Lennox MPD-3530CPM-B, MPDR-3328CPE-B, MPDR-3328CPM-B, MPD-3530CNE-B, MPDR-3328CNE-B User Manual
...
INSTALLATION INSTRUCTIONS
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.
MPD Direct-Vent
Gas Fireplaces
P/N 850014 Rev. V 08/2011
This manual is one of a set of two supporting this product.
Refer to P/N 875014M for Care and Operation Instructions.
Ce manuel est disponible en francais, simplement
en faire la demande. Numéro de la pièce 850014CF.
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.
MODELS
MPDT-3328CNM-B
MPDT-3328CPM-B
MPDR-3328CNM-B
MPDR-3328CPM-B
MPD-3530CNM-B
MPD-3530CPM-B
OTL Report No. 116-F-13-4
Please read and understand these instructions
MILLIVOLT:
MPD-4035CNM-B
MPD-4035CPM-B
MPD-4540CNM-B
MPD-4540CPM-B
Portland
US
MPDT-3328CNE-B
MPDT-3328CPE-B
MPDR-3328CNE-B
MPDR-3328CPE-B
MPD-3530CNE-B
MPD-3530CPE-B
before starting installation.
ELECTRONIC:
MPD-4035CNE-B
MPD-4035CPE-B
MPD-4540CNE-B
MPD-4540CPE-B
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
TABLE OF CONTENTS
Packaging .................................................... 2
Introduction ................................................. 2
General Information ..................................... 2
Requirements for the
Commonwealth of Massachusetts ............ 4
New York City Approval ................................ 4
Cold Climate Insulation ................................ 5
Manufactured Home Requirements ............. 5
Location 5
Vent Termination Clearances ....................... 6
Appliance and Vent Clearances .................... 8
Pre-Installation Steps ................................. 10
Typical Installation Sequence .................... 10
Detailed Installation Steps .......................... 10
Step 1. Framing .......................................... 10
Fireplace and Framing Specifications ....... 11
Step 2. Routing Gas Line ........................... 12
Step 3. Preparing Appliance Vent Collar ..... 13
Step 4. Installing Vent System ................... 13
Vertical Termination Systems .................. 14
Vent Section Length Chart ...................... 14
Vertical Vent Tables and Figures .............. 17
Horizontal Termination System ............... 19
Horizontal Vent Tables and Figures ......... 21
Venting Using Flexible Vent Pipe ............. 24
Step 5. Field Wiring ................................... 25
Step 6. Optional Blower Kit Wiring ............ 26
Step 7. Connecting Gas Line ..................... 26
Step 8. Verifying Appliance Operation ........... 27
Step 9. Installing Logs ............................. 28
Step 10. Remove/Install Glass Door .......... 32
Step 11. Burner Adjustments ..................... 32
Step 12. Hood Installation .......................... 34
Finishing Requirements ............................. 34
Step 13. Attaching Safety-in-Operation
Warnings ................................................ 35
Installation Accessories ............................. 36
Gas Conversion Kits .................................. 38
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) Glowing Embers (in bottom compart-
ment).
• Literature Kit (envelope in bottom com-
partment containing Care and Operation
Instructions, Installation Instructions, Safety-
In-Operation Warning Labels, Warranty).
• (1) Vent Restrictor (attached to Literature Kit
envelope).
• (1) Hood (inside firebox).
INTRODUCTION
The 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.
The 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.
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 Compo-
nents 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" inner
and 7-1/2" 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.
Children and adults should be alerted to the
hazards of high surface temperature and
should stay away to avoid burns or clothing
ignition.
Les enfants et les adultes devraient être
infor-més des dangers que posent les
températures de surface élevées et se
tenir à distance afin d’éviter des brûlures
ou que leurs vêtements ne s’enflamment.
DO NOT ATTEMPT TO ALTER OR MODIFY
THE CONSTRUCTION OF THE APPLIANCE
OR ITS COMPONENTS. ANY MODIFICATION
OR ALTERATION MAY VOID THE WARRANTY,
CERTIFICATION AND LISTINGS OF THIS UNIT.
2
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
WARNING
Improper installation, adjustment, alteration, service or
maintenance can cause injury
or property damage. Refer to
this manual. For assistance or
additional information consult
a qualified installer, service
agency or the gas supplier.
WARNING
Failure to comply with these
installation instructions will result
in an improperly installed and
operating appliance, voiding its
warranty. Any change to this appliance and/or its operating controls
is dangerous.
WARNING
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.
Note: Installation and repair should be done
by a qualified service person. The appliance
should be inspected before use and at least
annually by a professional service person.
More frequent cleaning may be required due
to excessive lint from carpeting, bedding
material, etcetera. It is imperative that control
compartments, burners and circulating air
passageways of the appliance be kept clean.
Remarque: L’installation et la réparation
devrait être confiées à un technicien qualifié. L’appareil devrait faire l’objet d’une
inspection par un technicien professionnel
avant d’être utilisé et au moins une fois
l’an par la suite. Des nettoyages plus
fréquents peuvent être nécessaires si les
tapis, la literie, et cetera produisent une
quantité importante de pous-sière. Il est
essentiel que les compartiments abritant
les commandes, les brûleurs et les conduits de circulation d’air de l’appareil
soient tenus propres.
Do not use these appliances if any part
has been under water. Immediately call a
qualified, professional service technician
to inspect the appliance and to replace
any parts of the control system and any
gas control which have been under water.
Ne pas utiliser cet appareil s’il a été
plongé, même partiellement, dans
l’eau. Appeler un technicien qualifié
pour inspecter l’appareil et remplacer
toute partie du système de commande
et toute commande qui a été plongée
dans l’eau.
IMPROPER INSTALLATION OR USE OF THIS
APPLIANCE CAN CAUSE SERIOUS INJURY OR
DEATH FROM FIRE, BURNS, EXPLOSION OR
CARBON MONOXIDE POISONING.
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.
These appliances comply with National
Safety Standards and are tested and listed
by OMNI-Test Laboratories, Inc. (Report No.
116-F-13-4) 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.
Both millivolt and electronic versions of
these appliances are listed by OMNI-Test
Laboratories for installation in bedrooms
and Manufactured Homes.
Misc. Codes / Standards
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.
These fireplaces are designed as supplemental
heaters. Therefore, it is advisable to have an
alternate primary heat source when installed
in a dwelling.
Millivolt Models - The millivolt appliances are
manually controlled and feature a spark igniter
(piezo) that allows the appliance's pilot gas to
be lit without the use of matches or batteries.
This system provides continued service in the
event of a power outage.
Millivolt models come standard with a manually
modulated gas valve; flame appearance and heat
output can be controlled at the gas valve. The BTU
Input for these appliances is shown in Table 1.
Electronic Models - Electronic models have a
fixed rate gas valve. Input of electronic models
is shown in Table 1.
Input (BTU/HR) Gas Valves (all models)
Models
MPDT/R-3328
(Millivolt)
MPD-3530
(Millivolt)
MPD-4035
(Millivolt)
MPD-4540
(Millivolt)
MPDT/R-3328
(Electronic)
MPD3530
(Electronic)
MPD4035
(Electronic)
MPD4540
(Electronic)
Input Rate (BTU / HR)
Nat. Gas Prop. Gas
17,500 high
11,700 low
20,000 high
12,800 low
27,000 high
18,500 low
29,000 high
20,500 low
17,500 17,500
20,000 20,000
27,000 27,000
29,000 29,000
17,500 high
14,000 low
20,000 high
15,200 low
27,000 high
21,500 low
29,000 high
22,500 low
Table 1
3
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Gas Pressure - All Models
Tables 2 and 3 show the appliances' inlet and
manifold gas pressure requirements:
Inlet Gas Supply Pressure
(all models)
Fuel # Minimum Maximum
Natural Gas
Propane
4.5" WC
(1.12 kPa)
11.0" WC
(2.74 kPa)
10.5" WC
(2.61 kPa)
13.0" WC
(3.23 kPa)
Table 2
Manifold Gas Supply Pressure
(all models)
Fuel # Low High
Natural
Gas
Propane
(Lo) 1.6" WC
(0.40 kPa)
(Lo) 6.3" WC
(1.57 kPa)
(Hi) 3.5" WC
(0.87 kPa)
(Hi) 10.0" WC
(2.49 kPa)
Table 3
Test gauge connections are provided on the
front of the millivolt and electronic gas control
valve (identified IN for the inlet and OUT for the
manifold side). The control valves have a 3/8"
(10mm) NPT thread inlet and outlet side of the
valve (refer to Figures 1 and 2).
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.
These appliances must be isolated from the
gas supply piping system (by closing their
individual manual shut-off valve) during any
pressure testing of the gas supply piping
system at test pressures equal to or less
than 1/2 psig (3.5 kPa).
These appliances and their individual shut-off
valves must be disconnected from the gas
supply piping system during any pressure
testing of that system at pressures greater
than 1/2 psig (3.5 kPa).
These appliances must not be connected to a
chimney or flue serving a separate solid fuel
burning appliance.
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 "*" in Table 4 ).
For elevations above 4500 feet, 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 or by 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.
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.
Flame breadth, height and width will dimenish
4% for every 1,000 feet of altitude.
Burner Orifice Sizes
Elevation 0-4500 feet ( 0-1372 meters)
Model
Series
MPDT-3328
MPDR-3328
MPD-3530
MPD-4035
MPD-4540
Table 4
Nat.Gas
drill size (inches)
#45 (0.0820")*
39L66•
#44 (0.0860")*
60J80•
#37 (0.1040")*
24M10•
#36 (0.1065")*
18L40•
* Standard size installed at factory
• Part /Cat. Number
Propane
drill size (inches)
0.048 inch
99K78•
#55 (0.0520")*
19L52•
0.063 inch
21L01•
#52 (0.0635")*
37G00•
Gas Valve Diagrams
See Figure 1 for Millivolt models and Figure 2
For Electronic Models.
Main Gas Control Knob
OFF/PILOT/ON
N
O
T
O
it
L
I
P
O
F
F
OUT
IN
Manifold Pressure Tap
Inlet Pressure Tap
Pilot Adjustment
I
P
W
O
L
H
I
HI/LO Variable
Flame Height
Adjustment
Screw
T
O
L
HTPTHTPT
Figure 1: SIT Millivolt Gas Valve
Electronic
Gas Control
Valve
P
SI
Inlet
Pressure
Port
IN
ON/OFF Switch Manifold Pressure Port
R
E
IT
IGN
ON
OFF
CONTROL
Figure 2: Honeywell Electronic Gas Valve
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 flexible 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 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.
NEW YORK CITY, NEW YORK (MEA)
Installation of these fireplaces are approved
for installation in New York City in the US state
of New York.
4
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • 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 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.
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.
REAR VENT
APPLICATION
TOP VENT
APPLICATION
APPLICATION
TOP VENT
INSTALLATION
VERTICAL VENT
(Rear Vent Application)
HORIZONTAL VENT
(Rear Vent Application with a chase)
RECESSED
REAR VENT
APPLICATION
TOP VENT
TOP VENT
APPLICATION
TOP VENT
APPLICATION
HORIZONTAL VENT
(Rear Vent Application without a chase)
APPLICATION
TOP VENT
APPLICATION
HORIZONTAL VENT
(Top Vent Application)
Figure 3: Typical Locations
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).
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
locat-ing television sets and decorative plants.
VERTICAL VENT
(Top Vent Application)
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 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 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.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
5
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
LOWEST DISCHARGE OPENING OF VENT
TERMINATION HEIGHTS FOR VENTS ABOVE
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 and Figures
4 and 5.
12”
(305mm)
Minimum
Vertical Vent Termination Clearances
Horizontal Overhang
2 FT MIN.
Termination
Storm Collar
Flashing
Concentric
Vent Pipe
FLAT OR SLOPED ROOFS
Vent
*H = MINIMUM HEIGHT FROM ROOF TO
2 FT
MIN.
Lowest
Discharge
Opening
H*
1 inch (25.4 mm) Minimum
Clearance to Combustibles
Vertical
Wall
X
12
Roof Pitch is X/12
Figure 5
Horizontal Vent Termination Clearances
The vent / air intake termination clearances
above the high side of an angled roof are as
shown in the following chart:
Termination Heights For Vents
A
bove Flat Or Sloped Roofs
ef. NFPA 54 / ANSI Z223.1
R
oof Pitch *H (ft) *H (m)
R
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 4 - Multiple Terminations
The horizontal vent termination must have a minimum of 6" (152 mm) clearance to any overhead
combustible projection of 2-1/2" (64 mm) or less (see Figure 6). For projections exceeding 2-1/2"
(64 mm), see Figure 6. For additional vent location restrictions refer to Figure 7 on Page 7.
Horizontal Vent Termination Clearances
Combustible Projection
inches or less in length
2-1/2
Combustible Projection greater
than 2-1/2 inches in length
Ventilated
Soffit
Unventilated
Soffit
18"
(457 mm)
12"
(305 mm)
6"
(152 mm)
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.
