

Fuel # Minimum Maximum

Natural

Gas

Propane

5.5 in. WC
(1.37 kPa)

11.0 in. WC
(2.74 kPa)

10.5 in. WC
(2.61 kPa)

13.0 in. WC
(3.23 kPa)

Table 2: Inlet Gas Supply Pressure

Fuel # Low High

Natural

Gas

Propane

1.6 in. WC
(.4 kPa)

6.3 in. WC
(1.57 kPa)

3.5 in. WC
(.87 kPa)

10.0 in. WC
(2.49 kPa)

Table 3: Manifold Gas Supply Pressure

Orifice Sizes—Sea Level To High Altitude
(All Models)

These appliances are tested and approved

for installation at elevations of 0–4500 feet
(0–1372 meters) above sea level, using the

standard burner orifice sizes (marked with

an asterisk (*) in Table 4). For elevations
above 4500 feet, 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; or

• 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/CSA-B149.1 codes—latest edition.

Install the appliance according to the
regulations of the local authorities having
jurisdiction and, in the USA, the National Fuel

Gas Code NFPA 54 / ANSI Z223.1—latest
edition or , in Canada, the CAN/CSA-B149.1-

latest edition.

NOTE: Flame appearance will diminish 4%
per thousand feet of altitude.

Model Nat.Gas

drill size (inches)

MDLX40 0.1405 in.

(#28)*

• H2286

MDLX45 0.154 in

(#23)*

• H8808

Propane

drill size (inches)

0.086 in.
(#44)*

• H2287

0.093 in.
(#42)*

• H4816

Table 4: Burner Orifice Sizes
Elevation 0–4500 ft ( 0–1372 m)

* Standard size installed at factory

• Part /Cat. Number

Gas Valve Diagram

The SIT Proflame gas valve is shown in
Figure 1.

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 fitter licensed in the

Commonwealth of Massachusetts.

• The exible gas line connector used shall
not exceed 36 inches (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 floor level where the
gas fireplace 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.

Test gauge connections are provided on the
front of the gas control valve (identified IN

for the inlet and OUT for the manifold side).

Propane tanks are at pressures that will
cause damage to valve components. Verify
that the tanks have step-down regulators to
reduce the pressure to safe levels.

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).

4

Green Wire

(From DFC Wire

Harness)

Manifold (Out)

Test Port

Inlet (In) Test Port

Wire

(From DFC Wire

Harness)

Main Gas Inlet

3/8 in. NPT

Figure 1: SIT Proflame Valve

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

Connect GTMS
Wire Harness

Pressure
Regulator
Tower

Yellow Ground Wire
(From DFC Wire
Harness)

Drywall

Top Of Fireplace
Opening

Non-Combustible

HORIZONTAL VENT

VERTICAL VENT

HORIZONTAL VENT

VERTICAL VENT

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

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 floor on which appliance rests, if
floor is above ground level. Gas line holes
and other openings should be caulked or
stuffed with unfaced fiberglass insulation.

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 cold transfer to the
fireplace and into the room. It also helps
to sheetrock inside surfaces and tape for

maximum air tightness and caulk firestops.

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 and the Manufactured Home
Construction and Safety Standard, Title 24

CFR, Part 3280, in the United States, or the

Standard for Installation in Mobile Homes,
CAN/CSA Z240 MH Series, in Canada.

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 et conformément à la norme

Manufactured Home Constructions and
Safety, Title 24 CFR, Part 3200 aux Unis ou à
la norme Can/CSA-Z240 Série MM, Maisons

mobiles au Canada.
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, unless a certified kit is used.

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, sauf si une trousse
de conversion est utilisée.

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 or the Canadian Electrical Code CSA
C22.1—latest edition.

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.

Figure 2: Typical Installation

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.

These direct-vent appliances are uniquely
suited for installations requiring a utility shelf

positioned directly above the fireplace. Utility
shelves like these are commonly used for
locating television sets and decorative plants.

Cross Corner

Application

Room Divider

Application

Recessed

Application

Island

Application

Flat

Application

Application

Flat on Wall

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 (see

Figure 7 on Page 8).
The minimum height from the base of the

appliance to the underside of combustible
materials used to construct a utility shelf in
this fashion is shown in Figure 7 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.

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

5

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

3"

(76 mm)

Termination Kit

Combustible Projection

greater than 2-1/2 inches in length

Horizontal Vent Termination Clearances

Combustible Projection

2-1/2 inches or less in length

24"

(610 mm)

Ventilated Or

Unventilated Soffit

12

X

Roof Pitch is X/12

2 FT
MIN.

2 FT MIN.

Lowest

Discharge

Opening

H*

*H = MINIMUM HEIGHT FROM ROOF TO
LOWEST DISCHARGE OPENING OF VENT

TERMINATION HEIGHTS FOR VENTS ABOVE

FLAT OR SLOPED ROOFS

Horizontal Overhang

Vertical

Wall

Vent

Termination

Storm Collar

Concentric

Vent Pipe

Flashing

1 inch (25.4 mm) Minimum
Clearance to Combustibles

VENT TERMINATION CLEARANCES

These instructions should be used as a
guideline and do not supersede local codes
in any way. Install vent according to local
codes, these instructions, the current
National Fuel Gas Code (ANSI-Z223.1) in
the USA or the current standards of CAN/
CSA-B149.1 in Canada.

Vertical Vent Termination Clearances

Terminate multiple vent terminations according
to the installation codes listed above. Also see
Figure 3.

Terminate single vent caps relative to building
components according to Figures 3 and 4.

12”

(305mm)

Minimum

Vertical Vent Termination Clearances

The vent / air intake termination clearances
above the high side of an angled roof is as
shown in the following chart:

Figure 4

Horizontal Vent Termination Clearances

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 3: Multiple Terminations

6

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 5). For projections
exceeding 2-1/2 in. (64 mm), see Figure 6 on Page 7. For additional vent location restrictions

refer to Figure 6 on Page 7.

See Figure 28 on Page 18 for the recess allowances, into
exterior walls, of the square horizontal terminations.

Figure 5: Side Elevation View

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

NOTE: Local Codes Or Regulations May Require
Different Clearances.

NOTE: Location Of The Vent Termination Must Not
Interfere With Access To The Electrical Service.

3 ft.

X

A



3 ft.

Exterior Wall

Horizontal

Termination

B

V

L

X

= Air Supply Inlet

* See Item D in the Text Below.

*18”

24 in.

Inside Corner

Center Line

of Termination

18”

36 in.

DETAIL D

F

V

Ventilated Soffit

V

Fixed

Closed

Window

V

C

A

= Vent Terminal

V

Inside

Corner Detail

G

V

A

= 9 in. in U.S.



A

=12 in. in Canada

B

C

C

C

Operable

V

Window

B

B

= Area where Terminal is NOT permitted

B



A

J

Minimum Clearances Canadian Installation * US Installation **

A = Clearance above grade, veranda, porch, deck
or balcony.

B = Clearance to window or door that may be opened. 6 in. (15.2 cm) for appliances < 10,000 BTU/hr (3kW),

C = Clearance to permanently closed window 12 inches (305 mm) recommended to prevent window

12 inches (30 cm) * 12 inches (30 cm) **

12 in. (30 cm) for appliances > 10,000 BTU/hr (3kW) and <
100,000 BTU/hr (30kW), 36 inches (91 cm) for appliances
> 100,000 BTU/hr (30kW)*

condensation

H

E

D

M

I

X

V

K

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 inches (30 cm) for appliances
> 50,000 BTU/hr (15kW)*

9 inches (229 mm) recommended to prevent window

condensation

V

D = Vertical clearance to ventilated soffit located

24 inches (61.0 cm) 24 inches (61.0 cm)

above the terminal within a horizontal distance of

36 in. (91.4cm) from the center line of the terminal

E = Clearance to unventilated soffit 24 inches (61.0 cm) 24 inches (61.0 cm)
F = Clearance to outside corner 5 inches (12.7 cm) 5 inches (12.7 cm)
G = Clearance to inside corner 36 in. (91.4 cm) 24 inches (61.0 cm)
H = Clearance to each inside of center line extended

above meter / regulator assembly

3 feet (91 cm) within a height of 15 feet above the meter /

regulator assembly *

3 feet (91 cm) within a height of 15 feet above the meter

/ regulator assembly **

I = Clearance to service regulator vent outlet 3 feet (91 cm) * 3 feet (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 inches (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 inches (30 cm) for appliances
> 50,000 BTU/hr (15kW)*

K = Clearance to mechanical air supply inlet 6 feet (1.83 meters) * 3 feet (91 cm) above, if within 10 feet (3 m) horizontally**
L = Clearance above paved sidewalk or paved

7 feet (2.13 m) ‡ 7 feet (2.13 m) ‡

driveway located on public property

M = Clearance under veranda, porch, deck or

18 in. (46.0 cm) * ‡ 18 in. (46.0 cm) ** ‡

balcony

* In accordance with the current CSA-B149.1 National Gas and B149.2 Propane Installation Code—Latest Editions.

** In accordance with the current ANSI Z223.1 / NFPA 54 National Fuel Codes—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.

Figure 6: Exterior Horizontal Vent Termination Clearance Requirements

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

7

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

17 in.

431.8 mm

14 in.

355.6 mm

8 1/4 in.

209.6 mm

45°

12 in.

304.8 mm

5 in.

127 mm

12 (305)

10 (254)

8 (203)

6 (152)

4 (102)

7

(178)

17

(432)

15

(381)

13

(330)

2 (51)

9

(229)

11

(279)

MINIMUM CLEARANCES TO COMBUSTIBLES

The appliance is approved with zero clearance to combustible materials
on all sides (as detailed in Table 5), with the following exception: 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. In addition, when the unit is recessed, the side walls surrounding

the unit must not extend beyond the front edge of the unit (see

Figure 2).

