Lennox MLDVT-45NM Guide d'installation

Marque: Lennox

Modèle: MLDVT-45NM

Catégorie: Cheminées

Taper: Guide d'installation

INSTALLATION INSTRUCTIONS

Please read and understand these instructions

before starting installation.

INSTALLER: Leave this manual with the appliance.

CONSUMER: Retain this manual for future reference.

INSTALLATEUR : Laissez cette notice avec l’appareil.

CONSOMMATEUR : Conservez cette notice pour

consultation ultérieure.

AVERTISSEMENT : Assurez-vous de bien suivre les

instructions données dans cette notice pour réduire au

minimum le risque d’incindie ou d’explosion ou pour

éviter tout dommage matériel, toute blessure ou la mort.

WARNING: If the information in these instructions

is not followed exactly, a ﬁre or explosion may

result, causing property damage, personal injury,

or death.

WARNING /AVERTISSEMENT/AVISO

• HOT GLASS WILL CAUSE

BURNS.

• DO NOT TOUCH GLASS

UNTIL COOLED.

• NEVER ALLOW CHILDREN

TO TOUCH GLASS.

• UNE SURFACE VITRÉE CHAUDE

PEUT CAUSER DES BRÛLURES.

• LAISSER REFROIDIR LA SURFACE

VITRÉE AVANT D'Y TOUCHER.

• NE PERMETTEZ JAMAIS À UN ENFANT

DE TOUCHER LA SURFACE VITRÉE.

• EL VIDRIO CALIENTE

CAUSARÁ QUEMADURAS.

• USTED DEBE NUNCA

TOCAR EL VIDRIO CALIENTE.

• LOS NIÑOS DEBEN NUNCA

TOCAR EL VIDRIO.

- Do not store or use gasoline or other flammable

vapors and liquids in the vicinity of this or any other

appliance.

- WHAT TO DO IF YOU SMELL GAS:

• Do not try to light any appliance.

• Do not touch any electrical switch; do not use any

phone in your building.

• Immediately call your gas supplier from a

neighbor’s phone. Follow the gas supplier’s

instructions.

• If you cannot reach your gas supplier, call the fire

department.

- Installation and service must be performed by a

qualified installer, service agency or the gas supplier.

- Ne pas entreposer ni utilizer d’essence ni d’autres vapeurs

ou liquides inﬂammables dans le voisinage de cet appareil

ou de tout autre appareil.

- QUE FAIRE SI VOUS SENTEZ UNE ODEUR DE GAZ :

• Ne pas tenter d’allumer d’appareil.

• Ne touchez à aucan interrupteur. Ne pas vous servir des

téléphones se trouvant dans le bâtiment où vous trouvez.

• Appelez immédiatement votre fournisseur de gaz depuis

un voisin. Suivez les instructions du fournisseur.

• Si vous ne pouvez rejoindre le fournisseur de gaz,

appelez le service des incindies.

- L’installation et l’entretien doivent être assurés par un

installateur ou un service d’entretien qualiﬁé ou par le

fournisseur de gaz.

P/N 506015-10 Rev. B 04/2013

This manual is one of a set of two supporting this product.

Refer to P/N 506017-09 for Care and Operation Instructions.

Ce manuel est disponible en francais, simplement

en faire la demande. Numéro de la pièce 506223-56.

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.

Report No. 100326540PRT-001

ELECTRONIC:MILLIVOLT:

MLDVT Direct-Vent

Gas Fireplaces

MLDVT30NE-2

MLDVT35NE-2

MLDVT-35NE-FB

MLDVT40NE-2

MLDVT-40NE-FB

MLDVT45NE-2

MLDVT-30PM

MLDVT-35PM

MLDVT-35PM-FB

MLDVT-40PM

MLDVT-45PM

MLDVT-30NM

MLDVT-35NM

MLDVT-35NM-FB

MLDVT-40NM

MLDVT-40NM-FB

MLDVT-45NM

MODELS

™

DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

TABLE OF CONTENTS

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

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

General Information .................... 2

Requirements for the Commonwealth

of Massachusetts ...................... 4

Cold Climate Insulation.................. 4

Manufactured Home Requirements ........ 5

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

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

Minimum Clearance to Combustibles ....... 8

Pre-Installation Steps ................... 8

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

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

Optional Blower Kit Wiring ............... 9

Framing.............................. 9

Fireplace and Framing Speciﬁcations ...... 10

Routing Gas Line ..................... 11

Installing the Venting System . . . . . . . . . . . . 12

Vertical Termination Systems ............ 12

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

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

Horizontal Vent Tables and Figures ........ 20

Venting Using Flexible Vent Pipe.......... 22

Field Wiring.......................... 23

Optional Blower Kit Wiring .............. 24

Connecting Gas Line................... 24

Verifying Appliance Operation............ 25

Installing Logs ....................... 26

Removing/Installing Glass Door .......... 29

Adjusting Burner...................... 29

Installing Hood ....................... 31

Finishing Requirements ................ 31

Attaching Safety-in-Operation Warnings.... 32

Installation Accessories ................ 33

Gas Conversion Kits ................... 35

Please read and understand these

instructions before beginning

your installation.

PACKAGING

The assembled vented gas ﬁreplace heater

is packaged with:

• (1 set) Logs

(Packaged in a carton inside the ﬁrebox)

• (1 bag) Volcanic Stone

(In bottom compartment)

• (1 bag) Glowing Embers

(In bottom compartment)

• Literature Kit

(Envelope in bottom compartment

containing Care and Operation

Instructions, Installation Instructions,

Safety-In-Operation Warning Labels,

Warranty)

• (1) U-Shaped Vent Restrictor

(Attached to Literature Kit envelope)

• (1) Hood

(Inside ﬁrebox)

INTRODUCTION

Millivolt appliances have a millivolt gas

control valve with piezo ignition system. If

any optional accessories that will require

electrical power are to be installed, the

electrical power must be provided at the

time of appliance installation.

Electronic appliances are designed to

operate on natural or propane gas. An

electronic intermittent pilot ignition system

provides safe, efﬁcient operation. External

electrical power is required to operate

these units. In the event of a power outage,

four (4) “AA” batteries (in battery holder)

provide backup power for appliance

operation (excluding [optional] blower).

These vented gas ﬁreplace heaters

are sealed combustion, air-

circulating gas ﬁreplaces designed for

residential applications.

Approved Vent Components

These ﬁreplaces are designed, tested and

listed for operation and installation with the

following vent components only:

• Secure Vent® Direct-Vent System

Components manufactured by Security

Chimneys International,

• Secure Flex® Flexible Vent Components

manufactured by Security Chimneys

International, and

• Z-FLEX® Model GA Venting Systems

listed to UL1777 and ULCS635

manufactured by Flexmaster

Canada Limited.

Use only the correct size venting (4 1/2 in.

inner and 7 1/2 in. outer).

These approved vent system components

are labeled for identiﬁcation. DO NOT use

any other manufacturer’s vent components

with these appliances.

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.

NOTE: Children and adults should be alerted

to the hazards of high surface temperature

and should stay away to avoid burns or

clothing ignition.

Remarqué : Les enfants et les adultes

devraient être infor-més des dangers

que posent les températures de surface

élevées et se tenir à distance aﬁn d’éviter

des brûlures ou que leurs vêtements ne

s’enﬂamment.

DO NOT ATTEMPT TO ALTER OR

MODIFY THE CONSTRUCTION OF THE

APPLIANCE OR ITS COMPONENTS.