Termination Kit
Side Elevation View
Termination Kit
Note - See Figure 37 on Page 20 for the exterior wall recess
Figure 6
allowances of the square horizontal termination.
6
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
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EXTERIOR HORIZONTAL VENT TERMINATION CLEARANCE REQUIREMENTS
NOTE: Local Codes Or Regulations
* See Item D in the Text Below.
Exterior Wall
*18”
Horizontal
Termination
Inside Corner
B
V
L
V
6”
Detail D
F
V
A
X
Ventilated Soffit
V
Fixed
Closed
Window
V
C
= Air Supply Inlet
C
C
C
V
Inside
Corner Detail
V
A
B
Operable
V
Window
B
B
= Vent Termination
G
B
= Area where Termination is not Permitted
May Require Different Clearances.
NOTE: Location Of The Vent Termination
Must Not Interfere With Access To The
Electrical Service.
= 9” in U.S.
A
= 12” in Canada
3 ft.
X
A
J
A
3 ft.
P
N
V
Q
H
M
V
I
N
O
D
E
V
Figure 7
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
7
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
MINIMUM CLEARANCES TO COMBUSTIBLES
Appliance And Vent Clearances
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 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 (see Figure 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 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.
MINIMUM CLEARANCES* Inches (millimeters)
Back 1/2 in. (13)
0 (0) from Spacers Or Dimples
Sides 1/2 in. (13)
0 (0) from Spacers Or Dimples **
Top Spacers 0 (0)
Floor 0 (0)
From Bottom of Unit To Ceiling 64 (1626)
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 10, Step 1 for clearance requirements to the nailing
flange located at each side of the unit and any screw heads adjacent to it.
Models
MPDT-3328
MPDR-3328
MPD-3530 46-1/2 (1181) 48-1/4 (1226) 35-1/4 (895) 35-1/4 (895)
MPD-4035
MPD-4540
Do not insulate the
space between the
appliance and the
Shelf Above Fireplace With Rear Venting
Top Vent - With One 90 Degree Elbow Rear Vent - Straight Out The Back
Secure Vent Secure Flex Secure Vent Secure Flex
44-1/2 (1130) 46-1/4 (1175) 33-1/4 (845) 33-1/4 (845)
51-1/2 (1308) 53-1/4 (1353) 40-1/4 (1022) 40-1/4 (1022)
area above it.
Shelf Height
see table)
(
Combustible Shelf Height - Inches (millimeters)
Do not insulate the
space between the
appliance and the
area above it.
Shelf Height
see table)
(
Shelf Above Fireplace With Top Venting
Figure 8:
Shelf Height Minimum Clearances
8
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
12 (305) MANTEL
10 (254) MANTEL
8 (203) MANTEL
6 (152) MANTEL
4 (102) MANTEL
4
(102)
14
(356)
12
(305)
10
(254)
2 (51) MANTEL
TOP OF
APPLIANCE
6
(152)
NOTE - Hood shown as positioned in louvered
front model. The hood position in the flush
faced front model is lower than shown.
8
(203)
MANTEL CLEARANCES
Inches (mm)
17"
14"
Min. Distance To
Unprotected
Perpendicular Side Wall
8-1/4"
45°
Combustible Materials
Allowed In Shaded
Area “Safe Zone”
12"
5"
Top View Of
Fireplace
Side
Wall
Side
Wall
Min. Distance
To Protected
Perpendicular
Side Wall
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 Figures 65 and 66 on Page 34 ).
Non-combustible materials, such as surrounds and other appliance trim, may be installed on the appliance face with these exceptions: 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. See Figure 9. 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.
Figure 9: Minimum Mantel Clearances
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.
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.
WARNING
AVERTISSEMENT
Combustible materials may project beyond one side of the fireplace
opening as long as they are kept within the shaded areas illustrated here.
Figure 10: Minimum Distance to Side Wall
9
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
PRE-INSTALLATION STEPS
The appliance is shipped with all gas controls
and components installed and pre-wired.
Before installing the appliance, follow these
steps:
1. Remove the shipping carton.
2. Remove the shipping pad, exposing the front
glass door.
3. Open the two latches securing the glass
door (under the firebox floor). Remove the
door by tilting it outward at the bottom and
lifting it up. Set the door aside, taking care
to protect it from inadvertent damage. See
Removing Glass Panels on Page 32.
4. See Figure 11. Remove the top louvered
panel and locate the pressure relief plates.
Lift the pressure relief plates, and remove the
cardboard from beneath each plate (taking
care not to damage the white gasket).
5. Remove the log set from the firebox. Handle
logs carefully to prevent breakage.
6. Remove the embers and volcanic stone from
the control compartment.
Pressure Relief
Plates
REMOVE
D
OAR
B
D
CAR
EFORE USING
B
Remove cardboard before using appliance.
Take care not to damage white gasket.
Figure 11
REMOVE
B
D
CAR
EFORE USING
B
D
OAR
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 pages referenced in the following steps
for detailed procedures.
Step 1. FRAMING (Page 10): Construct the
appliance framing. Position the appliance within
the framing and secure with nailing brackets.
IMPORTANT! Bend up the appropriate header
spacing standoffs for the drywall/finish material thickness to be used (see Figure 60, page
32). Bend up the outer pair for 1/2" materials
and the inner pair for 5/8" materials.
Bend out the appropriate nailing flanges for
the drywall/finish material to be used. Nailing
flanges are provided for flush framing, 1/2-inch
and 5/8-inch framing depths (see Figure 12).
Step 2. ROUTING GAS LINE (Page 12): Route
gas supply line to appliance location.
Step 3. PREPARING APPLIANCE VENT COLLAR
(MPD-3530/4035/4540 models with combined
top/rear vent) (Page 13).
Step 4. INSTALLING VENT SYSTEM (Page 13):
Install the vent system and exterior termination.
Step 5. FIELD WIRING (Page 25).
a. Millivolt Appliances – Install the operat-
ing control switch (not factory provided). If
installing the optional forced air circulating
blower, bring in electrical service line.
b. Electronic Appliances – Field wire and
install operating control switch.
Step 6. WIRING - OPTIONAL FORCED AIR
BLOWER KIT (Page 26).
Step 7. CONNECTING GAS LINE (Page 26):
Make connection to gas supply.
Step 8. VERIFYING APPLIANCE OPERATION
(Page 27).
Step 9. INSTALL LOGS, VOLCANIC STONE,
AND GLOWING EMBERS (Page 28).
Step 10. INSTALLING GLASS DOOR ASSEMBLY (Page 32).
Step 11. BURNER ADJUSTMENTS (Page 32):
Adjust burner to ensure proper flame appearance.
Step 12. HOOD INSTALLATION (Page 34).
Step 13. ATTACHING SAFETY-IN-OPERATION
WARNINGS (Page 35).
DETAILED INSTALLATION STEPS
Step 1. FRAMING
Frame the appliance as illustrated in Figures
13 and 14 on Pages 10 and 11 (Figure 14
applies to corner framing installations only).
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 standoff spacers when they are bent
up vertically, maintaining the 3" 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.
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. See
Figure 12. Use 8d nails or their equivalent.
IMPORTANT!
Bend up the appropriate header spacing top
standoffs before installing the fireplace.
Header Spacing Top Standoffs
(two pairs on front edge of firebox top)
Lift up outer pair for
1/2" finish materials.
Lift up inner pair for
5/8" finish materials.
Unit Nailing Flange
(No clearance to
combustible framing
is required.)
Side
Framing
Unit Secured to Framing
by Nailing Flange
Left Side Front Corner of Fireplace Shown
(Right side requirements are the same)
NOTE: The nailing flanges, combustible
members, and screw heads 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 in this manual.
10
Figure 12
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
.oNledoM A B C D E
8233-TDPM
.ni 4/133 4/133 ----- 4/373 8/721
mm 548 548 ----- 959 723
8233-RDPM
.ni 4/133 4/133 8/591 ----- 8/721
mm 548 548 894 ----- 723
0353-DPM
.ni 4/153 4/153 61/1112 4/393 61
mm 598 598 155 0101 604
5304-DPM
.ni 4/104 4/104 61/1162 4/344 61
mm 2201 2201 876 7311 604
0454-DPM
.ni 4/154 4/104 61/1162 4/344 61
mm 9411 2201 876 7311 604
FIREPLACE AND FRAMING SPECIFICATIONS
Framing
Notes
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 4-1/2" Inner; 7-1/2" Outer
Efficiencies %
Fireplace
Model
MPDT-3328 62 45 64 49
MPDR-3328 61 53 64 55
MP
D-3530
MPD-4035 67 59 67 60
MP
D-4540
Natural Gas Propane
EnerGuide
AFUE
(P4)
62 53 60 55
67 59 67 59
AFUE
EnerGuide
(P4)
Viewable Glass Size
33" Model
35" Model
40" Model
45" Model
B
27-1/2" Wide
17" High
29-1/2" Wide
18-7/8" High
34-1/2" Wide
24" High
39-1/2" Wide
24" High
VENT FRAMING:
TOP VENT WITH ONE
90° ELBOW
VENT FRAMING:
REAR VENT WITH
NO ELBOWS
10-1/2
(
)
267
5-1/8
(130)
5-1/8
D
(130)
(178)
(178)
7
7
Framing should be
constructed of 2x4
or larger lumber.
C
E
A
1/2
A
Dimension “E” is the required framing depth when the
finish material (drywall) thickness is 1/2 in. (13mm).
Vertical Venting through the Ceiling
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" (267 mm x 267 mm)
inside dimensions, about this center mark (see Figure 18).
12-1/8
(308)
12-1/8
(308)
Inches (mm)
Top View
(Louvered Front Model Shown)
Rear/Side
Framing
Spacers
Header
Spacing
Top
Standoffs
Notes:
[1] MPD models have a top and rear vent. MPDR models
have a rear vent only. MPDT models have a top vent only.
[2] Collars protrude one inch on MPDT-3328 and MPDR-3328 models.
G
H
Concentric Flue:
Flue
4-1/2" (114 mm);
Combustion Air
7-1/2" (190 mm).
See Notes [1] and [2].
J
.oNledoM A B C D E F G H J K L M N
.ni 8/133 8/103 71 2/172 8/133 8/591 2/112 4/301 61/316 3 23/118 3/22 31
8233-TDPM
8233-RDPM
Figure 13
mm 148 567 234 996 148 894 645 372 371 67 212 07 033
.ni 8/153 8/123 91 2/192 8/153 61/1112 8/742 1 61/72 9 3 9 3 61
0353-DPM
mm 298 618 384 947 298 155 236 613 022 67 022 67 604
5304-DPM
.ni 8/104 8/173 42 2/143 8/104 61/1162 8/792 1 61/514 9 3 9 3 61
mm 9101 349 016 678 9101 876 957 973 022 67 022 67 604
0454-DPM
.ni 8/104 8/173 42 2/193 8/154 61/1162 8/743 61/771 9 3 9 3 61
mm 6411 349 016 3001 6411 876 688 344 022 67 022 67 604
Front View
E
A
D
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
3 (76)
in louvered front model.
Optional Electrical Inlet
C
B
Field-Provided Junction
NOTE: Eyebrow hood
shown as positioned
Gas Inlet (either
side and bottom)
Knockout requiring a
Box (either side)
1-3/8 (35)
K
6 (152)
Right Side View
N
L
1/2 (13)
See Note [2].
1-5/8 (42)
M
F (rear vent
models only)
Electrical Inlet
2-3/4" x 2"
(70 x 51 mm)
Cover Plate
with Knockout
11
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
FIREPLACE FRAMING SPECIFICATIONS
.oNledoM A B C D E F
.ni 8/133 2/184 61/543 61/371 4/142 5
8233-TDPM
8233-RDPM
mm 148 2321 278 734 616 721
.ni 8/153 2/175 8/504 61/391 4/382 8/16
0353-DPM
mm 298 1641 2301 784 037 651
.ni 8/104 61/316 23/1134 61/391 61/1103 8/77
5304-DPM
mm 9101 4551 1011 784 977 002
.ni 8/154 8/366 61/5164 61/391 61/333 4/39
0454-DPM
mm 6411 6861 2911 784 348 842
Note:
• Rear Vent Applications in Corner Installations: The horizontal vent length
(from a to b) must not exceed 28 inches (711 mm).
• MPDT-3328 AND MPDR-3328 Models: Dimensions A through F occur when
one 45-degree elbow is connected directly to the appliance collar.
• MPD-3530, MPD-4035, and MPD-4540 Models: Dimensions D through F
occur when one 45-degree elbow is connected directly to the appliance collar.
Figure 14: Corner Framing with Horizontal Termination
Step 2. ROUTING GAS LINE
Route a 1/2" (13 mm) gas line to the left side
of the appliance as shown in Figure 15. 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 25).