Combustible Shelf Height—

Top Vent—with 2 Feet Vertical Vent and One 90 Degree Elbow

Model Secure Vent
MDLX40 *84-1/16 (2135)
MDLX45 *89-1/16 (2252)

* Includes 3 in. clearance to combustibles (required above vent components)

Inches (millimeters)

®

APPLIANCE MINIMUM CLEARANCES*

Inches (millimeters)

Sides 1/2 (13), 0 (0) Spacers **

Top Spacers 0 (0)

Floor 0 (0)

Back 1/2 (13), 0 (0) Spacers

Bottom of Appliance To Ceiling 69 (1743)

Vent 3 (76) Top * / 1 (25.4) Sides & Bottom

SERVICE CLEARANCES Feet (meters)

Front 3 feet (0.9 meters)

Table 5

*Note: 3 in. (75 mm) above any horizontal/inclined vent component.
**Note: 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. See Page 28 for hearth extension requirements.

Shelf Height

To provide for the lowest possible shelf surface, the venting attached
to the top vent should be routed in a way to minimize obstructions to
the space above the appliance. Do not insulate the space between
the appliance and the area above it (see Figure 7). The minimum
height from the base of the appliance to the underside of combustible
materials used to construct a utility shelf in this fashion is shown in
Figure 7.

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 9 and Figure 51 on Page 28.

Non-combustible 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 8. Mantels constructed of
non-combustible materials may be installed at any height above the

appliance opening. 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.

8

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

Do not insulate the
space between the
appliance and the
area above it.

Figure 7

Figure 8

Combustible Materials
Allowed In Shaded Area
"Safe Zone"

Side
Wall

Figure 9

Shelf Height

(see table)

Shelf Above Fireplace With Top Venting

MANTEL

MANTEL

MANTEL

MANTEL

MANTEL

MANTEL

Top of Appliance

Top View of

Fireplace

Minimum Distance to
Protected Side Wall

Side
Wall

Minimum Distance to
Unprotected Side Wall

2 1/2 ft
(to centerline)
Vertical
Vent (minimum)

MANTEL

CLEARANCES

Inches (mm)

Fireplace

(side view)

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

WARNING

Failure to position the parts in
accordance with these diagrams
or failure to use only parts specifi­cally approved with this appliance
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
approuvées avec cet appareil sont
utilisées.

DETAILED INSTALLATION STEPS

The appliance is shipped with all gas
controls and components installed and pre­wired.

1. Remove the shipping carton, exposing the
front glass door on the valve access side.

2. Using a Phillips screwdriver, unfasten two

(2) screws located at the top of the glass

frame (see Figure 46 on page 26). 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.

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 21) Connect 120 VAC electrical

power to the appliance receptacle.

Step 5. (Page 23) Remove glass

door assembly.

Step 6. (Page 23) Make connection to

gas supply.

Step 7. (Page 23) Verifying

appliance operation.

Step 8. (Page 24) Install ceramic panels,

logs, and glowing embers
OR
contemporary burner/floor kit,
porcelain panels, and media.

Step 9. (Page 26) Install glass

door assembly.

Step 10. (Page 26) Adjust burner to ensure

proper flame appearance.

Step 11. (Page 29) Attach safety in

operation warnings.

Step 1. FRAMING

Frame these appliances as illustrated in
Figure 11 on Page 10, unless the appliance
is to be installed in a corner. See Figure 12
on Page 11 for corner framing installations.
All framing details must allow for a minimum
clearance to combustible framing members
as shown in Table 5 on Page 8.

If the appliance is to be elevated above floor
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 fit around
them. All construction above the appliance
must be self-supporting, DO NOT use the
appliance for structural support.

The fireplace should be secured to the side
framing members using the unit's nailing
flanges—one top and bottom on each side
of the fireplace front (see Figure 10). Use 8d

nails or their equivalent.

Use Top Flange For
1/2” Thick Drywall

Front Of
Fireplace

Use Center Flange
For Flush Mount

Use Bottom Flange For
5/8” Thick Drywall

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”
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” 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.

Unit Being Secured by Its Nailing

Flanges to the Framing

Figure 10

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

9

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

E

A

B

D

Top View

Front View

5-3/32 (129)

Right Side View

14-1/8
8-1/2”
(216)

5-1/4”
(133)

(359)

26-15/32

(672)

C

25-29/32

(658)

25-1/2

(648)

7

2-1/2 (64)

(178)

19-5/8

(498)

Gas Inlet

(This
Side
Only)

Electrical

Inlet

8-3/8

(213)

F

G

H

J

Framing should be constructed

of 2x4 or larger lumber.

A

B

C

8-1/2
(216)

13

(

330

)

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

15

(

381

)

6-1/2
(165)

1/2 A

Framing Dimensions

Models A B C

MDLX40

in. 50-3/4 43 75-1/8

mm 1289 1092 1908

MDLX45

in. 56-7/8 48 80-1/16

mm 1445 1219 2034

Thermal Efficiency (%)

Natural Gas Propane

Models P4 P4

MDLX40 35.8 TBD
MDLX45 51.2 TBD

MDLX40

MDLX45

10

Figure 11: Fireplace and Framing Specifications

Model

No.

Notes

A B C D E F G H J

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

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

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

Fireplace Dimensions

Diagrams, illustrations and photo­graphs are not to scale – consult
installation instructions. Product
designs, materials, dimensions,
specifications, colors and prices are
subject to change or discontinuance
without notice.

Vent Size

Coaxial DV

Vent Size

8" Inner

11" Outer

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Right Side
Front Corner
Of Fireplace
Framing

6-1/4”

(159 mm)

19-5/8”

(498 mm)

C

Back wall of chase/enclosure

(including any finishing materials)

D

A

B

Model

No.

MDLX40

MDLX45

Figure 12: Corner Framing with Square Termination (SV8HTS)

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 13. 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 flexible gas line connector and 1/2 inch
shutoff valve. (See Step 6 on Page 22).

The incoming gas line should be piped into
the valve compartment and connected in one
of the two methods as shown in Figure 36
on Page 23.

Figure 13

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 National Fuel
Gas Code, NFPA 54—latest edition (USA) or
CAN/CSA-B149.1—latest edition (Canada).

A B C D

in. 50-5/8 83-5/8 59-1/8 41-7/8

mm 1286 2124 1502 1064

in. 56-3/4 89-7/8 63-1/2 44-7/8

mm 1441 2283 1613 1140

Never use galvanized or plastic pipe. Refer to
Table 6 for proper sizing of the gas supply
line, if black iron pipe is being used. Gas lines
must be routed, constructed and made of
materials that are in strict accordance with

local codes and regulations. We recommend
that a qualied individual such as a plumber

or gas fitter be hired 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. Certainly no one

unfamiliar and unqualied should attempt

sizing or installing gas piping.

Schedule 40 Pipe

Length (feet)

0–10 1/2 in. 3/8 in.

10–40 1/2 in. 1/2 in.

40–100 1/2 in. 1/2 in.

100–150 3/4 in. 1/2 in.
150–200 3/4 in. 1/2 in.

Table 6: Schedule 40 Black Iron
Pipe—Inside Diameter

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

Natural

Gas

Propane

Gas

Notes:

• All appliances are factory-equipped with

a flexible gas line connector and 1/2 inch
shutoff valve (see Figure 36 on Page 23).

• 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 23).

• A pipe joint compound rated for gas

should be used on the threaded joints.
Ensure propane resistant compounds are
used in propane applications. Be very

careful that the pipe compound does not
get inside the pipe.

• It is recommended to install a sediment

trap in the supply line as close as possible
to the appliance (see Figure 36 on
Page 23).

• Check with local building ofcial for local
code requirements.

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.

11

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

RESTRICTOR

APPLIANCE VENT OUTLET

Install the restrictor as shown from

inside the unit, in the inner fireplace collar.

When vertically terminating the vent system above

the roof, install a vent restrictor in the top vent of

the fireplace outlet.

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 vent 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 and -B149.2 in Canada.

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 flue serving a separate solid fuel burning
appliance. The vent pipe is tested to be run

inside an enclosing 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.

Installation of Vent Restrictor

A vent restrictor may be needed with this
appliance. The restrictor is installed in
the appliance top flue outlet as shown in
Figure 14,

For vertical venting from 6 feet to 12 feet
or more, from the top of the fireplace to the
top of the termination, the installation of a
vent restrictor is required.

If necessary, install a vent restrictor in the
appliance flue outlet as shown in Figure 14.
The vent restrictor is held in place by friction,
only.

Note: The restrictor is included within the
firebox.

Select Venting System—Horizontal or Vertical

With the appliance secured in framing, de­termine vent routing and identify the exterior
termination location. The following sections

describe vertical (roof) and horizontal (exterior
wall) vent applications. Refer to the section

relating to your installation. A list of approved
venting components is shown on Page 30.

Figure 14: Vent Restrictor Installation

12

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Termination

Flashing And
Storm Collar

Firestop/Spacer

SV8 6/12/24/36/48
Vent Sections

40' Max

(12.2 M)

6' Min

(1.8 M)

1" (25 mm)
Minimum
Clearance to
Combustibles

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0515.21010034

5.451578.21110035

5.061573.31020035

5.271573.41000505

77157.41100506

38152.51010506

6815.51000044

5.091578.51100045

5.691573.61010045

5.502521.71011507

70252.71000606

5.112526.71100607

5.712521.81010607

5.922521.91001607

5.232573.91000055

73257.91100056

5.142521.02000707

6425.02100708
25212010708
46222001708
67232000808

97252.32000066

5.082573.32100809

5.382526.32100

067

5.982521.42010067

5.103521.52001067

5.013578.52000909

5135.621009001

5.523521.72000077

0335.72100078
63382010078

54357.82000 01001

5.943521.92100 01011

27313000088

5.673573.13100089

5.973526.13000 11011

5.814578.43000099

32452.531000901

56457.8300000101

VERTICAL TERMINATION SYSTEMS (ROOF)

See Figure 15 and Figures 23 through 25 on
Page 16 and their associated Vertical Vent

Tables which illustrate the various vertical
venting configurations that are possible for
use with these appliances. Secure Vent® pipe
applications are shown in these Figures. A
Vertical Vent Table summarizes each system’s
minimum and maximum vertical and horizontal

5.4573.0100001

957.0200002

5152.1110002

length values that can be used to design and
install the vent components in a variety of

1257.1020002

applications.
The vertical vent system terminates through

the roof. The minimum vent height above
the roof and/or adjacent walls is specified in

ANSI Z223.1-(latest edition) (In Canada, the
current CAN/CSA-B149.1 installation code)

by major building codes. Always consult

your local codes for specic requirements. A

general guide to follow is the Gas Vent Rule
(refer to Figure 4 on Page 6).

