Heat & Glo STS-42 Manual

07/03 35035 Rev D 1
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.
INSTALLATION & OPERATING
INSTRUCTIONS
STS-42
OUTDOOR WOODBURNING FIREPLACE
This fireplace must be installed outside. Significant cold air infiltration will result if it is installed inside a structure.

2 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
CAUTION:
o not expose the fireplace to the elements (i.e. rain, etc.) and keep the fireplace dry at all times. Wet insula-
tion will produce an odor when the fireplace is used.
TABLE OF CONTENTS
A. Listings and Code Approvals ...................................................................................................................... 3
B. Description of the Fireplace System ............................................................................................................ 3
C. Fireplace System Components ................................................................................................................... 4
D. Pre- nstallation Preparation ......................................................................................................................... 8
E. Chimney Requirements ............................................................................................................................. 10
F. nstallation of Fireplace ............................................................................................................................. 12
G. Operating nstructions ............................................................................................................................... 21
H. Maintenance nstructions .......................................................................................................................... 25
ndex ......................................................................................................................................................... 27
Warranty ................................................................................................................................................... 28
WARNING!
This appliance is tested and listed for use only with the optional accessories listed in these instructions. Use
of optional accessories not specifically tested for this appliance could void the warranty and/or result in a
safety hazard.
Safety Precautions
1. Please read these installation instructions completely before beginning installation procedures. Failure to follow them
could cause a fireplace malfunction resulting in serious injury and/or property damage.
2. Always check your local building codes prior to installation. The installation must comply with all local, regional, state
and national codes and regulations.
3. An adequate supply of replacement combustion air from outside the house must be a ailable to the fire for the
fireplace to operate properly. To achie e this, the use of the optional outside air kit is highly recommended.
In the e ent the home is unusually tightly sealed, the optional combustion air kit may not pro ide all the air required to
support combustion. Hearth & Home Technologies is not responsible for any smoking or related problems that may
result from the lack of adequate combustion air. It is the responsibility of the builder/contractor to ensure that adequate
combustion air has been pro ided for the fireplace.
4. The fireplace must be installed with the Hearth & Home Technologies SL Series Chimney System.
The chimney system must always terminate outside the building. Be sure to follow all chimney specifications gi en in
these installation instructions.
5. NEVER lea e children unattended when there is a fire burning in the fireplace.
6. This fireplace is built for solid fuel only. NEVER use gasoline, gasoline type lantern fuel, kerosene, charcoal light fluid,
or similar liquids in this fireplace. Keep any flammable liquids a safe distance from the fireplace.
7. O NOT use chimney cleaners or flame colorants in your fireplace.
8. The flue damper must be open at all times when the fireplace is in use.
9. While ser icing this fireplace, always shut off any electricity or gas to the fireplace. This will pre ent possible electric
shock or burns. Also, make sure the fireplace is completely cooled before ser icing.
10. To ensure a safe fireplace system and to pre ent the build up of soot and creosote, inspect and clean the fireplace
and chimney prior to use and periodically during the burning season. See Maintenance Instructions in this manual
for cleaning instructions.