Left Side Front
Corner of Fireplace
Framing
Pipe Coupling
(Recommended)
6-1/2"
(152 mm)
3"
(76 mm)
Also see Figure 13.
Figure 15: Route Gas Line
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).
12
MPD and MPDR units
MPD and MPDT units
C
Back wall of chase/enclosure (including any finishing materials)
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 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.
Schedule 40
Black Iron Pipe
Inside Diameter (Inches)
Schedule 40 Pipe
Length (feet)
Natural
Gas
Propane
Gas
0-10 1/2 3/8
10-40 1/2 1/2
40-100 1/2 1/2
100-150 3/4 1/2
150-200 3/4 1/2
Table 6
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
b
F
7"
(178 mm)
E
D
a
A
B
Notes:
• All appliances are factory-equipped with
a flexible gas line connector and 1/2 inch
shutoff valve (see Figure 50 on Pagec 25).
• 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 25).
• 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. Appliances using Propane should
have a sediment trap at the base of the tank.
• Check with local building official for local
code requirements (i.e. are below grade
penetrations of the gas line allowed?, etc).
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.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
RESTRICTOR
APPLIANCE REAR
VENT OUTLET
A vent restrictor may be needed when
horzontally terminating the vent system from
the rear of the appliance (when using the
appliance rear vent), install vent restrictor in
the rear vent of the fireplace outlet on
MPD-3530/4035/4540 series models, in any
installation that has a vertical vent run in
excess of three feet (0.914 meters).
VENT RESTRICTOR INSTALLATION
(REAR VENT)
INNER FIREPLACE
COLLAR
If needed, install the restrictor orientated as
shown, either from inside or outside the unit,
in the inner fireplace collar.
Step 3. PREPARING APPLIANCE VENT
COLLAR (MPD-3530/4035/4540 models
with combined top/rear vent)
Each of the unit’s two vent collars are sealed
with a cover plate and a seal plate and gasket.
The cover, and seal plate and gasket must be
removed from the vent collar being used. Refer
to Figure 16 for top vent usage and Figure 17
for rear, and the following steps to prepare the
appropriate collar for use.
From the vent collar being used, remove the four
screws securing the vent seal plate and gasket.
Remove and discard the seal plate and gasket.
When the top vent collar is being used, from
inside the firebox, loosen the two screws in the
keyhole slots of the cover plate and remove the
remaining two cover plate securing screws.
Remove and discard the cover plate. Reinstall
and securely tighten all four screws.
When the rear vent collar is being used, from
inside the firebox, remove the two screws securing the lintel to the rear wall of the firebox,
then remove the lintel. Remove the four cover
plate securing screws. Remove and discard
the cover plate.
Reinstall and securely tighten all four cover
plate screws. Re-secure the lintel to the rear
wall of the firebox.
Use only approved vent 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 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 18
(MPDT-3328, MPD-3530, MPD-4035 and MPD-
4540) or rear flue outlet as shown in Figure 19
(MPD-3530, MPD-4035 and MPD-4540). It is
held in place by friction, only.
Note: The vent restrictor is included in the
firebox.
ON MPD-3530/4035/4540 SERIES MODELS
(COMBINED TOP AND REAR VENT UNITS)
TOP VENT SEAL & COVER PLATE REMOVAL
WHEN USING THE TOP VENT
(OUTSIDE UNIT)
CABINET TOP
GASKET
VENT SEAL PLATE
SECURING
SCREWS
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 Pages 34 and 35.
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 MPD-3530/4035/4540
and MPDT-3328 series models.
If needed, install the restrictor orientated as
shown, either from inside or outside the unit,
in the inner fireplace collar.
RESTRICTOR
INNER
FIREPLACE
COLLAR
APPLIANCE TOP
VENT OUTLET
Figure 18
WARNING
Failure to reinstall and securely
tighten cover plate screws could
result in leakage of flue products
into the living space. Vent cover
plate and vent seal cap must
remain securely in stalled on
unused vent collar. Failure to
do so could result in leakage of
flue products into living space.
Step 4. INSTALLING 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'installation locaux et aux exigences du foumisseunde gaz.
TOP VENT
FIREBOX TOP
VENT
COVER PLATE
(INSIDE UNIT)
CROSS SECTION
COVER PLATE
SECURING SCREWS
Figure 16
ON MPD-3530/4035/4540 SERIES MODELS
(COMBINED TOP AND REAR VENT UNITS)
REAR VENT SEAL & COVER PLATE REMOVAL
WHEN USING THE REAR VENT
COVER PLATE
SECURING SCREWS
LINTEL
SECURING
SCREWS
LINTEL
(INSIDE UNIT)
REAR VENT
CROSS SECTION
VENT SEAL PLATE
GASKET
SECURING
SCREWS
CABINET BACK
(OUTSIDE UNIT)
Figure 17
Figure 19
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
13
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
TRAHCHTGNELNOITCESTNEV
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9 57.0 2 0 0 0 0 2
5.01 578.0 0 1 0 0 0 1
51 52.1 1 1 0 0 0 2
5.91 526.1 2 1 0 0
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12 57.1 0 2 0 0 0 2
5.22 578.1 0 0 1 0 0 1
5.52 521.2 1 2 0 0 0 3
5.13 526.2 0 3 0 0 0 3
5.43 578.2 0 0 0 1 0 1
5.73 521.3 1 1 1 0 0 3
5.34 526.3 0 2 1 0 0 3
54 57.3 0 0 2 0 0 2
5.64 578.3 0 0 0 0 1 1
5.94 521.4 1 0 2 0 0 3
15 52.4 1 0 0 0 1 2
5.55 526.4 0 1 2 0 0 3
75 57.4 0 0 1 1 0 2
66 52.5 0 2 2 0 0 4
5.76 526.5 0 0 3 0 0 3
96 57.5 0 0 0 2 0 2
27 6 1 0 3 0 0 4
5.37 521.6 1 0 0 2 0 3
5.97 526.6 0 1 0 2 0 3
18 57.6 0 0 0 1 1 2
09 5.7 0 2 1 0 1 4
5.
19
526.7 0 0 2 0 1 3
39 57.7 0 0 0 0 2 2
69 8 1 0 1 2 0 4
5.79 521.8 1 0 0 0 2 3
201 5.8 2 0 0 0 2 4
5.301 526.8 0 0 0 3 0 3
801 9 1 0 0 3 0 4
411 5.9 0 2 0 0 2 4
711 57.9 1 0 5 0 0 6
5.811 578.9 1 1 0 3 0 5
621 5.01 0 0 1 3 0 4
5.031 578.01 1 0 1 3 0 5
531 52.11 0 0 6 0 0 6
831 5.11 0 0 0 4 0 4
5.931 526.11 0 0 0 0 3 3
5.241 578.11 1 0 0 4 0 5
VERTICAL TERMINATION SYSTEMS (ROOF)
See Figure 20 and Figures 30 through 32
on Page 17 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; 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-(latest edition) (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 (refer to
Figure 5 on Page 6).
Vertical (Straight) Installation
(Figure 20)
Determine the number of straight vent sections required. 4-1/2" (114 mm), 10-1/2" (267
mm), 22-1/2" (572 mm), 34-1/2" (876 mm)
and 46-1/2" (1181 mm) net section lengths
are available (see Tables on this page and
Pages 35 and 36 - 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.
14
SV4.5CGV-1
Termination
Max. 40 ft
(12.2 m)
Figure 20
SV4.5FA or
SV4.5FB Flashing
AND SV4.5SC
Storm Collar
1 in (25.4 mm)
Minimum
Clearance to
Combustibles
SV4.5VF
Firestop/Spacer*
*When using Secure Flex,
use Firestop/Spacer
SF4.5VF.
SV4.5L6/12/24/36/48
Vent Sections
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5.451 578.21 1 1 0 0 3 5
5.061 573.31 0 2 0 0 3 5
5.271 573.41 0 0 0 5 0 5
771 57.41 1 0 0 5 0 6
381 52.51 0 1 0 5 0 6
681 5.51 0 0 0 0 4 4
5.091 578.51 1 0 0 0 4 5
5.691 573.61 0 1 0 0 4 5
5.502 521.71 0 1 1 5 0 7
702 52.71 0 0 0 6 0 6
5.112 526.71 1 0 0 6 0 7
5.712 521.81 0 1 0 6 0 7
5.922 521.91 0 0 1 6 0 7
5.232 573.91 0 0 0 0 5 5
732 57.91 1 0 0 0 5 6
5.142 521.02 0 0 0 7 0 7
642 5.02 1 0 0 7 0 8
252 12 0 1 0 7 0 8
462 22 0 0 1 7 0 8
672 32 0 0 0 8 0 8
972 52.32 0 0 0 0 6 6
5.
082 573.32
5.382 526.32 1 0 0 0 6 7
5.982 521.42 0 1 0 0 6 7
5.103 521.52 0 0 1 0 6 7
5.013 578.52 0 0 0 9 0 9
513 5.62 1 0 0 9 0 01
5.523 521.72 0 0 0 0 7 7
033 5.72 1 0 0 0 7 8
633 82 0 1 0 0 7 8
543 57.82 0 0 0 01 0 01
5.943 521.92 1 0 0 01 0 11
273 13 0 0 0 0 8 8
5.673 573.13 1 0 0 0 8 9
5.973 526.13 0 0 0 11 0 11
5.814 578.43 0 0 0 0 9 9
324 52.53 1 0 0 0 9 01
564 57.83 0 0 0 0 01 01
1 0 0 8 0 9
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Effective Vent Length
Note: Convert inches into metric equivalent
measurement, as follows:
Millimeters (mm) = Inches x 25.4
Centimeters (cm) = Inches x 2.54
Meters (M) = Inches x .0254
Model Effective Length
SV4.5L6 4-1/2"
SV4.5L12 10-1/2"
SV4.5L24 22-1/2"
SV4.5L36 34-1/2"
SV4.5L48 46-1/2"
Table 7
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
First Vent
Component
Align the dimple (four places)
with the opening of the locking
incline channel on appliance
collar. Twist vent component
clockwise to engage and seal.
Locking
Incline Channel
Dimple
Appliance collar
Vent / Appliance Collar
Connection
upper vent section with the opening of
1 inch
(25.4 mm)
minimum
clearance to
combustibles
Support Straps
(Plumber’s tape)
8 feet (2.4 m)
Maximum
Blocking
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 14 to select the type of
vertical installation desired. Vent sections are
available in net lengths of 4-1/2" (114 mm),
10-1/2" (267 mm), 22-1/2" (572 mm), 34-1/2"
(876 mm) and 46-1/2" (1181 mm). Refer to the
Vent Section Length Chart on page 14 for an
aid in selecting length combinations. Elbows are
available in 90° and 45° configurations. Refer
to Figure 25 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 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 SV4.5LA Telescopic Vent Section
has an effective length of from 1-1/2" (38 mm)
to 7-1/2" (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 screws.
Maintain a minimum 1" (25 mm) clearance to
combustible materials for all vertical elements.
Clearances for all horizontal elements are 3"
(76 mm) on top, 1" (25 mm) on sides and 1"
(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, 10-1/2" x 10-1/2" (267mm x 267mm)
inside dimensions, about this center mark
(Figure 21).
Min. 10-1/2"
(267 mm)
Min. 10-1/2"
(267 mm)
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.
Figure 22
Arrow
Arrow
Align the dimple (four places) of the
the locking incline channel on the
lower vent section. Twist vent
component clockwise to engage and
seal until arrow and dimple align.
Dimple
Locking
Incline Channel
Connected
Vent Sections
Vent / Vent Section
Connection
Arrow
Figure 23
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 22 ). 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" 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 you would a vent 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 23.
D. 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. Remember to maintain 1" (25
mm) clearance to combustibles, framing
members, and attic or ceiling insulation
when running vertical chimney sections.
Attic insulation shield (96K94) may be used
to obtain the required clearances indicated
here. See installation accessories table on
pages 35 and 36.
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 (2.4m) 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" length may be used to secure the
support straps to the vent pipe. See Figure 24.
Figure 21
B. Attach vent components to appliance Secure Vent SV4.5 direct vent system compo-
nents are unitized concentric pipe components
featuring positive twist lock connections (see
Figure 19 ).
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.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Figure 24
15
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
SV4.5E90
(90
°
Elbow)
8-1/8"
(206 mm)
Swivel Joint
(360
°
swivel)
4-13/16"
(122 mm)
SV4 .5E45
(45
°
El bow)
Swivel Joint
(360
°
swivel)
C
D
Storm
Collar
F. Change vent direction to horizontal/inclined
run - At transition from or to a horizontal/in-
clined 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.
See Figure 25.
Figure 25
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 5' (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) and
slightly elevated plane in a direction away
from the fireplace 1/4" per foot (20 mm per
meter) of horizontal vent. Use a carpenter’s
level to measure from a constant surface and
adjust the support straps as necessary.
Framing Dimensions for Roof
Pitch C D
0/12 10-1/2 in. 10-1/2 in.