ANY MODIFICATION OR ALTERATION

MAY VOID THE WARRANTY,

CERTIFICATION, AND LISTINGS OF

THIS UNIT.

DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

Codes and Standards

These appliances comply with National

Safety Standards and are tested and

listed by ETL/Intertek. (Report No.

100326540PRT-001) to ANSI Z21.88

(in Canada, CSA-2.33), and CAN/

CGA-2.17-M91 in both USA and Canada, as

vented gas ﬁreplace heaters.

These appliances are listed by ETL/

Intertek for installation in bedrooms and

manufactured homes.

The installation must conform to local

codes or, in the absence of local codes, with

the National Fuel Gas Code, ANSI Z223.1/

NFPA 54—latest edition (In Canada, the

current CAN/CSA-B149.1 installation code).

The appliance, when installed, must

be electrically grounded and wired in

accordance with local codes or, in the

absence of local codes, with the National

Electrical Code, ANSI/NFPA 70—latest

edition, or the Canadian Electrical Code,

CSA C22.1—latest edition.

Provide adequate clearances around

air openings and adequate accessibility

clearance for service and proper operation.

Never obstruct the front or back 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.

It is advisable to have an alternate primary

heat source when installed in a dwelling.

These appliances must not be connected to

a chimney or ﬂue serving a separate solid

fuel burning appliance.

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.

Table 1: Input Rate, Gas Valves

Models Input Rate (BTU/HR)

Natural Gas Propane Gas

MLDVT-30 13,500 high

10,500 low 12,500 high

9,000 low

MLDVT-35 16,000 high

12,500 low 15,000 high

11,500 low

MLDVT-40 20,000 high

15,500 low 20,000 high

15,800 low

MLDVT-45 23,000 high

17,500 low 22,000 high

17,000 low

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.

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.

Remarqué : 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.

NOTE: 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.

Remarqué : Ne pas utiliser cet appareil

s’il a été plongé, même partiellement,

dans l’eau. Appeler un technicien

qualiﬁé pour inspecter l’appareil et

remplacer toute partie du système de

commande et toute commande qui a été

plongée dans l’eau.

NOTE: Only trim kit(s) supplied by

the manufacturer shall be used in the

installation of this appliance.

Remarqué : Seules les trousses de

garniture fournies par le fabricant

doivent être utilisées pour l’installation

de cet appareil.

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.

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

REQUIREMENTS FOR THE

COMMONWEALTH OF

MASSACHUSETTS

These ﬁreplaces are approved for

installation in the U.S. 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 ﬂexible gas line connector used

shall not exceed 36 in. (92 cm)

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 identiﬁcation 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.

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 conduction

of cold transferring to the ﬁreplace and

into the room. It also helps to sheetrock

inside surfaces and tape for maximum air

tightness and caulk ﬁrestops.

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).

Oriﬁce Sizes—Sea Level to

High Altitude

These appliances are tested and approved

for installation at elevations of 0–4500 ft

(0–1372 m) above sea level using the

standard burner oriﬁce sizes (marked with

an “*” in Table 4).

For elevations above 4500 ft, contact your

gas supplier or qualiﬁed service technician.

Deration

At higher elevations, the amount of BTU fuel

value delivered must be reduced by either:

• Using gas that has been derated by the

gas company.

• Changing the burner oriﬁce 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.

NOTE: Flame breadth, height and width will

diminish 4% for every 1,000 feet of altitude.

Table 4: Burner Oriﬁce Sizes,

Elevation 0–4500 ft ( 0–1372 m)

Model Natural Gas

drill size

(inches)

Propane

drill size

(inches)

MLDVT-30 #50 (0.070 in.)*

H4873•

#59 (0.041 in.)*

H7838•

MLDVT-35 (0.0748 in.)*

H1355•

(0.045 in.)*

75L10•

MLDVT-40 #44 (0.086 in.)*

60J80•

#55 (0.052 in.)*

19L52•

MLDVT-45 (0.090 in.)*

37L70•

#54 (0.055 in.)*

99K79•

* Standard size installed at factory

• Catalog number

In Canada—CAN/CGA-2.17-M91

(high altitude):

THE CONVERSION SHALL BE CARRIED

OUT BY A MANUFACTURER’S

AUTHORIZED REPRESENTATIVE, IN

ACCORDANCE WITH THE REQUIREMENTS

OF THE MANUFACTURER, PROVINCIAL

OR TERRITORIAL AUTHORITIES HAVING

JURISDICTION AND IN ACCORDANCE

WITH THE REQUIREMENTS OF THE

CAN/CGA-B149.1 OR CAN/CGA-B149.2

INSTALLATION CODES.

Gas Pressure

Table 2 and Table 3 show the appliance

inlet and manifold gas pressure

requirements.

Table 2: Inlet Gas Supply Pressure

Fuel Minimum Maximum

Natural Gas 4.5 in. WC

(1.12 kPa) 10.5 in. WC

(2.61 kPa)

Propane 11.0 in. WC

(2.74 kPa) 13.0 in. WC

(3.23 kPa)

Table 3: Manifold Gas Supply Pressure

Fuel Low High

Natural Gas 2.2 in. WC

(0.55 kPa) 3.5 in. WC

(0.87 kPa)

Propane 6.3 in. WC

(1.57 kPa) 10.0 in. WC

(2.49 kPa)

Test gauge connections are provided on

the front of the electronic gas control valve

(identiﬁed IN for the inlet and OUT for the

manifold side). The control valves have a

3/8 in. (10 mm) NPT thread inlet and outlet

side of the valve (Figure 1 and Figure 2 ).

Figure 1: SIT Millivolt Gas Valve

HTPTHTPT

IN OUT

HI/LO Variable

Flame Height

Adjustment

Manifold Pressure Tap

Inlet Pressure Tap

Pilot Adjustment

Screw

Main Gas Control Knob

OFF/PILOT/ON

Figure 2: SIT Electronic Gas Valve

Orange Wire

(from DFC

Wire

Harness)

Main

Gas Inlet

3/8 in. NPT

Green Wire

(from DFC Wire

Harness)

Inlet (IN) Test Port

Manifold (OUT)

Test Port

Hi/Lo

Flame

Control

Knob

Yellow Ground Wire

(from DFC

Wire Harness)

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.

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

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 Table 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.

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 3).

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 3).

Figure 3: Typical Locations

NOITACILPPA

TNEVPOT

APPLICATION

TOP VENT

TNEVPOT

NOITACILPPA

RECESSED

INSTALLATION

TOP VENT

APPLICATION

NOITACILPPA

TNEVPOT

NOITACILPPA

TNEVPOT

HORIZONTAL VENT

(Top Vent Application)

VERTICAL VENT

(Top Vent Application)

NOTE: 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.

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.

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 (Table 8).

MANUFACTURED HOME

REQUIREMENTS

This appliance may be installed in

an aftermarket permanently located,

manufactured home and must be installed

in accordance with the manufacturer’s

instructions.

Cet appareil peut être installé cómme

du matéri-el d’origine dans une maison

préfabriquée (É.U. seulement) ou

mobile et doit être installé selon les

instructions du fabricant.

This appliance is only for use with the type

of gas indicated on the rating plate. This

appliance is not convertible for use with

other gases, 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.

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

Horizontal Vent

Termination Clearances

The horizontal vent termination must have

a minimum of 6 in. (152 mm) clearance

to any overhead combustible projection of

2 1/2 in. (64 mm) or less. For projections

exceeding 2 1/2 in. (64 mm), see Figure 7.