07/03 35035 Rev D 3
STS-42 INSTALLATION INSTRUCTIONS
WARNING!
This fireplace and its components are designed to be installed and operated as a system. Any alteration to or
substitution for items in this system, unless allowed by these installation instructions, will void the Underwrit-
ers Laboratories listing and may void the product warranty. It may also create a hazardous installation. Read
through these instructions thoroughly before starting your installation and follow them carefully throughout
your project.
1. The Heat-N-Glo fireplace system consists of the following:
a. Fireplace/Integral Grate/Cooling Air System
b. Refractory
c. Chimney Termination Cap
d. Chimney System
e. Hearth Extension
2. Optional Components Include:
a. Glass Doors
b. Weather Co er
Note: Illustrations used throughout these instructions
reflect typical installations and are for design purposes
only. Actual installation may ary slightly due to indi idual
design preferences. Howe er, minimum and maximum
clearances must be maintained at all times.
The illustrations and diagrams used throughout these
installations instructions are not drawn to scale.
B. DESCRIPTION OF THE FIREPLACE SYSTEM
Figure 1 - Typical Fireplace System
A. LISTINGS AND CODE APPROVALS
This fireplace system has been tested and listed in
accordance with UL 127 standards, and has been listed by
Underwriters Laboratories Inc. for installation and operation
in the United States as described in this manual.
This fireplace has been tested and listed for use with the
optional components listed on page 4. These optional
components may be purchased separately and installed at
a later date. Howe er, installation of an outside air kit will
require significant reconstruction, and should be installed
at the time of the initial fireplace installation.
Check with your local building code agency prior to installing
this fireplace to ensure compliance with local codes,
including the need for permits and follow-up inspections. If
you need assistance during installation, please contact your
local dealer or the Heat-N-Glo Technical Ser ices
Department, Hearth & Home Technologies Inc., 800 W.
Jefferson, Lake City, MN 55041.
Heat-N-Glo® is a registered trademark of Hearth & Home
Technologies Inc., a Di ision of HON Industries.

4 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
C. FIREPLACE SYSTEM COMPONENTS
1. Firep ace Components
Fireplace imensions
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HX4 - Hearth Extension
GR21 Integral Grate
WC42S - Weather Cover
Bi-Fold Glass oors
M1842
M1842B
M1842S

07/03 35035 Rev D 5
STS-42 INSTALLATION INSTRUCTIONS
2. Chimney Components
The following pictures show only those chimney components which may be safely used with this fireplace.
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6 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
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2111LS"21"¾01
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SL11 - Chimney Stabilizer SL1130 - Offset/Return
RF570 - Roof Flashing
Flat to 6/12 Pitch
RF571 - Roof Flashing
6/12 to 12/12 Pitch
CB576
Chimney Bracket
JB577
Joint Band
AS10
Straight Attic
Insulation Shield
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835SF°0"71
045SF°03"62
Chimney Sections
Firestop Spacer

07/03 35035 Rev D 7
STS-42 INSTALLATION INSTRUCTIONS
L S33 (3 x 3)
L S46 (4 x 6)
ecorative Shroud
TR11
Round
Termination Cap TR11T
Round Telescoping
Termination Cap
ST1175
Square
Termination Cap
CT56
Chase Top
CAK5A
Chimney Air Kit

8 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
Figure 3 - Installation Along a Wall or an Exterior Chase Figure 4 - Corner Installation
WARNING!
To prevent contact with sagging or loose insulation, the fireplace must not be installed against vapor barriers
or exposed insulation. Localized overheating could occur and a fire could result.
These are
rough
framing
dimensions
only.
D. PRE-INSTALLATION PREPARATION
1. Firep ace Locations and Space Requirements
This fireplace is intended for installation on an outdoor patio or in your yard. It must ne er be installed inside of the
warm air en elope of your structure. Significant cold air infiltration will result if it is installed inside of the structure.
Figure 2 shows two typical installations.
Figures 3 and 4 show two typical installations assuming an outside air kit is being used. Therefore, an allowance must
be made for 90° bends. Less space is required when ducting goes directly outside without forming elbows.
CLEARANCES!
A minimum 1½ air clearance must be maintained
at the back and sides of the fireplace assembly ex-
cept at the nailing flange where the clearance is
½.
Chimney sections at any level require a 2 mini-
mum air space clearance between the framing and
chimney section.
Note: If the fireplace is a freestanding fireplace, it must
be located a minimum of 10 from a combustible struc-
ture.
A minimum height of 6 4 measured from the base of the
fireplace to the bottom of the termination cap is permit-
ted in this installation.
Figure 2 - Fireplace Locations

