Vermont Castings MLDV500NSCSB Manual

20306748 12/14 Rev. 1
INSTALLER: Leave this manual with the appliance.
CONSUMER: Retain this manual for future
reference.
MLDV Direct Vent Gas Fireplace
Installation & Operating Instructions
Model: MLDV500NSCSB, MLDV500PSCSB
DANGER
HOT GLASS WILL
CAUSE BURNS.
DO NOT TOUCH GLASS
UNTIL COOLED.
NEVER ALLOW CHILDREN
TO TOUCH GLASS.
A barrier designed to reduce the risk of burns from the hot
viewing glass is provided with this appliance and shall
be installed for the protection of children and
other at risk individuals.
20306543
• 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.
– Leave the building immediately.
– 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.
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.
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 for use only 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.
* Aftermarket: Completion of sale, not for purpose of resale, from
the manufacturer.
WARNING:
FIRE OR EXPLOSION HAZARD
Failure to follow safety warnings exactly
could result in serious injury, death or
property damage.
CERTIFIED
SAFETY BARRIER

220306748
MLDV Series Gas Fireplace CONTENTS
Thank you and congratulations on your purchase of a
Vermont Castings Group Fireplace.
PLEASE READ THE INSTALLATION AND OPERATION INSTRUCTIONS BEFORE USING THE APPLIANCE!
IMPORTANT: Read all instructions and warnings carefully before starting installation.
Failure to follow these instructions may result in a possible fire hazard and will void the warranty.
Important Safety Information ............................................... 3
Code Approval ....................................................................... 4
Product Features................................................................... 5
Product Specifications...................................................... 5
High Elevations ................................................................ 5
Gas Pressures.................................................................. 5
Gas Specifications & Orifice Size..................................... 5
Fireplace & Framing Dimensions ........................................ 6
Pre-Installation Information.................................................. 7
Before You Start ............................................................... 7
Items Required for Installation.......................................... 7
Firebox Framing ............................................................... 7
Fireplace Location............................................................ 7
Clearances ............................................................................. 8
Clearances to Combustibles ............................................ 8
Secure Fireplace to Floor or Framing.................................. 9
Finishing Material ............................................................. 9
Venting Installation.............................................................. 10
Installation Precautions .................................................. 10
Optional Top Vent Application......................................... 10
Installation Planning ....................................................... 12
For Horizontal Termination ............................................. 12
For Vertical Termination.................................................. 12
Installing a Vent System in an Outside Chase ............... 12
Termination Location ...................................................... 13
Termination Clearances.................................................. 14
How to Use the Vent Graph............................................ 14
Rear Wall Vent Installation ............................................. 15
Horizontal w/Vertical Rise Termination Configurations... 16
Vertical Side Wall Applications ....................................... 18
Below Grade Installations............................................... 19
Vertical Through-the-Roof Applications .......................... 20
Installation for Vertical Termination................................. 21
Flat Ceiling Installation ................................................... 21
Flex Vent Installation ...................................................... 23
4 x 7 Flex Pipe................................................................ 25
Fireplace Installation........................................................... 26
Check Gas Type............................................................. 26
Installing Gas Piping to Fireplace Location .................... 26
Installing Items Needed.................................................. 26
Check Gas Pressure — Millivolt .................................... 27
Electrical Installation —Millivolt........................................ 28
Electrical Wiring.............................................................. 28
Remote Wall Mounted Switch ........................................ 28
Optional Fan/Blower (BLOTBLDV)................................. 28
Operating Instructions —Millivolt..................................... 31
For Your Safety............................................................... 31
Lighting Pilot for the First Time....................................... 31
Lighting Pilot................................................................... 32
Lighting Burner............................................................... 33
Check Gas Pressure ...................................................... 34
Electrical Installation — Signature Command ................. 34
Electrical Wiring.............................................................. 34
Junction Box Wiring........................................................ 35
Command Center Wall Installation................................. 35
Wall Switch Installation................................................... 35
Signature Command Wiring Diagram............................. 36
Optional Fan/Blower System — Signature Command..... 37
BLOTSDVSC.................................................................. 37
BLOTSDV....................................................................... 38
Operating Instructions — Signature Command ............... 39
For Your Safety............................................................... 39
Operating Instructions .................................................... 40
To Turn Off Gas To Appliance......................................... 40
Signature Command System Operation.............................41
Features ..........................................................................41
Battery Installation...........................................................41
System Configuration/Setup............................................41
Cold Climate Option ........................................................41
Key Combinations for System Settings...........................42
Functions/Operation........................................................43
Command Center Operations .........................................43
Self Diagnostics Chart.....................................................43
Final Installation .................................................................. 44
Glass Frame Removal.................................................... 44
Brick Installation ............................................................. 44
Eyebrow/Canopy Installation.......................................... 44
Rockwool Placement...................................................... 45
Log Placement ............................................................... 45
Safety Barrier Installation Instructions............................ 47
Cleaning and Maintenance ................................................. 48
Burner, Pilot and Control Compartment ......................... 48
Pilot Flame ..................................................................... 48
Burner............................................................................. 48
Burner Flame.................................................................. 48
Venting System .............................................................. 49
Glass Door ..................................................................... 49
Logs................................................................................ 49
Rock Wool ..................................................................... 49
Troubleshooting .................................................................. 50
Standing Pilot Ignition Millivolt System........................... 50
Signature Command System ......................................... 52
Replacement Parts .............................................................. 53
Firebox Components and Accessories........................... 53
Logs................................................................................ 54
Standing Pilot—Millivolt Control .................................... 55
Signature Command System ......................................... 56
Venting Components........................................................... 57
Massachusetts Residents Only.......................................... 62
Warranty ............................................................................... 63
Efficiencies........................................................................... 64