Vertical (Straight) Installation

(Figure 15)

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 Tables on
this page and Page 30—Vent Sections).

Plan the vent lengths so that a joint does not
occur at the intersection of ceiling or roof
joists. Refer to the Vent Section Length Chart.

Figure 15

5457.3002002

1552.4100012

7557.4001102

6652.5022004

9657.5000202
2761030

1857.6000112

095.7021014

3957.7000022
6981012

Table 7: Vent Section Length Chart

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

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

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5.01578.0010001

5.91526.12100

5.22578.1001001

5.52521.2120003

5.13526.2030003

5.43578.2000101

5.73521.3111003

5.34526.3021003

5.64578.3000011

5.94521.4102003

5.55526.4012003

5.76526.5003003

5.37521.6100203

5.97526.6010203

5.19526.7002013

5.79521.8100023

2015.8200024

5.301526.8000303

80191003

4115.9020024

71157.9105006

5.811578.9110305

6215.01001304

5.031578.01101305

53152.11006006

8315.11000404

5.931526.11000033

5.241578.11100405

4

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3

Model Effective Length

SV8L6 4-1/2 in.
SV8L12 10-1/2 in.
SV8L24 22-1/2 in.
SV8L36 34-1/2 in.
SV8L48 46-1/2 in.

Table 8: Effective Vent Length

13

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Minimum

13 in.

(330 mm)

Minimum

13 in.

(330 mm)

Vertical (Offset) Installation

Analyze the vent routing and determine the

quantities of vent sections and number of
elbows required. Refer to Vertical Vent

Figures and Tables on Page 16 to select
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 on Page 13 for an aid
in selecting length combinations. Elbows are

available in 90° and 45° congurations. Refer
to Figure 20 on Page 15 for the SV8 E45 and
SV8 E90 elbow dimensional specications.

Where required, a telescopic vent section

(SV8LA) 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 fixed length pieces develops a joint in
a undesirable location, or will not build up to

the required length. The SV8LA Telescopic

Vent Section has an effective length of from

1-1/2 in. (38 mm) to 6-3/4 in. (171 mm). The

SV8LA is fitted 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 SV8 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.

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, 13 in. x 13 in. (330 mm x 330 mm)

inside dimensions, about this center mark
(Figure 16).

Roof
Framing

Ceiling
Framing

Plumb
Bob

B. Attach vent components to appliance—
Secure Vent® SV8 direct-vent system

components are unitized concentric pipe
components featuring positive twist lock
connections (see Figure 17).

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.

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

Arrow

Appliance Collar or
Vent Section

dimple align.

Dimple

Locking Incline
Channel

Connected Vent
Sections

Arrow

Figure 17

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 inlet of
the four inclined channels on the collar (refer
to Figure 17). 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 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 of the vertical vent

figures and tables. 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 17.

D. Install firestop/spacer at ceiling—When

using Secure Vent, use SV8BF restop/

spacer at ceiling joists. If there is living space
above the ceiling level, the firestop/spacer
must be installed on the bottom side of the
ceiling. If attic space is above the ceiling, the
firestop/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. Remember to maintain 1

in. (25 mm) clearance to combustibles,
framing members, and attic or ceiling
insulation when running vertical chimney
sections. Attic insulation shield (H3908)
may be used to obtain the required
clearances indicated here. See installation
accessories on Page 30. The gap between

the vent pipe and a vertical firestop can be
sealed with non-combustible caulking.

E. Support the vertical vent run sections—

Note: Proper venting support is very
important. The weight of the vent must not
be supported by the fireplace in any degree.

Support the vertical portion of the venting

system every 8 feet (2.4 m) above the

fireplace vent outlet.

Blocking

Support Straps
(Plumber's tape)

8 feet (2.4 m)

Maximum

1 inch (25.4
mm) minimum
clearance to
combustibles

Figure 18

14

Figure 16

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

C

D

Storm
Collar

One method of support is by utilizing field
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. See Figure 18 on Page 14.

F. Change vent direction to horizontal/
inclined run—At transition from or to a

horizontal/inclined run, install the SV8 E45
and SV8 E90 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 17 on Page 14 and Figure 19.

10"

(254mm)

Swivel Joint

(360° swivel)

SV8E45

(45° Elbow)

6"

(153mm)

Swivel Joint

(360° swivel)

SV8E90

(90° Elbow)

Figure 19

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 3 ft (914 mm)

along horizontal/inclined vent runs using
conventional plumber’s tape. See Page 17,

Figure 26. It is very important that the
horizontal/inclined run be maintained in a

straight (no dips), slightly elevated plane. The
recommended incline is approximately 1/4 in.
per foot (20 mm per meter) horizontal, in

a direction away from the fireplace. The
rise per foot run ratios that are smaller are
acceptable all the way down to at or near
level. Use a carpenter’s level to measure from
a constant surface and adjust the support
straps as necessary.

It is important to 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.

H. Frame roof opening—Identify location for
vent at the roof. Cut and/or frame opening
per Roof Framing Chart (Figure 20).

Framing Dimensions for Roof

Inches (millimeters)

Pitch C D

0/12

6/12

12/12

13 in.

(330 mm)

13 in.

(330 mm)

13 in.

(330 mm)

13 in.

(330 mm)
15-1/2 in.

(394 mm)
20-1/2 in.

(541 mm)

Figure 20: Roof Framing

I. Install the roof flashing—Extend the vent
sections through the roof structure. Install
the roof flashing over the vent section and
position such that the vent column rises

vertically (use carpenters level) (Figure

21). Nail along perimeter to secure flashing

or adjust roofing to overlap the flashing
edges at top and sides only and trim where
necessary. Seal the top and both sides of the
flashing with waterproof caulking.

J. Install the storm collar—Install the storm
collar, supplied with the flashing, over the
vent/flashing joint (see Figure 21). Loosen
the storm collar screw. Slide collar down
until it meets the top of the flashing. Tighten
the adjusting screw. Apply non-combustible
caulking or mastic around the circumference
of the joint to provide a water tight seal.

Storm

Flashing

Collar

Figure 21

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

K. Install the vertical termination—The
final step involves installation of the Vertical
Termination. Extend the vent sections to

the height as shown in the "Vertical vent
termination section" on Page 6. The SV8VTR

Vertical Termination (Figure 22) can be
installed in the exact same fashion as any
other Secure Vent® section. Align the
termination over the end of the previously
installed section, adjusting the radial
alignment until the four locking dimples of
the termination are aligned with the inlets
of the four incline channels of the last vent
section. Push the termination down until
it fully engages, then twist the termination
clockwise running the dimples down and
along the incline channels until they seat at
the end of the channels.

Figure 22

If the vent system extends more than 5 feet

(1.5 m) above the roof ashing, stabilizers

may be necessary. Additional screws may
be used at section joints for added stability.
Guide wires may be attached to the joint
for additional support on multiple joint
configurations.

15

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

V

H

1

H

V

1

Ceiling
Firestop/Spacer
(SV8BF)

Wall
Firestop/Spacer
(SV8HF)

H

V

V1

Ceiling

Firestop/Spacer

(SV8BF)

40 feet (12.2 meters)

Maximum

6 feet (1.8 meters)

Minimum

Ceiling

Firestop/Spacer

(SV8BF)

VERTICAL VENT FIGURES/TABLES

Notes:

• SecureVent® (rigid vent pipe) is shown in

the Figures.

• It is very important that the horizontal/

inclined run be maintained in a straight (no
dips), slightly elevated plane. The recom­mended incline is approximately 1/4 in.
per foot (20 mm per meter) horizontal, in
a direction away from the fireplace. The
rise per foot run ratios that are smaller are
acceptable all the way down to at or near
level.

• SV8BF (Secure Vent) firestop/spacer must

be used anytime vent pipe passes through a
combustible floor or ceiling. SV8HF (Secure
Vent) firestop/spacer must be used anytime
vent pipe passes through a combustible wall.

• Two 45 degree elbows may be used in place

of one 90 degree elbow. The same rise to
run ratios, as shown in the venting figures
for 90 elbows, must be followed if 45 degree
elbows are used.

Table A

H Maximum

feet (meter) feet (meter)

10 (3.1) 2.5 (0.762)
15 (4.65) 3.5 (1.07)
20 (6.2) 4.5 (1.37)

V + V1 + H = 40 feet (12.4 meters) Max.

V + V1 = 11 feet (3.3 meters) Minimum for MDLX40

V + V1 = 10.5 feet (3.2 meters) Minimum for MDLX45

Example: If 20 feet of (H) horizontal
vent run is needed, then 4-1/2 feet
minimum of (V) vertical vent will be
required.

A Vent Restrictor, as shown in
Figure 14 on Page 12, must be used
in this application.

V Minimum

A Vent Restrictor, as shown in Figure 15 on Page
12, may need to be used in this application

Figure 23: Top Vent—Straight

Figure 24: Top Vent—Two 90 Degree Elbows (Corner Framing with Square

Termination (SV8HTS))

Table B

H + H

Maximum

1

feet (meter) feet (meter)

10 (3.1) 2.5 (0.762)
15 (4.65) 3.5 (1.06)
20 (6.2) 4.5 (1.37)

H + H1 = 20 feet (6.2 m) Max.

V + V1 + H + H1 = 40 ft. (12.4 m) Max.

V + V1 = 11 feet (3.3 meters) Min. for MDLX40

V + V1 = 10.5 feet (3.2 meters) Min. for MDLX45

V Minimum

A Vent Restrictor, as
shown in
Figure 14 on Page 12,
must be used in this
application.