For additional vent location restrictions,

refer to Table 6.

Figure 6: Horizontal Vent Termination

Clearances, Side Elevation

(152 mm)

12"

(305 mm)

Combustible Projection greater

Combustible Projection

2-1/2 inches or less in length

18"

(457 mm)

Ventilated

Soffit Unventilated

Soffit

than 2-1/2 inches in length

Termination Kit

Figure 7: Horizontal Vent Termination

Clearances

Termination Kit

All horizontal terminations

may be located as close as

6” (152mm) to any

(non-combustible and

combustible) exterior

sidewall. This distance

may be decreased to 2”

(51mm) for non--

combustible exterior

sidewalls only, if the

SV4.5HT-2 termination

is used.

Figure 5: Vertical Vent Termination

Clearances

Roof Pitch is X/12

2 FT

MIN.

2 FT MIN.

Lowest

Discharge

Opening

*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

Table 5: Termination Heights for Vents

above Flat or Sloped Roofs

Roof Pitch Feet * Meters *

Flat to 6 1/2 10.3

6 1/2 to 7 1/2 1 1/4 0.38

7 1/2 to 8 1/2 1 1/2 0.46

8 1/2 to 9 1/2 20.61

9 1/2 to 10 1/2 2 1/2 0.76

10 1/2 to 11 1/2 3 1/4 0.99

11 1/2 to 12 1/2 41.22

12 1/2 to 14 1/2 51.52

14 1/2 to 16 1/2 61.83

16 1/2 to 18 1/2 72.13

18 1/2 to 201/2 7 1/2 2.29

20 1/2 to 21 1/2 82.44

VENT TERMINATION CLEARANCES

These instructions should be used

as a guideline and do not supersede

local codes in any way. Install venting

according to local codes, these

instructions, 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, Figure 4, Figure 5, and Table 5.

Figure 4: Multiple Terminations

12 in.

(305 mm)

Minimum

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

Table 6: Exterior Horizontal Vent Termination Clearances

Fixed

Closed

Window

Operable

Window

= Area where Termination is not Permitted

= Air Supply Inlet

X= Vent Termination

3 ft

= 9 in. in U.S.

= 12 in. in Canada

Inside

Corner Detail

*18 in.

Ventilated Soffit

Horizontal

Termination

Detail D

Exterior Wall

6 in.

Inside Corner

* See Item D in the Text Below.

NOTE: Local Codes Or Regulations

May Require Different Clearances.

NOTE: Location Of The Vent Termination

Must Not Interfere With Access To The

Electrical Service.

U.S. Installation ** Canadian Installation *

AClearance above grade, veranda, porch, desk, or balcony 12 in. (300 mm) ** 12 in. (300 mm) *

BClearance to window or door that may be opened 6 in. (150 mm)

for appliances < 10,000 Btuh (3 kW),

9 in. (230 mm)

for appliances > 10,000 Btuh (3 kW), and < 50,000 Btuh (15 kW),

12 in. (300 mm)

for appliances > 50,000 Btuh (15 kW) **

6 in. (150 mm)

for appliances < 10,000 Btuh (3 kW),

12 in. (300 mm)

for appliances > 10,000 Btuh (3 kW)

CClearance to permanently closed window 9 in. (229 mm)

recommended to prevent window condensation 12 in. (305 mm)

recommended to prevent

window condensation

DVertical clearance to ventilated sofﬁt located above the

termination within a horizontal distance of 18 in. (458 mm) 18 in. (458 mm) 18 in. (458 mm)

EClearance to unventilated sofﬁt 12 in. (305 mm) 12 in. (305 mm)

FClearance to outside corner 5 in. (127 mm)

minimum 5 in. (127 mm)

minimum

GClearance to inside corner 2 in. (50.8 mm)

minimum—SV4.5HT-2 •

6 in. (152 mm)

minimum—SV4.5HTSS

2 in. (50.8 mm)

minimum—SV4.5HT-2 •

6 in. (152 mm)

minimum—SV4.5HTSS

HClearance to each inside of center line extended above

meter / regulator assembly 36 in. (910 mm)

within a height of 15 ft above the meter / regulator assembly ** 36 in. (910 mm)

within a height of 15 ft above the meter /

regulator assembly *

IClearance to service regulator vent outlet 36 in. (910 mm)** 36 in. (910 mm)*

JClearance to nonmechanical air supply inlet to building or

the combustion air inlet to any other appliance 6 in. (150 mm)

for appliances < 10,000 Btuh (3 kW),

9 in. (230 mm)

for appliances > 10,000 Btuh (3 kW) and < 50,000 Btuh (15 kW),

12 in. (300 mm)

for appliances > 50,000 Btuh (15 kW)**

6 in. (150 mm)

for appliances < 10,000 Btuh (3 kW),

12 in. (300 mm)

for appliances > 10,000 Btuh (3 kW)

KClearance to a mechanical air supply inlet 36 in. (910 mm) above if within 10 ft (3 m) horizontally ** 72 in. (1830 mm) *

LClearance above paved sidewalk or paved diveway located

on public property 84 in. (2130 mm) ‡ 84 in. (2130 mm) ‡

MClearance under veranda, porch, deck or balcony 12 in. (300 mm) *‡ 12 in. (300 mm) *‡

NDepth of alcove (maximum) 72 in. (1830 mm) ** 72 in. (1830 mm) *

OClearance to termination (alcove) 6 in. (15.2 mm) ** 6 in. (15.2 mm)*

PWidth of alcove (minimum) 36 in. (910 mm) ** 36 in. (910 mm) *

QClearance to combustible above (alcove) 18 in. (457 mm) ** 18 in. (457 mm) *

‡

*‡

•

In accordance with the current CSA-B149.1 National Gas And Propane Installation Code

In accordance with the curent ANSI SZ223.1/NFPA 54 National Fuel Gas Codes

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 two sides beneath the ﬂoor

2 in. clearance to non-combustibles for SV4.5HT-2 only

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

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Figure 8: Minimum Mantel Clearances

8 (203)

(51)

(102)

(152)

(203)

(254)

(305)

10 (254)

14 (356)

18 (457)

16 (406)

12 (305) Top of

Appliance

inches (millimeters)

Mantel

Depth

Hood

Header

Figure 9: Minimum Distance to

Side Wall

3 1/2 in.

(89 mm)

6 in.

(152 mm)

Top View of

Fireplace

45o

Combustible

mantel legs may

project beyond either side

of the fireplace opening

as long as they are kept

within the shaded area

illustrated here.

Combustible Materials

Allowed In Shaded Area

“Safe Zone”

Combustible Walls

shown in dark gray

At 6 in. minimum

side wall clearance,

a combustible wall

can project to any

length.

Table 8: Shelf Height Minimum Clearances

Shelf Height

(see table)

Do not insulate the

space between the

appliance and the

area above it.

Models Top Vent—with One 90° Elbow

Secure Vent Secure Flex

MLDVT-30/35 46 1/2 in. (1181 mm) 48 1/4 in. (1226 mm)

MLDVT-40/45 51 1/2 in. (1308 mm) 53 1/4 in. (1349 mm)

Wall Finishes, Surrounds,

and 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 (Figure 39 on Page 31).

Non-combustible materials, such as

surrounds and other appliance trim,

may be installed on the appliance face,

but they must not cover any portion of

the removable glass panel or control

compartment.