20306748 3
MLDV Series Gas Fireplace
•in a recreational vehicle
•where curtains, furniture, clothing, or other flam-
mable objects are less than 42" from the front, top,
or sides of the fireplace
•in high traffic areas
•in windy or drafty areas
5. This fireplace reaches high temperatures. Keep chil-
dren and adults away from hot surfaces to avoid burns
or clothing ignition. Fireplace will remain hot for a time
after shutdown. Allow surfaces to cool before touching.
6. 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 recom-
mended 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.
7. Do not modify fireplace under any circumstances. Any
parts removed for servicing must be replaced prior to
operating fireplace.
8. Turn fireplace off and let cool before servicing, install-
ing, or repairing. Only a qualified service person should
install, service, or repair the fireplace. Have burner
system inspected annually by a qualified service
person.
9. You must keep control compartments, burners, and
circulating air passages clean. More frequent cleaning
may be needed due to excessive lint and dust. Turn off
the gas valve and pilot light before cleaning fireplace.
10. Have venting system inspected annually by a quali-
fied service person. If needed, have venting system
cleaned or repaired. See Cleaning and Maintenance.
11. Keep the area around your fireplace clear of combus-
tible materials, gasoline, and other flammable vapor
and liquids. Do not run fireplace where these are used
or stored. Do not place items such as clothing or dec-
orations on or around fireplace.
12. Do not use this fireplace to cook food or burn paper or
other objects.
INSTALLER
Please leave these instructions with the appliance.
OWNER
Please retain these instructions for future reference .
IMPORTANT SAFETY INFORMATION
This fireplace is a vented product. This fireplace must be
properly installed by a qualified service person. The glass
door must be properly seated and sealed. If this unit is not
properly installed by a qualified service person with glass
door properly seated and sealed, combustion leakage
can occur.
CARBON MONOXIDE POISONING: Early signs of carbon
monoxide poisoning are similar to the flu with headaches,
dizziness and/or nausea. If you have these signs, the fire-
place may not have been installed properly. Get fresh air
at once! Have the fireplace inspected and serviced by a
qualified service person. Some people are more affected
by carbon monoxide than others. These include pregnant
women, people with heart or lung disease or anemia, those
under the influence of alcohol, and those at high altitudes.
Propane/LP gas and natural gas are both odorless. An
odor-making agent is added to each of these gases. The
odor helps you detect a gas leak. However, the odor added
to these gases can fade. Gas may be present even though
no odor exists.
Make certain you read and understand all warnings. Keep
this manual for reference. It is your guide to safe and proper
operation of this fireplace.
1. 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.
2. For propane/LP fireplace, do not place propane/LP
supply tank(s) inside any structure. Locate propane/
LP supply tank(s) outdoors. To prevent performance
problems, do not use propane/LP fuel tank of less than
100 lbs. capacity.
3. If you smell gas
•shut off gas supply.
•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 neigh-
bor’s phone. Follow the gas supplier’s instructions.
4. Never install the fireplace
WARNING
• Read this owner’s manual carefully and completely before trying to assemble, operate, or service this
fireplace.
• Any change to this fireplace or its controls can be dangerous.
• Improper installation or use of this fireplace can cause serious injury or death from fire, burns, explosions,
electrical shock and carbon monoxide poisoning.

420306748
MLDV Series Gas Fireplace CODE APPROVAL
13. Never place anything on top of fireplace.
14. Do not use any solid fuels (wood, coal, paper, card-
board, etc.) in this fireplace. Use only the gas type
indicated on rating plate.
15. This appliance, when installed, must be electrically
grounded in accordance with local codes or in the
absence of local codes, with the National Electrical
Code, ANSI/NFPA 70, or the Canadian Electrical Code,
CSA C22.1.
16. Do not obstruct the flow of combustion and ventilation
air in any way. Provide adequate clearances around
air openings into the combustion chamber along with
adequate accessibility clearance for servicing and
proper operation.
17. When the appliance is installed directly on carpeting,
tile or other combustible material other than wood
flooring, you must set appliance on a metal or wood
panel or hearth pad extending the full width and depth
of the appliance.
18. Do not use fireplace if any part has been exposed to
or has been under water. Immediately call a qualified
service technician to inspect the appliance and replace
any part of the control system and any gas control
which as been submerged in water.
19. Do not operate fireplace if any log is broken.
20. Do not use a blower insert, heat exchanger insert, or
any other accessory not approved for use with this
fireplace.
21. Do not operate the fireplace with glass door removed,
cracked, or broken.
CODE APPROVAL
Direct Vent type appliances draw all combustion air from
outside of the dwelling through the vent pipe.
These appliances have been tested by CSA and found to
comply with the established standards for DIRECT VENT
GAS FIREPLACE HEATERS in the USA and Canada as
follows:
LISTED VENTED GAS FIREPLACE HEATER
TESTED TO:
ANSI Z21.88-2014 / CSA 2.33-2014 STANDARDS
A manufactured home (USA only) or mobile home OEM
installation must conform with the Manufactured Home
Construction and Safety Standard, Title 24 CFR, Part
3280, or when such a standard is not applicable, the
Standard for Manufactured Home Installations, ANSI/
NCSBCS A225.1, or Standard for Gas Equipped Rec-
reational Vehicles and Mobile Housing, CSA Z240.4.
IMPORTANT:
PLEASE READ THE FOLLOWING
CAREFULLY
It is normal for fireplaces fabricated of steel to give off
some expansion and/or contraction noises during the
start up or cool down cycle. Similar noises are found with
your furnace heat exchanger or car engine.
IMPORTANT:
PLEASE READ THE FOLLOWING
CAREFULLY
It is not unusual for gas fireplaces to give off some odor
the first time it is burned. This is due to the manufacturing
process.
Please ensure that your room is well ventilated
during burn off — open all windows.
It is recommended that you burn your fireplace for at
least ten (10) hours the first time you use it. Place the
fan switch in the “OFF” position during this time.
WARNING
Never connect unit to private (non-utility)
gas wells. This gas is commonly known as
wellhead gas.