(267 mm) (267 mm)
6/12 10-1/2 in. 12 in.
(267 mm) (305 mm)
12/12 10-1/2 in. 17-3/4 in.
(267 mm) (451 mm)
Figure 26
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 27 ). 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 28
K. 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 the "Vertical vent termination section" on page 5. The SV4.5CGV-1
Vertical Termination (Figure 29 ) 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 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.
16
It is important to maintain the required clearances to combustibles: 1" (25 mm) at all sides
for all vertical runs; and 3" (76 mm) at the
top, 1" (25 mm) at sides, and 1" (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 and Figure 26.
Figure 27
J. Install the storm collar - Install the storm
collar, supplied with the flashing, over the vent/
flashing joint. See Figure 28. 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.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Figure 29
If the vent system extends more than 5' (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.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
SF4.5VF.
VERTICAL VENT FIGURES/TABLES
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)
and recommended to be in a slightly elevated
plane, in a direction away from the fireplace of
1/4" rise per foot (20 mm per meter) which is
ideal, though 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 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.
Note: An elbow is acceptable as 1 foot of
vertical rise, except where an elbow is the
only vertical component in the system. (See
Figure 39 on page 21 ).
Ceiling
Firestop/
Spacer
SV4.5VF*
Max. 40 ft
(12.2 m)
*When using
Secure Flex, use
Ceiling Firestop/
Spacer SF4.5VF.
TABLE A
H Maximum V Minimum
(meters)
feet feet
(meters)
2 (0.610) 1 (0.305)
4 (1.219) 2 (0.610)
6 (1.829) 3 (0.914)
V
8 (2.438) 4 (1.219)
V + H = 40 feet (12.2 meters) Max.
H = 8 feet (2.4 meters) Max.
Ratio V to H ratio is 1:2
This table shows a 1 (V) to 2 (H) ratio.
For every 1 foot of (V) vertical, you are
allowed 2 feet of (H) horizontal run, up
to a maximum horizontal run of 8 feet.
Example: If 8 feet of (H) horizontal vent
run is needed, then 4 feet minimum (V)
vertical vent will be required.
Figure 31: Rear Vent - ONE 90-DEGREE ELBOW
H
Ceiling
Firestop/Spacer
SV4.5VF*
Wall
Firestop/Spacer
V1
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
SV4.5HF**
Figure 32: Top Vent - TWO 90-DEGREE ELBOWS
Ceiling
Firestop/Spacer
SV4.5VF*
*When using Secure Flex, use
Ceiling Firestop/Spacer
H
TABLE B
H Maximum
(meters)
feet
(1.524)
5
(1.524)
5
(3.048)
10
(4.572)
15
(6.096)
20
V + V1+ H = 40 feet (12.2 m) Max.
H = 20 feet (6.096 meters) Max.
Example: If 20 feet of (H) horizontal vent run is needed, then 4 feet
minimum of (V) vertical vent will
be required.
V
This table shows a 1 (V) to 5 (H) ratio.
For every 1 foot of (V) vertical, you
are allowed 5 feet of (H) horizontal
run, up to a maximum horizontal
run of 20 feet.
An elbow is acceptable as 1 foot of
vertical rise except where an elbow
is the only vertical component in the
system. See Figure 39.
V Minimum
feet
Elbow Only
1
2
3
4
(meters)
(0.305)
(0.610)
(0.914)
(1.219)
A Vent Restrictor, as shown in Figure
18 on Page 13, must be used in this
application.
Figure 30: Top Vent - STRAIGHT
WARNING
Separate sections of concentric flexible vent pipe may NOT be joined
together under any circumstances.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
17
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
VERTICAL VENT FIGURES/TABLES
(continued)
TABLE C
+H
Maximum H Maximum V Minimum
H
1
2
4
6
8
(meters)
(0.610)
(1.219)
(1.829)
(2.438)
(meters)
feet feet feet
(1.524)
5
(3.048)
10
(4.572)
15
(6.096)
20
V + V1+ H + H1 = 40 feet (12.2 m) Max
H = 8 feet (2.438 meters) Max.
H + H1= 20 feet (6.096 meters) Max.
1
2
3
4
(meters)
(0.305)
(0.610)
(0.914)
(1.219)
Example: If 20 feet of (H) horizontal vent run is needed,
then 4 feet minimum of (V) vertical vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For every 1 foot of
(V) vertical, you are allowed 5 feet of (H) horizontal run, up
to a maximum horizontal run of 20 feet.
Figure 33: Rear Vent - THREE ELBOWS
V1
H1
Ceiling
Firestop/Spacer
SV4.5VF*
Wall
Firestop/Spacer
SV4.5HF**
V
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
Ceiling
Firestop/Spacer
SV4.5VF*
H
TABLE D
H
Maximum
H +
1
feet feet
10
15
20
(meters) (meters)
5
5
(1.524) Elbow Only
(1.524)
(3.048)
(4.572)
(6.096)
H + H1 = 20 feet (6.096 m) Max.
+ H + H1 = 40 ft. (12.192 m) Max.
V + V
1
V Minimum
1
2
3
4
(0.305)
(0.610)
(0.914)
(1.219)
Example: If 20 feet of (H) horizontal vent run is needed, then 4 feet
minimum of (V) vertical vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For every 1 foot of (V) vertical, you are allowed 5 feet of (H) horizontal run, up to a maximum
horizontal run of 20 feet.
An elbow is acceptable as 1 foot of vertical rise except where an
elbow is the only vertical component in the system. See Figure 39.
Figure 34: Top Vent - THREE ELBOWS
Ceiling
V
1
Firestop/Spacer
SV4.5VF*
Wall
Firestop/Spacer
SV4.5HF**
H
H
1
V
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
18
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
HORIZONTAL (OUTSIDE WALL)
TERMINATION SYSTEM
Figures 35, and Figures 39 to 44 on pages
21 to 23 and their associated Horizontal Vent
Table 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 8 on page 7 for location guidelines.
Secure Vent SV4.5 direct vent system components
are unitized concentric pipe components featuring
positive twist lock connection, (refer to Figure 22
on page 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.
A. Plan the vent run -
Analyze the vent routing and determine the
types and quantities of sections required
4-1/2" (114 mm), 10-1/2" (267 mm), 22-1/2" (572
mm), 34-1/2" (876 mm) and 46-1/2" (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 25 on page 16.
Maintain a minimum 1" (25 mm) clearance to
combustibles on the vertical sections. Clearances
for the horizontal runs are; 3" (76 mm) on top, 1"
(25 mm) on sides, and 1" (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 9 on page 8. Cut and/or frame an
opening, 10-1/2" x 12-1/8" (267 mm x 308mm)
inside dimensions, about this 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, 10-1/2" x 10-1/2" (267 mm x 267
mm) inside dimensions, about this center (refer
to Figure 21 on page 15 ).
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 22 on page 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.
TYPICAL HORIZONTAL VENT INSTALLATION
Building
Support
Framing
SV4.5E90
ertical
V
Rise
Support
Brackets
Elbow
Ceiling
Firestop/Spacer
Figure 35
The unitized design of the Secure Vent compo-
nents 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.
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 23 on page 15.
F. 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.
Remember to maintain 1" (25 mm) clearance
to combustibles, framing members, and attic
or ceiling insulation when running vertical
chimney sections.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
Horizontal / Inclined Run
See Figure 24 on page 15 for
vertical vent section support.
SV4.5L6/12/24/36/48
Vent Sections
Support bracket spacing
every 5 ft (1.52 m)
Fireplace
Exterior
Wall
Exterior
Wall
G. Support the vertical run sections -
On the vertical run, support the venting system every 8 feet (2.4m) 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. See Figure 24 on page 15.
H. 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. See Figure 25 on
page 16.
I. Continue installation of horizontal/inclined
sections - Continue with the installation of the
straight vent sections in horizontal/inclined run
as described in Step E. Install support straps
every 5 ft. (1.52 m) along horizontal/inclined
vent runs using conventional plumber’s tape.
See Figure 35, it is very important that the
horizontal/inclined run be maintained in a
straight (no dips) and recommended to be in
a slightly elevated plane, in a direction away
from the fireplace of 1/4" rise per foot (20 mm
per meter) which is ideal, though 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" (25 mm) at all sides
for all vertical runs; and 3" (76 mm) at the
top, 1" (25 mm) at sides, and 1" (25 mm) at
the bottom for all horizontal/inclined runs.
SV4.5HT-2
Termination
SV4.5HT-2
Termination
19
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Siding
Stucco
1-1 /4" Maxi mum Rece ss of
the Square Termination into
Exterior Finishing Mate ria l
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
10 in.(254 mm)**
SV4.5HT-2
Square Termination
Ma xi mu m Extent of
Ve nt R un Se ct ion s
Relativ e to Ext erior
Su rf ac e of Framing
Last Vent Section. Use
T e l es cop i c V e n t
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 t op an d sides of th e
ter min atio n, u p t o t he
underla yment, stu cco, or
mas on r y w al l s ur fac e.
**For thicknesses greater
than 10 inches, see Table 8.
*Caulk
*Caulk
Firestop/Spacer (SV4.5HF) shown
on the exterior side of the wall. It
may also be installed on the
interior side.
SV4.5HT-2
Termination
10-1/2"
(267mm)
7"
(178)
5-1/8"
(130 mm)
12-1/8"
(308 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,
Elbow or Appliance Collar
See Figure 13 on page 11
for Min. Distance to Base
of Appliance.
Base of Appliance
3"
(76 mm)
1"
(25.4 mm)
Adapter
SV4.5RCH
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. 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 SV4.5 HT termination is to be attached, see
Figure 37. 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 37, refer to Table 8 on page 21. This table
lists the additional venting components needed
(in addition to the termination and adapter) for
a particular range of wall thicknesses.
K. Attach termination adapter - Attach the
adapter (adapter - SV4.5RCH - provided with the
termination) to the vent section or telescoping
vent section), elbow or appliance collar as shown
in Figure 36 in the same manner as any SV4.5
vent component (refer to Step E).
L. 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 inch
spacer clearance at the top as shown in Figure
36, and nail into place.
Figure 36
Installing the Square Horizontal Termination (SV4.5HT-2)
(The Firestop/Spacer may also be installed over
the opening at the interior side of the framing.)
M. Install the desired termination -
1. Install the square termination (SV4.5HT-2
or SV4.5HTSS)- For the last step , from out-
side the exterior wall, slide the collars of the
termination onto the adapter (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" (32 mm) as
shown in Figure 37.
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). pipe.
IMPORTANT: 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,
we recommend the use of a Termina-
tion Guard. See Page 36. This can be
purchased at your local dealer.
20
Figure 37
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.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
HORIZONTAL VENT FIGURES/TABLES
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 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.
Note: It is very important that the horizontal/inclined run be maintained
in a straight (no dips) and recommended to be in a slightly elevated
plane, in a direction away from the fireplace of 1/4" rise per foot (20
mm per meter) which is ideal, though 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.
WARNING
Under no circumstances, may separate sections of
concentric flexible vent pipe be joined together.
Venting Components Required for Various Exterior Wall Thick-
nesses, when using Typical Termination Kits
Vent Components Required Exterior Wall Thickness - inches (mm)
Termination Kit Only 6 to 9-1/4 (152 to 235)
Termination Kit and 6 In. Vent
Section (SV4.5L6)
Termination Kit and 12 in.
Vent Section (SV4.5L12)
Termination Kit and Tele-
scopic Section (SV4.5L12)
Table 8
10-3/4 to 14 (273 to 356)
16-3/4 to 20 (426 to 508)
11-3/4 to 20 (299 to 508)
Note: See Figure 37 showing wall thickness range
when using SV4.5HT-2 termination kit.
TABLE F
H Maximum V Minimum
(meters)
feet
(0.914)
3
**When using Secure
Flex, use Wall Firestop/
Spacer SF4.5HF.
feet
Elbow Only
(meters)
H
Wall Firestop/
Spacer
SV4.5HF**
Square termination (SV4.5HT-2) shown.
See Table 3 as an aid in venting component selection
for a particular range of exterior wall thicknesses.
Figure 39: Top Vent - ONE 90-DEGREE ELBOW -
ELBOW CONNECTION AT APPLIANCE
TABLE G
H Maximum
(meters)
feet feet
(1.524)
5
V Minimum
(meters)
1 (0.305)
10 (3.048) 2 (0.610)
15 (4.572) 3 (0.914)
20 (6.096) 4 (1.219)
V + H = 40 feet (12.2 m) Max.
H = 20 ft. (6.096 m) Max.
Example: If 20 feet of (H)
horizontal vent run is needed,
then 4 feet minimum of (V)
vertical vent will be required.
This table shows a 1 (V) to 5
(H) ratio. For every 1 foot of
(V) vertical, you are allowed
5 feet of (H) horizontal run,
up to a maximum horizontal
run of 20 feet.
V
H = 28 in. (711 mm) Maximum.