Example: If 20 feet of (H+ H1) horizon-
tal vent run is needed, then 4-1/2 feet
minimum of (V) vertical vent will be
required.

Figure 25: Top Vent—Three Elbows

16

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Support

HORIZONTAL (OUTSIDE WALL)
TERMINATION SYSTEM

See Figures 26–31 and their associated
Horizontal Vent tables that illustrate the
various horizontal venting configurations that
are possible for use with these appliances.

Secure Vent® pipe applications are shown

in these Figures. A Horizontal Vent table
summarizes 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 specific areas.
Refer to Figure 6 on Page 7 for location
guidelines.

Secure Vent SV8 direct-vent system
components are unitized concentric pipe
components featuring positive twist lock
connection, (refer to Figure 17 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. It is recommended that you
plan the vent lengths so that a joint does
not occur at the intersection of ceiling or

roof joists. Make allowances for elbows as

indicated in Figure 20 on Page 15.

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
11 on Page 10. Cut and/or frame an opening,

15 in. x 13 in. (381 mm x 330 mm) inside
dimensions, with 9 in. above center and 7 in.

below center.
C. Frame ceiling opening—If the vertical

route is to penetrate a ceiling, use plumb line
to locate the center above the appliance. Cut
and/or frame an opening, 13 in. x 13 in. (330

mm x 330 mm) inside dimensions, about this

center (refer to Figure 17 on Page 14).
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 16 on Page 14).

Building

Support

Framing

SV8E90

Vertical

Rise

Brackets

Elbow

Ceiling

Firestop/Spacer

Support the vertical portion of the venting system
every 8 feet (2.4m) above the fireplace vent outlet.

Horizontal / Inclined Run

Support Bracket Spacing
Every 3 ft (914 mm)

2-1/2 Foot Vertical

Fireplace

Figure 26: Typical Horizontal Vent Installation

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

17 on Page 14.

F. Install firestop/spacer at ceiling—When
using Secure Vent, use SV8BF restop/spacer
at ceiling joists. If there is living space above
the ceiling level, the firestop/ spacer must be
installed on the bottom side of the ceiling. If
attic space is above the ceiling, the firestop/
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.

Remember to maintain 1 in. (25 mm) clear­ance to combustibles, framing members,
and attic or ceiling insulation when running
vertical chimney sections.

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

SV8HTS
Termination
Shown

SV8 L6/12/24/36/48

Vent Sections

Vent (min.)

Exterior
Wall

SV8HTS
Termination
Shown

Exterior
Wall

G. Support the vertical run sections—See

Step E on Page 14.

H. Change vent direction—At transition from or

to a horizontal/inclined run, install the SV8E45
and SV8E90 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 17 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 on Page 14. Install

support straps every 3 feet (1914 mm) along

horizontal/inclined vent runs using conventional
plumber’s tape.

See Figure 26, It is very important that the

horizontal/inclined run be maintained in a
straight (no dips), slightly elevated plane. The
recommended incline is approximately 1/4"
per foot (20 mm per meter) horizontal, in a
direction away from the fireplace. The rise per
foot run ratios that are smaller are acceptable
all the way down to at or near level.

It is important to 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.

Use a carpenter’s level to measure from a
constant surface and adjust the support straps
as necessary.

17

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Firestop/Spacer (SV8HF) shown

on the exterior side of the wall. It

may also be installed on the

interior side.

SV8HTS

Termination

Shown.

13"

(330mm)

8 Z\x"

(216)

6 Z\x"

(165 mm)

15"

(381 mm)

Note: Centerline of Vent Piping is

NOT the Same as the Centerline of

the Framed Opening.

6 to 48 inch Vent Section,

Telescopic vent section.

See Figure 9 on page 7

for Min. Distance to Base

of Appliance.

Base of Appliance

3"

(76 mm)

Adapter
SV8RCH

1"

(25 mm)

1"

(25 mm)

Siding

Stucco

1 1/4 in. Maximum Recess of
Square Termination into
Exterior Finishing Material

Exterior Surface of

Framing

5 in. to 8 1/2 in.

(127 to 216 mm)

Exterior Surface of Siding

Minimum wall thickness

5 in. (127 mm)

Interior Surface of

Finished Wall

Maximum wall thickness

8 1/2 in. (216 mm)

SV8HTS

Square Termination

shown

Maximum Extent of
Vent Run Sections
Relative to Exterior
Surface of Framing

Last Vent Section. Use
Telescopic Vent
Section (SV8LA), If
Necessary

Adapter

SV8RCH

SV8HTS

Square Termination

Shown

Venting Connection and Exterior Wall Recessing

of the Horizontal Square Termination (SV8HTS).

J. Assemble vent run to exterior wall—If not
previously measured, locate the center of the
vent at the exterior wall. Prepare an opening as
described in Step B on Page 17. Assemble the
vent system to point where the terminus of the

last section is within 5 in. (127 mm) to 8-1/2
in. (216 mm) inboard of the exterior surface to

which the SV8HTS termination is to be attached,
see Figure 29 and Table 9 on Page 19.

If the terminus of the last section is not
within this distance, use the telescopic vent
section SV8LA, as the last vent section. For
wall thicknesses greater than that shown in
Figure 28, refer to Table 9 on Page 19. This table
lists 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 (adaptor—SV8RCH—provided with the

termination) to the vent section or telescoping
vent section), or elbow as shown in Figure 27

in the same manner as any SV vent component
(refer to Step E on Page 17).

See Figure 12 on Page 10 for Minimum
Distance to Base of Appliance

Figure 27: Installing the Square Horizontal Termination (SV8HTS)

L. Install Firestop/Spacer at exterior wall
—When using the square termination, install

SV8HF Firestop/Spacer over the opening at the
exterior side of the framing, long side up, with
the 3 inch spacer clearance at the top as shown
in Figure 27, and nail into place.

(The Firestop/Spacer may also be installed over

the opening at the interior side of the framing).

M. Install the square termination (SV8HTS)—
For the last step, from outside the exterior
wall, slide the collars of the termination onto
the adaptor (the outer over the outer and the

inner inside the inner) 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

horizontal termination must not be recessed
into the exterior wall or siding by more than
the 1-1/4 in. (32 mm) as shown in Figure 28.

IMPORTANT: 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 they are in the same area as a hot
termination.

18

Horizontal terminations have been designed to perform in a wide range of weather
conditions. Our terminations meet or exceed industry standards.

When selecting the locations of your horizontal terminations, do not place the
termination where water from eaves and adjoining rooflines may create a heavy flow of
cascading water onto the termination cap. If the cap 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.

Take care to carefully follow the installation instructions for the termination, including
the use of silicone caulking where required.

For wall thicknesses greater than

u

Figure 28: Wall Thickness and Horizontal Termination Requirements

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

8-1/2 inches, see Table 8

u

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

H

V

Wall Firestop/Spacer

(SV8HF)

Ceiling

Firestop/Spacer

(SV8BF)

See Table 8 as an aid in venting component selection for a particular
range of exterior wall thicknesses.

Vent Components Required Exterior Wall Thickness—inches (mm)

Termination Kit Only 5 to 8-1/2 (127 to 216)
Termination Kit and 6 In. Vent

Section (SV8L6)

Termination Kit and Tele-

scopic Section (SV8LA)

Termination Kit and Tele-

scopic Section (SV8LA) and

9-3/4 to 14 (248 to 356)

6-3/4 to 15-1/4 (171 to 387)

11-1/4 to 19-3/4 (286 to 502)

6 in. vent section (SV8L6)

Table 9: Venting Components Required for Various Exterior
Wall Thicknesses, when using Square Termination Kit
(SV8HTS—see Figure 28)

Table C

H Maximum

V Minimum

feet (meter) feet (meter)

3.5 (1.07) 2.5 (0.762)

6.5 (1.98) 3.5 (1.07)

8.5 (2.6) 4.5 (1.37)

10.5 (3.2) 5.5 (1.68)

12.5 (3.8) 6.5 (1.98)

14.5 (4.4) 7.5 (2.3)

16.5 (5.0) 8.5 (2.6)

18.5 (5.6) 9.5 (2.9)
20 (6.0) 10 (3.0)

V + H = 40 feet (12.4 m) Max.

H = 20 ft. (6.2 m) Max.

Example: If 20 feet of (H)
horizontal vent run is needed,
then 10 feet minimum of (V)
vertical vent will be required.

HORIZONTAL VENT FIGURES/TABLES

Notes:

• SecureVent® components (rigid vent pipe and terminal) are shown

in the Figures.

• Two 45 degree elbows may be used in place of one 90 degree elbow.

The same rise to run ratios, as shown in the venting figures for 90
elbows, must be followed if 45 degree elbows are used.

• SV8BF (Secure Vent) firestop/spacer must be used anytime vent pipe

passes through a combustible floor or ceiling. SV8HF (Secure Vent)
firestop/spacer must be used anytime vent pipe passes through a

combustible wall.

• Itisveryimportantthatthehorizontal/inclinedrunbemaintainedina

straight (no dips), slightly elevated plane. The recommended incline
is approximately 1/4 in. per foot (20 mm per meter) horizontal, in a
direction away from the fireplace. The rise per foot run ratios that
are smaller are acceptable all the way down to at or near level.

Square termination (SV8HTS) shown.

See Table 9 as an aid in venting component selection for
a particular range of exterior wall thicknesses.

Figure 29: Top Vent—One 90 Degree Elbow (Elbow Connection Not Directly at Appliance)

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

19

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

V

H

H

1

Wall Firestop/Spacer

(SV8HF)

Wall Firestop/Spacer

(SV8HF)

Ceiling

Firestop/Spacer

(SV8BF)

V

H

H

1

V

1

Wall Firestop/Spacer

(SV8HF)

Ceiling

Firestop/Spacer

(SV8BF)

Wall

Firestop/Spacer

(SV8HF)

Ceiling

Firestop/Spacer

(SV8BF)

HORIZONTAL VENT FIGURES/TABLES

(continued)

See Table 9 on Page 19 as an aid in venting component selection for a particular range of
exterior wall thicknesses.