20306748 5
MLDV Series Gas Fireplace
PRODUCT FEATURES
•This appliance has been certified for use with either
natural or propane gas. See appropriate data plates.
•This appliance is not for use with solid fuels.
•The appliance is approved for bedroom or bedsitting
room installations.
•The appliance must be installed in accordance with local
codes if any. If none exist use the current installation
code. ANSI Z223.1/NFPA 54 in the USA, CSA B149 in
Canada.
•This appliance is mobile home appr-oved.
•The appliance must be properly connected to a venting
system.
•The appliance is not approved for closet or recessed
installations.
PRODUCT SPECIFICATIONS
Figure 1 -
MLDV Series Fireplace (Millivolt Control shown)
Off/Pilot/On Knob
Hi/Lo Knob
On/Off/RS
Switch
Ignitor
5/8" Nailing
Flange
1/2" Nailing
Flange
Insulation Board
HIGH ELEVATIONS
Input ratings are shown in BTU per hour and are cer-
tified without deration for elevations up to 4,500 feet
(1,370 m) above sea level.
For elevations above 4,500 feet (1,370 m) in USA,
installation must be in accordance with the current ANSI
Z223.1/NFPA 54 and/or local codes having jurisdiction.
In Canada, please consult provincial and/or local
authorities having jurisdiction for installation at eleva-
tions above 4,500 feet (1,370 m).
GAS PRESSURES
Natural Propane (LP)
Inlet Minimum 4.5” w.c. 11.0” w.c.
Inlet Maximum 10.5” w.c. 13.0” w.c.
Manifold Pressure 3.5” w.c. 10.0” w.c.
Max.Input Min. Input Orifice
Model Fuel BTU/h BTU/h Size
MLDV500NV Nat. 34,000 22,000 #33
MLDV500PV LP 34,000 27,000 1.8 mm
MLDV500NSC Nat. 34,000 22,000 #33
MLDV500PSC LP 34,000 27,000 1.8 mm
GAS SPECIFICATIONS & ORIFICE SIZE

620306748
MLDV Series Gas Fireplace FIREPLACE AND FRAMING DIMENSIONS
Figure 2 -
Fireplace and Framing Dimensions
WARNING
Do not fill spaces around firebox with
insulation or other materials. This could
cause a fire.
NOTE
COLD CLIMATE INSULATION
If you live in a cold climate, seal all cracks
around your appliance, and wherever cold air
could enter the room, with noncombustible
material. It is especially important to
insulate the outside chase cavity between
the studs and under the floor on which the
appliance rests, if the floor is above ground
level.
NOTE: Refer to cold climate pilot information on Page 44
for more information on standing pilot vs. intermittent pilot
options.
33” (838 mm)
41” (1041 mm)
36” (914 mm)
30(6” (784 mm)
206”
(524 mm)
2256M”
(565 mm)
1/2” or 5/8”
Min. Rough
Opening
Height
276QE”
(694 mm)
Min. Rough Opening Width
(4256O” 91080 mm)
Min. Rough
Opening
Depth
50(6”
(1292 mm)
2256M”
(565 mm)
7256O” (1791 mm)
5256M” (1327 mm)
5256M” (1327 mm)
3656M”
(921 mm)
1”
(25 mm)
34”
(864 mm)
9556QE”
(246 mm)
6”
(152 mm)
506M”
(1289 mm)
256O"
(64 mm)
356”
(79 mm)
1456O”
(368 mm)
2”
(51 mm)
386M”
(984 mm)
446”
(1133 mm)
466”
(1184 mm)
156O”
(38 mm)
76”
(187 mm)
1080 mm)
1079.5 mm)

20306748 7
MLDV Series Gas Fireplace
PRE- INSTALLATION INFORMATION
BEFORE YOU START
Read this homeowner manual thoroughly and follow all
instructions carefully. Inspect all contents for shipping
damage and immediately inform your dealer if any damage
is found. Do not install any unit with damaged, incomplete,
or substitute parts. Check your packing list to verify that
all listed parts have been received. You should have the
following:
•Fireplace (Firebox and Burner System)
•Log Set
• Rock Wool
ITEMS REQUIRED FOR INSTALLATION
Tools and Building Materials
• Phillips Screwdriver
• Hammer
• Saw and/or saber saw
• Measuring Tape
• Electric Drill and Bits
• Pipe Wrench
• Framing Materials
• Wall Finishing Materials
• Level
• Pliers
• Square
• Tee Joint
• Caulking Material (noncombustible)
• Fireplace Surround Material (noncombustible)
• Piping Complying with Local Codes
• Pipe Sealant Approved for use with Propane/LPG
(Resistant to sulfur compounds)
FIREBOX FRAMING
Firebox framing can be built before or after the appliance
is set in place. Construct firebox framing following Figure 2
for firebox and framing dimensions. The framing headers
may rest on the top of the firebox standoffs. Do not bring
headers below top of standoffs. NOTE: When planning
your framing and installation, keep in mind that your gas
line will come in on the right side of the box (as you are
facing it) and your electricity will come in on the left side.
The firebox may be installed directly on a combustible floor
or raised on a platform of an appropriate height. When
the firebox is installed directly on carpeting, tile, or other
combustible material, other than wood flooring, the firebox
shall be installed on a metal or wood panel extending the
full width and depth of the enclosure.
FIREPLACE LOCATION
Plan for the installation of your appliance. This includes
determining where the unit is to be installed, the vent
configuration to be used, framing and finishing details,
and whether any optional accessories (i.e. blower, wall
switch, or remote control) are desired. Consult your local
building code agency to ensure compliance with local
codes, including permits and inspections.
The following factors should be taken into consideration:
•Clearance to side-wall, ceiling, woodwork, and windows.
Minimum clearances to combustibles must be main-
tained.
•This fireplace may be installed along a wall, across a
corner, or use an exterior chase. Refer to Figure 3 for
suggested locations.
•Location should be out of high traffic areas and away
from furniture and draperies due to heat from appliance.
•Never obstruct the front opening of the fireplace.
•Do not install in the vicinity where gasoline or other
flammable liquids may be stored.
•Vent pipe routing. See Venting section found in this
manual for allowable venting configurations.
•These units can be installed in a bedroom. See National
Fuel Gas Code ANSI Z233.1/NFPA 54 — (current
edition), the Uniform Mechanical Code — (current edi-
tion), and Local Building Codes for specific installation
requirements.
•These units can be installed in a bathroom.
Y
EAB
C
D
F
Y
X
Figure 3 -
Locate Gas Fireplace
** Island (C) and room divider (D) installation is possible as long as
the horizontal portion of vent system (X) does not exceed 20'. See
Install Horizontal Termination Configuration on Pages 18 and 19.
* When you install your fireplace in (D) room divider or (E) flat on
wall corner positions (Y), a minimum of 6" clearance must be
maintained from perpendicular wall and front of fireplace.
A Flat on Wall
B Cross Corner
C Island**
D Room Divider*
E Flat on Wall Corner*
F Chase Installation
Y 6" Minimum