Vertical installation clearances to

combustible mantels vary according to the

depth of the mantel (Figure 8). Mantels

constructed of non-combustible materials

may be installed at any height above the

appliance opening. However, do not allow

anything to hang below the ﬁreplace hood.

Minimum clearance requirements include

any projections such as shelves, window

sills, mantels, etc. above the appliance.

NOTE: We recommend the use of high

temperature paint (rated 175 °F, or higher)

on the underside of the mantel.

MINIMUM CLEARANCE TO

COMBUSTIBLES

The appliance is approved with zero

clearance to combustible materials on

all sides (Table 7), 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 (Figure 3).

Hearth Extension—A hearth extension is

not required with this appliance. If a hearth

extension is used, do not block the lower

control compartment door. Any hearth

extension used is for appearance only

and does not have to conform to standard

hearth extension installation requirements.

Shelf Height—To provide for the lowest

possible shelf surface, use the alternate

rear vent outlet, 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 (Table 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

Table 8.

The appliance should 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, etc., a metal or wood

barrier covering the entire bottom surface

must be used.

Table 7: Minimum Clearances *

Back 1/2 in. (13 mm)

0 in. (0 mm) from Spacers or Dimples

Sides 1/2 in. (13 mm)

0 in. (0 mm) from Spacers or Dimples **

Top of

Fireplace

3 in. (76 mm)

0 in. (0 mm) with standoff(s) in vertical

position (Figure 10)

Floor 0 in. (0 mm)

From

Bottom

of Unit To

Ceiling

minimum of 64 in. (1626 mm)

Vent 3 in. (76 mm)—Top * ***

1 in. (25.4 mm)—Sides and Bottom

Front

Service 36 in. (914 mm)

* Note: 3 in. (75 mm) above any horizontal/

inclined vent component.

** Note: See Frame the Fireplace on Page 9

for clearance requirements to the nailing ﬂange

located at each side of the unit and any screw heads

adjacent to it.

*** Note: Top vent clearance can be reduced to 2 in.

on horizontal runs when ﬁrst elbow is located at

least 6 ft above the ﬁreplace.

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

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DETAILED INSTALLATION STEPS

Follow these steps to complete ﬁreplace

installation:

Wire the [Optional] Blower Kit Before

Installation in the Framing

Remove the left side blower cover panel

screw, and blower cover panel (Table 11).

Retain the panel and screw for later

reinstallation.

Slide the blower through the opening

and position it with the bracket oriented

to the front of the ﬁrebox and the blower

discharge to the rear of the ﬁrebox. Bend

the two tabs in the ﬁrebox ﬂoor to secure

the blower to the ﬂoor.

Reinstall the blower cover panel and secure

with the removed screw.

Access the blower supply wiring through

the front of the ﬁrebox and plug it into the

junction box in the right, rear of the ﬁrebox

(Figure 28).

Install the blower control switch according

to its included instructions.

Frame the Fireplace

Frame the appliance as illustrated in

Table 9 on Page 10. For corner

framing installations, use Table 10 on

Page 10. All framing details must allow

for a minimum clearance to combustible

framing members as shown in Table 7 on

Page 8.

If the appliance is to be elevated above ﬂoor

level, a solid continuous platform must be

constructed below the appliance.

Bend up the outer pair for 1/2 in. materials

and the inner pair for 5/8 in. materials.

Headers may be in direct contact with the

appliance top standoff spacers when they

are bent up vertically, maintaining the 3 in.

clearance to the ﬁreplace top, 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.

Bend out the appropriate nailing ﬂanges

for the drywall/ﬁnish material to be

used (Figure 10). Nailing ﬂanges are

provided for:

• ﬂush framing,

• 1/2 in., and

• 5/8 in. framing depths.

Secure the ﬁreplace to the side framing

members using the unit’s nailing ﬂanges—

one top and bottom on each side of the

ﬁreplace front (Figure 10). Use 8d nails or

their equivalent.

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.

1. Wire the [Optional] Blower Kit Before

Installation in the Framing

2. Frame the Fireplace

3. Route the Gas Line

4. Install the Vent System

5. Field Wiring

6. Wire the [Optional] Blower Kit After

Installation in the Framing

7. Connect the Gas Line

8. Verify Proper Appliance Operation

9. Install the Logs, Volcanic Stone, and

Embers

10. Install the Glass Door

11. Adjust the Burner

12. Install the Hood

13. Attach the Safety-in-

Operation Warnings

PRE-INSTALLATION STEPS

The appliance is shipped with all gas

controls and components installed and pre-

wired. Before installing the appliance, follow

these steps:

1. Remove the shipping carton.

2. Remove the shipping pad, exposing the

front glass door.

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

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Table 9: Fireplace Framing Speciﬁcations

Model A B C D

(178)

5-1/8

12-1/8

(308)

10-1/2

(267)

(130)

1/2

Vent Framing—Top Vent

with One 90° Elbow

Dimension “D” is the required framing depth when the

ﬁnish material (drywall) thickness is 1/2 in. (13mm).

Inches (millimeters)

Framing should be

constructed of 2 x 4

or larger lumber

MLDVT-30 in. 30 1/4 35 1/4 38 3/4 16

mm 768 895 984 406

MLDVT-35 in. 35 1/4 35 1/4 38 3/4 16

mm 895 895 984 406

MLDVT-40 in. 40 1/4 40 1/4 43 3/4 16

mm 1022 1022 1111 406

MLDVT-45 in. 45 1/4 40 1/4 43 3/4 16

mm 1149 1022 1111 406

Based on CSA P. 4.1-09

Note:

Diagrams, illustrations and photographs are not to scale. Consult installation

instructions. Product designs, materials, dimensions, speciﬁcations, colors, and

prices are subject to change or discontinuation without notice.

Table 10: Fireplace Framing Speciﬁcations—Corner Installation with Horizontal Termination

Model A B C D E

Inches

(millimeters)

Back wall of chase/enclosure

(including any finishing materials)

7 (178)

MLDVT-30 in. 30 1/4 53 3/16 37 29/32 26 13/16 12 1/4

mm 768 1350 963 681 311

MLDVT-35 in. 35 1/4 57 1/2 40 5/8 28 3/4 13 3/4

mm 895 1461 1032 730 349

MLDVT-40 in. 40 1/4 61 13/16 43 11/32 30 11/16 15 1/8

mm 1022 1554 1101 779 384

MLDVT-45 in. 45 1/4 66 1/8 46 1/16 32 5/8 16 1/2

mm 1149 1680 1170 829 419

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

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Figure 11: Route the Gas Line

(76 mm)

Left Side Front

Corner of Fireplace

Framing

6-1/2"

(152 mm)

Pipe Coupling

(Recommended)

Also see Table 11.

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).

Never use galvanized or plastic pipe.

Refer to Table 13 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

qualiﬁed 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 unqualiﬁed should attempt

sizing or installing gas piping.

NOTE: The nailing ﬂanges, combustible

members, and screw heads in areas directly

adjacent to the nailing ﬂanges are EXEMPT

from the 1/2 in. (13 mm) clearance to

combustible requirements for the ﬁrebox

outer wrapper.

Combustible framing may be in direct

contact with the nailing ﬂanges and may be

located closer than 1/2 in. (13 mm) 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 in

this manual.

Vertical Venting through the Ceiling

Use a plumb line from the ceiling above

the appliance to locate center of the

vertical run. Cut and/or frame an opening,

10 1/2 x 10 1/2 in. (267 x 267 mm) inside

dimensions, about this center mark

(Figure 14).