Table D

H + H1 Maximum

V Minimum

feet (meter) feet (meter)

3.5 (1.07) 2.5 (0.762)

6.5 (1.98) 3.5 (1.07)

8.5 (2.6) 4.5 (1.37)

10.5 (3.2) 5.5 (1.68)

12.5 (3.8) 6.5 (1.98)

14.5 (4.4) 7.5 (2.3)

16.5 (5.0) 8.5 (2.6)

18.5 (5.6) 9.5 (2.9)
20 (6.0) 10 (3.0)

V + H + H1 = 40 feet (12.4 m) Max.

H + H

= 20 ft. (6.2 m) Max.

1

Figure 30: Top Vent—Two 90 Degree Elbows

Table E

H + H

= 20 feet (6.2 m) Max.

1

V + V

+ H + H1 = 40 ft. (12.4 m) Max.

1

V = 2.5 feet Min. (0.762 m)

V + V

= 11 feet (3.35 m) Min. for MDLX40

1

V + V

= 10.5 feet (3.2 m) Min. for MDLX45

1

20

See Table 9 on Page 19 as an aid in venting component selection for a particular range of exterior wall thicknesses.

Figure 31: Top Vent—Three 90 Degree Elbows

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Main Power Cord

ELECTRONIC WIRING DIAGRAM

J-BOX/RECEPTIACLE

WIRING

120V, 60HZ, 1PH

Factory Wired

Field Wired

Junction Box

Tab Intact

Tab
Intact

n e e r G - d n u o r G

e t i h W - l a r

t
u e N

120 VAC - Black

Green
Ground
Screw

White

Green

Neutral
Side of
Receptacle

Hot
Side of
Receptacle

Black

Step 4. FIELD WIRING

CAUTION

Ground supply lead must be con­nected to the wire attached to the
green ground screw located on the
outlet box. 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 National Electrical Code,
ANSI/NFPA 70-latest edition. (In
Canada, the current CSA C22-1 Cana­dian Electrical Code).

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.

The gas valve is set in place and pre-wired at
the factory.

Electronic Wiring

Note: The electronic appliance must be
connected to the main power supply.

1. Route a 3-wire 120Vac 60Hz 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's
securing screws (see Figure 11 on Page 10).

3. Remove the cover plate's knockout and then

feed the power supply wire through the knock­out opening and into the unit junction box.

4. Connect the black power supply wire to the
power outlet's red pigtail lead and the white

power supply wire to the common terminal of
the outlet as shown in Figures 32 and 33.

5. Connect the ground supply wire to the pig­tail lead attached to outlet's green ground
screw.

6. Install the wall-mounted ON/OFF control, as

described in "Installing and initializing the
Remote Control System" on Page 22, in a

convenient location near the fireplace.

7. After the wiring is complete, replace the

cover plate.

Figure 33: J-BOX WIRING

(Schematic representation only)

A wiring diagram is provided here
for reference purposes only. This
information is also provided on
schematics attached directly to the
appliance on a pullout panel located
within the control compartment.

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

Figure 32

Note: On models
without pressure

switch, these

connectors are

plugged together.

BR

Air Pressure Switch

Power Vent Only

Battery Holder with Switch

Battery Holder w/Switch

ON/Remote/OFF

Main Wire

Harness

G

Y

ON/ Remote
/OFF

Y

B

O

R

Battery Holder
Wire Harness

GR

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

G

BL

R

O

G

Power Vent Blower

BL

W

R

B

WH

B

Power Vent

Models Only

B

W

885 Valve

G

Optional
Split Flow

Reset Switch

(See instructions.)

B

Pilot Tube

Control Module

IPI Pilot

B

Fuse

B

Flame
Sensor

Spark
Electrode

B

Ground Y

G

W

580489-01

21

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Hot Fireplace Will Cause

Severe Burns

Never Allow Children to

Touch Glass or other Fire­place Parts

WARNING

Installing and initializing the Remote
Control System

REQUIRED ITEMS (not provided):

• Standard Junction Box

• Paper Clip or similar object (for remote
control system initialization)

Installing and Wiring the Receiver
(Wall Switch)

The Receiver for the Total Comfort Control™
Remote Control System connects directly to
the gas valve, stepper motor, and fan control
module with an umbilical cord wiring harness.

1. Install a junction box (not provided) on

the wall adjacent to the appliance, within
reach of the remote system umbilical cord
wiring harness. Position the 6-pin termi­nal within the junction box in preparation
for attachment to the remote receiver.

2. When wall nish is complete, install the

receiver in the previously installed junc­tion box, and connect the 6-pin terminal
to the 6-pin connector on the back of the
receiver.

3. Install the receiver cover plate, taking care
to ensure the receiver switch is properly
indexed with the switch cover when align­ing the components for attachments.

Initializing the Remote Control System

After completing fireplace installation, initialize
the remote control system before operating
the fireplace.

4. Insert the three (3) provided AAA batteries

into the battery bay in the Transmitter, tak­ing care to correctly align polarity (+/–).

5. Insert the four (4) provided AA batteries

into the Receiver battery bay (behind the

wall switch plate), taking care to correctly

align polarity (+/–).

6. On the Receiver, place the three-position

slider switch in the REMOTE position

(Figure 34).

7. On the Receiver front cover, insert the end
of a paper clip (or other similar object; not

provided) into the hole marked “PRG.”

The Receiver will “beep” three times to

indicate it is ready to synchronize with
the Transmitter.

8. On the Transmitter, press the ON button.

The Receiver will “beep” four times to

indicate acceptance of the Transmitter’s
command (and set the Receiver to the

Transmitter’s specic code). The system

is now initialized.

The remote control system provides remote
operation of the following fireplace functions:

• Primary burner ON/OFF

• Flame height and heat output adjustment
(six levels)

The Receiver accepts commands via radio

frequency from the Transmitter and does not
require line-of-sight operation.

The slider switch on the Receiver can be set to
one of three positions:

• ON (manual override)

• OFF (manual override)

• REMOTE (remote control)

See the fireplace Care and Operation Instruc­tions for detailed instructions on using the
remote control system to operate the fireplace.

Three-position slider switch

in REMOTE position

On

Remote

Off

PRG

Figure 34: Receiver (Wall Switch)

LCD Display

ON/OFF Key

ROOM
TEMP.

UP/

DOWN

Arrow

Key

MODE

Key

Figure 35: Transmitter (Remote Control)

Key

WARNING

Fire hazard. Can cause severe
injury or death. The receiver
causes ignition of the appliance.
The appliance can turn on
suddenly. Keep away from
the appliance burner when
operating the remote system or
activating manual bypass of the
remote system.

CAUTION

Property damage hazard.
Excessive heat can cause
property damage. The
appliance can stay lit for many
hours. Turn off the appliance
if it is not going to be attended
for any length of time. Always
place the Transmitter where
children can not reach it.

22

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Gas Valve

Access Plate

Right Side

Modesty Panel

Gas
Valve

3/8" NPT x

Flare Fitting

3/8" Flex Tubing

3/8" Nipple

3/8" Union

3/8" Close
Nipple

3/8" Shut-off Valve

1/2" x 3/8"

Reducer

Gas

Stub

1/2" x 3/8" Flare

Shut-off Valve

Gas Solid Line Connector

Gas Flex Line Connector

*Sediment
Trap

3"

Min

Igniter

Step 5. REMOVE GLASS DOOR FRAME

Remove the glass door assembly. See
Installation and Removal of Glass Door on
Page 26.

Step 6. CONNECTING GAS LINE

All codes require a shut-off valve mounted in the

supply line. The orientation of the shut-off valve
should face the front. Figure 36 illustrates two
methods for connecting the gas supply. A Sedi­ment Trap is recommended to prevent moisture
and debris in gas line from damaging the valve.

The flex-line method is acceptable in the U.S.A.
where local codes permit, however, Canadian
requirements vary depending on locality. Instal­lation must be in compliance with local codes.

These appliances are equipped with a gas ex-

line for use in connecting the unit to the gas
line. See Figure 36 for flex-line description. The
flex-line is rated for both natural and propane
gas. A manual shut off valve is also provided
with the flex-line.

The gas control valve is located on the right
side of the unit.

When using solid gas line connector, access

the valve by removing the front door assembly
on the valve access side and the access plate
(see Figure 37).

The electronic control valve has a 3/8 in. (10 mm)

NPT thread gas supply inlet.

Bring the shutoff valve on the end of the ex-line

over to the hard pipe and tighten with wrenches
from above through the firebox opening.

Secure all joints tightly using appropriate
tools and sealing compounds (ensure propane
resistant compounds are used in propane ap­plications). It is recommended to seal around
the gas line to prevent cold air leakage.

Figure 37

TEST ALL CONNECTIONS FOR GAS LEAKS
(FACTORY AND FIELD):

WARNING

Never use an open flame to
check for leaks.

Turn on gas supply and test for gas leaks using a
gas leak test solution (also referred to as bubble

leak solution).

Note: Using a soapy water solution is an

effective leak test solution but it is not recom­mended, because the soap residue that is left
on the pipes/fittings can result in corrosion

over time.

A. Light the appliance (refer to the

lighting instructions label in the control
compartment or in the Care and Operation

Instructions manual).

B. Brush all joints and connections with the

gas leak test solution to check for leaks. If
bubbles are formed, or gas odor is detected,
turn the receiver or remote control to the

“OFF” position. Either tighten or refasten

the leaking connection, then retest as
described above.

C. When the gas lines are tested and leak

free be sure to rinse off the leak testing
solution.

D. Re-install the access plate, making certain

the gasket has not been damaged.

Step 7. CHECKING APPLIANCE
OPERATION

Turn on burner then observe the individual

tongues of ame on the burner. Make sure all

ports are open and producing flame evenly
across the burner. If any ports are blocked, or
partially blocked, clean out the ports.

With gas line installed run initial system

checkout before closing up the front of the
unit. Follow the lighting instructions provided
in the Care and Operation Instructions
manual.

