Mason-Lite MFP39VF Owner's manual

Report No. 08-154
Do not store or use gasoline or other
ammable 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 and follow the gas
supplier’s instructions.
• If you cannot reach your gas supplier, call
the re department.
Installation and service must be performed
by a qualied installer, service agency, or
the gas supplier.
WARNING:
If the information in these instructions is
not followed exactly, a re or explosion may
result causing property damage, personal
injury or death.
This rebox has been tested and approved
by PFS-TECO under ANSI Z21.91 for use
with any ANSI Z21.11.2 approved gas logs.
IMPORTANT:
READ THESE INSTRUCTIONS CAREFULLY
BEFORE STARTING INSTALLATION OF
THIS FIREPLACE.
Do not store gasoline or other ammable
vapors and liquids in the vicinity of this or any
other appliance.
FOR USE ONLY WITH A LISTED GAS-FIRED
UNVENTED DECORATIVE ROOM HEATER
NOT TO EXCEED 40,000 BTU/H.
DO NOT BUILD A WOOD FIRE.
Carefully review the instructions supplied
with the decorative type unvented room
heater for the minimum replace size
requirement.
DO NOT INSTALL AN APPLIANCE IN THIS
FIREBOX UNLESS THIS FIREBOX MEETS
THE MINIMUM DIMENSIONS REQUIRED
FOR THE INSTALLATION.
INSTALLER:Leave this manual with the
appliance.
CONSUMER: Retain this manual for future
reference.
Installation and Operation
Instructions
Vent Free Universal Masonry Firebox
Models MFP39/44/49VF

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2
TABLE OF CONTENTS
EXAMPLE LABEL.
Below is a sample picture of the rating plate that is located inside the lower dome side of your replace. Model Number, Date
of Manufacture and Serial Number should be stamped on the plate where indicated.
Cover Page..........................................................................................................1
Table of contents................................................................................................2
Example Rating Label......................................................................................2
Fireplace Parts Diagram ....................................................................................3
Customer Service & Replacement Parts..........................................................3
General Information ........................................................................................... 4
Introduction .....................................................................................................4
Before Beginning the Installation .....................................................................4
Statement of Intended Use ..............................................................................4
Product Overview.............................................................................................4
Firebox Dimensions ......................................................................................... 4
Safety Information.........................................................................................5 - 6
Carbon Monoxide Poisoning............................................................................5
General Safety Concerns.................................................................................5
Installing Television (TV) Above Fireplace .......................................................6
Location...............................................................................................................7
Typical Installations..........................................................................................7
Framing Dimensions ........................................................................................ 7
Seismic & Non-Seismic Code ..........................................................................7
Supporting Floor System...................................................................................8
Floor Framing...................................................................................................8
Rebar Locations...............................................................................................8
Wood Floor .........................................................................................................8
Crawl Space or Upper Floor.............................................................................8
Weight Determination ........................................................................................9
Other Weight Considerations...........................................................................9
Clearances .................................................................................................10 - 11
The Importance of Clearances.......................................................................10
Clearances to combustibles...........................................................................10
Clearances to Combustible trim.....................................................................10
Interior Wall Materials..................................................................................... 11
Trim Facings.................................................................................................................... 11
Adjoining Room Walls .................................................................................... 11
Air for Combustion & Ventilation............................................................. 11 - 12
Providing Adequate Ventilation ...................................................................... 11
Unusually Tight Construction ......................................................................... 11
Unconned Space..........................................................................................12
Determining Total Air Volume .........................................................................12
Important Pre-Installation Information ...........................................................13
Overview..............................................................................................................13
Additional Materials Required ........................................................................13
Leveling and Aligning Components................................................................13
Field Assembly Procedures............................................................................13
Firebox Assembly Procedures.................................................................14 - 16
Raised and Flush Hearth Application..................................................................16
Other Installations.....................................................................................16 - 17
Gas Piping Installation.........................................................................................16
Electrical Line Feed.............................................................................................16
Firebrick Liner Installation ...................................................................................17
Modular Firebrick Liner........................................................................................17
Initial Fireplace Operation ...............................................................................17
Appendix I ........................................................................................................18
Appendix II .......................................................................................................19
Appendix III ......................................................................................................20
Limited Lifetime Warranty ...............................................................................23
Installer/Customer/Unit Information ............................................................... 24
FOR USE WITH LISTED ANSI Z21.11.2 UNVENTED DECORATIVE ROOM
HEATERS NOT TO EXCEED 40,000 BTU/HR (11.723W) CONSULT WITH
INSTRUCTIONS FOR THIS FIREBOX FOR FURTHER INFORMATION.
Refer to installation instructions and check local codes prior to installing. This appliance
must be installed in accordance with local codes if any, if not, in accordance with the
National Fuel Gas Code ANSI Z223.1 installation codes.
MFP586-NS_05/2022
ANSI Z21.91 Ventless Firebox Enclosures for Gas-Fired Unvented Decorated Room Heaters.
16” - 22” : MAX. PROJ.
22” & ABOVE: 10” MAX. PROJ.
0” - 10” : NO PROJECTIONS
10” - 16” : 1-1/2” MAX. PROJ.
DISTANCE FROM SIDE OPENINGS
3” MIN. : 1-3/4” MAX. PROJ.
MANTEL CLEARANCES
6391 Jurupa Ave., Riverside, CA 92504
THIS APPLIANCE NEEDS FRESH AIR FOR SAFE OPERATION
AND MUST BE INSTALLED SO THERE ARE PROVISIONS
FOR ADEQUATE COMBUSTION AND VENTILATION AIR.
DO NOT REMOVE THIS LABEL
SERIAL No.
LABC & LARC Compliant
MODEL No.:
MFP44VF MFP49VFMFP39VF
DATE OF MFG:
BOTTOM 0”
0”
42”
18-¹/2”
TOP/
BACK/
SIDES
OPENING
TO CEILING
CLEARANCES TO COMBUSTIBLES
RECESS
DEPTH
Tested & Listed By
Report No.
08-154
ICC Evaluation Services
Report No. 2401
EXAMPLE ONLY