07/03 35035 Rev D 9
STS-42 INSTALLATION INSTRUCTIONS
WARNING!
o not apply combustible finishing materials over any part of the stainless
face of this fireplace or a structure fire may result. The fireplace front may
only be covered with noncombustible materials such as ceramic tile, brick
or stone. o not cover or block any cooling air slots. o not cover any
portion of the opening to the fireplace that would prevent the installation of
an authorized glass door.
Figure 6 - Sidewalls and Surrounds
4. Sidewa s/Surrounds
Adjacent combustible side walls must be located a minimum of 12 from the fireplace opening. See Figure 6. If you
are using a decorati e surround constructed of combustible material, it must be located within the shaded area
defined in Figure 6. Short stub walls are also acceptable if they are contained within the shaded area.
CLEARANCES!
A minimum 1½ air clear-
ance must be maintained
at the back and sides of
the fireplace assembly
except at the nailing
flange where the clear-
ance is ½.
Chimney sections at any
level require a 2 mini-
mum air space clearance
between the framing and
chimney section.
3. Framing the Firep ace
The STS-42 fireplace will fit a framed opening of
49 wide x 423/8 tall. The finished ca ity depth must
be no less than 241/8.
Figure 5 shows a typical framing (using 2 x 4
lumber) of the fireplace, assuming combustible
materials are used. All required clearances to
combustibles around the fireplace must be adhered
to. Any framing across the top of the fireplace must
be abo e the le el of the top standoffs.
2. Constructing an Outdoor Enc osure
This fireplace is intended to be installed outside the house. It may be installed against the outside wall of the house
or as a freestanding fireplace on your porch, patio, or in your yard.
When installing the outdoor fireplace against an outside wall, it must be enclosed to pre ent impact damage to the
outside of the fireplace. Build the outside enclosure out of standing building materials, being careful to maintain the
minimum air clearances specified in these installation instructions.
When installing this fireplace as a freestanding fireplace on your porch, patio or in your yard, it must be enclosed to
pre ent impact damage to the fireplace. Howe er, the enclosure must not be finished on all four sides. The exterior of
the enclosure may be finished in a textured plywood, a wood clapboard siding, brick or a cultured stone. Vinyl siding
is not recommended for use on the front of the fireplace due to the heat the fireplace produces. This can cause the
inyl siding to deteriorate.
Figure 5 - Framing the Fireplace

10 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
Figure 7 - Chimney Offset/Return
Examp e: Your A dimension from
Figure 7 is 14½. Using Table 1 the
dimension closest to, but not less than
14½ is 145/8 using a 30° offset/return.
It is then determined from the table that
you would need 33 (Dimension B)
between the offset and return. The
chimney components that best fit your
application are two SL1112s.
WARNING!
o not com-
bine offsets to
create an off-
set greater
than 30° from
vertical. This
may create a
fire hazard
since the natu-
ral draft may
be restricted.
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Offset/Returns Table 1 30° Offset Chart
1. Using Offsets and Returns
a. To bypass any o erhead obstructions, the chimney may be offset using a 30° offset/return (SL1130). Perform the
following steps to determine the correct chimney component combination for your particular installation.
b. An offset and return may be attached together or a chimney section(s) may be used between an offset and
return.
1) Measure how far the chimney needs to be shifted to enable it to a oid the o erhead obstacle. See Figure 7,
dimension A to determine chimney sections required to achie e the needed shift.
2) After determining the offset dimension, refer to Table 1 and find the A dimension closest to but not less
than the distance of shift needed for your installation.
3) The B dimension that coincides with the A dimension represents the required ertical clearance that is
needed to complete the offset and return.
4) Read across the chart and find the number of chimney sections required and the model number of those
particular chimney parts.
5) Whene er the chimney penetrates a floor/ceiling, a firestop spacer must be installed.
6) The effecti e height of the fireplace assembly is measured from the base of fireplace to top of starter collar.
See Figure 6.
E. CHIMNEY REQUIREMENTS
When planning your fireplace location, the chimney construction and necessary clearances must be considered. The
fireplace system and chimney components ha e been tested to pro ide flexibility in construction. The following figures are
the minimum distances from the base of the fireplace. Minimum overall straight height is 6 4 if the fireplace is
freestanding a minimum of 10 from a combustible structure. See Figure 2, page 8.
1. Minimum o erall straight height 14 ft.
2. Minimum height with offset/return 16 ft.
3. Maximum height 90 ft.
4. Maximum chimney length between an offset and return 20 ft.
5. Maximum distance between chimney stabilizers 35 ft.
6. Double offset/return minimum height 24 ft.
7. Maximum unsupported chimney length between the offset and return 6 ft.
8. Maximum straight unsupported chimney height abo e the fireplace 35 ft.