820306748
MLDV Series Gas Fireplace CLEARANCES
CLEARANCES TO COMBUSTIBLES
71” Minimum
Ceiling
12” Max.
Depth
14” Min.
From Opening
6” Min.
to Opening
Figure 4 -
Side Wall and Ceiling Clearances
Side Wall
Combustible
Mantel
Figure 5 -
Mantel clearances.
6"
5"
3"
256O"456O"45°
356O"
1" 156O"
Fireplace
Opening
Wall
Combustible
Material Area
Top View
Follow these instructions carefully to
ensure safe installation. Failure to follow
instructions exactly can create a fire hazard.
The appliance cannot be installed on a
carpet, tile or other combustible material
other than wood flooring. If installed on
carpet or vinyl flooring, the appliance
shall be installed on a metal, wood or
noncombustible material panel extending
full width and depth of the appliance.
WARNING
NOTE: When eyebrow canopy is used, minimum clearance to combustibles is 21⁄4" maximum out from fireplace front at
71⁄2" minimum from opening. Figure 5a. When eyebrow is not used, clearances to combustibles is 8" maximum out from
fireplace front at 10" minimum from opening or 12" maximum out from fireplace front at 14" minimum from opening. Figure 5
8” Max.
10”
Min.
756O”
Min.
156O”
Max. 256M” Max.
14”
Min.
12” Max.
3/4"
Marble
Combustible
Breastplate
Figure 5a -
Mantel Clearance with Eyebrow Canopy
Eyebrow
Canopy

20306748 9
MLDV Series Gas Fireplace
The fireplace must be secured to the floor and/or to framing
studs as shown in Figure 6. Use two (2) wood screws or
masonry/ concrete screws to secure fireplace to the floor.
Use four (4) screws to attach fireplace to framing. The side
nailing flanges are 1/2" or 5/8" to accommodate different
wall thickness.
SECURE FIREPLACE TO FLOOR OR FRAMING
Figure 6 -
Secure Fireplace to Floor and Framing Studs
Framing
Screws
Nailing Flange
Insulation Board
DO NOT REMOVE
FP1989
NOTE
DO NOT REMOVE INSULATION
BOARD
FINISHING MATERIAL
NOTE: Any remote wiring (i.e. remote control, wall switch,
and optional fan) must be done prior to final finishing to
avoid costly reconstruction.
Only noncombustible materials (i.e. brick, tile, slate, steel,
or other materials with a UL fire rating of Zero) may be
used to cover the black painted face of the appliance. It is
permissible to bring combustible wall board to the top and
side edges of the black painted face. A 300°F minimum
adhesive may be used to attach facing materials to the
black surface. If joints between the finished wall and the
fireplace surround are sealed, a 300°F minimum sealant
material (General Electric RTV103 or equivalent) must be
used.

10 20306748
MLDV Series Gas Fireplace
INSTALLATION PRECAUTIONS
Consult local building codes before beginning the
installation. The installer must make sure to select the
proper vent system for installation. Before installing vent
kit, the installer must read this fireplace manual and vent
kit instructions.
Only a qualified installer/service person should install vent-
ing system. The installer must follow these safety rules:
•Wear gloves and safety glasses for protection.
•Use extreme caution when using ladders or when on
rooftops.
•Be aware of electrical wiring locations in walls and
ceilings.
The following actions will void the warranty on your venting
system:
•Installation of any damaged venting component.
•Unauthorized modification of the venting system.
•Installation of any component part not manufactured
or approved by Vermont Castings Group.
•Installation other than permitted by these instructions.
VENTING INSTALLATION
Read all instructions completely and
thoroughly before attempting installation.
Failure to do so could result in serious injury,
property damage or loss of life. Operation
of improperly installed and maintained
venting system could result in serious injury,
property damage or loss of life.
WARNING
Failure to follow these instructions
will void the warranty.
NOTICE
OPTIONAL TOP VENT APPLICATION
The appliance is shipped as a rear vent unit. If the installa-
tion layout requires the unit to be a top vent configuration,
the appliance can be converted by following the steps
below.
When removing and refitting the plates and adapter, be
sure the associated gaskets are undamaged and refitted
as required.
1. Remove the eight (8) screws securing the flue pipe
adapter to the fireplace body. Figure 7
2. Set the flue pipe adapter aside, complete with the
gasket. Do not damage the gaskets as the adapter and
gasket must be refitted.
Screws
Flue Pipe
Cover
Flue Pipe
Adapter
FP1991
Figure 7 -
Remove 16 screws from Flue Pipe Adapter and Flue Pipe
Cover
After conversion to top vent configuration,
the 5" (127 mm) flue pipe should be
concentric with the 8" (203 mm) outer collar
within 1/4".
WARNING
3. Remove the eight (8) screws securing the flue pipe cover
to the top of the intake box and remove the cover and
gasket. Figure 7
4. Remove six (6) screws securing the flue pipe to the
back of the intake box and remove the pipe and gasket.
Figure 8
5. Replace the flue pipe to top of firebox. Ensure the gasket
is in place and undamaged. Secure with six (6) screws.
Figure 9
6. Place the flue pipe cover and gasket removed in Step
3 over the flue opening in bottom of the intake box.
7. Refit the flue pipe adapter and gasket to the top of fire-
place. Secure the adapter with six (6) screws removed
in Step 1.
This fireplace must be vented to the
outside. The venting system must NEVER
be attached to a chimney serving a separate
solid fuel burning appliance. Each gas
appliance must use a separate vent system.
Do not use common vent systems.
WARNING

20306748 11
MLDV Series Gas Fireplace
VENTING INSTALLATION
Flue Cover
Screws
Flue Pipe
FP1992
Figure 8 -
Remove Flue Pipe
Screws
Flue Pipe
FP1993
Figure 9 -
Attach Flue Pipe to Top Vent Configuration
* A minimum of 3" clearance to the top is required along horizontal
length until flue pipe penetrates outside wall.
** A minimum 1" clearance to combustibles permitted all around
flue at outside wall
*3” **1”
**1”
**1”
**1”
*3”
Figure 10 -
Combustible Clearances for Vent Pipe