Note: Lighting Instructions are also found on
the literature tag tied to the bracket above the
gas valve. To access the tag, reach into the
right side opening.

When rst lighting the appliance, it will take

a few minutes for the line to purge itself of
air. Once purging is complete, the pilot and
burner will light and operate as indicated

in the instruction manual. Subsequent
lighting of the appliance will not require such

purging. Inspect the pilot flame (remove logs,

if necessary, handling carefully).

Electronic Appliance Checkout

To light the burner, turn ‘ON’ the optional
remote wall switch or turn the appliance

mounted ON/OFF switch to the “ON” position.

Ensure the igniter lights the pilot. The pilot
flame should engulf the flame sensor as
shown in Figure 38.

Figure 36: Gas Connection

Note: The gas supply line
must be installed in accor­dance with building codes
by a qualified installer
approved and/or licensed
as required by the locality.
In the Commonwealth of
Massachusetts, installation
must be performed by a
licensed plumber or gas
fitter.

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

Pilot
Hood

Flame Rod
(Sensor)

Figure 38

23

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Step 8. LOG, VOLCANIC STONE, AND GLOWING
EMBER PLACEMENT

NOTE: If installing the Contemporary Burner/Floor
Kit, skip this step and instead refer to the instructions
provided with the kit.

WARNING

• DO NOT operate this appliance without the
required accessories properly installed:

—floor (log set or contemporary kit), and
—panels (ceramic or porcelain).

WARNING

• DO NOT attempt to install the logs until the
appliance installation has been completed, the
gas line connected and tested for leaks and the
initial burner operation has been checked out.

• The size and position of the log set was engineered
to give the appliance a safe, reliable and attractive
flame pattern. Any attempt to use a different log
set in the fireplace will void the warranty and will
result in incomplete combustion, sooting, and
poor flame quality.

• Logs get very hot and will remain hot up to one
hour after gas supply is turned off. Handle only
when logs are cool. Turn off all electricity to the
appliance before you install grate, volcanic stone,
embers and logs.

• This appliance is not designed to burn wood. Any
attempt to do so could cause irreparable damage to
the appliance and prove hazardous to your safety.

• If logs are not installed according to the log
installation instructions, flame impingement and
improper combustion could occur and result in soot
and/or excessive production of carbon monoxide
(CO), a colorless, odorless, toxic gas.

Step 4. Position the individual logs as shown in Figures 42 through

46. Logs should be placed in the order shown. Place logs 2
and 3 against the pins on the grate, NOT over them.

Proper log and twig placement is critical to encourage

outstanding ame appearance and prevent sooting. When

positioned properly as shown, twigs will be positioned
between flame peaks and will not impinge any flames.

Cat. No. Model Description

88L53 FGE Bag of Glowing Embers
80L42 FDVS Bag of Volcanic Stone
H8312 PGE Bag of Platinum Embers

Table 10: Firebox Accessories / Parts

Figure 39

For Propane Gas Only: Do Not Place Embers On Main Ports.

Glowing Embers (Rockwool)

Step 1. Install the ceramic or porcelain panels per the instructions

provided in kit (P/N 750182M).

Step 2. Place volcanic stone around the burner (the entire bag of

volcanic stone will NOT be used). DO NOT PLACE VOLCANIC
STONE ON THE BURNER. See Figure 41.

Step 3. Separate the glowing embers (rockwool) into pieces about the

size of a quarter (see Figure 39). Keep the pieces fluffed, not
matted. Distribute these pieces over the burner as shown in

Figure 40. Do not use more than necessary. When properly

positioned, the Glowing Embers will cover approximately 75%
of the burner on natural gas. For propane gas, do not place
embers on main ports.

Note: Excessive use of embers may result in sooting or poor flame.
This appliance is provided with enough Glowing Embers for several
applications, do not feel compelled to use all that is in a new bag. For
best glowing effect, replace the ember material annually. Replacement
Glowing Embers are available (Catalog Number 88L53).

24

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

Figure 40

Volcanic Stone

Figure 41

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

MDLX40 & MDLX45 Log Placement

2

6

Figure 42

3

7

5

1

Log Number Description

1 Log, Center
2 Log, Rear
3 Log, Center/Left
4 Log, Center/Right
5 Log, Rear/Top
6 Log, Front/Left
7 Log, Front/Center

2

4

Figure 44

Align Groove At The Bottom Of Log (2) Over
The Grate And Push It Towards The Rear.

3

4

Figure 43

1

Align Two Holes At Bottom Of Log (1)
Over The Pins On The Gas Burner.

Engage Logs (3 & 4) With The Grate Pins And Align Groves At
The Bottom Of The Logs Over The Grate.

Figure 45

6 5

Engage Log (6) With The Grate Pin
And Align Groove At The Bottom Of
The Log Over The Grate.

Align Hole At Bottom Of Log (5)
Over The Pin On Log (2).

Engage Log (7)
With The Pin On
Log (4).

Figure 46

7

2

4

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

25

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Step 9. INSTALLATION AND REMOVAL
OF GLASS DOOR

WARNING

• When reinstalling the glass

door, the door latch screws
must be securely tightened
to prevent the glass door
from falling out, which could
potentially cause damage and
possible injury.

• Do not attempt to substitute the

materials used on this door,
or replace cracked or broken
glass.

• Handle this glass with extreme

care! Glass is susceptible to
damage – Do not scratch or
handle roughly while reinstall­ing the glass door frame.

• The glass door of this appli-

ance must only be replaced
as a complete unit as provided
by the manufacturer. Do not
attempt to replace broken,
cracked or chipped glass sepa­rately.

• Do not attempt to touch the

front enclosure glass with your
hands while the fireplace is in
use.

WARNING

Do not operate appliance with
the glass front removed, cracked
or broken.

AVERTISSEMENT

Ne pas utiliser l'appareil si le
panneau frontal en verre n'est
pas en place, est craqué ou
brisé.

Only doors certified with the appliance
shall be used.

Seules des portes certifiées pour cet
appareil doivent être utilisées.

CAUTION: DO NOT abuse glass door by
striking or slamming shut.

Installing Glass Enclosure Panel
(see Figure 47)

Retrieve the glass door. Visually inspect the
gasket on the backside of the frame. Gasket
surface must be clean, free of irregularities
and seated firmly.

Position the door in front of the firebox opening
with the top of the door held away from the
fireplace (Figure 47). Lower the bottom of the
door assembly on the bottom door track and
set on padded surface. Pivot the door up after
engaging and centering in the base channel.

Using a Phillips screwdriver, fasten the door

frame to the door latch with the two (2) screws.

The latch should pull forward to engage the
door frame.

Install the door modesty shield on top flange
glass door as follows: grab the door modesty
shield with both hands, with the open hem
going down and engage it with the upper lip
of the glass door frame by pushing it all the

way down. Make sure the installed shield is

firmly in place.

With the rescreen hanging on the screen rod,

insert the right side of the rod into the existing

hole on the right modesty panel. Bend down

the rod at the center and drop the left end into
the slot on the left modesty panel, being careful
not to scratch the paint.

Top Flange Glass door
assembly

Screws

Firebox Floor

Glass Door Assembly

Glass Door Latch (2)

Figure 47: Installing the Glass Door

Step 10. BURNER ADJUSTMENTS

Flame Appearance and sooting

Proper flame appearance is a flame which is
blue at the base and becomes yellowish-orange

in the body of the ame. When the appliance is

first lit, the entire flame may be blue and will
gradually turn yellowish-orange during the first
15 minutes of operation. After 15 minutes of
operation, if the flame is blue, or if the flame is

orange with evidence of sooting (black tip), the

air shutter opening may need to be adjusted.
If the air shutter opening is closed too far,

sooting may develop. Sooting is indicated by
black puffs developing at the tips of very long
orange flames. Sooting results in black deposits
forming on the logs, appliance inside surfaces
and on exterior surfaces adjacent to the vent
termination.

Sooting is caused by incomplete combustion
in the flames and lack of combustion air enter­ing the air shutter opening. To achieve a warm
yellowish-orange flame with an orange body
that does not soot, the shutter opening must be
adjusted between these two extremes.

Air Shutter Adjustment Guidelines

• If there is smoke or soot present, rst check

the log set positioning to ensure that the
flames are not impinging on any of the logs.
If the log set is properly positioned and a
sooting condition still exists, then the air
shutter opening should be increased.

• The more offsets in the vent system, the larger

the air shutter opening will need to be.

• An appliance operated with the air shutter

opened too far, may have flames that appear
blue and transparent. These weak, blue and
transparent flames are termed anemic.

• Propane models may exhibit ames which

candle or appear stringy. If this is present
and persists, adjust the air shutter to a more
closed position, then operate the appliance
for a few more minutes to ensure that the
flame normalizes and the flames do not
appear sooty.

The following chart is provided to aid you in
achieving the correct air shutter adjustment
for your installation.

Amount of

Primary Air

If air shutter is
closed too far

If air shutter is
open too far

Flame

Color

Flame will
be orange

Flame will
be blue

Air Shutter

Adjustment

Air shutter
gap should be
increased

Air shutter
gap should be
decreased

Table 11: Air Shutter Adjustment

26

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Air Shutter

Opening

Burner

Orifice

Gas

Valve

Venturi

Venturi

Burner Air Shutter Adjustment Procedure

WARNING

• Air shutter adjustment should

only be performed by a quali­fied professional service
technician.

• Ensure that the front glass

door assembly is in place and
sealed After adjustment.

CAUTION

Main Burner Factory Air Shutter

Opening Setting—Inches (millimeter)

Model Nat.Gas Propane Gas

MDLX40
MDLX45

1/16 (1.59) 9/32 (7.14)
1/16 (1.59) 9/32 (7.14)

Soot will be produced if the air
shutter is closed too much. Any
damage due to carboning result­ing from improperly setting the
air shutter is not covered under
the warranty.