Route the Gas Line

Route a 1/2 in. (13 mm) gas line to the

left side of the appliance as shown in

Figure 11. 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 in. shutoff valve. (see Connect the

Gas Line on Page 24).

Table 11: Fireplace Speciﬁcations

Front View

Top View

*CONCENTRIC FLUE

FLUE: 4 1/2 (114)

COMBUSTION AIR:

7 1/2 (190)

9 1/4 (235)

1/2

(13)

16 (406)

1 5/8 (42)

EYEBROW

HOOD

GAS INLET

KNOCKOUT

(Either Side)

Right Side View

5 7/8

(149)

NOTE: It is recommended that the gas be stubbed in from the left

side only.

3 (76)

9 1/2

(241)

ELECTRICAL INLET

KNOCKOUT - 2-3/4 X 2

(70 X 51) COVER PLATE

(With KNOCKOUT -

Right Side Only)

OPTIONAL

ELECTRICAL

INLET KNOCKOUT,

REQUIRING A FIELD

PROVIDED

JUNCTION BOX

(Either Side)

5.125

(130.2)

0.5 (12.7) 0.525 (13.3)

Left Side View

BLOWER

ACCESS PANEL

Model E F G H J K L M

MLDVT-30 in. 32 1/4 28 1/8 23 1/4 27 30 1/4 20 10 28

mm 819 714 590 686 768 508 254 711

MLDVT-35 in. 32 1/4 28 1/8 23 1/4 32 35 1/4 25 12 1/2 33

mm 819 714 590 813 895 635 317 838

MLDVT-40 in. 37 1/4 33 1/8 28 1/4 37 40 1/4 30 15 38

mm 946 841 718 940 1022 762 381 965

MLDVT-45 in. 37 1/4 33 1/8 28 1/4 42 45 1/4 35 17 1/2 43

mm 946 841 718 1067 1149 889 445 1092

Table 12: Thermal Efﬁciency (%)

Model Natural Gas Propane

AFUE P4 AFUE P4

MLDVT-30 62 51 62.8 54

MLDVT-35 63 59 63.2 61

MLDVT-40 65.8 61 66.6 61

MLDVT-45 68.1 59 68.9 61

Figure 10: Unit Secured to Framing by

Nailing Flange

NOTE: Bend up the appropriate

header spacing top standoffs

before installing the ﬁreplace.

Side

Framing

Unit Nailing

Flange

(No clearance to

combustible framing

is required)

Header Spacing Top Standoffs

(two pairs on front edge of firebox top)

Lift up outer pair for

1/2 in. finish materials Lift up inner pair for

5/8 in. finish materials

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

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 are shown on Page 33.

A vent restrictor may be needed when

vertically terminating the vent system above

the roof (when using the appliance top

vent), install vent restrictor in the top vent

of the ﬁreplace outlet (top vent units). If

needed, install the restrictor orientated as

shown, either from inside or outside the

unit, in the inner ﬁreplace collar.

Figure 12: Vent restrictor installation—

Top vent

A vent restrictor may be needed when

vertically terminating the vent system above

the roof (when using the appliance top vent),

install vent restrictor in the top vent of the

fireplace outlet on MPD35/40/45

and MPDT33 series models.

U-SHAPED VENT

RESTRICTOR

APPLIANCE TOP

VENT OUTLET

If needed, install the restrictor orientated as

shown, either from inside or outside the unit,

in the inner fireplace collar.

INNER

FIREPLACE

COLLAR

Vertical Termination Systems

See Figure 13, Figure 20, Table 17, and

Table 18 on Page 16 that illustrate the

various vertical venting conﬁgurations that

are possible for use with these appliances.

Secure Vent® pipe applications are shown in

these Figures; Secure Flex® pipe may also

be used. A vertical 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.

Both these vertical vent systems terminate

through the roof. The minimum vent height

above the roof and/or adjacent walls is

speciﬁed in ANSI Z223.1 (In Canada, the

current CAN/CSA-B149.1 installation code)

by major building codes. Always consult

your local codes for speciﬁc requirements.

A general guide to follow is the Gas Vent

Rule (Figure 6 on Page 6).

Install the Vent System

These instructions should be used

as a guideline and do not supersede

local codes in any way. Install venting

according to local codes, these

instructions, the current National Fuel

Gas Code (ANSI-Z223.1) in the USA or

the current standards of CAN/CSA-B149.1

in Canada.

Ensure clearances are in accordance

with local installation codes and the

requirements of the gas supplier.

Dégagement conforme aux codes

d’installa tion locaux et aux exigences

du foumisseunde gaz.

Use only approved vent components

(Page 2).

NOTE: 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 enclosed wall (such as a chase).

There is no requirement for inspection

openings in the enclosing wall at any of the

joints in the vent pipe.

Installation of Vent Restrictor

A vent restrictor may be needed with

this appliance, install vent restrictor

(provided) in the appliance top ﬂue outlet

as shown in Figure 12. It is held in place by

friction, only.

NOTE: The vent restrictor is included in

the ﬁrebox.

Table 13: Schedule 40 Black Iron Pipe—

Inside Diameter

Schedule 40

Pipe Length

(feet)

Natural

Gas Propane

Gas

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.

NOTE:

• All appliances are factory-equipped with

a ﬂexible gas line connector and 1/2 in.

shutoff valve (Figure 29).

• See Massachusetts Horizontal Vent

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

Connect the Gas Line on Page 24.

• 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.

• Check with local building ofﬁcial for

local code requirements.

NOTE: 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.

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

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Table 14: Vent Section Length

Nominal

Section Length

(in.) 6 12 24 36 48

Total Qty

Net Section

Length (in.) 4.5 10.5 22.5 34.5 46.5

Height of Vent Number of Vent Sections

in. ft

465 38.75 000010 10

475.5 39.625 010010 11

480 40 110010 11

492 41 101010 12

499.5 41.625 000110 11

504 42 100110 12

511.5 42.625 000011 11

520.5 43.375 020111 14

531 44.25 022011 15

538.5 44.875 100211 14

549 45.75 102111 15

558 46.5 000012 12

562.5 46.875 100012 13

568.5 47.375 010012 13

573 47.75 110012 14

580.5 48.375 001012 13

589.5 49.125 012210 15

595.5 49.625 111012 15

604.5 50.375 000013 13

615 51.25 010013 14

625.5 52.125 020013 15

631.5 52.625 101013 15

637.5 53.125 011013 15

651 54.25 000014 14

655.5 54.625 100014 15

672 56 020014 16

678 56.5 101014 16

688.5 57.375 111014 17

697.5 58.125 000015 15

702 58.5 100015 16

712.5 59.375 110015 17

720 60 001015 16

Table 15: Effective Vent Length

Model Effective Length

SV4.5L6 4 1/2 in.

SV4.5L12 10 1/2 in.

SV4.5L24 22 1/2 in.

SV4.5L36 34 1/2 in.

SV4.5L48 46 1/2 in.