H
Wall Firestop/
Spacer
7 in
(178 mm)
SV4.5HF**
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
Only the square termination (SV4.5HT-2) may be used.
See Table 8 as an aid in venting component selection
for a particular range of exterior wall thicknesses.
Figure 38: Rear Vent - NO ELBOWS
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.
Square termination (SV4.5HT-2) shown.
See Table 8 as an aid in venting component selection
for a particular range of exterior wall thicknesses.
Figure 40: Top Vent - ONE 90-DEGREE ELBOW -
ELBOW CONNECTION NOT DIRECTLY AT APPLIANCE
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
H
V
Ceiling
Firestop/
Spacer
SV4.5VF*
21
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
HORIZONTAL VENT FIGURES/TABLES (continued)
H
H
1
Ceiling
Firestop/Spacer
SV4.5VF*
Wall Firestop/
Spacer
SV4.5HF**
V
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
TABLE H
Maximum H Maximum
+H
H
1
(meters)
feet
(1.524)
5
(3.048)
10
(4.572)
15
(6.096)
20
V + H + H1 = 40 feet (12.2 m) Max.
H = 8 feet (2.438 meters) Max.
H + H1= 20 feet (6.096 meters) Max.
(meters)
feet
2 (0.610) 1 (0.305)
4 (1.219) 2 (0.610)
6 (1.829) 3 (0.914)
8 (2.438) 4 (1.219)
V Minimum
feet
(meters)
Example: If 20 feet of (H) horizontal vent run is needed,
then 4 feet minimum of (V) vertical vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For every 1 foot of
(V) vertical, you are allowed 5 feet of (H) horizontal run,
up to a maximum horizontal run of 20 feet.
See Table 8 on page 21 as an aid in venting component
selection for a particular range of exterior wall thicknesses.
Square termination (SV4.5HT-2) shown.
Figure 41: Rear Vent - TWO 90-DEGREE ELBOWS
Wall Firestop/Spacer
SV4.5HF**
H
1
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
Wall Firestop/Spacer
SV4.5HF**
Ceiling Firestop/Spacer
SV4.5VF*
Square termination (SV4.5HT-2) shown.
See Table 8 on page 21 as an aid in venting component
selection for a particular range of exterior wall thicknesses.
Figure 42: Top Vent - TWO 90-DEGREE ELBOWS
TABLE J
+ H
H
Maximum
1
(meters)
feet
H
V
(0.914) Elbow Only
3
(1.524)
5
(3.048)
10
(4.572)
15
(6.096)
20
V +H+ H1 = 40 feet (12.2 m) Max.
+ H1 = 20 ft. (6.096 m) Max.
H
V Minimum
(meters)
feet
1 (0.305)
2 (0.610)
3 (0.914)
4 (1.219)
Example: If 20 feet of (H) horizontal vent run
is needed, then 4 feet minimum of (V) vertical
vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For
every 1 foot of (V) vertical, you are allowed 5
feet of (H) horizontal run, up to a maximum
horizontal run of 20 feet.
An elbow is acceptable as 1 foot of vertical
rise except where an elbow is the only vertical
component in the system. See Figure 39.
22
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
HORIZONTAL VENT FIGURES/TABLES (continued)
Wall Firestop/Spacer
SV4.5HF**
H
1
H
2
+ H1+ H
H
feet feet feet
Maximum
2
(meters)
H Maximum
5 (1.524) 2 (0.610) 1 (0.305)
10 (3.048) 4 (1.219) 2 (0.610)
(4.572)
15
6 (1.829) 3 (0.914)
20 (6.096) 8 (2.438) 4 (1.219)
TABLE K
V + H + H1+ H2 = 40 feet (12.2 m) Max.
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
Ceiling
Firestop/Spacer
SV4.5VF*
V
H = 8 feet (2.438 meters) Max.
H + H1+ H2= 20 feet (6.096 meters) Max.
Example: If 20 feet of (H) horizontal vent run
is needed, then 4 feet minimum of (V) vertical
vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For every
1 foot of (V) vertical, you are allowed 5 feet of
H
(H) horizontal run, up to a maximum horizontal
run of 20 feet.
Square termination (SV4.5HT-2) shown.
See Table 8 on page 21 as an aid in venting component selection for a particular range of exterior wall thicknesses.
(meters)
V Minimum
(meters)
Figure 43: Rear Vent - THREE 90-DEGREE ELBOWS
*When using Secure Flex, use
Ceiling Firestop/Spacer SF4.5VF.
H
1
Wall Firestop/Spacer
SV4.5HF**
V
1
**When using Secure Flex, use
Wall Firestop/Spacer SF4.5HF.
Wall Firestop/Spacer
SV4.5HF**
Square termination (SV4.5HT-2) shown.
See Table 8 on page 21 as an aid in venting component
selection for a particular range of exterior wall thicknesses.
Ceiling
Firestop/Spacer
SV4.5VF*
H
TABLE L
H Maximum
(meters)
feet
(1.524)
5
(1.524)
5
10
15
20
V
(3.048)
(4.572)
(6.096)
+ H1 = 20 feet (6.096 m) Max.
H
+ V +H+ H = 40 ft. (12.192 m) Max.
V
1 1
V Minimum
feet
Elbow Only
1
2
3
4
Example: If 20 feet of (H) horizontal vent
run is needed, then 4 feet minimum of (V)
vertical vent will be required.
This table shows a 1 (V) to 5 (H) ratio. For
every 1 foot of (V) vertical, you are allowed 5
feet of (H) horizontal run, up to a maximum
horizontal run of 20 feet.
An elbow is acceptable as 1 foot of vertical
rise except where an elbow is the only vertical component in the system. See Figure 39.
(meters)
(0.305)
(0.610)
(0.914)
(1.219)
Figure 44: Top Vent - THREE 90-DEGREE ELBOWS
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
23
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
5" (127 mm)
Radius Minimum
Flexible Vent Section
GEAR
CLAMPS
Adapter
(SV4.5RF)
Appl y ONLY M IL-PAC BLACK H IGH
TEMPERATURE SEALANT (Catalog No.
10K81) to the outside surface of both
collars of the adapter (be especially
careful to fill the grooves of the outer
collar to be covered by the flexible
pipe ) and slide flex ible pipe over
inn er and ou ter adap ter coll ars.
NOTE: OUTER PIPE IS PULLED AWAY TO
SHOW THE DETAIL OF THE INNER PIPE
FLEX VENT
1-3/4 in. (44 mm)
Flexible Pipe and
Adapter Outer
Collar Overlap
1-3/4 in. (44 mm)
Flexible Pipe and
Adapter Inner
Collar Overlap
SECURING SCREW
(3 PLACES EQUALLY SPACED
JUST BELOW GEAR CLAMP)
Attach Adapter to Appliance
Collar, or Secure Vent Sections
SECURING SCREW
(3 PLACES EQUALLY SPACED
JUST BELOW GEAR CLAMP)
VERTICAL OR HORIZONTAL VENTING USING
SECURE FLEX KITS AND COMPONENTS
Secure Flex venting kits and components may
be used in any venting application where rigid
Secure Vent (SV4.5) direct vent components
can be used. All restrictions, clearances and
allowances that pertain to the rigid piping apply
to the flexible venting. Secure Flex kits may
not be modified; also, under no circumstances
may separate sections of flex pipe be joined
together. Secure Flex kits may be added to
the end of a vent run made up of rigid Secure
Vent (SV4.5) vent sections provided that doing
so does not violate any of the venting length,
height, routing, horizontal to vertical ratio requirements or clearance considerations detailed
in this manual.
Secure Flex kits come with an included adapter
that can be fitted to the appliance collar or the
inclined channel end of the last Secure Vent
(SV4.5) vent section in a rigid system in the
exact same fashion as any other Secure Vent
section. Align the dimpled end of the adapter
over the previously installed section or appliance
collar, adjusting the radial alignment until the
four locking dimples of the adapter are aligned
with the inlets of the four incline channels of
the last vent section or collar. Push on the
adapter until it fully engages, then twist the
adapter clockwise running the dimples down
and along the incline channels until they seat
at the end of the channels.
Attach the flexible vent to the adapter as follows (see Figure 45):
A. Install the Inner Flex Pipe -
1. Install the small gear clamp loosely around
the inner flexible vent pipe, push it back out
of the way.
2. Apply a bead of Mill-Pac Black (700°F) high
temperature sealant - Catalog No. 10K81) to
the inner adapter collar, approximately 1/2 inch
from the end.
3. Pull and extend the inner flexible vent pipe.
4. Slide the inner flex pipe over the adapter
collar. Ensure the flexible vent pipe completely
engages the adapter collar to a distance of
1-3/4 inches from the end, and that it is free
from damage or tears.
5. Slide the gear clamp down and tighten it
fully to secure the flexible vent to the adapter
inner collar approximately 3/4 inch from the
end of the flex.
6. Install three screws 120 degrees apart
through the flexible vent pipe and into the
adapter collar just below the gear clamp to
provide additional security to the connection.
B. Install the Outer Flex Pipe -
1. Install the large gear clamp loosely around
the outer flexible vent pipe, push it back out
of the way.
24
Figure 45
2. Apply a bead of Mill-Pac Black (700°F) high
temperature sealant - Catalog No. 10K81) to
the outer adapter collar; to the grooves of the
collar which extend approximately 1 inch from
the end and to the flat surface, approximately
1-3/8 inches from the end.
3. Pull and extend the outer flexible vent pipe.
4. Slide the outer flex pipe over the adapter
collar. Ensure the flexible vent pipe completely
engages the adapter collar to a distance of 1³⁄₄
inches from the end, and that it is free from
damage or tears.
5. Slide the gear clamp down and tighten it
fully to secure the flexible vent to the adapter
outer collar approximately 3/4 inch from the
end of the flex.
6. Install three screws 120 degrees apart
through the flexible vent pipe and into the
adapter collar just below the gear clamp to
provide additional security to the connection.
C. Route Flex Vent -
Ensure that the flex vent is properly routed to
provide the required clearance. Do Not allow
the flexible vent to bend in a radius tighter than
5" (127 mm). Refer to Figure 46. Support
horizontal sections of flex with metal straps at
2 foot (0.61 m) intervals.
D. Install Firestop/Spacers at ceilings and walls -
When Secure Flex penetrates a wall or ceiling,
a firestop/spacer is required: use the SF4.5 VF
firestop/spacer for ceilings and the SF4.5 HF
firestop/spacer for walls.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
See the appropriate sections and figures shown
throughout the venting section for their installation requirments.
Figure 46
E. Attach Flex Vent to Termination -
Secure Flex components can be purchased
separately and attached to bulk lengths of
Secure Flex flexible tubing cut to size at the
job site. Secure the flexible vent to the Secure
Flex terminations in the same manner (see
Figure 45 ) as it was attached to the adapter.
Note: Secure Flex vent must be attached
to Secure Flex terminations only. DO NOT
substitute Secure Vent terminations or the
Secure Vent adapter for Secure Flex components. The collars of Secure Flex terminations
and adapters have a different circumference
than that used with the Secure Vent pipe.
Additionally, Secure Flex components have
an extended length center tube for use in
attaching the flexible vent.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
TP-TH
TP
TH
APPLIANCE- MOUNTED
ON/OFF SWITCH
(OPTIONAL)
BK/W(1)
BK/W(1)
WALL-MOUNTED ON/OFF SWITCH (OPTIONAL)
THERMOSTAT (OPTIONAL)
JUNCTION BOX
BLACK
W
GR
120 V
AC
WALL MOUNTED CONFIGURATION FOR FAN SWITCH (OPTIONAL)
BK
R
WIRING DIAGRAM MILLIVOLT GAS VALVES
THERMOPILE
GAS VALVE
FAN
(OPTIONAL)
1. If any of the original wire as supplied must be replaced,
1. it must be replaced with Type AWM 105°C – 18 GA. wire.
2. 120V, 60Hz – Less than 3 amps.
BK
Transf.
120 V.
24 V
Factory Wired Field Wired
BL
Electronic Wiring Diagram (Honeywell)
Showing the Blower Wiring for the Optional
FBK-250 Kits
R
WH
BL
W
Gas Valve
B
R
IGNITER
BK
Schematic Representation Only
*ON/OFF Switch (Integral
with Gas Valve)
Optional
FBK-250
Module
*Leave the ON/OFF switch, which is integral
with the gas valve, in the ON position.
G
OPTIONAL APPLIANCE-MOUNTED ON/OFF SWITCH
OR OPTIONAL WALL SWITCH OR OPTIONAL THERMOSTAT
OR OPTIONAL REMOTE RECEIVER
PILOT
ASSEMBLY
OPT
BLOWER
Junction Box
White
Green
Red
Black
Neutral
Side of
Receptacle
Tab Intact
Green
Ground
Screw
Hot
Side of
Receptacle
Tab
Broken
Optional
Accessory
Switch
120 VAC - Black
neerG-dnuorG
etihW-lartueN
1. If any of the original wire as supplied must be replaced,
1. it must be replaced with Type AWM 105°C – 18 GA. wire.