12 20306748
MLDV Series Gas Fireplace VENTING INSTALLATION
INSTALLATION PLANNING
There are two basic types of direct-vent installation:
•Horizontal Termination
•Vertical Termination
It is important to select the proper length of vent pipe for
the type of termination you choose. It is also important to
note the wall thickness.
FOR HORIZONTAL TERMINATION
Select the amount of vertical rise desired. All horizontal run
of venting must have 1/4" rise for every 12" of run towards
the termination below 71/2feet of vertical rise. With 71/2feet
or more vertical rise off top of fireplace, the horizontal run
may run level. NEVER run vent piping downward.
You may use up to three 90° elbows in this vent configu-
ration. Refer to Horizontal Termination Configurations on
Pages 17 and 18.
FOR VERTICAL TERMINATION
Measure the distance from the fireplace floor to the ceil-
ing. Add the ceiling thickness, the vertical rise in an attic
or second story, and allow for sufficient vent height above
the roof line.
NOTE: You may use two 45° elbows in place of a 90° elbow.
You must follow rise to run ratios when using 45° elbows.
The appliance is approved for use with three 90° elbows
maximum or a combination of 90° and 45° elbows up to a
maximum of 270°.
For two-story applications, firestops are required at each
floor level. If an offset is needed in the attic, additional pipe
and elbows will be required.
NOTICE
When installing in a chase, you should insulate
the chase as you would the outside walls of
your home. This is especially important in cold
climates. Insulation should be considered a
combustible material. Maintain proper clearances
to all combustible materials.
WARNING
Always maintain minimum clearances around vent
systems. The minimum clearance to combustibles
for horizontal vent pipe are 3" at the top and 1" at the
sides and bottom of the vent system until the pipe
penetrates the nearest vertical wall (1" required). A
1" minimum clearance all around the pipe must be
maintained at outside wall and on vertical runs. Do
not pack the open air spaces with insulation or other
materials. This could cause high temperatures and
may present a fire hazard.
*Unless the vertical run is 71⁄2feet or higher (top vent
units only), the clearances for the horizontal run is
1" at the top.
Never run the vent pipe down. This may cause
excessive temperatures which could cause a fire.
WARNING
Treatment of firestops and construction of the chase
may vary from building type to building type. These
instructions are not substitutes for the requirements
of local building codes. You must follow all local
building codes.
WARNING
WARNING
Read all instructions completely and thoroughly
before attempting installation. Failure to do so
could result in serious injury, property damage or
loss of life. Operation of improperly installed and
maintained venting system could result in serious
injury, property damage or loss of life.
You may use a chase with a vent termination with exposed
pipe on the exterior of the house. Refer to Installing Vent
System in a Chase below. If pipe is enclosed in chase, it
is not exposed.
It is very important that the venting system maintain its
balance between the combustion air intake and the flue
gas exhaust. Certain limitations apply to vent configurations
and must be strictly followed.
INSTALLING A VENT SYSTEM IN AN
OUTSIDE CHASE
A chase is a vertical boxlike structure built to enclose
venting that runs along the outside of a building. A chase
is required for such venting.
Horizontal sections of this vent system require a
minimum of 3" clearances to combustibles at the top
of the flue and 1" clearance at the sides and bottom
until the flue penetrates the outside wall. A minimum
1" clearance all around the flue is acceptable at
this point of penetration. If vertical rise is 71⁄2"
feet or higher when top venting, the clearance to
combustibles is 1" on all sides of the horizontal run.
Vertical sections of this vent system require a
minimum of 1" clearance to combustibles on all
sides of the pipe.
WARNING

20306748 13
MLDV Series Gas Fireplace
VENTING INSTALLATION
V
X
X
X
D
E
B
B
B
C
B
M
B
A
J
K
F
L
VENT TERMINATION AIR SUPPLY INLET AREA WHERE TERMINAL IS NOT PERMITTED
H
I
Fixed
Closed
Operable
Operable Fixed
Closed
B
INSIDE
CORNER DETAIL
A
G
CFM145a
V
V
V
VV
V
V
V
1 In accordance with the current CSA-B149 Installation Codes
2 In accordance with the current ANSI Z223.1/NFPA 54 National Fuel
Gas Codes
† A vent shall not terminate directly above a sidewalk or paved
driveway which is located between two single family dwellings and
serves both dwellings
‡ Only permitted if veranda, porch, deck or balcony is fully open on a
minimum 2 sides beneath the floor.
NOTE: 1. Local codes or regulations may require different
clearances.
2. The special venting system used on Direct Vent
Fireplaces are certified as part of the appliance, with
clearances tested and approved by the listing agency.
3. Vermont Castings Group assumes no responsibility for
the improper performance of the appliance when the venting
system does not meet these requirements.
Figure 11 –
Termination Locations
CANADIAN INSTALLATIONS1US INSTALLATIONS2
A = Clearance above grade, veranda, porch,
deck or balcony
12" (30cm) 12" (30cm)
B = Clearance to window or door that may be
opened
6" (15cm) for appliances <10,000 BTU/h
(3kW)
12" (30cm) for appliances >10,000 BTU/h
(3kW) and <100,000 BTU/h (30kW)
36" (91cm) for appliances >100,000 BTU/h
(30kW)
6" (15cm) for appliances <10,000 BTU/h
(3kW)
9" (23cm) for appliances >10,000 BTU/h
(3kW) and <50,000 BTU/h (15kW)
12" (30cm) for appliances >50,000 BTU/h
(15kW)
C = Clearance to permanently closed window 12" (305mm) recommended to prevent
window condensation
12" (305mm) recommended to prevent
window condensation
D = Vertical clearance to ventilated soffit
located above the terminal within a hor-
izontal distance of 2' (610 mm) from the
center line of the terminal
18" (458mm) 18" (458mm)
E = Clearance to unventilated soffit 12" (305mm) 12" (305mm)
F = Clearance to outside corner see next page see next page
G = Clearance to inside corner see next page see next page
H = Clearance to each inside of center line
extended above meter/regulator assembly
3' (91cm) within a height of 15' (5m) above
the meter/regulator assembly
3' (91cm) within a height of 15' (5m) above
the meter/regulator assembly
I = Clearance to service regulator vent outlet 3' (91cm) 3' (91cm)
J = Clearance to non-mechanical air supply
inlet to building or the combustion air inlet
to any other appliance
6" (15cm) for appliances <10,000 BTU/h
(3kW)
12" (30cm) for appliances >10,000 BTU/h
(3kW) and <100,000 BTU/h (30kW)
36" (91cm) for appliances >100,000 BTU/h
(30kW)
6" (15cm) for appliances <10,000 BTU/h
(3kW)
9" (23cm) for appliances >10,000 BTU/h
(3kW) and <50,000 BTU/h (15kW)
12" (30cm) for appliances >50,000 BTU/h
(15kW)
K = Clearance to mechanical air supply inlet 6' (1.83m) 3' (91cm) above if within 10' (3m) horizontally
L = Clearance above paved sidewalk or
paved driveway located on public property
7' (2.13m)†7' (2.13m)†
M = Clearance under veranda, porch, deck or
balcony
12" (30cm)‡12" (30cm)‡
TERMINATION LOCATION