07/03 35035 Rev D 11
STS-42 INSTALLATION INSTRUCTIONS
Figure 8 - Chimney Height
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/ 4 "
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3
/ 4 "
2111LS01
3
/ 4 "
8111LS61
3
/ 4 "
6311LS43
3
/ 4 "
8411LS64
3
/ 4 "
* imensions reflect effective height.
Tab e 2
3. Number of Sections Required
To determine the chimney components needed to
complete your particular installation, follow the steps
below:
a. Determine the total ertical height of the fireplace
installation. This dimension is measured from the
base of the fireplace assembly to the point where
the smoke exits the termination cap.
b. Subtract the effecti e height of the fireplace
assembly from the o erall height of the fireplace
installation (measured from the base of the
fireplace to the bottom of the termination cap).
c. Refer to Table 2 to determine what components
must be selected to complete the fireplace
installation.
d. Determine the number of firestop spacers, stabi-
lizers, roof flashing, etc. required to complete the
fireplace installation.
2. Chimney Height Requirements (above roof
ine)
a. Major building codes specify a minimum chimney
height abo e the roof top. These specifications
are summarized in what is known as the Ten Foot
Rule. This rule states:
If the horizontal distance from the side of the
chimney to the peak of the roof is ten feet or less,
the top of the chimney must be at least two feet
abo e the peak of the roof, but ne er less than
three feet in o erall height abo e the highest point
where it passes through the roof.
If the horizontal distance from the side of the
chimney to the peak of the roof is more than ten
feet, a chimney height reference point is
established on the surface of the roof a distance
of ten feet from the side of the chimney in a
horizontal plane. The top of the chimney must be
at least two feet abo e this reference point, but
ne er less than three feet in height abo e the
highest point where it passes through the roof.
See Figure 8.
b. These chimney heights are necessary in the
interest of safety but do not ensure smoke-free
operation. Trees, buildings, adjoining roof lines,
ad erse wind conditions, etc. may create a need
for a taller chimney should smoking occur.

12 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
F. INSTALLATION OF FIREPLACE
WARNING!
Before starting, do the following:
1. Wear gloves and safety glasses for protection.
2. Keep hand tools in good condition. Sharpen cutting edges and make sure tool handles are secure.
3. Always maintain the minimum air space required to the enclosure to prevent fire.
Important: To ensure proper fit of the glass doors,
check the fireplace opening for square. Measure
diagonal distances of the opening to make sure they
are equal. If they are not equal, continue to shim
the fireplace until those diagonals are equal.
Figure 9 - Positioning the Metal Strips
1. Positioning the Firep ace
This fireplace may be placed on either a combustible
or noncombustible continuous flat surface. Follow the
instructions for framing on pages 8 and 9. Slide the
fireplace into position. Be sure to provide the
minimum air clearance at the sides and back of
the fireplace assembly.
2. P acing the Protective Meta Hearth Strips
Included with your fireplace you will find two metal
hearth strips measuring approximately 28 x 4. These
strips are used to pro ide added protection where the
fireplace and the hearth extension meet.
Slide each metal strip 2 under the front edge of the
fireplace. The indi idual pieces must o erlap each
other by 1 minimum in the middle of the fireplace to
pro ide continuous co erage of the floor. See Figure9.
These metal strips should extend from the front and
sides of the fireplace opening by 2.
3. Leve ing the Firep ace
Le el the fireplace side-to-side and front-to-back. Shim
with noncombustible material, such as sheet metal,
as necessary. Secure the fireplace (using the nailing
flanges located on either side of the fireplace) to the
ertical framing.

