Heatilator ST42A User manual

1Heatilator•ST42AInstallationManual•4012-051•RevC•10/03/13
Installationandserviceofthisreplaceshouldbe
performedbyqualiedpersonnel.Hearth&Home
TechnologiesrecommendsNFIcertiedprofes-
sionals,ortechnicianssupervisedbyan
NFIcertiedprofessional.
WOODBURNING FIREPLACE
Fire Risk.
WARNING
Forusewithsolidwoodfuelonly.
Otherfuelsmayoverreandgenerate
poisonousgases(i.e.carbonmonoxide).
Model(s):
Installation Manual
Installation and Fireplace Setup
WARNING
HOT SURFACES!
Glassandothersurfacesarehotduring
operationANDcooldown.
Hot glass will cause burns.
• DO NOTtouchglassuntilitiscooled
• NEVERallowchildrentotouchglass
• Keepchildrenaway
• CAREFULLY SUPERVISE children in same room as
replace.
• Alertchildrenandadultstohazardsofhightemperatures.
Hightemperaturesmayigniteclothingorotherammable
materials.
• Keep clothing, furniture, draperies and other ammable
materialsaway.
INSTALLER: Leave this manual with party responsible for use and operation.
OWNER: Retain this manual for future reference.
ST42A
NOTICE: DO NOT discard this manual!
• DO NOTstoreorusegasolineorotheram-
mablevaporsandliquidsinthevicinityofthis
oranyotherappliance.
• DO NOToverre.Overringwillvoidyour
warranty.
• Complywithallminimumclearancestocom-
bustiblesasspecied.Failuretocomplymay
causehousere.
WARNING: If the information in these
instructionsisnotfollowedexactly,are
or explosion may result causing property
damage, personal injury, or death.

2Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
Safety Alert Key:
• DANGER! Indicatesahazardoussituationwhich,ifnotavoidedwillresultindeathorseriousinjury.
• WARNING!Indicatesahazardoussituationwhich,ifnotavoidedcouldresultindeathorseriousinjury.
• CAUTION! Indicatesahazardoussituationwhich,ifnotavoided,couldresultinminorormoderateinjury.
• NOTICE:Indicatespracticeswhichmaycausedamagetothereplaceortoproperty.
Table of Contents
1 ProductSpecic&ImportantSafetyInformation
A.FireplaceCertication 4
B.Non-CombustibleMaterials 4
C.CombustibleMaterials 4
2 Getting Started
A.TypicalFireplaceSystem 5
B.DesignandInstallationConsiderations 6
1.SelectingFireplaceLocations 6
2.LocatingFireplace&Chimney 7
C.ToolsandSuppliesNeeded 8
D.InspectFireplaceandComponents 8
E.FireplaceSystemRequirements 8
3 Framing and Clearances
A.FireplaceDimensions 9
B.Clearances 10
MinimumClearancestoCombustibles 10
C.ConstructtheChase 11
D.FrametheFireplace 12
E.SecureandLeveltheFireplace 12
F. ProtectiveMetalHearthStrips 13
G.OutsideAirKit 14
AK17Installation 14
4 Chimney and Termination Requirements
A.ChimneyRequirements 15
B.Offsets/Returns 16
C.TerminationRequirements 17
5 Chimney Installation
A.TypicalChimneySystem 18
B.AssembleChimneySections 19
C.InstallChimneyAirKit 19
D.SecureOffset/Return 20
E.InstallCeilingFirestops 20
F. InstallAtticInsulationShield 21
G.RoofPenetration 22
H.InstallChase/ChaseTop 22
I. TerminationCapRequirements 23
J. InstallTerminationCap 23
6 Shrouds
A.RadiationShield 25
1.OpenTopShroud 25
2.MailboxStyleShroud 26
3.RoofedStyleShroud 26
7 Finishing
A.FinishingMaterial 27
B.HearthExtension,BuildingandFinishing 28
1.FireplaceInstalledFlushontheFloor
 andHearthExtensionRaisedtoBottom
 ofFireboxOpening 29
2.RaisedHearthExtensionandRaisedFireplace 30
C.Non-CombustibleSealantMaterial 31
D.MantelandWallProjections 32
E.Sidewalls/Surrounds 33
8 Fireplace Setup
A.GasLog/LighterProvision 34
9 Reference Materials
A.ChimneyComponents 35
B.OptionalComponents 39
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3
Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
Customer:
Lot/Address
Model (circle one): ST42A
YES IF NO, WHY?
WARNING! Risk of Fire or Explosion! Failure to install fireplace acording to these instructions can lead to a fire or
explosion.
Verifiedthatthechaseisinsulatedandsealed.(Pg.11)
Verifiedclearancestocombustibles.(Pg.10)
Fireplaceisleveledandsecured.(Pg.12)
Hearthextensionsize/heightdecided.(Pg.28)
Chimneyconfigurationcomplieswithdiagrams.
Chimneyinstalled,lockedandsecuredinplacewithproperclearance.
Chimneyairkitinstalled.
Firestopsinstalled.
ATTENTION INSTALLER:
Follow this Standard Work Checklist
Thisstandardworkchecklististobeusedbytheinstallerinconjuctionwith,notinsteadof,theinstructionscontainedinthisinstallation
manual.
Date Installed:
Location of Fireplace:
Installer:
Dealer/Distributor Phone #
Serial #:
Roofflashinginstalled.
Terminationinstalled.
Protectivehearthstripsinstalledpermanualrequirements.(Pg.13)
Fireplace Install
Outsideairkitinstalled.(Pg14)
ChimneySection4&5(Pg.15)
Atticinsulationshieldinstalled.
Shrouds Section 6 (Pg. 25)
Shroudisinstalledproperlyperinstructions.
Fi i hi
S ti 7 (P 27)
Hearth&HomeTechnologiesrecommendsthefollowing:
Commentscommunicatedtopartyresponsible
4012-052•RevA•05/06/13
Allpackagingandprotectivematerialsremoved.
Optionaldoorsproperlyinstalled.
Moldedbrickpanelsinstalledcorrectly.
Grateisproperlyinstalled.
Firescreenproperlyinstalled.
__________________________by______________________on_________
(Builder/Gen.Contractor)(Installer)(Date)
Comments:Furtherdescriptionoftheissues,whoisresponsible(Installer/Builder/OtherTrades,etc.)andcorrectiveactionneeded:
Manualbagandallofitscontentsareremovedfromthefireplaceandgiventotheparty
responsibleforuseandoperation.
•Thatthischecklistremainvisibleatalltimesonthefireplaceuntiltheinstallationiscomplete.
•Photographingtheinstallationandcopyingthischecklistforyourfile.
Combustiblematerialsnotinstalledinnon-combustibleareas.
Finishing Section 7 (Pg. 27)
Hearthextensioninstalledpermanualrequirements.
Fireplace Setup Section 8 (Pg. 34)
Verifiedallclearancesmeetinstallationmanualrequirements.
Mantelsandwallprojectionscomplywithinstallationmanualrequirements.

4Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
WARNING! Risk of Fire! Hearth & Home Technologies
disclaims any responsibility for, and the warranty and
agency listing will be voided by the following actions.
DO NOT:
• installoroperatedamagedreplace
• modifyreplace
• install other than as instructed by Hearth & Home
Technologies
• operate the fireplace without fully assembling all
components
• overre
• installunventedgaslogset
• installanycomponentnotapprovedbyHearth&Home
Technologies
• installpartsorcomponentsnotListedorapproved
Improper installation, adjustment, alteration, service or
maintenance can cause injury or property damage. For
assistance or additional information, consult a qualied
installer, service agency or your dealer.
B. Non-Combustible Materials
• Materialswhich willnot igniteand burn,composed of
anycombinationofthefollowing:
- Steel - Iron
- Brick - Tile
- Concrete - Slate
- Glass - Plasters
• MaterialsreportedaspassingASTM E 136, Standard
Test Method for Behavior of Metals, in a Vertical Tube
Furnace at 750° C
C. Combustible Materials
• Materialsmadeoforsurfacedwithanyofthefollowing
materials:
- Wood - Compressedpaper
- Plantbers - Plastic
- Plywood/OSB - Sheetrock(drywall)
• Anymaterialthatcanigniteandburn;ameproofedor
not,plasteredorun-plastered
1 ProductSpecic&ImportantSafetyInformation
A.FireplaceCertication
ThisreplacemaybeinstalledinsleepingroomsEX-
CEPTinmanufacturedhomes.Ifinstalledwithagaslog
set,provisionsfortheNationalFuelGasCodemustbe
met.
Thisreplacehasbeentestedandlistedforusewith
theoptionalcomponentsspeciedinthismanual.These
optionalcomponentsmaybepurchasedseparatelyand
installedatalaterdate.Anoutsideairkit,gasinsert,gas
logsetorgaslog-lightershouldbeinstalledatthetimeof
replaceinstallation.
HeatilatorisaregisteredtrademarkofHearth&Home
Technologies.
Thisreplacesystemhasbeentestedandlistedinaccor-
dancewithUL127andULC-S610standardsbyUnder-
writersLaboratoriesInc.forinstallationandoperationin
theUnitedStatesandCanada.