2. 120V, 60Hz – Less than 3 amps.
BK
Transf.
120 V.
24 V
Factory Wired Field Wired
BL
Electronic Wiring Diagram (Honeywell)
Showing the Blower Wiring for the Optional
FBK-100 and FBK-200 Kits
R
W
BL
W
Gas Valve
B
R
IGNITER
BK
*Blower speed control switch is provided in FBK200 blower kit.
Schematic Representation Only
**ON/OFF Switch (Integral
with Gas Valve)
**Leave the ON/OFF switch, which is integral
with the gas valve, in the ON position.
OPTIONAL APPLIANCE-MOUNTED ON/OFF SWITCH
OR OPTIONAL WALL SWITCH
OR OPTIONAL THERMOSTAT
OR OPTIONAL REMOTE RECEIVER
G
OPT
BLOWER
PILOT
ASSEMBLY
Junction Box
White
Green
Red
Black
Neutral
Side of
Receptacle
Tab Intact
Green
Ground
Screw
Hot
Side of
Receptacle
Tab
Broken
120 VAC - Black
neerG-dnuorG
Optional
Accessory
Switch
etihW-lartueN
Step 5. FIELD WIRING
CAUTION
The ground supply lead must be
connected to the wire attached to the
green ground screw located on the
outlet box (see wiring diagrams).
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.
Figure 48
Refer to Section A for millivolt appliances and
Section B for electronic appliances. The gas
valve is set in place and pre-wired at the factory
on both models.
A. Millivolt Wiring (see Figure 47)
Millivolt units are not provided with any
factory-installed controls; therefore, one of the
optional control switches is required to operate
the unit (ON/OFF Wall Switch, Unit-Mountable
ON/OFF Switch*, Thermostat, Remote Control).
See the fireplace Care and Operation Instruc-
tions for details.
[*If using a Unit-Mountable ON/OFF Rocker Switch
with an optional Style View Door, mount the Rocker
Switch on the door instead of the unit.]
1. If installing an ON/OFF wall switch or ther-
mostat, mount it in a convenient location on
a wall near the fireplace.
2. Wire the control switch within the millivolt
control circuit using the 15 feet of 2 conductor wire supplied with the unit.
Note: The supplied 15 feet of 2 conductor
wire has one end of each conductor connected to the gas valve circuit and the other
end of each conductor placed loose inside
the bottom compartment.
Verify proper operation after servicing.
S’assurer que l’appareil fonctionne adéquatement une fois l'entretien terminé.
Figure 47
CAUTION
In millivolt systems, do NOT connect
a Wall Switch to a 120V power supply.
B. Electronic Wiring
The electronic gas valve has an integrated ON/
OFF burner control switch. One of the following optional controls also may be used: ON/
OFF Wall Switch, Thermostat, Remote Control
(see fireplace Care and Operation Instructions
for details.).
Note: Electronic models must be connected to
the main power supply.
1. Route a 3-wire 120Vac 60Hz 1ph power
Figure 49
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
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 13, Page 11).
3. Remove the cover plate knockout; then feed
the power supply wire through the knockout
opening and into the unit junction box.
4. See Figures 48 & 49. Connect the black
power supply wire to the lower outlet’s red
pigtail lead.
Connect the white power supply wire to the
outlet’s common terminal.
5. Connect the ground supply wire to the
pigtail lead attached to the outlet’s green
ground screw.
(see Figures 48 & 49)
25
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
BLOWER CONTROL CIRCUIT WIRING
Receptacle
Receptacle
Note: Remote receiver should be located in the
wall, or if installed in the control compartment,
pulled all the way forward and completely to the
left or right against the corner posts.
6. If wall-mounted ON/OFF control or thermo-
stat is to be used, mount it in a convenient
location on a wall near the fireplace.
7. If an optional control is to be used, wire it in
the low voltage circuit as shown in Figures
48 and 49.
Note: The supplied 15 feet of 2 conductor wire
has one end of each conductor connected to
the gas valve circuit and the other end of each
conductor placed loose inside the bottom
compartment.
8. If the optional control switch is installed,
turn the appliance-mounted ON/OFF burner
control switch to the OFF position.
9. After the wiring is complete, replace the
cover plate.
Note: The gas valve-mounted ON/OFF switch
is shown in Figures 48 and 49. It is integral
with the gas valve and should be set to the
ON position.
WARNING
neerG - dnuorG
etihW - lar
t
ueN
Black
White
Green
Plug blower
into this
receptacle
Blower
Ground
120V, 60HZ, 1PH
* Wall-mounted
ON/ OFF Blower
Switch or Variable
Speed Control Switch.
120 VAC - Black
Junction Box
Tab
Broken
Tab Intact
Field Wired
Factory Wired
Red
Hot
Side of
Neutral
Side of
Green
Ground
Screw
A sediment trap is recommended in the gas
piping within the home to prevent moisture
and debris in the line from damaging the valve.
These appliances are equipped with a gas flex
line for use (where permitted) in connecting the
unit to the gas line. A gas flex line is provided
to aid in attaching the direct vent appliance to
the gas supply. The gas flex line can only be
used where local codes permit. Refer to Figure
51 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 in the lower
control compartment.
To access the valve open the lower control
compartment door (see Figure 52 ) by pushing
in the right top corner of the door. (The door
is hinged at the bottom.) Remove the bottom
compartment door by sliding the hinge pin,
located at the door’s left side, to the right until
it disengages from the left corner post hole.
Pull the door diagonally to the left, away from
the fireplace.
The millivolt control valve has a 3/8"
(10 mm) NPT thread inlet port. The electronic
control valve has a 1/2" (13 mm) NPT thread
inlet port and is fitted with a 1/2" x 3/8" (13 mm x
10 mm) NPT fitting.
Electronic models of these appliances are equipped with a threeprong (grounding) plug utilized
in connecting the electronic
components to the junction box
in the lower compartment. This
grounding plug provides protection against shock hazard and
should be plugged directly into
the properly grounded threeprong receptacle. DO NOT cut
or remove the grounding prong
from the plug.
Step 6. WIRING - OPTIONAL FORCED AIR
BLOWER KIT
FBK-100 and FBK-200 Kits
(See Figure 48 on page 25) -
An electrical outlet box is provided for the
installation of the FBK-100, FBK-200 forced air
blower kits. Electrical power must be provided
to this box to operate these blowers. Install the
blower kits according to the installation instructions provided with the kits.
Figure 50: Junction Box Wiring
FBK-250 Blower Kit
(See Figure 49 on page 25)-
An electrical outlet box is provided for the
installation of the FBK-250 forced air blower
kit. Electrical power must be provided to this
box to operate these blowers. Install the blower
kit according to the installation instructions
provided with the kit.
Note: The tab connecting the receptacles of
the outlet box must be broken in FBK-100 and
FBK-200 blower kit applications. See Figure 50.
Step 7. CONNECTING GAS LINE
Make gas line connections. All codes require a
shut-off valve mounted in the supply line. Figure
51 illustrates two methods for connecting the
gas supply. The flex-line method is acceptable
in the U.S., however, Canadian requirements
vary depending on locality. Installation must
be in compliance with local codes.
Secure all joints tightly using appropriate
tools and sealing compounds (ensure propane
resistant compounds are used in propane
applications).
All codes require a shut-off valve mounted
in the supply line. The orientation of the
shut-off valve should face the front. Figure
51 illustrates two methods for connecting the
gas supply. A sediment Trap is recommended
to prevent moisture and debris in the gas line
for damaging the valve.
TEST ALL CONNECTIONS FOR GAS LEAKS
(FACTORY AND FIELD):
WARNING
Never use an open flame to
check for leaks.
26
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
MILLIVOLT
Thermocouple
Hood Igniter Rod
3/8" Min
(9 mm)
Thermopile
Pilot
Nozzels
Gas
Stub
1/2" x 3/8" Flare
Shut-Off Valve
3/8" Flex Tubing
3/8" NPT x 3/8"
Flare Fitting
3/8" Nipple
3/8" Union
3/8" Close Nipple
3/8" Shut-Off Valve
1/2" x 3/8"
Reducer
Gas
Valve
Optional Gas Flex Line Connector
ELECTRONIC
Proper Flame
Adjustment
Pilot
Nozzle
3/8 To 1/2 Inch
(9 mm to 13 mm)
Ground
Electrode
Flame Rod
Hot Surface
Igniter
Subsequent lighting of the appliance will not
require such purging. Inspect the pilot flame
(remove logs, if necessary, handling carefully).
Millivolt Appliance Checkout
The pilot flame should be steady, not lifting
or floating. Flame should be blue in color with
traces of orange at the outer edge.
The top 3/8" (10 mm) at the pilot generator
(thermopile) and the top 1/8" minimum (tip)
of the quick drop out thermocouple should be
engulfed in the pilot flame.
The flame should project 1" (25 mm) beyond
the hood at all three ports (see Figure 53).
Replace logs if removed for pilot inspection.
Figure 51: Gas Connection
SIT Gas Valve
Piezo
Ignitor
Millivolt Gas Valve Showing
Piezo Ignitor Location
Figure 52
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
gas control knob (off/pilot/on) 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.
Step 8. VERIFYING APPLIANCE
OPERATION
With gas line installed, run initial system
checkout before closing up the front of the
unit. Follow the pilot lighting instructions
provided in the Care and Operation Instruc-
tions. For piezo igniter location on millivolt
appliances, see Figure 47 on Page 25.
Note: Lighting Instructions are also found on
the literature tag tied to the gas piping next
to the gas valve. To access the tag, open the
lower control compartment door (Figure 52)
by pushing in simultaneously the left and right
top corners of the door. (The door is hinged at
the bottom). Remove the bottom compartment
door by sliding the hinge pin, located at the
door’s left side, to the right until it disengages
from the left corner post hole.
When first 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.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
To light the burner; turn “ON” the remote wall
switch and rotate the gas valve control knob
counterclockwise to the “ON” position (“ON”
will be at the top side of the valve).
Figure 53
Electronic Appliance Checkout
To light the burner, turn ‘ON’ the unit-mounted
ON/OFF switch or the optional remote wall
switch. Ensure the igniter lights the pilot. The
pilot flame should engulf the flame rod as shown
in Figure 54.
Figure 54
27
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Glowing Embers
Step 9. INSTALL VOLCANIC STONE,
GLOWING EMBERS AND LOGS
NOTE: Turn off all electricity to the appliance
before you install volcanic stone, embers and
logs. 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.
Step 1. Remove the appliance front door (see
Removing Glass Encloslure panel on page 32.
Step 2. Install decorative volcanic stone -
Sprinkle the decorative volcanic stone in a pleasing pattern. The volcanic stone should be placed
directly on top of the firebox bottom, along the
front and to the back at the right and left sides of
the burner. Position any optional ceramic fiber
liners before placing the stone. Logs should be
positioned after the volcanic stone.
Note: 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).
Glowing Embers
Separate into Quarter
Size (separate) Pieces
Bag of Glowing
Embers (rockwool)
Figure 55
Step 3. Separate the Glowing Ember
(Rockwool) into pieces about the size of a
quarter (Figure 55 ). Keep the pieces fluffed
up, not matted. Distribute these pieces over
the front surface of the burner, as shown in
Figure 56. Do not use more than is necessary. When properly positioned, the Glowing
Embers will cover approximately 65% of the
front burner and with no appreciable gaps or
openings. Ensure that the main burner ports
remain uncovered by the ember material.
Figure 56
Step 4. Placement of Logs -
All top logs that rest on lower logs, do so over
notches, indents or nubs. Proper log placement
is critical to prevent sooting. Logs should be
placed in the gaps between the flame peaks and
should be positioned so they do not impinge
the flames.
Step 5. Position the individual logs as shown in
Figures 57, 58 and 59. Logs should be placed
in the order shown. All logs that have notches
to fit over the grate tines should be positioned
with these notches directly against the grate.
Handle logs carefully to prevent breakage.
Proper log placement is critical to encourage
outstanding flame appearance and prevent
sooting. When positioned properly as shown,
logs will be positioned between flame peaks
and will not impinge any flames.
Refer to Figure 57 for MPD-3328 Series appliances, to Figure 58 for MPD-3530 Series
appliances and to Figure 59 for MPD-4035
and MPD-4540 Series appliances.
REFERENCE
Firebox Accessories / Parts
Cat. No. Model No. Description
88L53 FGE Bag of Glowing Embers
80L42 FDVS
Bag of Decorative
Volcanic Stone
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,
vermiculite, 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.
28
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
MPD-3328 LOG PLACEMENT
Log
Number Description (Stamped #)
1
3
2
Position the individual logs as shown below. Logs should be placed
4
6
5
in the order shown. Position the rear log on the brackets at the
rear of the firebox with the log's notches directly over the brackets.