07/03 35035 Rev D 13
STS-42 INSTALLATION INSTRUCTIONS
Figure 11
Installing the Firestop Spacer
CAUTION:
Firestop spacers must be used whenever the
chimney penetrates a ceiling/floor area.
Figure 10
Assembling Chimney
Sections
WARNING!
Carefully follow the instructions for assembly
of the pipe and other parts needed to install this
fireplace system. Failure to do so may result in
a fire, especially if combustibles are too close
to the fireplace or chimney and air spaces are
blocked, preventing the free movement of cool-
ing air.
4. Assemb ing Chimney Sections
Attach either a straight chimney section or an offset to
the top of the fireplace (depending on your installation
requirement). Chimney sections are locked together
by pushing downward until the top section meets the
stop bead on the lower section.
The inner flue is placed to the inside of the flue section
below it. The outer casing is placed outside the outer
casing of the chimney section below it. See Figure10.
5. Insta ing Firestop Spacers
Mark and cut out an opening in the ceiling for the
firestop spacer being utilized (17 x 17 for an FS538,
17 x 26 for an FS540). Frame the opening with the
same dimension lumber used in the ceiling joists.
Install the firestop spacer.
These firestop spacers are designed to pro ide the
minimum 2 air space required around the chimney. In
all situations, the firestop spacers are to be nailed to
the ceiling joists from the bottom or fireplace side,
EXCEPT when the space abo e is an insulated ceiling
or attic space. In this situation, the firestop spacer must
be nailed from the top side to pre ent loose insulation
from falling into the required 2 air space around the
chimney. See Figure 11.

14 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
WARNING!
Maintain a minimum of 2 air clearance to all
parts of the chimney system at all times! Fail-
ure to maintain this 2 air clearance will cause
a structure fire.
CAUTION:
Inner flue and outer liner sections cannot be
disassembled once locked together. Plan ahead
to ensure the proper installation height is
achieved with the selected chimney compo-
nents.
Figure 12 - Installing an Insulation Shield
Note: You must pro ide support for the pipe during
construction and check to be sure inad ertent load-
ing has not dislodged the chimney section from the
fireplace or at any chimney joint.
WARNING!
When chimney sections exceeding six feet in
length are installed between an offset and re-
turn, structural support must be provided to re-
duce off-center loading and prevent chimney
sections from separating at the chimney joints.
Figure 13 - Offset/Return with Stabilizer
6. Attic Insu ation Shie d
An insulation shield should be installed when there is
a possibility of insulation coming into contact with the
factory built chimney system. The insulation shield is
installed by positioning it o er the ertical chimney
section where it penetrates a firestop spacer. The
firestop spacer will support the insulation shield. See
Figure 12.
7. Doub e-checking the Chimney Assemb y
Continue assembling the chimney sections up through
the firestop spacers as needed. While doing so, be
aware of the height and unsupported chimney length
limitations that are gi en on page 10 under Chimney
Requirements.
Check each section by pulling up slightly from the top
to ensure proper engagement before installing the
succeeding sections. If they ha e been connected
correctly, they will not disengage when tested.
8. Securing the Chimney System
When offsets and returns are joined to straight pipe
sections, they must be locked into position with the
screws pro ided (outer only), using the predrilled holes.
To pre ent gra ity from pulling the chimney sections
apart, the returns and the chimney stabilizers ha e
straps for securing these parts to joists or rafters. See
Figure 13.