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Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
2 Getting Started
A. Typical Fireplace System
Figure 2.1 Typical Fireplace System
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Non-combustible
roof flashing maintains
minimum clearance
around chimney
Additional lateral
support for chimney
above roof (or enclosed
in chase) if needed
Ceiling firestop
on floor of attic
Support straps
on rafter support
chimney (not shown)
Termination cap
Chimney penetrates roof
preferably without affecting
roof rafters
Offset & Return (with hanger straps)
Framing headed off
in ceiling joists
Enclosed space above
and around fireplace
Mantel and surround
Decorative facing
and trim
Hearth extension
Factory-built fireplace
Protective metal
hearth strip(s)
Outside
combustion air
Combustible framing/header
on top of V-shaped standoffs
Chimney system
Attic insulation shield (not shown)
must be used here to keep
insulation away from chimney
if attic is insulated
Storm Collar
Chimney Air Kit
Required in
Canada. Outlet
must be no
less than 4 ft.
(1.322 m) off
ground level.

6Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
1/2 in. (13 mm)
all configurations
66 in.
(1676 mm)
42 in.
(1067 mm)
20 in. (508 mm)
(hearth
extension)
64 in.
(1626 mm)
12 in. (305 mm)
min. to
perpendicular
wall.
Figure 2.2 Fireplace Locations
NOTICE:
• Illustrationsandphotosreecttypicalinstallationsand
are FORDESIGNPURPOSESONLY.
• Illustrations/diagramsarenotdrawntoscale.
• Actualinstallation/appearancemayvaryduetoindividual
design preference.
• Hearth&HomeTechnologiesreservestherighttoalter
its products.
NOTICE: In addition to these framing dimensions, also
reference the following section:
• Clearances (Section 3).
NOTICE:
Aminimum1/2in.airclearanceatthebackand
sidesofthereplaceassemblymustbemain-
tained.
Chimneysectionsatanylevelrequirea2in.mini-
mum air space clearance between the framing
and chimney sections.
B. Design and Installation Considerations
NOTICE: Checkbuildingcodespriortoinstallation.
• InstallationMUSTcomplywithlocal,regional,stateand
nationalcodesandregulations.
• Consultinsurancecarrier,localbuildinginspector,re
ofcialsorauthoritieshavingjurisdictionoverrestrictions,
installationinspectionandpermits.
• Before installing,determinethefollowing:
- Wherethereplaceistobeinstalled.
- Theventsystemcongurationtobeused.
- Gassupplypiping.
- Electricalwiring.
- Framingandnishingdetails.
- Whetheroptionalaccessories-devicessuchasa
fan,wallswitchorremotecontrol-aredesired.
1. Selecting Fireplace Locations
Thisreplacemaybeusedasaroomdivider,installed
alongawall,acrossacornerorusedinanexteriorchase.
SeeFigure2.2.
Locatingthereplaceinabasementshouldbeavoided.
Locatingnearfrequentlyopeneddoors,centralheat
outletsorreturns,orotherlocationsofconsiderableair
movementcanaffecttheperformance.
Outsideairmustbeusedforcombustion.Thisreplace
comesequippedwithanoutsideairinlettofeedcombus-
tionairfromoutsidethehome,alongwithanoutsideair
terminationcap;therigidmetalductisrequiredbutnot
supplied.Considerationshouldbegiventothesefactors
beforedecidingonalocation.