14 20306748
MLDV Series Gas Fireplace VENTING INSTALLATION
Figure 12 -
Allowable Venting
HOW TO USE THE VENT GRAPH
The Vent Graph should be read in conjunction with the
following vent installation instructions to determine the
relationship between the vertical and horizontal dimensions
of the vent system.
1. Determine the height of the center of the horizontal vent
pipe exiting through the outer wall. Using this dimension
on the Sidewall Vent Graph below, locate the point
intersecting with the slanted graph line.
2. From the point of this intersection, draw a vertical line
to the bottom of the graph.
3. Select the indicated dimension, and position the fire-
place in accordance with same.
Example: If the vertical dimension from the floor of the
fireplace is 11' (3.4 m) the horizontal run to the face of
the outer wall must not exceed 16' (4.9 m).
Sidewall Vent Graph showing the relationship between
vertical and horizontal dimensions for a Direct Vent flue
system.
Figure 13 -
Rear Wall Venting Graph (No Horizontal Elbows)
40
38
36
34
32
30
28
26
24
22
20
18
16
14
12
10
8
6
4
2
2 4 6 8 10 1214 16 1820
eg: A
Dimensions in Feet
Horizontal dimension from the finished outside wall to the
center of the pipe on the fireplace
Vertical Dimension From the Floor of Unit to the
Center of the Horizontal Vent Pipe
*NOTE: Termination in an alcove space (spaces open only on one side
and with an overhang) is permitted with the dimensions specified for
vinyl or non-vinyl siding and soffits. 1. There must be a 3' (914 mm) min-
imum between termination caps. 2. All mechanical air intakes within 10'
(1 m) of a termination cap must be a minimum of 3' (914 mm) below the
termination cap. 3. All gravity air intakes within 3' (914 mm) of a termina-
tion cap must be a minimum of 1' (305 mm) below the termination cap.
TERMINATION CLEARANCES
Termination clearances for buildings with combustible and non-combustible exteriors.
Outside Corner
Inside Corner
G =
Combustible
6" (152 mm)
Noncombustible
2" (51 mm)
F =
Combustible
6" (152 mm)
Noncombustible
2" (51 mm)
G
Balcony -
with no side wall
M =
Combustible &
Noncombustible
12" (305 mm)
M
Balcony -
with perpendicular side wall
M = 12" (305 mm)
P = 6” (152 mm)
M
F
Alcove Applications*
C
D
C
E
V
V
Combustible &
Noncombustible
E= Min. 2” (51 mm) for
non-vinyl sidewalls
Min. 12” (305 mm) for
vinyl sidewalls
O= 8’ (2.4 m) Min.
O
P
V
V
V
DMin. = Number of Termination caps x 3
CMax. = (2 / Number termination caps) x DActual
No. of
Caps DMIN.CMAX.
1 3' (914 mm) 2 x DACTUAL
2 6' (1.8 m) 1 x DACTUAL
3 9' (2.7 m) 2/3 x DACTUAL
4 12' (3.7 m) 1/2 x DACTUAL

20306748 15
MLDV Series Gas Fireplace
• Only one 45 degree elbow is allowed in these installa-
tions.
1. Rigid vent pipes and fittings have special twist-lock
connections. Assemble the desired combination of pipe
and elbows to the appliance adapter.
Twist-Lock Procedure: The female ends of the pipes
and fittings have three (3) locking lugs (indentations).
These lugs will slide straight into matching slots on
the male end of adjacent pipes and fittings. Push the
pipe sections together and twist one section clockwise
approximately one-quarter turn until the sections are
fully locked. Figure 15
NOTE: Sealant is not required to assemble fireplace
venting. Do not use silicone sealant at the inner flue
exhaust connections.
VENTING INSTALLATION
Female Locking
Lugs
Male Slots
NOTE: Horizontal
runs of vent must
be supported every
three feet (914 mm).
Use wall straps for
this purpose.
Figure 15 -
Rigid Vent Pipe Connections
REAR WALL VENT INSTALLATION (5" x 8"
VENTING ONLY)
When installed as a rear vent unit, this appliance may be
vented directly to a termination located on the rear wall
behind the appliance. Only an Vermont Castings Group
brand termination is allowed for this application.
•The maximum horizontal distance between the rear
of the appliance and the termination is 20" (508 mm).
Figure 14
Maximum
20"
Top View Flat Installation
Figure 14 - Rear Vent Application, Maximum Horizontal
Distance
101/2"
(267 mm)
101/2"
(267 mm)
81/2"
(216 mm)
Figure 16 -
Exterior Wall Framing Dimensions
Combustible Wall
Noncombustible
Wall
FP1954
2. Refer to venting and termination instructions for further
instructions.
3. Locate and cut the vent opening in the wall. For com-
bustible walls first frame in opening.
Combustible Interior Walls: Cut a 121/2" x 101/2" hole
through the interior wall.
Combustible Exterior Walls: Cut a 101/2" x 101/2"
square hole through the exterior wall frame. Figure 16
Noncombustible Walls: Hole opening should be 81/2"
(216 mm) in diameter.
4. The center of the hole should align with the center line
of the horizontal rigid vent pipe end. Allow 1/4" minimum
rise per foot. Figure 16
5. Apply a bead of non-hardening mastic around the
outside edge of vent cap. Position the vent cap in the
center of hole on the exterior wall with the word "UP"
on the vent cap facing up. Insure proper clearance of
1" to combustibles is maintained. Attach the vent cap
with four (4) wood screws supplied. Figure 17
NOTE: Replace the wood screws with appropriate
fasteners for stucco, brick, concrete or other types
of siding.
For vinyl siding, stucco or wood exterior, use vinyl
siding standoffs between vent cap and exterior wall for
Duravent or Selkirk Terminations only. The vinyl siding
standoff prevents excessive heat from melting the
vinyl siding material. NOTE: Vermont Castings Group
Termination does not require standoff. Bolt the vent
cap to the standoff or wall. Apply non-hardening mastic
around outside edge of the standoff instead of the vent
cap assembly. Use wood screws provided to attach the
standoff. Figure 18