To adjust the flame, rotate the air shutter toward
the back or toward the front of the fireplace.
Position the air shutter to the factory setting as
shown in the table in Figure 48. Allow the burner
to operate for at least 15 minutes. Observe the
flame continuously. If it appears weak or sooty
as previously described, adjust the air shutter
until the flame appearance is as desired.

Use the remote to adjust the flame height
as desired.

Propane models may exhibit a flame pattern
that may candle or appear stringy. If this is
problematic or persists as the appliance is
continually operated, adjust the air shutter
closed as described in the previous paragraphs.
Operate the appliance for a period of time as the
effect diminishes, ensuring that the appliance

does not develop sooty ames. When satised

that the appliance operates properly, proceed
to finish the installation.

Figure 48

Contemporary Media Shown (MDLX40)

Figure 49: Burner Flame Appearance

Rustic Oak Logs Shown (MDLX45)

Figure 50: Burner Flame Appearance

27

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Glass Door

Assembly

Fireplace

Finish Combustible
Or Non-Combustible
Material

Bottom Of
Fireplace

1/8 Inch
Minimum

Door Track

Finish Combustible
Or Non-Combustible
Material

Front Face
Of Fireplace

Floor Panel

FINISHING REQUIREMENTS
Wall Details

Complete finished interior wall. To install the appliance facing flush with
the finished wall, position framework to accommodate the thickness of
the finished wall (Figure 51).

Combustible
Finished Wall
Materials

Header
(2x4’s)

Combustible
materials are
allowed above
this point on
the face of the
appliance.

8-3/8" Min.

(213 mm)

The gray shaded
area must be
non-combustible
or Dura Rock

Vent & 90° Elbow

Appliance

3" Min.

(76 mm)*

2 Foot Vertical

1

*

Top of

Spacers

Non-combustible materials, such as surrounds and other appliance trim,
may be installed on the appliance front face with the exceptions.

Vertical installation clearances to combustible mantels vary according to the
depth of the mantel. See Figure 9. Mantels constructed of non-combustible
materials may be installed at any height above the appliance opening.

Combustible materials may project beyond the side of the fireplace open­ing as long as it is kept within the shaded area illustrated in Figure 10.

A hearth extension is not required with this appliance. If a hearth extension

is used, there are two methods of installation. One, the finish combustible
or non-combustible material could be ended by butting up against the
front face of the fireplace and the floor panel (refer to Figure 52).

Two, the finish combustible or non-combustible material could be ended
below the fireplace (refer to Figure 53). Remove the floor panel as shown
in Figure 52 by removing the screws on the right side of the panel and
sliding the left side away from the tab. Discard the screws and floor panel.

It is critical that there is at least a 1/8 in. gap between the bottom of
the door track and the surface of the finish material.

28

Top of Door Frame

Fireplace (right side)

Installations with horizontal terminations which have minimum

1

vertical vent height only will require 4”(102mm) minimum
side clearance as shown in shaded zone above. All other
installations require 1" (25mm) minimum side clearance as
specified in Table 4 on Page 5.

* Insulation is NOT ALLOWED in the clearance zones around vent
components. Keep this area free from combustible materials.

Figure 51

Figure 52

Figure 53

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

INSTALLER INSTRUCTIONS - ATTACHING SAFETY-IN-OPERATION WARNINGS

Step 11. INSTALLER INSTRUCTIONS—ATTACHING SAFETY-IN-OPERATION WARNINGS

It is the installer’s responsibility to ensure these warnings are properly affixed during installation.
These warning labels are a critical step in informing consumers of the safe operation of this appliance.

ATTACHING SAFETY-IN-OPERATION
WARNINGS

It is required that the set of safety instruction labels
that have been furnished with the fireplace be affixed
to the operation and control points of the fireplace. A
safety instruction label must be affixed to the receiver
wall switch plate where the fireplace is turned on and
off (See Figure A) and on the remote control handheld
transmitter (See Figure B). To properly complete the
installation of this fireplace, locate the multi-lingual
adhesive labels provided with the Care and Operation
Instructions and proceed as follows:

1. Locate the wall receiver that controls the fireplace
(verify the switch opera
ing it on and off). Clean the wall receiver plate
thoroughly to remove any dust and oils. Affix the

that controls the fireplace (Figure A). Choose
the language primarily spoken in the home. If
unknown, affix the English language label.

2. Locate the remote control transmitter and clean
it thoroughly to remove any dust and oils. Affix
the label to the surface of handheld transmitter
(Figure B). Choose the language primarily spo­ken in the home. If unknown, affix the English
language label.

3. If you are unable to locate the labels, please call
Lennox Hearth Products or your nearest Lennox
Hearth Products dealer to receive additional
safety instruction labels free of charge.

Cat. No. H8024 Replacement Label Kit

LENNOX HEARTH PRODUCTS
1-800-655-2008

Note: English is red text on clear label. French and
Spanish are white text on black label.

tes the fireplace by turn-

APPOSITION DES MISES EN GARDE RELATIVES
À LA SÉCURITÉ D’UTILISATION

Il est impératif que le jeu d’étiquettes de sécurité qui
ont été fournies avec le foyer soient collées à côté
des dispositifs de contrôle du foyer. Une étiquette de
sécurité doit être collée sur la plaque du récepteur
mural contrôlant l’allumage du foyer (voir Figure A)
et sur le boîtier de la télécommande (Figure B). Pour
achever l’installation correcte de ce foyer, procédez
comme suit avec les étiquettes adhésives en langues
étrangères fournies avec les instructions d’utilisation
et d’entretien :

1. Repérez le r
(vérifiez que l’interrupteur contrôle le fonction ­nement du foyer en le faisant basculer de Marche
à Arrêt, et vice-versa). Nettoyez soigneusement

reviecer llaw eht fo etalp eht fo ecafrus eht ot lebal

la plaque du récepteur mural pour éliminer la
poussière et les traces de graisse ou d’huile. Collez
l’étiquette sur la surface de la plaque du récepteur
mural qui contrôle le foyer (Figure A). Choisissez
la langue qui est principalement parlée dans la
résidence du propriétaire. En cas de doute, collez
l’étiquette en anglais.

2. Repérez la télécommande et nettoyez-la soigneuse­ment pour éliminer la poussière et les traces
de graisse ou d’huile. Collez l’étiquette
de la télécommande (Figure B). Choisissez la
langue qui est principalement parlée dans la
résidence du propriétaire. En cas de doute, collez
l’étiquette en anglais.

3. Si vous ne trouvez pas les étiquettes, veuillez
appeler Lennox Hearth Products ou votre distribu­teur Lennox Hearth Products local pour recevoir
gratuitement des étiquettes supplémentaires.

Étiquettes de remplacement, n° cat. H8024

LENNOX HEARTH PRODUCTS
1-800-655-2008

Remarque : Le texte anglais est rouge sur un support
transparent. Le texte français et espagnol est blanc
sur un support noir.

écepteur mural qui contrôle le foyer

sur le boîtier

COLOCACIÓN DE ADVERTENCIAS DE SEGURIDAD
EN OPERACIÓN

Se requiere que el juego de etiquetas de instrucciones
de seguridad que se incluyeron con la chimenea se
coloque en los puntos de operación y control de la
misma. Se debe colocar una etiqueta de instrucciones
de seguridad en la placa del interruptor de pared
del receptor desde el cual se enciende y se apaga
la chimenea (ver la Figura A) y en el transmisor de
control remoto (ver la Figura B). Para completar
correctamente la instalación de esta chimenea,
encuentre las etiquetas adhesivas multilingües
incluidas con las instrucciones de cuidado y operación
y haga lo siguiente:

1. Identifique el recepto
chimenea (verifique que el interruptor opera la
chimenea encendiéndola y apagándola). Limpie
bien la placa del receptor de pared para quitar el
polvo y aceite. Pegue la etiqueta en la superficie
de la placa del receptor de pared que controla la
chimenea (Figura A). Seleccione el idioma que
más se habla en la casa. Si no sabe cuál es, use la
etiqueta en inglés.

2. Identifique el transmisor de control remoto y límpielo
bien para quitar el polvo y aceite. Pegue la etiqueta
en la superficie del transmisor (Figura B). Seleccione
el idioma que más se habla en
cuál es, use la etiqueta en inglés.

3. Si no puede encontrar las etiquetas, sírvase
llamar a Lennox Hearth Products o al distribuidor
de Lennox Hearth Products más cercano para
recibir etiquetas de instrucciones de seguridad
adicionales gratuitas.

Juego de etiquetas de repuesto - Nº de cat. H8024

LENNOX HEARTH PRODUCTS
1-800-655-2008

Nota: La etiqueta en inglés es transparente con texto
rojo. Las etiquetas en francés y español son negras
con texto blanco.

r de pared que controla la

la casa. Si no sabe

Figure 54

SAFETY LABEL

DIAGRAMS

Figure A

DIAGRAMMES DES ÉTIQUETTES

DE SÉCURITÉ

On

Remote

Off

PRG

Figure B

DIAGRAMAS DE ETIQUETAS

DE SEGURIDAD

29

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

INSTALLATION ACCESSORIES

Listed Secure Vent® Components

Cat.

No.

H2266 SV8HTS Horizontal Square

H2265 SV8VTR Vertical Termination

H2250 SV8L6 6 inch (152mm)

H2251

H2252 SV8L24 24 inch (610mm)

H2253 SV8L36 36 inch (914mm)

H2254 SV8L48 48 inch (1219mm)

H2255 SV8LA Telescopic Section
H2256 SV8E45 45 Degree Elbow

H2257 SV8E90 90 Degree Elbow

Model

No.

Termination with
Firestop/Spacer
(H2260) and
Adaptor (H2267)

Vent Section

SV8L12 12 inch (305mm)

Vent Section

Vent Section

Vent Section

Vent Section

Description

H2262 SV8SU Support Strap

H2263 SV8SP Support Plate

H3908 SV8ARSA Attic Insulation

Shield (adjustable
12 in. to 22 in.)

2a

B

CTSO-33/44 Shrouds
for Single terminations

C

D

E

(ref. Instruction P/N

750193M)

A

CTSO-46 Shroud
for double
terminations

C

D

1 typ.