Table 14: Vent Section Length

Nominal

Section Length

(in.) 6 12 24 36 48

Total Qty

Net Section

Length (in.) 4.5 10.5 22.5 34.5 46.5

Height of Vent Number of Vent Sections

in. ft

45 3.75 002002

46.5 3.875 000011

51 4.25 1 0 0 0 1 2

55.5 4.625 012003

57 4.75 001102

67.5 5.625 003003

69 5.75 000202

73.5 6.125 1 0 0 2 0 3

79.5 6.625 010203

81 6.75 000112

91.5 7.625 0 0 2 0 1 3

93 7.75 000022

97.5 8.125 1 0 0 0 2 3

103.5 8.625 000303

108 9 100304

117 9.75 1 0 5 0 0 6

118.5 9.875 110305

126 10.5 001304

130.5 10.875 101305

135 11.25 006006

139.5 11.625 0 0 0 0 3 3

142.5 11.875 100405

144 12 100034

154.5 12.875 110035

160.5 13.375 020035

172.5 14.375 0 0 0 5 0 5

177 14.75 100506

186 15.5 000044

196.5 16.375 0 1 0 0 4 5

207 17.25 000606

211.5 17.625 1 0 0 6 0 7

217.5 18.125 010607

229.5 19.125 001607

232.5 19.375 0 0 0 0 5 5

241.5 20.125 000707

246 20.5 1 0 0 7 0 8

252 21 010708

276 23 000808

279 23.25 0 0 0 0 6 6

280.5 23.375 100809

289.5 24.125 010067

301.5 25.125 001067

310.5 25.875 000909

325.5 27.125 0 0 0 0 7 7

330 27.5 100078

345 28.75 00010 010

349.5 29.125 10010 011

372 31 000088

379.5 31.625 0 0 0 11 011

Vertical (Straight) Installation

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 (Table 14

and Installation Accessories on

Page 33). Plan the vent lengths so that

a joint does not occur at the intersection of

ceiling or roof joists (Table 14).

Figure 13: Vertical (Straight) Installation

SV4.5FA or

SV4.5FB Flashing

AND SV4.5SC

Storm Collar

SV4.5VF

Firestop/Spacer*

1 in (25.4 mm)

Minimum

Clearance to

Combustibles

SV4.5CGV-1

Termination

SV4.5L6/12/24/36/48

Vent Sections

*When using Secure Flex,

use Firestop/Spacer

SF4.5VF.

Max. 60 ft

(18.3 m)

Table 14: Vent Section Length

Nominal

Section Length

(in.) 6 12 24 36 48

Total Qty

Net Section

Length (in.) 4.5 10.5 22.5 34.5 46.5

Height of Vent Number of Vent Sections

in. ft

4.5 0.375 100001

90.75 200002

10.5 0.875 010001

15 1.25 110002

22.5 1.875 001001

31.5 2.625 030003

34.5 2.875 000101

37.5 3.125 111003

43.5 3.625 021003

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Attic insulation shield (H3907) may be

used to obtain the required clearances

indicated here (Installation Accessories

on Page 33). The gap between the

vent pipe and a vertical ﬁrestop can be

sealed with non-combustible caulking.

5. Support the vertical vent run

sections—Support the vertical portion of

the venting system every 8 ft (2.4 m) above

the ﬁreplace vent outlet. 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. Loop 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(Figure 16).

NOTE: Proper venting support is

very important. The weight of the vent

must not be supported by the ﬁreplace.

Figure 15: Twist Lock Vent Pipes

Align the dimple (four places)

of the upper vent section with

the opening of the locking

incline channel on the lower vent

section or appliance collar. Twist

vent component clockwise to

engage and seal until arrow and

dimple align.

Dimple

Locking

Incline

Channel

Connected Vent

Sections Arrow

Arrow

Appliance Collar or

Vent Section

Figure 16: Supporting the Vertical

Vent Run

Blocking

Support Straps

(Plumber's tape)

8 feet (2.4 m)

Maximum

1/2 inch (12.7

mm) minimum

clearance to

combustibles

connections (Figure 15).

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.

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

(Figure 15).

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.

NOTE: An elbow may also be attached

to the appliance collar. Attach in the

same manner as a vent section.

3. 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 (Figure 15).

4. Install ﬁrestop/spacer at ceiling—

When using Secure Vent, use SV4.5VF

ﬁrestop/spacer at ceiling joists; when

using Secure Flex®, use SF4.5VF

ﬁrestop/spacer. 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.

Maintain 1 in. (25 mm) clearance to

combustibles, framing members,

and attic or ceiling insulation when

running vertical chimney sections.

Vertical (Offset) Installation

Analyze the vent routing and determine the

quantities of vent sections and number of

elbows required. Refer to Table 14 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 Table 14 for an aid in selecting

length combinations. Elbows are available

in 90° and 45° conﬁgurations. Refer to

Figure 17 for the SV4.5E45 and SV4.5E90

elbow dimensional speciﬁcations.

Where required, a telescopic vent section

(SV4.5LA) may be used to provide the

installer with an option of 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 SV4.5LA telescopic vent section

has an effective length of from 1 1/2 in.

(38 mm) to 7 1/2 in. (191 mm). The

SV4.5LA is ﬁtted with a locking inclined

channel end (identical to a normal vent

section component) and a plain end with

3 pilot holes. Slip the plain end over the

locking channel end of a standard SV4.5

vent component the required distance and

secure with three (3) 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.

1. Frame ceiling opening—Use a

plumb line from the ceiling above the

appliance to locate center of the vertical

run. Cut and/or frame an opening,

10 1/2 x 10 1/2 in. (267 x 267 mm)

inside dimensions, about this center

mark (Figure 14).

Figure 14: Framing Ceiling Opening

Min. 10 1/2 in.

(267 mm)

Min. 10 1/2 in.

(267 mm)

2. Attach vent components to

appliance—Secure Vent® SV4.5

direct vent system components are

unitized concentric pipe components

featuring positive twist lock

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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

are seated at the end of the channels.

Figure 19: SV4.5CGV-1 Vertical

Termination

NOTE: If the vent system extends

more than 5 ft (1.5 m) above the roof

ﬂashing, 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.

Table 16: Framing Dimensions for Roof

Pitch C D

0/12 10 1/2 in.

(267 mm) 10 1/2 in.

(267 mm)

6/12 10 1/2 in.

(267 mm) 12 in.

(305 mm)

12/12 10 1/2 in.

(267 mm) 17 3/4 in.

(451 mm)

9. 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 18 ). 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.

Figure 18: Installing the Roof Flashing

and Storm Collar

Storm

Collar

10. Install the storm collar—Install the

storm collar, supplied with the ﬂashing,

over the vent/ﬂashing joint (Figure 18).

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.

11. Install the vertical termination—The

ﬁnal step involves installation of the

SV4.5CGV-1 vertical termination.

Extend the vent sections to the height

as shown in Vertical Vent Termination

Clearances on Page 6. The

SV4.5CGV-1 vertical termination

(Figure 19) installs 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

6. Change vent direction to horizontal/

inclined run—At transition from or

to a horizontal/inclined run, install

the SV4.5E45 and SV4.5E90 elbows

in the same manner as the straight

vent sections. The elbows feature

a twist section to allow them to be

routed about the center axis of their

initial collar section to align with the

required direction of the next vent run

element. Twist elbow sections in a

clockwise direction only so as to avoid

the possiblity of unlocking any of the

previously connected vent sections

(Figure 15).

Figure 17: Vent Elbows

SV4.5E90

(90

Elbow)

8 1/8 in.

(206 mm)

Swivel Joint

(360

swivel)

4 13/16 in.

(122 mm)

SV4.5E45

(45

Elbow)

Swivel Joint

(360

swivel)

7. Continue installation of horizontal/

inclined sections—Continue with the

installation of the straight vent sections

in horizontal/inclined run as described

on Page 14. Install support straps

every 5 ft (1.52 m) along horizontal/

inclined vent runs using conventional

plumber’s tape.