16 20306748
MLDV Series Gas Fireplace VENTING INSTALLATION
Figure 18 -
Install Duravent/Selkirk Vinyl Siding Standoff and
Termination
HOT
Cut Vinyl Siding Away
to Fit Standoff
Standoff #1250 or
5DT-VS
(Not required for Ver-
mont Castings Group
termination)
Termination
Bolt
Wood Screw
Nut
Apply
Mastic to
all Four
Sides
FP1956
Figure 19 -
Install Firestop on Horizontal Vent Pipe
Interior Wall
Surface
Firestop
Horizontal
Vent Pipe
Screw
Vent Cap
(Horizontal
Termination)
FP1957
HOT
Vent Cap
Wood Screw
Apply Mastic to all
Four Sides
Figure 17 -
Install Horizontal Termination
For more information, follow instructions
provided with terminations.
NOTICE
Do not recess vent termination into any
wall. This will cause a fire hazard.
WARNING
All rear vent through-the-wall applications
must use Vermont Castings Group-de-
signed 5 x 8 square termination. No other
manufacturer's termination is permitted in
this application.
NOTICE
6. Slide the stop over the vent pipe before connecting the
horizontal run to the vent cap. Figure 19
7. Carefully move the fireplace with vent assembly
attached toward the wall and insert the vent pipe into
the horizontal termination. The pipe overlap should
be a minimum of 11/4". Apply silicone to the outer pipe
connection. Fasten all vent connections with screws
provided.
8. Slide the wall thimble against the interior wall surface
and attach with screws. Figure 19
HORIZONTAL WITH VERTICAL RISE
(THROUGH-THE-WALL)
TERMINATION CONFIGURATIONS
Since it is very important that the venting system
maintain its balance between the combustion air
intake and the flue gas exhaust, certain limitations
as to vent configurations apply and must be strictly
adhered to.
The Vent Graph, showing the relationship between vertical
and horizontal side wall venting, will help to determine the
various dimensions allowable. Figure 13
Minimum clearance between vent pipes and combustible
materials is 3" on top and 1" from bottom and sides unless
otherwise noted (Exception: Outside wall with firestop: 1"
all around pipes are allowed). If the vertical run is 71/2feet
or more, off the top of the fireplace, the clearance is 1" on
all sides of the horizontal run.
When vent termination exits through foundations less than
20" below siding outcrop, the vent pipe must be flush with
the siding.
It is best to locate the fireplace in such a way that minimizes
the number of offsets and horizontal vent length.

20306748 17
MLDV Series Gas Fireplace
VENTING INSTALLATION
Figure 20 -
Maximum Three (3) 90° Elbows
Per Installation
3 x 90°
Elbows
3 x 90°
Elbows
FP1176
36"
(914 mm)
Max.
36"
(914 mm)
Max.
Figure 21 -
Maximum Horizontal Run with No Rise
FP1177
WARNING
When installing the appliance as a rear
vent unit, the 90° or 45° transition elbow
attached directly to the rear of the unit is
NOT INCLUDED in the following criteria
and calculations and, unless specifically
mentioned, should be ignored when
calculating venting layouts.
•If a 90° elbow is used in the horizontal vent run (level
height maintained) the horizontal vent length is reduced
by 36". Figure 23. This does not apply if the 90° elbows
are used to increase or redirect a vertical rise. Figure
22
Example: According to the vent graph (Page 17) the
maximum horizontal vent length in a system with a 7.5'
vertical rise is 20’ (6 m) and if a 90° elbow is required in the
horizontal vent it must be reduced to 17' (5.2 m).
In Figures 22 and 23 dimension A plus B must not be
greater than 17' (5.2 m).
Figure 23 -
Maximum Vent Run with Elbows
A + B = 17' Maximum
Horizontal 90° Elbow = 3' Reduction
7'6"
10' 7'
A
B
Figure 22 -
Horizontal Run Reduction
90°
7'6"
AB
FP1958
The horizontal vent run refers to the total length of vent
pipe from the flue collar of the fireplace (or the top of the
Transition Elbow) to the face of the finished outside wall
or the mounting flange of the termination.
•The maximum number of 90° elbows per side wall
installation is three (3). Figure 20
•If a 90° elbow is fitted directly on the top of the fireplace,
the maximum horizontal vent run before the termination
or a vertical rise is 36” (914 mm). Figure 21