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WARNING
Failure to position the parts in accordance
with these diagrams or failure to use only parts
specically approved with this appliance may
result in property damage or personal injury.
Fireplace Parts DiagramFireplace Parts Diagram
Figure 1: Exploded Diagram
CUSTOMER SERVICE & PARTS REPLACEMENT
Parts and accessories may be purchased from your
local dealer. Additional information is available from
Masonry Fireplace Industries,Inc. Accessory orders
will be accepted by mail, or you may call your order in
at: (800)-345-7078.
5
9
12
2
7
1
2X
2X
3X
8X
2X
8X
3
6
6B
6A
10
ITEM P/N DESCRIPTION QTY
1
MFP39-1
MFP44-1
MFP49-1
HEARTH (Left or Right) 2
2
MFP39-2
MFP44-2
MFP49-2
REAR WALL 4
3
MFP39-3
MFP44-3
MFP49-3
SIDE WALL 8
5
MFP39-5
MFP44-5
MFP49-5
DOME REAR - LOWER 1
6
MFP39-6
MFP44-6
MFP49-6
LINTEL 1
6A
MFP39-6A
MFP44-6A
MFP49-6A
LINTEL FRONT 1
6B
MFP39-6B
MFP44-6B
MFP49-6B
T-BAR 1
7
MFP39-7
MFP44-7
MFP49-7
DOME SIDE - LOWER 2
9
MFP39-9
MFP44-9
MFP49-9
DOME TOP 1
11 MFP170 RATING PLATE 1
12 #3 REBAR (Ø3/8”) 
MFP(39,44,49)SHBL- Herringbone
MFP(39,44,49)FRBL- Running Bond
Refractory Firebrick Liners
(Herringbone Pattern shown, also available in Running Bond -
see Page 17)
 QTY of rebar:
MFP39/44/49VF:
Eight (8) pieces 3/8” rebar x 34” long (included with unit)
Eight (8) pieces 3/8” rebar x 12” long (Not included)

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Introduction
We extend a warm welcome from all of us at Masonry
Fireplace Industries, LLC. (MFI), proud manufacturers of
Mason-Lite Fireplaces.
Thank you for Choosing MFI.
You may have thought long and hard before you chose the
replace which would grace your home. Rest assured that
every component of the Fireplace has been tested to ensure
long-term durability.
Before Beginning the Installation
Read these instructions carefully before beginning the
installation of this Vent-Free replace. Also read the gas
log appliance manufacturer’s literature regarding sizing
and suitability for installation into this Enclosure prior to
installation.
Statement of Intended Use:
The Mason-Lite Vent-Free Universal Masonry Fireplace is a
modular refractory masonry unit designed for eld assembly.
The rebox is constructed using pre-cast, interlocking
refractory blocks. The blocks are then secured to each other
using high temperature mortar. The system includes all parts
necessary for the assembly of a complete masonry vent-free
decorative gas log enclosure.
In addition to the basic enclosure, a standard 1-1/8” thick,
high temperature refractory brick is required to line the
interior of the rebox.
These replaces are not intended to serve as a primary
heat source, rather, the replace was expressly created as a
supplemental source of heat.
The MASON-LITE is Designed for Use Only with any Vent
free decorative gas log sets meeting standard ANSI Z21.11.2
Vent free decorative gas log sets meeting standard ANSI
Z21.11.2, are supplied by others and are limited to any listed
vent-free gas-red log sets with heat input ratings up to
40,000 Btu/hr.
WARNING
Any application other than the “Intended
Use” as stated above is in violation of the
manufacturer’s instructions and is hereby
prohibited. Such violation may cause
immediate hazard, property damage or
loss of life and will void all liabilities to the
manufacturer and will void all warranties
explicit or implied.
GENERAL INFORMATION
*32"
A
A
*38"
*45 3/4"
4 1/2"
43"
39"
28 1/2"
28"
23"
SECTION A-A
Figure 2
ALL DIMENSIONS ARE IN INCHES.
* VERTICAL DIMS. ARE DRY STACK MIN., HIGH
TEMPERATURE MORTAR THICKNESS MAY ADD A
TOTAL OF 1 INCH TO OVERALL HEIGHT.
MODEL
MFP39VF
MFP44VF
MFP49VF
W1
43”
48”
53”
W2
39”
44”
49”
W3
29-1/4”
34-1/4”
39-1/4”
Product Overview
Mason-Lite replaces are designed as Factory Built - Field
Assembled Fireplaces to be installed on both combustible and
non-combustible oor systems. They have been extensively
tested to perform with excellent results in this environment.
Attention: Be advised that all the illustrations in this manual
are for general reference only. They are not drawn to scale.
Actual design elements will vary from case to case. Pay
attention to specied minimum clearances as they relate to
combustible materials.
Firebox Dimensions:

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Carbon Monoxide Poisoning: Early signs of carbon
monoxide poisoning resemble the u, with headaches,
dizziness, or nausea. If you have these signs, the replace
may not be working properly. Get fresh air at once! Have
the replace serviced.
Note: Some people are a󰀨ected more than others by carbon
monoxide. These may include pregnant women, people
with heart or lung disease, are anemic, anyone under the
inuence of alcohol, and those at high altitude.
General Safety Concerns
1. If you smell gas
l Shut o󰀨 gas supply.
l Do not try to light any appliance.
l Do not touch any electrical switch; do not use any
phone in your building.
l immediately call your gas supplier from a neighbor’s
phone. Follow the gas supplier’s instructions.
l If you cannot reach your gas supplier, call the re
department.
2. This replace shall not be installed in a bedroom or
bathroom.
3. Never install the replace
l In a recreational vehicle.
l Where curtains, furniture, clothing, or other ammable
objects are less than 36 inches from the front, top, or
sides of the replace.
l In high tra󰀩c areas.
l In windy or drafty areas.
4. Do not use this replace as a wood-burning replace.
5. Do not add extra logs or ornaments such as pine cones,
vermiculite, or rock wool. Using these added items can
cause soot build-up.
WARNING
DO NOT USE OR STORE GASOLINE OR
OTHER FLAMMABLE LIQUIDS OR GASES IN
OR NEAR THE FIREPLACE!
SAFETY INFORMATION
DANGER
Carbon monoxide poisoning may lead to
death!
IMPORTANT
Read this owners manual carefully and
completely before trying to assemble,
operate, or service this replace. Improper
use of this replace can cause serious injury
or death from burns, re, explosion, electrical
shock, and carbon monoxide poisoning.
6. This replace is designed to be smokeless. If logs
appear to smoke, turn o󰀨 replace and call a qualied
service person.
7. Avoid any drafts that alter burner ame patterns. Do
not allow fans to blow directly into the replace. Do not
place a blower inside burn area of the rebox. Ceiling
fans may create drafts that alter burner ame patterns.
Soot build-up and improper burning will occur. Soot
build-up can settle on household surfaces outside the
replace.
8. This replace needs fresh air ventilation to run properly.
The Vent free decorative gas log set must have an
oxygen depletion sensor (ODS) pilot light safety system.
The ODS shuts down the replace if not enough fresh
air is available. See Air for Combustion and Ventilation,
page 10. If the replace keeps shutting o󰀨, see appliance
manufacturers’ troubleshooting instructions.
9. Do not run replace
l Where ammable liquids or vapors are used or stored.
l Under dusty conditions.
10. Do not use this replace to cook food or burn paper or
other objects.
11. Never place any objects in the replace or on logs.
12. Fireplace glass doors are not permitted in this decorative
room heater. Fireplace front becomes very hot when
running replace. Keep children and adults away from
hot surfaces to avoid burns or clothing ignition. The
replace will remain hot for a time after shut down. Allow
surfaces to cool before touching.
13. Carefully supervise young children when they are in the
room with the replace.
14. Do not use replace if any part has been exposed to
or under water. Immediately call a qualied service
technician to inspect the replace and to replace any
part of the control system and gas control which has
been under water.
15. Do not operate the replace if any log is broken. Do not
operate the replace if a log is chipped (dime-sized or
larger). Verify proper log placement prior to operating
appliance.
16. Turn replace o󰀨 and let cool before servicing. Only a
qualied service person should service and repair the
replace.
17. Operating the replace above elevations of 4,500 feet
may cause pilot outage.
Carbon Monoxide Poisoning

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6
Installing Television (TV) Above Fireplace
Before installing a television (TV), be aware that this is a
heat producing replace. Objects placed above the unit are
exposed to elevated temperatures.
IMPORTANT NOTICE
TVs should not be used in situations where the actual
TV temperature exceeds the manufacturer’s technical
specication. Contact the TV manufacturer directly if
you cannot locate this information or have questions
regarding this information.
NOTE: The homeowner must understand that MFI
does not take responsibility for any negative impact
to televisions placed near this replace.
WARNING
Ensure clearances to combustibles are maintained
when building a mantel or shelves above the replace.
Elevated temperatures on the wall or in the air above
the replace can cause melting, discoloration or
damage to decorations, a television (TV) or other
electronic components.
SAFETY INFORMATION Continued
When choosing a location for your replace, avoid locations
that are subject to too much draft or locations where you
may encounter obstructions that may be in the way of the
replace once installed. Always check local codes and
familiarize yourself with the surrounding construction.
Carefully review the instructions supplied with the
decorative type unvented room heater for the minimum
rebox size requirement.
DO NOT INSTALL THE APPLIANCE IN THIS FIREBOX
UNLESS THIS FIREBOX MEETS THE MINIMUM
DIMENSIONS REQUIRED FOR THE INSTALLATION.
ATTENTION
A re or an explosion could occur causing
property damage, injury or loss of life if you
do not follow the information in this manual!
NOTE: THIS MANUAL MUST BE REPRODUCED ONLY
IN ITS ENTIRETY.

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LOCATION
Note: You may need to provide combustion and ventilation
air from an outside source to adequately satisfy local codes
so avoid installing a combustion air inlet where the opening
could be blocked by snow, bushes or other obstacles. Note
that the access for outside air inlet is located on the right
hand side of the replace.
A ush installation is recommended where living space
is limited or at a premium. Check local codes for any
restrictions.
Projected installations can extend any distance into the
room. A projection may be ideal for a new addition on an
existing, nished wall.
Corner installations make use of space that may not
normally be used and provides a wider and more e󰀩cient
range for heat disbursement.
An internal wall installation provides a discreet option for
room separation and can also be ideal as an addition to an
existing wall.
W
H
D
Figure 4
*Height may vary. Maintain 1/2 inch clearance to
top of lintel (see Figure 12, page 10).
Model W H D
MFP39VF 43” *41” 28”
MFP44VF 48” *41” 28”
MFP49VF 53” *41” 28”
*
IMPORTANT
Vent-free heaters add moisture to the air.
Installing a replace in rooms without
enough ventilation air may cause mildew to
form from too much moisture.
IMPORTANT
Make sure the replace is level. If the replace
is not level, the log set will not work properly.
ATTENTION
You may need a building permit to install
a MASON-LITE fireplace. Check with the
local jurisdiction before you get started.
Figure 3
Internal
Wall
Installation Corner
Installation
Flush
Installation
Full
Projection
Installation
Seismic & Non-Seismic Code
Framing DimensionsTypical Installations
Mason-Lite Fireplaces have been tested and passed the
seismic requirements for Modular Masonry Fireplaces
throughout the entire United States. We understand that not
every installation needs the extra security that is involved
in a high seismic zones. Rebar is ONLY REQUIRED on
Mason-Lite units in seismic zones 3 & 4 shown in the map in
appendix III, page 20. We will supply rebar to all replaces
shipped to zones 3 and 4 in the United States unless
otherwise requested.