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. 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.

8. Frame roof opening—Identify location

for vent at the roof. Cut and/or frame

opening (Table 16).

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Table 17: Top Vent—Two 90° Elbows

Ceiling

Firestop/Spacer

SV4.5VF*

Wall

Firestop/Spacer

SV4.5HF**

*When using Secure Flex, use

Ceiling Firestop/Spacer SF4.5VF.

**When using Secure Flex, use

Wall Firestop/Spacer SF4.5HF.

H Maximum V Maximum

feet meters feet meters

51.524 elbow only

51.524 10.305

10 3.048 20.610

15 4.572 30.914

20 6.096 41.219

V + V1 + H = 60 ft (18.3 m) maximum

H = 20 ft (6.096 m) maximum

Install the U-shaped vent restrictor in any vent run

with more than 8 ft of vertical rise (Figure 12).

If 20 ft of (H) horizontal vent run is needed,

then 4 ft minimum of (V) vertical vent will

be required.

This table shows a 1 (V) to 5 (H) ratio. For

every 1 ft of (V) vertical, you are allowed

5 ft of (H) horizontal run, up to a maximum

horizontal run of 20 ft.

An elbow is acceptable as 1 ft of vertical rise

except where an elbow is the only vertical

component in the system (Table 20).

WARNING

Under no circumstances, may

separate sections of concentric

ﬂexible vent pipe be joined

together.

Vertical Vent Tables and Figures

NOTE: Secure Vent® rigid vent pipe

is shown in the ﬁgures. Secure Flex®

ﬂexible vent pipe may also be used.

NOTE: 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.

NOTE: SV4.5VF (Secure Vent), SF4.5VF

(Secure Flex) ﬁrestop/spacer must be

used anytime vent pipe passes through

a combustible ﬂoor or ceiling. SV4.5HF

(Secure Vent), SF4.5HF (Secure Flex)

ﬁrestop/spacer must be used anytime

vent pipe passes through a combustible

wall.

NOTE: Two 45° elbows may be used in

place of one 90° elbow. The same rise

to run ratios, as shown in the venting

ﬁgures for 90°, must be followed if 45°

elbows are used.

NOTE: An elbow is acceptable as 1 foot

of vertical rise, except where an elbow

is the only vertical component in the

system (Table 20).

Figure 20: Top Vent—Straight

u Ceiling Firestop /

Spacer (SV4.5VF)

u When using

Secure Flex, use

Firestop / Spacer

SF4.5VF

A Vent Restrictor

(Figure 12) must

be used in this

application

60 ft (18.3 m)

Maximum

A Vent Restrictor (Figure 12) must be used in

this application.

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Table 18: Top Vent—Three Elbows

H + H1 Maximum V Minimum

Ceiling

Firestop/Spacer

SV4.5VF* Wall

Firestop/Spacer

SV4.5HF**

*When using Secure Flex, use

Ceiling Firestop/Spacer SF4.5VF.

**When using Secure Flex, use

Wall Firestop/Spacer SF4.5HF.

feet meters feet meters

51.524 Elbow Only

51.524 10.305

10 3.048 20.610

15 4.572 30.914

20 6.096 41.219

H + H1 = 20 ft (6.1 m) maximum

V + V1 + H + H1 = 60 ft (18.3 m) maximum

Install the U-shaped vent restrictor in any vent run with more than 8 ft of

vertical rise (Figure 12).

If 20 ft of (H) horizontal vent run is needed, then 4 ft minimum

of (V) vertical vent will be required.

This table shows a 1 (V) to 5 (H) ratio. For every 1 ft of (V)

vertical, you are allowed 5 ft of (H) horizontal run, up to a

maximum horizontal run of 20 ft.

An elbow is acceptable as 1 ft of vertical rise except where an

elbow is the only vertical component in the system (Table 20).

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8. Change vent direction—At transition

from or to a horizontal/inclined run,

install the SV4.5E45 and SV4.5E90

elbows in the same manner as the

straight vent sections. The elbows

feature a twist section to allow them

to be routed about the center axis of

their initial collar section to align with

the required direction of the next vent

run element. Twist elbow sections in a

clockwise direction only so as to avoid

the possiblity of unlocking any of the

previously connected vent sections

(Figure 17).

9. Continue installation of horizontal/

inclined sections—Continue with the

installation of the straight vent sections

in horizontal/inclined run as described

in Step 5. Install support straps

every 5 ft. (1.52 m) along horizontal/

inclined vent runs using conventional

plumber’s tape (Figure 21). 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. Rise per foot run ratios

are acceptable 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) on all sides for all

vertical runs; and

• 3 in. (76 mm) at the top,

• 1 in. (25 mm) on sides, and

• 1 in. (25 mm) at the bottom for all

horizontal/inclined runs.

NOTE: Top vent clearance can be

reduced to 2 in. on horizontal runs

when ﬁrst elbow is located at least 6 ft

above the ﬁreplace.

10. 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 2. Assemble the vent system

to point where the terminus of the

last section is within 7 in. (178 mm)

to 11 1/4 in. (286 mm) inboard of

the exterior surface to which the

SV4.5HT termination is to be attached

(Figure 23). If the terminus of the last

section is not within this distance,

use the telescopic vent section

SV4.5LA, as the last vent section.

For wall thicknesses greater than that

shown in Figure 23, refer to Table 19

on Page 20. This table lists the

additional venting components needed

(in addition to the termination and

adaptor) for a particular range of wall

thicknesses.

4. 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 (Figure 15). 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

are seated 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.

NOTE: An elbow may also be attached

to the appliance collar. Attach in

the same manner as you would a

vent section.

5. 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 15).

6. Install ﬁrestop/spacer at ceiling—

When using Secure Vent, use SV4.5VF

ﬁrestop/spacer at ceiling joists; when

using Secure Flex, use SF4.5VF

ﬁrestop/spacer. 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.

NOTE: Maintain 1 in. (25 mm) clearance

to combustibles, framing members, and

attic or ceiling insulation when running

vertical chimney sections.

7. Support the vertical run sections—On

the vertical run, support the venting

system every 8 ft (2.4 m) above the

ﬁreplace vent outlet with ﬁeld provided

support straps (Plumber’s tape). Attach

the straps to the vent pipe and secure

to the framing members with nails or

screws (Figure 16).

Horizontal Termination System

Figure 21, and Table 20 to Table 23 on

Page 20 illustrate the various horizontal

venting conﬁgurations that are possible for

use with these appliances. Secure Vent®

pipe applications are shown in these

ﬁgures; Secure Flex® pipe may also be

used. 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.

Both of these horizontal vent systems

terminate through an outside wall. Building

Codes limit or prohibit terminating in

speciﬁc areas. Refer to Figure 3 on

Page 5 for location guidelines.

Secure Vent SV4.5 direct vent system

components are unitized concentric pipe

components featuring positive twist

lock connection (Figure 15). 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.

1. 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 venting

so that a joint does not occur in the

ceiling or roof joists. Allow for elbows

as indicated in (Figure 17).

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.

NOTE: Top vent clearance can be

reduced to 2 in. on horizontal runs

when ﬁrst elbow is located at least 6 ft

above the ﬁreplace.

2. Frame exterior wall opening—

Locate the center of the vent outlet

on the exterior wall according to

the dimensions shown in Table 9

on Page 10. Cut and/or frame

an opening, 10 1/2 x 12 1/8 in.