Position the right log (log no. 3) by inserting the pin from the rear
log into the hole on its upper end. Place the left log and then the
smaller left and right top logs. All logs that have notches to fit over
the grate tines should be positioned with these notches directly
against the grate. All top logs that rest on lower logs, do so over
flattened mounting faces in the bottom logs.
1 Log, Rear (39-12)
2 Log, Left (39-1)
3 Log, Right (39-2)
4 Log, Top Center (39-13)
5 Log, Top/Left (39-3 )
6 Log, Top/Right (39-4)
Catalog Number for the entire log set: 24M15
Proper log and twig placement is critical to encourage outstanding
flame appearance and prevent sooting.
1
4
3
2
5
6
Figure 57
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
29
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
MPD-3530 LOG PLACEMENT
Log
1
3
2
Number Description (Stamped #)
1 Log, Rear (39-5)
2 Log, Left (39-1)
3 Log, Right (39-2)
4 Log, Top Center (39-6)
5 Log, Top/Left (39-3)
6 Log, Top/Right (39-4)
Catalog Number for the entire log set: 24M22
4
5
6
Position the individual logs as shown below. Logs should be placed
in the order shown. Position the rear log on the brackets at the
rear of the firebox with the log's notches directly over the brackets.
Position the right log (log no. 3) by inserting the pin from the rear
log into the hole on its upper end. Place the left log and then the
smaller left and right top logs. All logs that have notches to fit over
the grate tines should be positioned with these notches directly
against the grate. All top logs that rest on lower logs, do so over
flattened mounting faces in the bottom logs.
Proper log and twig placement is critical to encourage outstanding
flame appearance and prevent sooting.
1
4 3
30
2
Figure 58
5
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
6
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
MPD-4035 AND MPD-4540 LOG PLACEMENT
Log
1
2
3
Number Description (Stamped #)
1 Log, Center (39-8)
2 Log, Rear (138)
3 Log, Right (39-10)
4 Log, Left (39-9)
5 Log, Top/Left (39-11)
6 Log, Top/Right (39-11)
Catalog Number for the entire log set: 24M25
4
5
6
Position the individual logs as shown below. Logs should be placed
in the order shown. Position the center log on the burner first, then
place the glowing embers as shown in Figure 56. Place the rear
log, both the right and left, and then the smaller left and right top
logs. All logs that have notches to fit over the grate tines should
be positioned with these notches directly against the grate. All top
logs that rest on lower logs, do so over flattened mounting faces
in the bottom logs.
Proper log and twig placement is critical to encourage outstanding
flame appearance and prevent sooting.
1
4
3
2
Figure 59
5
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
6
31
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Step 10. REMOVING AND INSTALLING
THE GLASS DOOR
WARNING
• Do not attempt to substitute the
materials used on these doors,
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(s) of this appliance must only be replaced as
a complete unit as provided
by the manufacturer. Do not
attempt to replace broken,
cracked or chipped glass separately.
• 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.
Removing the Glass Enclosure Panel
(see Figure 60 )
Remove the top louver assembly or radiant
panel.
To access the glass door securing latches,
first open the lower control compartment door
(Figure 60 ) by pushing in simultaneously the
left and right top corners of the door (the door
is hinged at the bottom).
Remove the bottom compartment door by
sliding the hinge pin, located at the door’s left
side, to the right until it disengages from the
left corner post hole. Pull the door diagonally
to the left, away from the fireplace.
Locate the two (2) latches at the top of the
control compartment and disengage them from
the door frame bottom vee-flange, pulling down
on their handles to open them.
Installing the Glass Enclosure Panel
(see Figure 60 )
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 bottom of the door held away from the
fireplace (Figure 60 ). Hook the top flange of
the door frame over the top of the firebox frame.
Let the bottom of the door frame swing gently
in towards the fireplace ensuring that the gasket
seats evenly as the door frame draws shut.
Fasten the two latches located underneath the
firebox floor to the door's vee-flange. Close
both the latches securely.
Lower Compartment Door and Hinge
Glass
Door
Glass Door Frame
Bottom Vee-flange
Figure 60
Glass Door Frame
Top Flange
Firebox Floor
Step 11. BURNER ADJUSTMENTS
Flame Appearance and Sooting
Proper flame appearance is a flame that is blue
at the base and becomes yellowish-orange in
the body of the flame.
When the appliance is first lit, the entire flame
may be blue and will gradually turn yellowishorange during the first 15 minutes of operation.
If the flame remains 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, first
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 flames 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.
Air Shutter Adjustment Guidelines
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
32
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
WARNINGS
• Air shutter adjustment should
only be performed by a qualified professional service technician.
• Ensure front glass panel are
in place and sealed during
adjustment.
CAUTIONS
• Soot will be produced if the
air shutter is closed too much.
Any damage due to sooting,
resulting from improperly
setting the air shutter, is not
covered under the warranty.
• The air shutter door and
nearby appliance surfaces
are hot. Exercise caution to
avoid injury while adjusting
flame appearance.
1. Refer to Figures 61, 62 and 63 for proper
flame appearance. To adjust the flame, rotate
the adjustment rod toward the back or toward
the front of the fireplace (rod located in the
lower control area). Position the air shutter
to the factory setting as shown in the table
in Figure 64.
2. Light appliance (follow lighting procedure
on lighting label in control compartment or
in the Care and Operation Instructions).
3. Allow the burner to operate for at least 15
minutes while observing the flame continuously to ensure that the proper flame appearance has been achieved. If the following
conditions are present, adjust accordingly.
• If flame appears weak or sooty, adjust
the air shutter, incrementally, to a more
open position until the proper flame
appearance is achieved.
• If flame remains blue, adjust the air
shutter, incrementally, to a more closed
position until the proper flame appearance is achieved.
4. Leave the control knob (OFF/PILOT/ON)
in the ON position and the burner ON/OFF
switch (and remote switches, if applicable)
in the OFF postion.
5. When satisfied that the burner flame appear-
ance is normal, reinstall the lower control
compartment door, then proceed to finish
the installation.
Figure 61 MPD-3328 MODEL
Figure 62 MPD-3530 MODEL
Figure 63 MPD-4035 AND MPD-4540 MODEL
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
33
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Adjustment Rod Up
(Fully Open Position)
Air Shutter
Burner Tube
Adjusting Set Screw
Adjustment Rod Down
(minimum air
opening position)
Figure 64
Step 12. HOOD INSTALLATION
Refer to Figures 65 and 66. All models must
have hoods installed prior to operating.
On all clean face units, slide the hood into the slots
on the lower edge of the radiant panel (Figure 65).
On louvered face units, slide the hood into the slots
on the lower edge of the cabinet top (Figure 66).
FINISHING REQUIREMENTS
RIAYROTCAF
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RETTUHS
GNITTES
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.taN 23/1 )8.O(
8233-TDPM
.porP 61/3 )67.4(
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8233-RDPM
.porP 61/3 )67.4(
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0353-DPM
5304-DPM
0454-DPM
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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 (Figures 65 and 66 )
See Page 5 for
Cold Climate Insulation and
Page 8 for Clearances.
Combustible
Finished Wall
Materials
Combustible
material may
touch top of
appliance.
Combustible
materials
NOT allowed
below this point
on face
of appliance.
Hood must be installed as shown.
Figure 65
Combustible
Finished Wall
Materials
Combustible
material may
touch top of
appliance.
Combustible
materials
NOT allowed
below this point
on face
of appliance.
This area must remain
clear of combustible
materials.
Header
Spacing
Top Standoff
Top of Appliance
Radiant panel
Top of Door Frame
Clean Face Models
This area must remain
clear of combustible
materials.
Header
Spacing
Top Standoff
Top of Appliance
Louvers
Top of Door Frame
Min. 1"
(25 mm)
Min. 1"
(25 mm)
Hood must be installed as shown.
Louver Face Models
Figure 66
34
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
STEP 13. 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 safe operation of this appliance.
ATTACHING SAFETY-IN-OPERATION
WARNINGS
It is required that the safety instruction labels
furnished with the fireplace be affixed to the operation and control point of the fireplace. A safety
instruction label must be affixed to the wall switch
plate where the fireplace is turned on and off (See
Figure A) or wall thermostat (See Figure B) and if
used on the remote control handheld transmitter
(Figure C). 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 switch or wall thermostat that
controls the fireplace (verify the switch operates
the fireplace by turning it on and off). Clean the
wall switch plate or wall thermostat thoroughly
to remove any dust and oils. Affix the label to
the surface of the plate of the wall switch that
controls the fireplace (Figure A) or the wall
thermostat (Figure B). Choose the language
primarily spoken in the home. If unknown, affix
the English language label.
2. If a remote control is used to control the fireplace,
locate the transmitter and clean it thoroughly
to remove any dust and oils. Affix the label to
the surface of handheld transmitter (Figure C).
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
1-800-9-LENNOX
Note: English is red text on clear label. French and
Spanish are white text on black label.
APPOSITION DES MISES EN GARDE RELATIVES
À LA SÉCURITÉ D’UTILISATION
Il est impératif que les étiquettes de sécurité fournies
avec le foyer soient collées à côté des dispositifs
de contrôle du foyer. Une étiquette de sécurité doit
être collée sur la plaque de l’interrupteur contrôlant
l’allumage du foyer (voir Figure A) ou sur le thermostat
mural (voir Figure B) et, le cas échéant, sur le boîtier
de la télécommande (Figure C). Pour achever l’instal-
lation 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 l’interrupteur ou le thermostat mural qui
contrôle le foyer (vérifiez que l’interrupteur
contrôle le fonctionnement du foyer en le faisant
basculer de Marche à Arrêt, et vice-versa). Nettoyez
soigneusement la plaque murale de l’interrupteur
ou le thermostat mural pour éliminer la poussière
et les traces de graisse ou d’huile. Collez l’étiquette
sur la surface de la plaque de l’interrupteur mural
qui contrôle le foyer (Figure A) ou du thermostat
mural (Figure B). Choisissez la langue qui est
principalement parlée dans la résidence du
propriétaire. En cas de doute, collez l’étiquette en
anglais.
2. Si une télécommande est utilisée pour contrôler
le foyer, nettoyez la soigneusement pour éliminer
la poussière et les traces de graisse ou d’huile.
Collez l’étiquette sur le boîtier de la télécommande (Figure C). 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
1-800-9-LENNOX
Remarque : Le texte anglais est rouge sur un support
transparent. Le texte français et espagnol est blanc
sur un support noir.
COLOCACIÓN DE ADVERTENCIAS DE SEGURIDAD
EN OPERACIÓN
Se requiere que las etiquetas de instrucciones de
seguridad incluidas con la chimenea se coloquen en
el punto de operación y control de la misma. Se debe
colocar una etiqueta de instrucciones de seguridad
en la placa del interruptor de pared desde el cual se
enciende y se apaga la chimenea (ver la Figura A) o en el
termostato de pared (ver la Figura B) y en el transmisor
de control remoto (Figura C) si se usa. 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 interruptor o el termostato de pared
que controla la chimenea (verifique que el interruptor
opera la chimenea encendiéndola y apagándola).
Limpie bien la placa del interruptor o el termostato
de pared para quitar el polvo y aceite. Pegue la
etiqueta en la superficie de la placa del interruptor que
controla la chimenea (Figura A) o en el termostato
de pared (Figura B). Seleccione el idioma que
más se habla en la casa. Si no sabe cuál es, use la
etiqueta en inglés.
2. Si se usa un control remoto para controlar la
chimenea, encuentre el transmisor y límpielo bien
para quitar el polvo y aceite. Pegue la etiqueta en
la superficie del transmisor (Figura C). Seleccione
el idioma que más se habla en la casa. Si no sabe
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
1-800-9-LENNOX
Nota: La etiqueta en inglés es transparente con texto
rojo. Las etiquetas en francés y español son negras
con texto blanco.