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8
I-JOISTS
Example Only
Anchor
Brackets
I-Joist
Example Only
Simpson
Strong Tie
A-35 or
Equivalent
SUPPORTING FLOOR SYSTEM
Floor Framing
It is important to take into consideration that the load for the
Mason-Lite Fireplace is considerable, but, more important,
that it is a dead load that will have to be absorbed by a
relatively small amount of existing oor space.
It is the ultimate responsibility of the installer to ensure that
proper concrete slab supports are used.
WARNING
To the licensed design professional and/or
building contractor: It is your responsibility
to be certain that the Mason-Lite can be
properly supported by the combustible oor
system on which the replace will rest.
For replace support foundations installed on concrete
refer to Appendix I and II (pages 18 & 19) for specic
instructions.
Rebar locations
Lay-out the position of the replace and drill holes where the
rebar will be located. Secure the #3 rebar 4 inches into the
concrete foundation with ITW Epoxy or Simpson Epoxy. Follow
manufacturer’s instructions for installation of rebar into slab.
Wood Floor
Anchorage of replace to wood oor construction is required.
Refer to Figure 8, page 9 for anchorage dimensions. Four
anchors are required to attach to the sub-ooring framing.
Crawl Space or Upper Floor:
For installation of rebox over combustible crawl spaces or
upper oors, anchorage of the rebox is required. Illustrations
of examples of possible anchorage methods are shown in
Figures 5 thru 7 depending upon the type of oor framing.
Final method of anchorage is to be determined by licensed
design professional.
For conventional framing, where the oor joists are parallel
with the sides of the rebox, the addition of oor joists to
align with the anchor brackets allows the brackets to be
directly connected to the oor joists.
Note that additional oor joists may be required to support
the weight of the rebox and chimney. Where the oor joists
run parallel to the front of the rebox, anchorage can be
accomplished in like manner as shown in Figure 5 using
blocking between the oor joist.
For oors supported by I-Joists, the method of anchorage is
illustrated in Figures 6 and 7. Figure 10, page 9 illustrates
the general arrangement of anchorage to oor framing.
It is important to take into consideration that the load for
the Mason-Lite Fireplace must be considered as additional
dead load that will have to be supported by the oor
framing. Additional oor joists or I-joists may be required as
determined by the licensed design professional.
The dead weights for the replace are noted in Table I. It is
the task and responsibility of the general contractor/installer
to see that the proper reinforcement for weight loads are
made by a licensed design professional prior to the replace
installation.
As stated above, it is desirable to place additional framing
for alignment of anchor rods. Refer to Figure 10 for anchor
rod locations.
EXAMPLE ONLY
2X FLOOR JOIST
2X FLOOR JOIST
Figure 5
Floor Sheathing
not shown for
clarity
A35 Brackets
(16 required)
Figure 6
I-Joist Anchoring
Top View
Figure 7
I-Joist
Anchoring
Bottom
View

mason-lite.com 9
F
A4"
10"
WEIGHT DETERMINATIONS
The following are dead load weight estimates for the Mason-Lite Fireplace.
Other Weight Considerations:
Fireplace nished facing (surround): This information needs to be obtained from the contractor.
1 For wood structural members having a moisture content of less than 16 per cent at time of installation and used under
dry conditions, the deection resulting from L + 0.5D is permitted to be substituted for the deection resulting from L + D.
Note that MASON-LITE cannot accept responsibility for structural oor support details. All drawings are presented as mere
illustrations to indicate the presence of the underlying oor system. It is the responsibility of the general contractor/installer
to consult with a local licensed design professional for guidance in building a proper oor support system.
Table I
Fireplace Model MFP39VF MFP44VF MFP49VF
Fireplace Weight 809 lbs. 896 lbs. 987 lbs.
High temperature mortar,
Rebar & Ready Mix Concrete 350 lbs. 357 lbs. 364 lbs.
Firebrick Lining 333 lbs. 345 lbs. 356 lbs.
Floor Area 43” x 28” (8.12 ft²) 48” x 28” (9.33 ft²) 53” x 28” (10.30 ft²)
Table II - Deection Limits
Construction L S or W D +L1
Floor Members I/360 --- I/240
Model A
MFP39VF 38-3/4”
MFP44VF 43-3/4”
MFP49VF 48-3/4”
Figure 8 Figure 9
Typical Anchorage Layout
Figure 10
EXAMPLE ONLY
SECTION VIEW
ROTATED 90CW
10"
Fireplace
Outline

mason-lite.com
10
CLEARANCES
The Importance of Clearances
Warning to the structural engineer and/or building contractor:
It is your responsibility to be certain that the Mason-Lite can
be properly supported by the combustible oor system on
which the replace will rest. Be advised that this engineering
equation will be in addition to any live or dead weights that
the oor has to carry.
Clearances to Combustibles
Nothing is more important than paying strict attention to
giving clearance between replace surfaces and surrounding
“combustibles” the most common of which are:
lDrywall
lWood ooring
lPlywood sub-ooring
lFraming materials
lParticle board
lMill board
lPlywood paneling
Required Clearances are:
Unit front, sides, rear: 0"
Combustible Floor: 0"
Combustible Sheathing above opening top: 8" (203 mm)
Sheathing or trim to opening sides: 8" (203 mm)
Mantle above opening: 12" (305 mm)
Opening to sidewall: 24" (610 mm)
Insulation from rebox: 0"
The Mason-Lite Vent-Free replace may be installed at
“zero clearance” to plywood sheathing and to uninsulated
wood framing members at the unit bottom, sides, rear and
top when used for enclosing any listed vent-free gas-red
log set with maximum heat input ratings up to 40,000 Btu/
hr. However, when a Vent-Free replace is to be installed on
carpeting, wood ooring, or any combustible material other
than tile or concrete, the Vent-Free replace shall then be
installed on a metal or wood platform extending the full width
and depth of the Vent-Free replace.
Clearance to Combustible Trim:
Mason-Lite Vent-Free Fireplaces are designed to be custom
nished with facing trim and mantle to be an owner option.
However, all such trim material must meet standard replace
code requirements.
Non-combustible facing material must be applied to a
minimum of eight inches (8”) beyond the sides of the nished
opening of the Vent-Free replace and non-combustible
facing material must cover a minimum of twelve inches (12”)
above the nished opening of the installed unit.
Clearance to combustible trim are those distances required
to ensure that combustible mantle and facing material will
not be exposed to excessive heat while the unit is operating.
These clearances should be adequate to prevent
discoloration or warping of trim facings due to heat. However,
circumstances unique to each installation create variables
that may be beyond the scope of this manual. Therefore
be sure to follow gas log appliance manufacturer’s explicit
installation instructions regarding all minimum trim facing,
mantle height and side wall clearance requirements.
Parts of the combustible mantle assembly located above
and projecting more than one and one-half inches (1-1/2”)
inches from the rebox opening shall be kept at least twelve
inches (12”) from the top of the opening.
Mantle shelves with horizontal projection of ten inches (10”)
from the face of the replace must be held to a minimum
vertical distance of twenty inches (20”) from the top of the
nished replace opening.
Figure 11
Figure 12
Note: Mantle height clearances may vary among gas log
appliance manufacturers or with the use of rebox canopies.
Be sure to follow the gas log appliance manufacturer’s explicit
installation instructions for mantle height clearance requirements.
12"
NON-COMBUSTIBLE
ONLY ZONE
20" MIN
1 1/2"
10"
SAFE ZONE FOR
PROJECTION OF
COMBUSTIBLE
MATERIAL
TOP OF FIREPLACE OPENING
MANTEL
LINTEL FRONT
UNVENTED
FIREPLACE
DOME TOP
ALLOW 1/2" MIN
CLEARANCE
1-1/2”
8” MIN
NON-
COMBUSTIBLE
FACIA