2a

2b

2a

2b

2b

A

2a

Open Top Shroud Kits

Inches (millimeters)

Cat. No. Model A B C D *E

H1985 CTSO-33

H1987

CTSO-44

H1986 CTSO-46

37-5/8

(955)

48-5/8
(1235)

48-5/8
(1235)

37-5/8

(955)

48-5/8
(1235)

73 1/4

(1860)

7-1/2

(191)

7-1/2

(191)

7-1/2

(191)

24-1/2

24-1/2

24-1/2

typ.

B

(622)3 (76)

(622)3(76)

(622)3(76)

12typ.

E

30

The following flashings come packaged
with a storm collar

H3236 SV8F Flat Roof Flashing
H2258 SV8FA 1/12 to 7/12 Adjust-

able Flashing

H2259 SV8FB 7/12 to 12/12

Adjustable Flashing

H3237 SV8SC6 Storm Collars,

6 pack

H2260 SV8HF Firestop/Spacer—

Horizontal
(3-1-1 spacing)

H2261 SV8BF Firestop/Spacer—

Vertical
(1-1-1 spacing)

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

A

B

C

(ref. Instruction P/N 750194M)

D

Closed Top Shroud Termination Kits

Inches (millimeters)

Cat. No. Model A B C D

H1988 CTSA-33

34

(864)

5

(127)

34

(864)

(864)

34

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

GAS CONVERSION KITS

WARNING

This conversion kit shall be installed by a qualified service agency in
accordance with the manufacturer’s instructions and all applicable codes
and requirements of the authority having jurisdiction. If the information in
these instruction is not followed exactly, a fire, explosion or production of
carbon monoxide may result causing property damage, personal injury
or loss of life. The qualified service agency is responsible for the proper
installation of this kit. The installation is not proper and complete until the
operation of the converted appliance is checked as specified in the manu­facturer’s instructions supplied with the kit.The qualified service agency
performing this installation assumes responsibility for this conversion.

AVERTISSEMENT

Cette trousse de conversion doit être installée par un technicien agréé,
selon les instructions du fabricant et selon toutes les exigences et tous les
codes pertinents de l’autorité compétente. Assurez-vous de bien suivre
les instructions dans cette notice pour réduire au minimum le risque
d’incendie, d’explosion ou la production de monoxyde de carbone pouvant
causer des dommages matériels, des blessures ou la mort. Le tecnicien
agréé est responsable de l’installation de cette trousse. L’installation n’est
pas adéquate ni complète tant que le bon fonctionnement de l’appareil
converti n’a pas été vérifié selon les instructions du fabricant fournies avec
la trousse. Le fournisseur de service qualifié ayant réalisé l'installation
assume les responsabilités liées à la conversion.

Step 1. TURN OFF THE GAS SUPPLY TO THE
APPLIANCE and disconnect power supply at
the circuit breaker. Ensure appliance is cold.

CAUTION: THE GAS SUPPLY SHALL BE
SHUT OFF PRIOR TO DISCONNECTING
THE ELECTRICAL POWER, BEFORE PRO­CEEDING WITH THE CONVERSION.

ATTENTION. AVANT D’EFFECTUER
LA CONVERSION, COUPEZ D’ABORD
L’ALIMENTATION EN GAZ, ENSUITE,
COUPEZ L’ALIMENTATION ÉLEC­TRIQUE.

Step 2. Remove the front glass door/frame

and the access plate from the appliance. See
Figures 37 and 47.

Step 3. Carefully remove the logs and the
grate assembly / contemporary media.

Exercise care so as not to break the logs /
contemporary media.

Step 4. Refer to Figure 55. Remove the two

5/16-in. screws securing the burner to the
burner brackets. Carefully slide the burner to
the left to clear the venturi from the orifice.
Set aside the screws and burner assembly in
a secure location for later reinstallation.

In Canada:
THE CONVERSION SHALL BE CARRIED
OUT IN ACCORDANCE WITH THE
REQUIREMENTS OF THE PROVINCIAL
AUTHORITIES HAVING JURISDICTION
AND IN ACCORDANCE WITH THE
REQUIREMENTS OF THE CAN/
CSA-B149.1 INSTALLATION CODE.

LA CONVERSION DEVRA ÊTRE
EFFECTUÉE CONFORMÉMENT
AUX RECOMMANDATIONS DES
AUTORITÉS PROVINCIALES AYANT
JURIDICTION ET CONFORMÉMENT
AUX EXIGENCES DU CODE
D'INSTALLATION CAN/CSA-B149.1.

Gas conversion kits are available to adapt
your appliance from the use of one type of
gas to the use of another. These kits contain
all the necessary components needed to
complete the task including labeling that
must be affixed to ensure safe operation.

Kit part numbers are listed below, and the fol­lowing steps detail the conversion procedure.

Fireplace

Model No.

MDLX40IN GCK-

MDLX45IN GCK-

Table 12: Natural Gas to Propane Gas
Conversion Kits

Fireplace

Model No.
MDLX40IP GCK-MDLX-

MDLX45IP GCK-MDLX-

Table 13: Propane Gas to Natural Gas
Conversion Kits

Conversion Kit

Model No.

MDLX40NP

MDLX45NP

Conversion Kit

Model No.

40PN

45PN

Conversion
Kit Cat. No.

H8668

H8669

Conversion
Kit Cat. No.

H8670

H8671

Burner Assembly

Gas Valve Assembly

Burner Orifice

Figure 55

Step 5. Remove the control compartment
access door and gasket by removing the

twelve (12) screws securing it, and set it

aside for later reinstallation.The gas valve
can be accessed through the opening, or
the complete assembly can be removed by
sliding the assembly to the right.

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

31

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Step 6. Refer to the instructions provided
with the SIT regulator conversion kit. Using

a Torx T20 (with 1/4-in. shank and center
hole) or slotted screwdriver, remove and

discard the two pressure regulator mounting
screws, the pressure regulator tower, and the

diaphragm assembly (if applicable). Properly
dispose of all removed components. Make

sure the rubber gasket installed on the back
of the replacement pressure regulator is
properly positioned.

Step 7. Install the new stepper motor
pressure regulator assembly using the
supplied screws. Securely tighten the screws

(25 lb-in).

Step 8. Attach the enclosed identification
label to the valve body where it can be easily
seen.

Step 9. Make stepper motor and valve
electrical connections.

Step 10. Remove the pilot hood assembly to
access the hexed pilot orifice. Using a 5/32­in. allen wrench, remove and replace the pilot
orifice with the one provided with the kit.

NOTE: Use extreme care to avoid
damaging the igniter assembly.

Step 11. Refer to Figure 57 and remove the
pilot hood assembly to access the hexed pilot
orifice. Remove and replace the orifice with
the one provided with the kit.

Step 12. (Refer to Figure 55 on Page 31 and
Figure 56)

VERIFY THE PROPER ORIFICE SIZE
BEFORE INSTALLING IT.

Pilot
Hood

Pilot
Orifice

Figure 57

A. Remove the orifice from the manifold

and replace it with the one provided in
the kit. See the following table for orifice
sizes for natural and propane models.
Figure 58 illustrates the orifice. Use
pipe joint compound or Teflon tape on
all pipe fittings before installing (ensure
propane resistant compounds are used in
propane applications, do not use pipe joint

compounds on are ttings).

B. Retrieve the burner and slide the venturi

tube over the orifice. Set the burner
assembly into its position and secure it.

C. Reinstall the grate assembly.
Step 13. Reassemble the remaining

components by reversing the procedures
outlined in the preceding steps.

Step 14. Attach the conversion label provided
in the conversion kit to the rating plate on the
appliance.

Step 15. Apply gas to the system and relight

appliance. With the main burner "ON", test

the new pressure regulator assembly and all
gas line joints for leaks using a gas leak test
solution. See Test All Connections For Gas Leaks
on Page 23.

Burner Orifice Sizes

Elevation 0-4500 feet ( 0-1372 meters)

Model Natural Gas

drill size (inches)

MDLX40

MDLX45

0.1405 in. (#28)*

• H2286

0.161" (#20)*

• H2288

* Standard size installed at factory

• Part /Cat. Number

Propane

drill size (inches)

0.086 in. (#44)*

• H2287

0.093" (#42)*

• H4816

Table 14

Figure 58

Step 16. Relight the main burner and verify
proper burner ignition and operation. See
Burner Adjustments Pages 26 and 27.

Inspect the pilot system for proper flame. The
pilot flame should engulf the flame sensor as
shown in Figure 38 on Page 2.

The lighting instructions can be found on the
lighting label in the control compartment or

in the Care and Operation Manual provided

with the appliance.
Step 17. Using a manometer, test the inlet

and manifold gas pressures. See Tables 2
and 3 on Page 4.

ALWAYS TEST PRESSURES WITH THE

VALVE REGULATOR CONTROL AT THE
HIGHEST SETTING.

SEE PAGE 26 FOR AIR SHUTTER
ADJUSTMENT GUIDELINES.

32

(from DFC Wire Harness)

Manifold (OUT) Test Port

Inlet (IN) Test Port

Wire

(from DFC Wire

Harness)

Main Gas Inlet

3/8" NPT

Figure 56

Green Wire

Connect GTMS
wire harness.

Pressure Regulator
Tower

Yellow Ground Wire
(from DFC Wire Harness)

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

Flame
Sensor

Figure 59

Igniter Rod

Pilot Hood

Pilot
Nozzles

NOTES

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

33

LENNOX HEARTH PRODUCTS • MONTEBELLO® DLX DIRECT VENT GAS FIREPLACES (MDLX40/45) • INSTALLATION INSTRUCTIONS

Lennox Hearth Products reserves the right to make changes at any time, without notice, in design,
materials, specifications, and prices, and also to discontinue colors, styles, and products.
Consult your local distributor for fireplace code information.

Printed in U.S.A. © 2012 Lennox Hearth Products

P/N 506023-15 Rev. A 07/2012

34

NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

1508 Elm Hill Pike, Suite 108 • Nashville, TN 37210