07/03 35035 Rev D 15
STS-42 INSTALLATION INSTRUCTIONS
9. Insta ing the Termination Cap
If a roof flashing is to be used, install the roof flashing
appropriate to the roof pitch and install a round
termination cap following the instructions shipped with
the cap.
For chase installations you can use a round termination
cap (TR11), a round telescoping termination cap
(TR11T) or a square termination cap (ST1175). A chase
installation must use a chase top. Chase tops are
a ailable from your Heat-N-Glo distributor.
a. Install the chimney sections up through the chase
enclosure. When using a TR11 round termination
cap, the uppermost top section of pipe must extend
6 abo e the top of the chase collar to allow
installation of the storm collar and termination cap.
See Figure 14.
Figure 14 - Installing a TR11 Round Termination Cap
b. For installations utilizing a TR11T telescoping
round termination cap, the uppermost chimney
section must be below the top of the chase top,
but not more than 14½ below the top of the chase
top flashing collar. See Figure 15.
Figure 15 - Installing a TR11T Round Telescoping
Termination Cap
c. For installations utilizing an ST1175 square
termination cap the last chimney section must not
be more than 4½ below the chase top. See
Figure16.
Figure 16
Installing an ST1175 Square Termination Cap
d. Attach the chase top to the top of the chase.
e. Install the termination cap, following the
instructions pro ided with it.

16 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
11. Insta ing the Chimney Air Kit
When installing the chimney air kit, follow the
instructions pro ided with this accessory.
Figure 17 - Cooling Air Location
Note: The cooling air kit must terminate at least six
feet abo e ground le el.
10. Insta ing the Required Coo ing Air Kit
(furnished)
The cooling air kit is supplied as a standard feature
with this fireplace and is required for safe operation.
Installation must be done at the time of initial
construction. The cooling air inlet tubes must be a
minimum of 72 abo e the base of the fireplace. This
is to pre ent potential blockage by snow or yard debris.
See Figure 17.
To install the air kit collar, slide one of the tabs of the
collar down into the seam. See Figure 18.
Secure the collar tabs to the fireplace by placing the
screws into the holes pro ided. See Figure 19.
Repeat for the other side.
Figure 18 - Insert the Tabs
Figure 19 - Securing the Tabs

07/03 35035 Rev D 17
STS-42 INSTALLATION INSTRUCTIONS
Note: Use only a noncombustible material to finish
the face of the fireplace below the le el of the front
standoffs. A noncombustible material such as USG
MICORE CV230 Mineral Fiber Board, or USG
DUROCK Cement Board is recommended for this
purpose.
Figure 20 - Air Clearance Around Gas Line
12. Comp etion of the Enc osure
Complete the fireplace enclosure, allowing space for
outside air ducts and gas piping if desired. Electrical
wiring should not come in contact with the fireplace. A
minimum clearance of 1½ must be maintained
between the fireplace sides and the enclosure as
well as the fireplace back and the enclosure. See
pages 8 and 9 for framing details.
CAUTION:
When using a gas log set, the fireplace damper
must be set in the fully open position. This en-
sures proper venting of combustion products.
WARNING!
This fireplace was not tested by the fireplace
manufacturer for use with an unvented gas log
heater. To reduce risk of injury, do not install
an unvented gas log heater in this fireplace un-
less it has been specifically tested and listed
by Underwriters Laboratories Inc. for use in
this specific model fireplace. Unless the
unvented gas log heater is tested and listed for
use in this factory built fireplace, a fire hazard
may be created that can result in a structure
fire.
13. Gas Log/Lighter Provisions
Knockouts are pro ided on both sides of the fireplace
to allow for connection of a certified gas log lighter or
a decorati e gas appliance with a maximum input of
100,000 BTU/hour, incorporating an automatic gas
shutoff de ice and complying with the Standard for
ecorative Gas Appliances for Installation in
Vented Fireplaces, ANSI Z21.60. The decorati e gas
appliance should be installed in accordance with the
National Fuel Gas Code, ANSI Z223.1-1980. The side
refractories are designed to allow ½ iron pipe to pass
through. Use a noncombustible sealant to seal any
opening between the gas pipe and refractory on the
inside. Repack the insulation remo ed to seal around
the gas pipe where it exits the side of the fireplace. A
minimum 1½ air clearance must be pro ided around
the ½ iron pipe for a minimum of 4 inches beyond the
fireplace. See Figure 20.
CLEARANCES!
A minimum 1½ air clearance must be maintained
at the back and sides of the fireplace assembly ex-
cept at the nailing flange where the clearance is½.
Chimney sections at any level require a 2 minimum
air space clearance between the framing and chim-
ney section.