(267 x 308 mm) inside dimensions,

about this center.

3. 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, 10 1/2 x 10 1/2 in.

(267 x 267 mm) inside dimensions,

about this center (Figure 14).

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

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Figure 21: Typical Horizontal Vent Installation

Vertical

Rise

SV4.5E90

Elbow

Horizontal / Inclined Run SV4.5HT-2

Termination

Firestop/Spacer

SV4.5L6/12/24/36/48

Vent Sections

Support bracket spacing

every 5 ft (1.52 m)

Vertical Vent

SV4.5HT-2

Termination

Support

Brackets

Building

Support

Framing

Ceiling

Fireplace

Exterior

Wall

Exterior

Wall

TYPICAL HORIZONTAL VENT INSTALLATION

Figure 22: Installing the Square Horizontal Termination

SV4.5HT-2

Termination

10-1/2 in.

(267mm)

7 in.

(178)

5 1/8 in.

(130 mm)

12 1/8 in.

(308 mm)

Note: Centerline of Vent Piping is

NOT the Same as the Centerline of

the Framed Opening.

6 to 48 in. Vent Section,

Telescopic vent section,

Elbow or Appliance Collar

Min. Distance to Base

of Appliance.

Base of Appliance

3 in.

(76 mm)

1 in.

(25.4 mm)

Adapter

SV4.5RCH

To help minimize water

infiltration it is recommended that

the Firestop/Spacer (SV4.5HF)

be installed on the exterior

side of the wall.

Figure 23: Venting Connection and Exterior Wall Recessing of the Horizontal

Square Termination (SV4.5HT-2)

Siding

Stucco

1 1/4 in. Maximum recess of

the Square Termination into

Exterior Finishing Material

Exterior Surface of

Framing

6 in. to 9 1/4 in.

(152 to 235 mm)**

Exterior Surface of Siding

Interior Surface of

Finished Wall

Maximum wall thickness

9 1/4 in. (235 mm)**

SV4.5HT-2

Square Termination

Maximum Extent of

Vent Run Sections

Relative to Exterior

Surface of Framing

Last Vent Section. Use

Telescopic Vent

Section (SV4.5LA), If

Necessary

Adapter

SV4.5RCH

SV4.5HT-2

Square Termination

Venting Connection and Exterior Wall Recessing of the

Horizontal Square Termination (SV4.5HT-2).

*Use silicone caulking to seal

the top and sides of the

termination, up to the

underlayment, stucco, or

masonry wall surface.

** For thicknesses greater

than 9 1/4 in., see Venting

Components Required for

Various Exterior Wall Thicknesses,

when using Typical Termination Kits

*Caulk

11. Attach termination adaptor—Attach

the adaptor (SV4.5RCH, provided with

the termination) to the vent section

or telescoping vent section), elbow or

appliance collar as shown in Figure 23

in the same manner as any SV4.5 vent

component (Step 5).

12. Install Firestop/Spacer at exterior

wall—When using the square

termination, install SV4.5HF

(Secure Vent®), SF4.5HF (Secure Flex®)

ﬁrestop/spacer over the opening at

the exterior side of the framing, long

side up, with the 3 in. spacer clearance

at the top (Figure 22), and nail into

place. The ﬁrestop/spacer may also be

installed over the opening at the interior

side of the framing.

13. Install the desired termination

a. SV4.5HT-2 or SV4.5HTSS Square

termination—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 23.

b. SVHRK Snorkel Cap—The snorkel

cap is designed to be ﬁtted into a

basement window box. The SVHRK

cap is for use with ﬂex vent. The

vertical distance between the inlet

and outlet of the cap is 28 in.

(711 mm).

NOTE: The vent termination is hot while

in operation and for a period of time

following the use of the ﬁreplace. To

prevent contact with hot surfaces, use

a termination guard (Page 33). This

can be purchased at your local dealer.

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.

LENNOX HEARTH PRODUCTS • MERIT® SERIES DIRECT-VENT GAS FIREPLACES • MLDVT-30/35/40/45 • INSTALLATION INSTRUCTIONS

DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.

Table 20: Top Vent—One 90° Elbow, Elbow Connection at Appliance

Wall Firestop/

Spacer

SV4.5HF**

**When using Secure

Flex, use Wall Firestop/

Spacer SF4.5HF.

H Maximum V Minimum

feet meters feet meters

30.914 Elbow Only (30/35/40 Models)

2.5 0.762 Elbow Only (45 Model)

Install the U-shaped vent restrictor in any vent run with more than 8 ft of vertical rise (Figure 12).

Square termination (SV4.5HT-2) shown.

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

Table 21: Top Vent—One 90° Elbow, Elbow Connection NOT at Appliance

Ceiling

Firestop/

Spacer

SV4.5VF*

Wall Firestop/

Spacer SV4.5HF**

*When using Secure Flex, use

Ceiling Firestop/Spacer SF4.5VF.

**When using Secure Flex, use

Wall Firestop/Spacer SF4.5HF.

H Maximum V Minimum

feet meters feet meters

51.524 10.305

10 3.048 20.610

15 4.572 30.914

20 6.096 41.219

V + H = 60 ft (18.3 m) maximum

H = 20 ft (6.096 m) maximum

Install the U-shaped vent restrictor in any vent run with more than 8 ft of vertical rise (Figure 12).

Square termination (SV4.5HT-2) shown.

If 20 ft of (H) horizontal vent run is needed, then 4 ft minimum of (V) vertical vent will be required.

This table shows a 1 (V) to 5 (H) ratio. For every 1 ft of (V) vertical, you are allowed 5 ft of (H) horizontal run, up to a

maximum horizontal run of 20 ft.

Horizontal Vent Tables and Figures

NOTE: Secure Vent® components (rigid vent

pipe and terminal) are shown in the ﬁgures;

Secure Flex® components (ﬂexible vent pipe

and terminal) may also be used.

NOTE: Two 45° elbows may be used in place

of one 90° elbow. The same rise to run ratios,

as shown in the venting ﬁgures for 90° elbows,

must be followed if 45° elbows are used.

NOTE: 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. Rise per foot run ratios are

acceptable to at or near level.

NOTE: SV4.5VF (Secure Vent), SF4.5VF

(Secure Flex) ﬁrestop/spacer must be

used anytime vent pipe passes through

a combustible ﬂoor or ceiling. SV4.5HF

(Secure Vent), SF4.5HF (Secure Flex)

ﬁrestop/spacer must be used anytime vent

pipe passes through a combustible wall.

WARNING

Under no circumstances, may

separate sections of concentric

ﬂexible vent pipe be joined together.

Table 19: Venting Components Required

for Various Exterior Wall Thicknesses,

when using Typical Termination Kits

Vent Components

Required Exterior Wall Thickness

Termination Kit Only 6–9 1/4 in.

(152–235 mm)

Termination Kit and 6 in.

Vent Section (SV4.5L6) 10 3/4–14 in.

(2733–356 mm)

Termination Kit and 12 in.

Vent Section (SV4.5L12) 16 3/4–20 in.

(426–508 mm)

Termination Kit and

Telescopic Section

(SV4.5L12)

11 3/4–20 in.

(299–508 mm)

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Lennox MLDVT-45NM Guide d'installation

Marque: Lennox

Modèle: MLDVT-45NM

Catégorie: Cheminées

Taper: Guide d'installation

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