mason-lite.com 11
Interior Wall Materials:
Wall materials, such as drywall, should be set ush with the
rough front face of the Vent-Free replace. This will allow for
placement of required non-combustible surround material in
such a way that the surround material can lay at against the
nished wall surface and also align with the leading edge of
the re brick interior of the Vent-Free replace (see Figure
15).
Trim Facings:
Parts of the combustible mantle assembly located along the
sides of the rebox opening, which project more than one
and one-half inches (1-1/2”) from the face of the replace,
shall be kept at least eight inches (8”) from the rebox
opening.
Adjoining Room Walls:
Interior wall surfaces of adjoining room walls must be at a
minimum horizontal measure of twenty four inches (24”)
away from the nished opening of the Vent-Free replace.
Energy e󰀩cient homes require homes to be airtight but at the
same time provide su󰀩cient fresh air to breathe. Fresh air
enters the home through air conditioning duct vents, around
doors and windows but also must provide enough fresh air
for proper combustion on all fuel-burning appliances in the
home.
Exhaust fans, replaces, clothes dryers, and fuel-burning
appliances draw air from the house to operate. You must
provide adequate fresh air for these appliances. This will
insure proper venting of vented fuel-burning appliances.
AIR FOR COMBUSTION & VENTILATIONCLEARANCES Continued
Non-combustible
Flex Hose
Figure 16 Exterior
IMPORTANT
Outside Air Kits are not approved for use
with this replace intended for Unvented Gas
Logs. Installing an Air Kit through the side
wall of the replace may a󰀨ect the proper
function of the ODS pilot system.
Providing Adequate Ventilation
In accordance with the National Fuel Gas Code NFPA
54/ANSI Z223.1, Section 5.3, Air for Combustion and
Ventilation, all spaces in homes fall into one of the three
following ventilation classications:
1. Unusually Tight Construction
2. Unconned Space
3. Conned Space
The following information will help you classify your space
and provide adequate ventilation.
Unusually Tight Construction
The air that leaks around doors and windows may
provide enough fresh air for combustion and ventilation.
However, in homes of unusually tight construction, you must
provide additional fresh air. Unusually tight construction is
dened as construction where:
a. Walls and ceilings exposed to the outside atmosphere
have a continuous water vapor retarder with a rating of
one perm* or less with openings gasketed or sealed and...
b. Weather stripping has been added on openable windows
and doors and...
c. Caulking or sealants are applied to areas such as joints
around window and door frames, between sole plates
and oors, between wall-ceiling joints, between wall
panels, at penetrations for plumbing, electrical, and gas
lines, and other openings.
FRAMING
Figure 15
8" MIN. NON-COMBUSTIBLE MATERIAL
1-1/2"
24"
MIN
D1
W
Figure 14
8" MIN. NON-COMBUSTIBLE MATERIAL
Model W D1
MFP39VF 43” 73-1/2”
MFP44VF 48” 77”
MFP49VF 53” 80-1/2”
FRAMING
1-1/2"
33"
MIN

mason-lite.com
12
AIR FOR COMBUSTION & VENTILATION Continued
WARNING
If the area in which the heater may be operated
is smaller than that dened as an unconned
space, provide adequate combustion and
ventilation air by one of the methods described
in the National Fuel Gas Code, ANSI Z223.1
Section 5.3 or applicable local codes.
IMPORTANT
Do not provide openings for inlet or outlet
air into an attic if the attic has a thermostat-
controlled power vent. Heated air entering
the attic will activate the power vent.
* A perm is a unit of permeance or water vapor transmission,
the US perm-inch is dened as the passage of 1 grain of
vapor through 1 square foot of 1 inch thick material in 1 hour
under a pressure di󰀨erence of 1 inch of mercury.
If your home meets all the three criteria above, you must
provide additional fresh air.
Unconned Space
An unconned space has a minimum total air volume of
50 cu.ft. (cubic feet) for each 1,000 Btu/Hr input rating of all
appliances in the total space (cu.ft. = length x width x height
of space). Include adjoining rooms only if there are doorless
passageways or ventilation grills between the rooms. If the
Btu per 50 cu.ft. is less than 1,000 Btu/Hr, then fresh air will
be provided by the natural air ow into the house.
Conned Space
A conned space has an air volume of less than 50 cu.ft.
for each 1,000 Btu/Hr input rating of all appliances in the
space (cu.ft. = length x width x height of space). Include
adjoining rooms only if there are door less passageways or
ventilation grills between the rooms.
Determining Total Air Volume
Use this work sheet to determine if you have a conned
or unconned space. The space to be considered includes
not only the room in which you will install the replace but
also any adjoining rooms with ventilation grills between them
or door less passageways.
1. Determine the total volume of your space
L x W x H = _______ cu.ft.
Example: Space size = 20 ft. long x 20 ft. wide x 8 ft. high
(ceiling height) = 3,200 cu.ft.
If adjoining ventilation to adjoining room is supplied with
grills or openings, add the volume of these rooms to the
total volume of the space.
2. Divide the space volume by 50 cu.ft. to determine the
maximum Btu/Hr the space can support.
_______ cu.ft. (volume of space)
50 cu ft. = (Maximum Btu/Hr the space can support)
Example: 3200 cu ft. (Volume of space) / 50 cu. Ft. = 64.0
or 64,000 (maximum Btu/Hr the space can support.)
3. Add the Btu/Hr of all fuel burning appliances in the space.
Vent-free replace _______ Btu/hr
Gas water heater* _______ Btu/hr
Gas furnace _______ Btu/hr
Vented gas heater _______ Btu/hr
Gas replace logs _______ Btu/hr
Other gas appliances* _______ Btu/hr
Total = _______ Btu/hr
Example: Gas water heater 40,000 Btu/hr
Vent-free replace +36,000 Btu/hr
Total = 76,000 Btu/hr
* Do not include direct-vented gas appliances. Direct vent
draws combustion air from the outdoors and vents to the
outdoors.
4. Compare the maximum Btu/Hr the space can support
with the actual amount of Btu/Hr used.
_________ Btu/Hr (maximum the space can support)
_________ Btu/Hr (actual amount of Btu/Hr used)
Example:
64,000 Btu/Hr (maximum the space can support)
76,000 Btu/Hr (actual amount of Btu/Hr used)
The space in the previous example was a conned
space because the actual Btu/Hr used was more than the
maximum Btu/Hr the space could support. If you nd
you have a Conned Space, you must provide additional
fresh air. Your options are as follows:
a) Re-work worksheet, adding the space of an adjoining
room that may not have qualied for the extra volume. If
the extra space provides enough volume to convert the
area to an unconned space, remove door to adjoining
room or add ventilation grills between rooms.
b) Vent room directly to the outdoors.
c) Install a lower Btu/Hr gas log (if lower Btu/Hr size makes
room unconned).
If the actual Btu/Hr used is less than the maximum Btu/Hr
the space can support, the space is an unconned space.
You will need no additional fresh air ventilation.
Local codes may have stricter denitions for conned space
and/or for unusually tight construction. Check you local codes.