18 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
Figure 21 - Factory Built Hearth Extension
Figure 22 - Field Constructed Hearth Extension
WARNING!
Hearth extensions are to be installed only as illustrated to prevent high temperatures from occurring
on concealed combustible materials. Hearth sealing strips prevent burning or hot particles from
inadvertently falling directly on combustible surfaces in the event the building should settle and
disturb the original construction.
14. Hearth Extension
A hearth extension must be installed with all fireplaces to protect the combustible floor in front of the fireplace from
both radiant heat and sparks.
The construction of, and materials used for a hearth extension are shown in Figures 21 and 22. A hearth extension of
this construction may be co ered with any noncombustible decorati e material and may ha e a maximum thickness
as per the illustration. Seal gaps between the hearth extension and the front of the fireplace with a bead of
noncombustible sealant.
Field constructed hearth extensions should be constructed in accordance with the instructions in Figure 22. The field
constructed hearth extension must be constructed from ½ MICORE CV230, or a material with an equi alent insulation
alue.

07/03 35035 Rev D 19
STS-42 INSTALLATION INSTRUCTIONS
Figure 23 - Position the Hearth Extension
15. Position the Hearth Extension
Position and secure the hearth extension o er the
protecti e metal strips that ha e been placed partially
under the fireplace front. These strips should be
protruding approximately 2 from under the fireplace
front and 2 on both sides of the fireplace opening.
Seal the crack between the hearth extension and
fireplace with a bead of noncombustible sealant.
See Figure 23. Apply a noncombustible finishing
material of your choice to the hearth extension.
16. Finishing Materia
o not install combustible materials over the face
of the fireplace! This poses a safety hazard and
may start a fire. You may only use noncombustible
material o er the face of the fireplace.
a. Combustible Material
Material which is made of or surfaced with wood,
compressed paper, plant fibers, plastics, or any
material capable of igniting and burning, whether
flame proofed or not, plastered or unplastered.
b. Noncombustible Material
Material which will not ignite and burn. Such
materials are those consisting entirely of steel,
iron, brick, tile, concrete, slate, glass or plasters,
or any combination thereof.
c. Noncombustible Sealant Material
Sealants which will not ignite and burn; General
Electric RTV103 Black (or equi alent), Rutland,
Inc. Fireplace Mortar #63 (or equi alent).
After completing the framing and applying the
facing material (dry wall) o er the framing, a ½
wide (maximum) bead of noncombustible sealant
must be used to close off any gaps at the top and
sides between the fireplace and facing to pre ent
cold air leaks.
Only noncombustible materials may be used to
co er the metal fireplace front.
17. Mante
A combustible mantel may be positioned no lower than
12 abo e the top of the fireplace opening. See Figure
6, page 9. The combustible mantel may ha e a
maximum depth of 12. Combustible trim pieces that
project no more than 1½ from the face of the fireplace
can be placed no closer than 6 from the top of the
fireplace opening. Combustible trim must not co er the
metal surfaces of the fireplace. This mantel clearance
is in accordance with Section 7-3.3.3 of ANSI/
NFPA211.
18. G ass Doors
This fireplace has been tested and listed for use with
doors as specified in Section C, Fireplace System
Components. Please refer to the manual packed with
each set of doors for installation instructions.
19. Chase Top
Construct a chase of desired materials maintaining a
minimum 2 air space around the chimney.

20 35035 Rev D 07/03
STS-42 INSTALLATION INSTRUCTIONS
WARNING!
Never install a single wall slip section or smoke-pipe in
a chase structure. The higher temperature of this single
wall pipe may radiate sufficient heat to combustible
chase materials to cause a fire.
WARNING!
etailed instructions for installation of the chase top, storm collar and termination
cap are packaged with these parts. To avoid danger of fire, all instructions must be
strictly followed, including the provision of air space clearance between chimney
system and enclosure. To protect against the effects of corrosion on those parts
exposed to the weather, we recommend that the chase top and termination cap be
painted with a rust-resistant paint.