SAFETY LABEL
DIAGRAMS
Figure A
DIAGRAMMES DES ÉTIQUETTES
DE SÉCURITÉ
Figure B Figure C
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
DIAGRAMAS DE ETIQUETAS
DE SEGURIDAD
35
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
S
e
a
l
a
n
t
INSTALLATION ACCESSORIES
Listed Secure Vent™ Components
Cat. No. Model Description
H1968 SV4.5HT-2 Horizontal Square
Termination with
Firestop/ Spacer (H2246)
and Adaptor (74L61)
H2152 SV4.5CGV-1 Vertical Termination Cap,
High Wind
H4687 SV4.5CTS Chase Top Termination,
Square
(Ref. Instr. #750207M)
H4716 SV4.5CTS-B Chase Top Termination,
Square, Black
(Ref. Instr. #750207M)
H4717 SV4.5CTS-TC Chase Top Termination,
Square, Terra Cotta
(Ref. Instr. #750207M)
94L10* SV4.5HTSS Horizontal Small Square
Termination with
Firestop/Spacer (96K80)
and Adapter (74L61)
98L27* SV4.5HTSSL Horizontal Small Square-
Long Termination with
Firestop/Spacer (96K80)
and Adapter (74L61)
17M52 SV4.5HGS-1 Termination Guard,
Square (1 pack)
(Ref. Instr. #750109M)
17M53 SV4.5HGS-12 Termination Guard, Hori-
zontal Square (12 pack)
(Ref. Instr. #750109M)
87L02 SV4.5HGS Termination Guard for
Horizontal Square Termination (Deluxe) (1 pack)
(Ref. Instr. #750055M)
Listed Secure Vent™ Components
Cat. No. Model Description
Vent Sections
(Rigid)
The following flashings come packaged with a storm collar:
77L70 SV4.5L6 6 Inch (152 mm)
77L71 SV4.5L12 12 Inch (305 mm)
77L72 SV4.5L24 24 Inch (610 mm)
77L73 SV4.5L36 36 Inch (914 mm)
77L74 SV4.5L48 48 Inch (1219 mm)
77L75 SV4.5LA Telescopic Length Slip
Section (2" to 7-1/2" rigid)
77L76 SV4.5E45 45 Degree Elbow
77L77 SV4.5E90 90 Degree Elbow
10K81 SFMP Mill-Pac, Black, High-
Temperature Sealant
89L40 SFMP-12 Mill-Pac, Black, High-
Temperature Sealant,
Bulk 12 pack
99L02 SV4.5HRK14 Horizontal Riser Kit, 14",
(Ref. Instr. #750146M)
99L03 SV4.5HRK36 Horizontal Riser Kit, 36",
(Ref. Instr. #750146M)
96K93 SV4.5SU Support Strap
H5816 SV4.5-
TWSK10
Through Wall Shield Kit
(used to shield the
direct-vent pipe from
blown insulation)
(Ref. Instr. #750247M)
77L78 SV4.5F Flat Roof Flashing
36
H5820 SV4.5HTSK Termination Shroud
(Guard) for Horizontal
Square Termination
(1 pack)
(Ref. Instr. #750246M)
H3907 SV4.5ARSA Attic Insulation Shield w/
adjustable height, 12"-22"
77L79 SV4.5FA 1/12 to 7/12 Adjustable
Flashing
77L80 SV4.5FB 7/12 to 12/12 Adjustable
Flashing
77L81 SV4.5SC6 Storm Collar (6 per box)
H6183 SV4.5HF5 Firestop Spacer, 5", rigid
H6184 SF4.5HF5 Firestop Spacer, 5", flex
H1988 CTSA-33 Chase Top Shroud Kit,
Arch Top 3 X 3 Ft.,
(Ref. Instr. #750194M)
H1985 CTSO-33 Chase Top Shroud Kit,
Open Top 3 X 3 Ft.,
(Ref. Instr. #750193M)
H1987 CTSO-44 Chase Top Shroud Kit,
H2246 SV4.5HF-10 Firestop / Spacer-Horizon-
tal, rigid (3-1-1 spacing),
10 Pack
H2247 SV4.5VF-10 Firestop/Spacer-Vertical,
rigid (1-1-1 spacing),
10 Pack
96K92 SV4.5SP Support Plate
Open Top 4 X 4 Ft.,
(Ref. Instr. #750193M)
H1986 CTSO-46 Chase Top Shroud Kit,
Open Top 4 X 6 Ft.,
(Ref. Instr. #750193M)
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
*Only for use with MPDT/R-3328 and MPD-3530 models.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
INSTALLATION ACCESSORIES CONTINUED
Listed Secure Flex™ Components
Cat. # Model Description
These termination kits include firestop/spacer, gear clamps and flex adaptor.
60L10 SF-18 18 feet (5.49 m) *
compressed flex
(Ref. Instr. #750053M)
98K03 SF-12 12 feet (3.66 m)*
compressed flex
(Ref. Instr. #750052M)
H2248 SF4.5HF-10 Firestop / Spacer -
Horizontal, flex (3-1-1
spacing), 10 Pack
H2249 SF4.5VF-10 Firestop/Spacer-Vertical,
flex (1-1-1 spacing), 10 Pk
56L74 SFVT30 Vertical Termination for flex
(flat to 6/12) with flex adaptor,
section of rigid vent, roof
support collar assembly, roof
flashing and storm collar.
(Ref. Instr. #750052M)
56L75 SFVT45 Vertical Termination for flex
(6/12 to 12/12) with flex
adaptor, section of rigid
vent, roof support collar
assembly, roof flashing,
and storm collar.
(Ref. Instr. #750052M)
91L66 SFGC4-6 Gear Clamp 4.5 in. (114 mm)
for flex (6 pack)
91L67 SFGC7-6 Gear Clamp 7.5 in. (190.5
mm) for flex (6 pack)
H7748 H7748 36" Flex Connector
Kit. 36" of flex with two
adapters for mating two
rigid sections of vent
together.
Listed Secure Flex™ Components
Cat. # Model Description
H1969 SF4.5HT-2 Horizontal Square Termina-
77L87 SFKIT12S Square Term. for flex
77L88 SFKIT18S Square Term. for flex
77L89 SFKIT24S Square Term. for flex
77L90 SFKIT36S Square Term. for flex
77L91 SFKIT48S Square Term. for flex
94L04* SFKIT12SS Small Square Termination for
94L05* SFKIT18SS Small Square Termination for
94L06* SFKIT24SS Small Square Termination for
94L07* SFKIT36SS Small Square Termination for
94L08* SFKIT48SS Small Square Termination for
94L09* SF-HTSS Horizontal Small Square
tion for flex (without flex
vent)
(with 12 inch [305 mm]
compressed flex vent**)
(with 18 inch [457 mm]
compressed flex vent**)
(with 24 inch [610 mm]
compressed flex vent**)
(with 36 inch [914 mm]
compressed flex vent**)
(with 48 inch [1219 mm]
compressed flex vent**)
flex, with 12 in. (305 mm) of
compressed flex vent**
(Ref. Instr. #750204M)
flex, with 18 in. (457 mm) of
compressed flex vent**
(Ref. Instr. #750204M)
flex, with 24 in. (610 mm) of
compressed flex vent**
(Ref. Instr. #750204M)
flex, with 36 in. (914 mm) of
compressed flex vent**
(Ref. Instr. #750204M)
flex, with 48 in. (1219 mm)
of compressed flex vent**
(Ref. Instr. #750204M)
Termination for flex, without
flex vent (Ref. Instr. #750204M)
*Only for use with MPDT/R-3328 and MPD-3530 models.
**All compressed flex vents can be expanded up to two times.
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
37
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • 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.
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.
Millivolt SIT Systems
Natural Gas To Propane Gas
Conversion Kits
Models Catalog No.
MPDT/R-3328 H2009
MPD-3530 H2011
MPD-4035 H2013
MPD-4540 H2015
Millivolt SIT Systems
Propane Gas to Natural Gas
Conversion Kits
Models Catalog No.
MPDT/R-3328 H2010
MPD-3530 H2012
MPD-4035 H2014
MPD-4540 H2016
Electronic HONEYWELL Systems
Natural Gas To Propane Gas
Conversion Kits
Models Catalog No.
MPDT/R-3328 26M59
MPD-3530 26M60
MPD-4035 26M61
MPD-4540 26M62
Electronic HONEYWELL Systems
Propane Gas To Natural Gas
Conversion Kits
Models Catalog No.
MPDT/R-3328 26M63
MPD-3530 26M64
MPD-4035 26M65
MPD-4540 26M66
INSTALLATION INSTRUCTIONS
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.
Open the bottom drop-down door. Open it (see
Figure 52 on page 27 ) by pushing in simultane-
ously the left and right top corners of the door.
(The door is hinged at the bottom.) Remove the
bottom compartment door by sliding the hinge
pin, located at the door’s left side, to the right
until it disengages from the left corner post
hole. Pull the door diagonally to the left, away
from the fireplace.
Remove the front glass door/frame from the
appliance.
Kit part numbers are listed here and the following steps detail the conversion procedure. Refer
to the instructions provided with the conversion
kit when performing any gas conversion.
38
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Burner Assembly
Gas Valve
Assembly
Orifice
Pressure
Regulator
Remove
These
Components
Pilot
Orifice
Spring
Adjusting
Screw
Slotted
Cap
PSI
OFFION
CONTROL
IGNITE
Manifold
Pressure
Test Port
Inlet Pressure Test Port
Step 2. Carefully remove the logs. Exercise
care so as not to break the logs.
Step 3. Refer to Figure 67.
A. Above the burner, remove the two baffle
securing screws. Remove the baffle.
B. Remove the two screws securing the trapezoidal plate to the burner. Remove the plate.
C. Remove the burner assembly with attached
venturi tube.
Millivolt Appliances
Step 4. SIT Systems - Refer to Figure 68 and
the instructions provided with the kit. Using a
Torx T20, remove and discard the three pressure
regulator mounting screws. Remove the pressure regulator, spring, poppet, diaphragm and
bushing. Discard all removed components.
Ensure the rubber gasket installed on the back of
the replacement pressure regulator is properly
positioned and install the new pressure regulator using the new screws supplied with the kit.
Tighten screws to 25 In. lb. torque.
Figure 68
Electronic Appliances
Step 7. Honeywell Electronic Valves - See
Figure 70 and the instructions provided with
the kit. Remove the slotted cap screw, o-ring,
pressure-regulating adjusting screw and spring.
Retain all parts for possible later use. Install
new components from the kit. Black cap and
red spring for propane gas units. Silver cap
and stainless steel spring for natural gas units.
Before installing the cap, attach manometer to
the manifold side pressure test fitting and adjust
screw until pressure reads 3.5 inches water
column (0.87 kPa) for natural gas, and 10.0
inches water column (2.49 kPa) for propane gas.
Figure 67
Step 5. Attach manometer to the manifold side
pressure test fitting and verify manifold pressure reads 3.5 inches water column (0.87 kPa)
for natural gas, and 10.0 inches water column
(2.49 kPa) for propane gas.
Step 6. Refer to Figure 69 and remove the
pilot hood assembly to access the hexed pilot
orifice. Remove and replace the orifice with
the one provided with the kit.
Figure 69
Figure 70
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
39
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
Retaining
Clip
Ignitor
Assembly
Pilot
Assembly
Pilot
Orifice
Flare Nut
See Figure 71 and replace the pilot orifice as
follows: Remove the ignitor assembly retainer
clip, and carefully remove the ignitor assembly.
Exercise extreme care to prevent damage to
or breakage of the ignitor assembly. Remove
the screw securing the pilot assembly to its
mounting bracket. Back off the flare nut at
the end of the pilot gas line to free the pilot
assembly from the gas line. Remove the pilot
orifice and replace it with the one provided with
the conversion kit. Reinstall the pilot assembly
by reversing the steps detailed here.
When reinstalling the ignitor assembly, use
extreme care to prevent damage and breakage. Do not apply any leverage to the ignitor
assembly while restoring the retainer clip to
its original position.
Note: If the ignitor is damaged, a replacement
kit is available, order Catalog Number 87L54.
Figure 71
All Models
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 flare fittings).
Step 8. (Refer to Figure 67 on page 39 )
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 72 illustrates
the orifice.
B. Retrieve the burner and hold the venturi tube
above the orifice . Place the shutter adjusting
rod in the propane slot of the shutter arm (see
Figure 64 on page 34 ). Set the burner assembly into its position and secure the trapezoidal
plate with the two screws previously removed.
C. Reinstall the baffle with the two baffle
securing screws.
Burner Orifice Sizes
Elevation 0-4500 feet ( 0-1372 meters)
Model
Series
MPDT-3328
MPDR-3328
MPD-3530
MPD-4035
MPD-4540
Table 9
Nat.Gas
drill size (inches)
#45 (0.0820")*
39L66•
#44 (0.0860")*
60J80•
#37 (0.1040")*
24M10•
#36 (0.1065")*
18L40•
* Standard size installed at factory
• Part /Cat. Number
Propane
drill size (inches)
0.048 inch
99K78•
#55 (0.0520")*
19L52•
0.063 inch
21L01•
#52 (0.0635")*
37G00•
Figure 72
Step 9. Reassemble the remaining components
by reversing the procedures outlined in the
preceding steps.
Step 10. Attach the conversion label provided
in the conversion kit next to the rating plate on
the appliance.
Step 11. Turn on gas supply and test for gas
leaks (refer to page 27).
40
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
NOTES
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • INSTALLATION INSTRUCTIONS
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
41
LENNOX HEARTH PRODUCTS • MERIT® PLUS DIRECT VENT GAS FIREPLACES (MPD33/35/40/45) • 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. © 2002/2011 Lennox Hearth Products
42
P/N 850014M Rev. V 08/2011
NOTE: DIAGRAMS & ILLUSTRATIONS ARE NOT TO SCALE.
1508 Elm Hill Pike, Suite 108 • Nashville, TN 37210
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