mason-lite.com 13
IMPORTANT PRE-INSTALLATION INFORMATION
Overview
You will nd that the Mason-Lite Fireplace is designed
for complete assembly at your construction site with all
necessary items delivered consisting of interlocking precast
parts, 50 lbs. of Mason-Lite high temperature mortar and
rebar.
The parts of the replace are made of Mason-Lite’s
incredibly strong blend of specialty cement and a lightweight
aggregate.
The design of the replace calls for the installation of a
refractory re brick liner. This should be a minimum of 1-1/8”
thick. The liner will be applied within the walls of the rebox.
Modular rebrick panels are also available from MFI.
Additional Materials Required:
1) Ready-Mix concrete - 2 cu.ft.
SURFACE CRACKS - The MASON-LITE FIREPLACES
are manufactured using high quality materials. During the
drying process, surface cracking may occur. These small
cracks (under 1/16” will not a󰀨ect the replace safety or
performance). During the assembly process, ll surface
cracks with thin-set high temperature mortar and brush
when drying for a smooth surface nish.
Leveling and Aligning Components:
It is important to assemble all Vent-Free replace
components ush, level and square. Since it is not intended
that high temperature mortar be used to lay a mortar joint of
any measurable thickness as is typical when laying brick or
concrete block, adjustments in component height and level
alignments are accomplished with the use of small shims.
These shims can be tapped into place to level and align
components. Once the Mason-Lite high temperature mortar
is set, the shims must be removed completely.
Be sure to re-grout any and all gaps where shims have been
inserted and then removed or where contact surfaces have
been separated by shim leveling.
Field Assembly Procedures
1) Mixing the MASON-LITE high temperature mortar –
You will require a 50 lb. bucket of MASON-LITE high
temperature mortar which will be more than enough to
adequately a󰀩x all the replace components, one to the
next. The high temperature mortar is premixed and dry
and is to be used to adhere all the replace components.
Be sure to use clean water and work it up into a mixture that
is pasty but not lumpy. If it is too thin, the components will
not adhere. Some trial and error may be necessary. You will
want to apply the mixture with a standard grout bag.
2) Moisten all surfaces which will have grout applied prior
to assembly. This will minimize shrinkage and cracks
developing in the joint areas. Best way to accomplish
this is with a bucket of water and a large sponge. Dip
sponge into water and apply a liberal amount of water to
the grout joint surface several minutes before the part is
to be assembled. The water will absorb into the surface
allowing the grout to properly cure.
3) Assembly of the Components – Once you have found the
proper consistency of the mixture, load it into the grout
bag and then place the components together applying
the mixture directly to the components where they
come together. As a rule, you can gure that you should
lay down about ½” (one-half inch) of a thread of high
temperature mortar. The line of high temperature mortar
should be approximately ½” (one-half inch) away from all
the edges of each separate component.
The high temperature mortar has a considerable amount
of holding power so do not overload the components
with too much high temperature mortar.
4) You will notice that some high temperature mortar will
“ooze out” when you place the next component on top
of or next to the component you previously place. This is
to be expected – it means the two pieces have properly
bonded -- and you will want to swipe the excess away
with a trowel. It is never intended that the surfaces of the
MASON-LITE components are to be completely covered
with high temperature mortar.
5) Do not apply the high temperature mortar in thick bands
even if the component you are working with is larger
than the rest. You will want to apply “stripes” of high
temperature mortar in these situations.
6) Making Sure Components Are Level – It is extremely
important that you pay careful attention to how you are
assembling the MASON-LITE. Since every component
builds on the next, it is critical, that from the beginning,
you are checking that the components are tting together
to be level and ush. If you have to make any kind of an
adjustment, do not try to do it “by loading an opening”
with high temperature mortar. That is completely
unacceptable, resulting in a replace that will not be
plumb or level. What you are advised to do is make use
of shims. You will nd these supplied with the MASON-
LITE and you can nudge them in between openings to
achieve the precision you need in making component
adjustments.
7) Once you have removed the shims, you will want to
cover any gaps that may have resulted with the grout.
WARNING
All surfaces where grout is applied must
have water sponged on several minutes prior
to assembly. This will minimize cracking of
grout joint and provide maximum strength.