18 20306748
MLDV Series Gas Fireplace VENTING INSTALLATION
Example: Elbow 1 = 90°
Elbow 2 = 45°
Elbow 3 = 45°
Elbow 4 = 90°
Total Angular Variation = 270°
Figure 24 -
Maximum Elbow Usage
1 + 2 + 3 + 4 = 270°
1
2
3
4
1
2
3
4
•For each 45° elbow installed in the horizontal run, the
length of the horizontal run MUST be reduced by 18"
(457 mm). This does not apply if the 45° elbows are
installed on the vertical part of the vent system.
•The maximum number of elbow degrees in a system is
270°. Figure 24
VERTICAL SIDE WALL APPLICATIONS
For 5 x 8 Venting
1. Locate and cut the vent opening in the wall. For
combustible walls first frame in opening.
Combustible Interior Walls: Cut a 121⁄2"H x 101⁄2" W
hole through the interior wall.
Combustible Exterior Walls: Cut a 101⁄2"H x 101⁄2"W
square hole through the exterior wall frame. Figure 25
Noncombustible Walls: Hole opening should be 81⁄2"
(216 mm) in diameter.
2. The center of the hole should line up with the center line
of the horizontal rigid vent pipe end. Allow 1/4" minimum
rise per foot. Figure 25
NOTE: #1222DA reducer must be used when 4x65⁄8"
venting is preferred. The 7TDVP58 reducer must be
used when 4" x 7" venting is preferred. Reducer must
be installed directly onto unit at the fireplace collar
before vertical rise.
WARNING
You may use a reducer from 5" x 8" to 4" x
65⁄8" or 4" x 7" for horizontal with vertical rise
applications. ONLY use framing instructions
below when using 4" x 65⁄8" or 4" x 7" venting.
If the reducer is installed at the rear of the
unit, you must immediately follow with a 90
elbow for a vertical rise before continuing
with any horizontal run. There is a minimum
total height of 7 feet from the fireplace floor
to the last section of pipe before horizontal
run. Refer to graph on Page 17.
101/2"
(267 mm)
101/2"
(267 mm)
81/2"
(216 mm)
Figure 25 -
Exterior Wall Framing Dimensions for 5" x 8"
Combustible
Wall
Noncombustible
Wall
FP1954
For 4 x 7 (or 4 x 65⁄8) Venting
1. Locate and cut the vent opening in the wall. For com-
bustible walls first frame in opening.
Combustible Interior Walls: Cut a 111⁄2"H x 91⁄2" W hole
through the interior wall.
Combustible Exterior Walls: Cut a 91⁄2"H x 91⁄2"W
square hole through the exterior wall frame. Figure 26
Noncombustible Walls: Hole opening should be 71⁄2"
(190 mm) in diameter.
2. The center of the hole should line up with the center line
of the horizontal rigid vent pipe end. Allow 1/4" minimum
rise per foot. Figure 26

20306748 19
MLDV Series Gas Fireplace
VENTING INSTALLATION
91/2"
(241 mm)
91/2"
(241 mm)
71/2"
(190 mm)
Combustible
Wall
Noncombustible
Wall
FP1954
Figure 26 -
Exterior Wall Framing Dimensions for 4" x 65/8" or 4" x 7"
BELOW GRADE INSTALLATIONS
When it is not possible to meet the required vent terminal
clearances of 12" above grade level, a snorkel kit is rec-
ommended. It allows installation depth down to 7" (178
mm) below grade level. The 7" (178 mm) is measured
from the center of the horizontal vent pipe as it penetrates
through the wall.
Ensure that sidewall venting clearances are observed.
If venting system is installed below ground, we recom-
mend a window well with adequate and proper drainage
to be installed around the termination area.
If installing a snorkel, a minimum 24" vertical rise is nec-
essary. The maximum horizontal run with the 24” vertical
pipe is 36". This measurement is taken from the collar of
the fireplace (or transition elbow) to the face of the exterior
wall. Refer to the Sidewall Venting Graph for extended
horizontal run if the vertical exceeds 24".
1. Establish vent hole through the wall.
2. Remove soil to a depth of approximately 16" below base
of snorkel. Install drain pipe. Install window well (not
supplied). Refill hole with 12" of coarse gravel leaving
a clearance of approximately 4" below snorkel. Figure
27
3. Install vent system.
4. Ensure a watertight seal is made around the vent pipe
coming through the wall.
5. Apply high temperature sealant caulking (supplied)
around the 5" and 8" snorkel collars.
6. Slide the snorkel into the vent pipes and secure to the
wall.
7. Level the soil so as to maintain a 4" clearance below
snorkel. Figure 27
Figure 27 -
Below Grade Installation
Screws
Minimum
4" Clearance
Ground
Window Well
Gravel
Drain
Foundation Wall
Firestop
12"
Minimum
Figure 28 -
Snorkel Installation, Recessed Foundation
Foundation
Recess
Watertight Seal
Around Pipe
Sheet Metal
Screws
Wall Screws
Snorkel
FP1966
WARNING
• Do not back fill around snorkel.
• A clearance of at least 4” must be
maintained between the snorkel and the
soil.
If the foundation is recessed, use recess brackets (not
supplied) for securing lower portion of the snorkel. Fasten
brackets to wall first, then secure to snorkel with self drilling
#8 x 1/2sheet metal screws. It will be necessary to extend
vent pipes out as far as the protruding wall face. Figure 28

20 20306748
MLDV Series Gas Fireplace VENTING INSTALLATION
VERTICAL THROUGH-THE-ROOF APPLICA-
TIONS
Install restrictor disc as shown in Figure 29 for vertically
vented applications.
Up to two (2) restrictor discs may be needed for 40' in-
stallation.
The two (2) restrictor discs suppled will work for most instal-
lations. If a third disc is needed order Part No. 56D3027.
You may use a reducer to 4" x 65⁄8" or 4" x 7" in vertically
vented applications. If a reducer is used, only one restrictor
may be used.
NOTICE
A restrictor disc must be installed on any
vertical termination that is higher than 12'.
Restrictor Disc
Fireplace Collar
Figure 29 -
Install Restrictor Disc into Fireplace Collar
This Gas Fireplace has been approved for,
•Vertical installations up to 40' (12 m) in height. Up to
a 10' (3 m) horizontal vent run can be installed within
the vent system using a maximum of two 90° elbows.
Figure 30
10' (3 m)
Maximum
10' (3 m)
Maximum
Maximum Height
40' (12 m)
Minimum Height
8' (2 m)
Support Straps
Every 3' (914 mm)
Figure 30 -
Support Straps for Horizontal Runs
Maximum Height
40' (12 m)
Minimum Height
8' (2 m)
Support Straps
Every 3' (914 mm)
FP1183
•Up to two 45° elbows may be used within the horizontal
run. For each 45° elbow used on the horizontal plane,
the maximum horizontal length must be reduced by 18"
(450 mm).
Example: Maximum horizontal length
No elbows = 10’ (3 m)
1 x 45° elbows = 8.5’ (2.6 m)
2 x 45° elbows = 7’ (2.1 m)
•A minimum of an 8' (2.5 m) vertical rise is required.