mason-lite.com
14
FIREBOX ASSEMBLY PROCEDURES
Note - Wipe excess water from surface prior to applying
grout. This will help grout to adhere to surface during
assembly.
Warning: All surfaces where grout is applied must have
water sponged on several minutes prior to assembly. This
will minimize cracking of grout joint and provide maximum
strength.
Place the Mason-Lite Fireplace hearth base on top of your
non-combustible oor. For concrete slabs, supporting oor
needs to be rated at ASTM 90.
1. Draw an outline of the hearth area based on the
dimensions shown in Figure 17. Position Hearth slabs
and mark rebar center locations. Drill 4 inches into
concrete slab and secure the 8 pieces of 12 inch rebar
with epoxy.
1/2” AWAY
FROM EDGES
2. Mix a batch of high temperature mortar and prepare
Right Side Hearth bottom surface to be bonded as
shown in Figure 18.
3. Align Right Side Hearth to the outline created. The
overall width should allow for an approximate gap of
1/8” between slabs for the additional high temperature
mortar to unite the remaining slab. Check for surface
atness, level if necessary.
4. Apply high temperature mortar to the remaining Hearth
except this time apply beading on surface to be facing
oor as shown in Figure 19.
5. Prepare side wall and rear wall mating surfaces with the
prepared high temperature mortar and begin assembly.
6. Keep the assembly of the next sections of the rebox
side walls moving up, keeping components moist,
mixing high temperature mortar as you need it and
threading the high temperature mortar appropriately as
you stack each section, one onto the next. Constantly
check for squareness and levelness while building each
course of block. As you complete each section, make
certain that you adhere the high temperature mortar at
each and every joint.
7. When you have arranged all the components into place
and you are working on the top rear rebox, check that
your work is level. If you need to, you can make some
adjustments in the top surface of the box assembly
simply by using shims. Once you are satised with
the degree of levelness, you can address any gap that
may have occurred with an appropriate amount of high
temperature mortar.
Figure 20
Figure 18
1/2” AWAY
FROM EDGES
1/2” HIGH
TEMPERA-
TURE MOR-
TAR BEAD
TYPICAL
Hearth section shown prepared
for Right Side position
APPLY HIGH
TEMPERATURE
MORTAR BEAD TO ALL
MATING SURFACES
Figure 19 Hearth shown prepared
for Left Side position
Figure 21
Apply high
temperature
mortar
Apply high temperature
mortar
Side Wall
Rear Wall
Side Wall
Figure 17
Two 26 ga. galv.
hearth ember
shields required
(not supplied)
Left Side Hearth 2nd
Right Side Hearth 1st
W
28”
Apply high
temperature
mortar
between joints
12 inch rebar
Model W
MFP39VF 43”
MFP44VF 48”
MFP49VF 53”

mason-lite.com 15
FIREBOX ASSEMBLY PROCEDURES Continued
Although you are cautioned to use Mason-Lite high
temperature mortar sparingly because it does have
such holding power, you should look over the rebox
assembly at the end and ll any gaps with high
temperature mortar especially at joint connections.
Adjustments must be made to ensure the replace is
level and square while the high temperature mortar is
still wet.
8. After fourth row of walls are in place, add 36” rebar to
all cells as shown in Figure 22. The rebar should enter
the holes in the Hearth and lie adjacent to the 12” rebar
secured in suboor. Then ll cells with approx. 2 cu.ft.
Ready-Mix Concrete.
9. Temporarily place Lintel between side walls, making sure
it is ush to the front and snug at the inside. Check for
alignment. Remove Lintel and apply high temperature
mortar on surfaces to be mated. Install Lintel.
10. Install Lower Rear Dome ush to the rear walls as shown
in Figure 23.
Figure 22
12 inch
rebar
Add rebar after
fourth row
Figure 23
Lintel
Lower Rear
Dome
T-Bar
Lintel
Front
Figure 24 Rating Plate
faces inside
All four top
surfaces to
be level
Lintel front
to be ush to
front face
Figure 25
11. Place Lower Side Domes between Lintel and Lower
Rear Dome to verify t. The face with the rating plate
faces the inside of the rebox as shown in Figure
24. Remove and prepare mating surfaces with high
temperature mortar. Assemble Lower Dome Sides and
check that all four top surfaces are level with each other.
Shim if necessary.
12. Now install the Smoke Dome Tops. Align outer edges
with Lower Dome Sides. Check for atness and
squareness.

mason-lite.com
16
OTHER INSTALLATIONS
FIREBOX ASSEMBLY PROCEDURES Continued
Raised and Flush Hearth Application:
If you would prefer to have a raised hearth, the Vent-Free
box can be raised to the desired height using wood studs or
concrete blocks.
When determining raised hearth height, be sure to allow for
the 3” thick rebox hearth and 1-1/2” thick rebrick oor, in
addition to the height of base platform.
Gas Piping Installation
The provision for installation of a gas pipe is only for
connection to a Vent free decorative gas log sets meeting
standard ANSI Z21.11.2
Familiarize yourself with requirements for installation as
outlined by the National Fuel Gas Code, ANSI Z223.1.
This gas pipe provision must only be connected to an
approved vent-free gas log heater certied to ANSI Z21.11.2
heater standard. Check local building codes for specic pipe
and material requirements.
1. Gas piping can be routed from the oor, rear or side
walls. With a masonry drill, follow the instructions from
the gas appliance manufacturer. Any wires must be
routed through separate conduit. Make sure provisions
are made for access to manual shut-o󰀨 valve.
2. After routing piping, ll hole around pipe with MASON-
LITE high temperature mortar.
Figure 27
Raised Wood
Platform
Figure 26
Concrete Block
Raised Platform
Figure 28 CSA Certied Manual
Shut-o󰀨 Valve
Tee-joint
Sediment
Trap
Approved
Flexible
Gas Line 3”
Minimum
Pipe
Nipple
Cap
From External
Regulator
(11-14” W.C. pressure)
For a “ush hearth” (replace oor ush with the room’s
oor) the base plate can be omitted from the assembly and
the rebox walls built directly on the concrete support slab.
The re brick oor of the rebox is then set directly to the
concrete support slab. This makes the replace nished re
brick oor approximately one and one-half inches (1-1/2”)
above the top of the concrete support slab.
Electrical Line Feed
Electrical line feed can be routed through the Standard
rebox back wall, side walls or oor by drilling an
appropriately sized hole using a masonry drill bit. Be sure
to follow the Vent free decorative gas log Manufacturer’s
explicit electrical line connection instructions for vented
masonry replace installations.
NOTE: Gas line and electric line must be routed through
separate access holes.
IMPORTANT: All access holes must be grouted with high
temperature mortar to seal any gaps or cracks.
Firebrick SideGas or
Electric Line
Figure 29

mason-lite.com 17
OTHER INSTALLATIONS Continued INITIAL FIREPLACE OPERATION
Firebrick Liner Installation
It is required that the interior sides, rear and bottom be
lined with minimum 1-1/8” thick rebrick. Mason-Lite Pre-
fabricated re brick liner walls can make the installation
easier.
All required through-wall accesses (gas and electrical line
feeds and combustion air supply access holes) should be
drilled before the required re brick lining is installed.
Modular Firebrick Lining
If using our Mason-Lite Firebrick Liners, simply use an extra
bucket of high temperature mortar. Install Hearth Liner rst,
rear next and sides last. Consider if brackets for grates
will be required, also if pre-drilling is required for gas lines,
electrical or if the outside combustion air kit is to be installed.
The following Firebrick Patterns are available from MFI:
Follow the gas appliance manufacturers’ requirements for
lighting and operating your vent free log. When rst operating
the replace, open a window in the room to allow smells
created from the heater and replace curing.
We suggest operating the heater for several 30 minute
intervals allowing the replace to cool for an hour in between.
This will allow any moisture in the brick and replace to
escape.
Keep in mind that it may require several operations to
completely remove any smell from the operation of a vent-
free heater and replace. If this condition continues, contact
your gas appliance dealer to inspect the gas heater for
proper operation.
MFP(XX)FRBL- Running Bond
MFP(XX)SHBL- Herring Bone
Figure 30
Figure 31
WARNING
DO NOT OPERATE FIREPLACE WITHOUT
FIREBRICK LINING. Doing so will void all
warranties and may cause a hazardous
condition.
WARNING
LIFTING HAZARD.
SINGLE-PERSON LIFT
COULD CAUSE INJURY.
USE ASSISTANCE WHEN
MOVING OR LIFTING

mason-lite.com
18
Appendix I
For installations regulated by the International Residential Code, the
support foundation for the fireplace installed on concrete shall
consist of a minimum of6inches thick reinforced concrete slab. The minimum specified compressive strength of
f’c, shall be as
required in Table R402.2 of the International Residential Code (IRC). Concrete subject to moderate or severe weathering as indicated in Figure R301.2(3) of the International Residential Code (IRC) shall be air entrained as specified in Table R402.2 of the International
Residential Code (IRC). The maximum weight of fly ash, other pozzolans, silica fume, slag or blended cements that is included in
concrete mixtures for garage floor slabs and for exterior porches, carport slabs and steps that will be exposed to deicing chemicals
shall not exceed the percentages of the total weight of cementitious materials specified in Section 4.2.3 of ACI 318. Materials
used to
produce concrete and testing thereof shall comply with the applicable standards listed in Chapter 3 of ACI 318.
For installations regulated by the International Building Code (IBC), the support foundation for the fireplace installed on concrete shall consist of a minimum of 6 inches thick reinforced concrete slab. The concrete strength and durability shall comply with Sections
1903, 1904 and 1905 of the International Building Code (IBC).
TABLE R402.2 MINIMUM SPECIFIED COMPRESSIVE STRENGTH OF CONCRETE
MINIMUM SPECIFIED COMPRESSIVE STRENGTHa(f’c)
Weathering Potentialb
TYPE OR LOCATION OF CONCRETE CONSTRUCTION Negligible Moderate Severe
Basement walls, foundations and other concrete not exposed to the weather 2,500 2,500 2,500c
Basement slabs and interior slabs on grade, except garage floor slabs 2,500 2,500 2,500c
Basement walls, foundation walls, exterior walls and other vertical concrete work exposed to the weather
2,500 3,000d3,000d
Porches, carport slabs and steps exposed to the weather, and garage floor slabs 2,500 3,000d,e,f 3,500d,e,f
a. Strength at 28 days psi. b. See Figure R301.2(3) for weathering potential.
c. Concrete in these locations that may be subject to freezing and thawing during construction shall be air-entrained concrete in
accordance with Footnote d.
d. Concrete shall be air-entrained. Total air content (percent by volume of concrete) shall be not less than 5 percent or more than
7 percent.
e. See Section R402.2 for maximum cementitious materials content. f. For garage floors with a steel troweled finish, reduction of the totalair content (percent by volume of concrete) to not less than
3 percent is permitted if the specified compressive strength of the concrete is increased to not less than 4,000 psi.

mason-lite.com 19
Appendix II
FIGURE R301.2(3) WEATHERING PROBABILITY MAP FOR CONCRETE
salts to be used extensively.
SEVERE MODERATE NEGLIGIBLE

mason-lite.com
20
Appendix II
MAP FOR
Mason-Lite Fireplaces have been tested and passed the seismic requirements for Modular Masonry Fireplaces throughout the entire United States. We understand that not every installation needs the extra security that is involved in a high seismic zones. Rebar is ONLY REQUIRED in Mason-Lite units in seismic zones 3 & 4 shown in the map below. We will supply rebar to all fireplaces shipped to in the United States unless otherwise requested.
0
0
0
0
0
1
1
1
1
1
1
2A
2A
2A
2A
2A
2A
1
1
1
1
1
1
2B
2B
2B
2B
3
3 4
3
3
3
3
3
33
4
4
4
4
0
4
3
1
2B
2B
0
4
3 3
4
2B
1
1
0
0
Guam Hagåtña
Puerto Rico San Juan
Oahu
Honolulu
Caribbean & Virgin Islands
Seismic Zones (Ground Acceleration)
Hawaii
Kauai
United States Seismic Zones Map
SEISMIC ACTIVITY MAP FOR THE UNITED STATES
Appendix III
Zone 1 = 0.075g
Zone 0 = 0.0g
Zone 2A = 0.15g Zone 2B = 0.20g Zone 3 = 0.30g Zone 4 = 0.40g