7
Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
2. LocatingFireplace&Chimney
Locationofthereplaceandchimneywillaffectperfor-
mance.
• Installwithinthewarmairspaceenclosedbythebuilding
envelope.Thishelpstoproducemoredraft,especially
duringlightinganddie-downofthere.
• Installingthereplaceinabasementisnotrecommended.
• Penetratethehighest partoftheroof.Thisminimizes
theeffectsofwindloading.
• Locate termination cap away from trees, adjacent
structures,unevenrooflinesandotherobstructions.
• Minimizetheuseofchimneyoffsets.
• Considerthereplacelocationrelativetooorandceiling
andatticjoists.
• Takeintoconsiderationtheterminationrequirementsin
Sections4and5.
Marginal Location:
• Below peak
Location NOT recommended:
• Not the highest point of the roof
• Wind loading possible
Multi-level Roofs
Windward
Leeward
Recommended Location:
• Above peak
Recommended:
• Insulated exterior chase
in cooler climates
Recommended Location:
• Above peak
• Inside heated space
Location NOT recommended:
• Too close to tree
• Below adjacent structure
• Lower roof line
• Avoid outside wall
Marginal Location:
• Wind loading possible
Figure 2.3 Recommended Chimney Locations
• Installtheoutsideairkitwiththeintakefacingprevailing
windsduringtheheatingseason.
• Ensure adequate outdoor air for all combustion
appliancesandexhaustequipment.
• Ensurefurnaceandairconditioningreturnventsarenot
locatedintheimmediatevicinityofthereplace.
• Avoidinstallingthereplaceneardoors,walkwaysor
smallisolatedspaces.
• Recessedlightingshouldbea“sealedcan”design.
• Attichatchesweatherstrippedorsealed.
• Atticmountedductworkandairhandlerjointsandseams
tapedorsealed.

8Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
C. Tools and Supplies Needed
Beforebeginningtheinstallationbesurethefollowing
toolsandbuildingsuppliesareavailable:
Reciprocatingsaw Framingmaterial
Pliers Non-combustiblesealant
Hammer Gloves
Phillipsscrewdriver Framingsquare
Flatbladescrewdriver Electricdrillandbits
Plumbline Safetyglasses
Level Tapemeasure
1/2-3/4in.length,#6or#8self-drillingscrews
Misc.screwsandnails
D. Inspect Fireplace and Components
WARNING! Risk of Fire and/or Explosion! Damaged
parts could impair safe operation. DO NOT install dam-
aged,incompleteorsubstitutecomponents.Keepre-
place dry.
• Removereplaceandcomponentsfrompackagingand
inspectfordamage.
• Vent system components and doors are shipped in
separatepackages.
• Reporttoyourdealeranypartsdamagedinshipment.
• Read all the instructions before starting the
installation. Follow these instructions carefully
during the installation to ensure maximum safety
andbenet.
E. Fireplace System Requirements
TheHeatilatorreplacesystemrequirementsconsistof
thefollowing:
• Fireplace
- Refractory(includedwithreplace)
- Firescreen(includedwithreplace)
- Grate(includedwithreplace)
- HearthExtension(required,soldseparately)
• OutsideAirSystem
- AirInletHood(includedwithreplace)
- Flex(required,soldseparately)
• ChimneySystem
- AtticInsulationShield(includedwithreplace)
- Chimneyairkit(requiredinCanada,soldseparately)
- Chimneyterminationcap(required,soldseparately)
• Non-combustiblenishmaterial

9
Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
3 Framing and Clearances
A. Fireplace Dimensions
Gas
Knockout
Outside
Air
58-7/8 in.
(1496 mm)
(effective height)
38-3/8 in.
(975 mm)
11-3/4 in.
(298 mm)
8-5/8 in.
(219 mm)
13 in.
[330 mm]
dia.
42 in.
(1067 mm)
23 in.
(585 mm)
7-1/2 in.
(192 mm)
39-1/8 in.
(995 mm)
Gas
Knockout
8-3/8 in.
(213 mm)
14 in.
(356 mm)
8-3/8 in.
(213 mm)
14 in.
(356 mm)
47 in.
(1194 mm)
28 in.
(711 mm)
23-1/2 in.
(597 mm)
14 in.
(356 mm)
5-7/8 in.
(149 mm)
Figure 3.1 Fireplace Dimensions

10 Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
B. Clearances
WARNING! Risk of Fire!
You must comply with all minimum air space clearances
tocombustiblesasspeciedinFigure3.2.DO NOTpack
required air spaces with insulation or other materials.
Framing or nishing material used on the front of, or in
frontof,thereplacecloserthantheminimumslistedmust
be constructed entirely of non-combustible materials (i.e.,
steel studs, concrete board, etc.). Failure to comply may
causere.
Figure 3.2 Clearances to Combustible Materials
Minimum Clearances to Combustibles
WITHIN ENCLOSURE AREA
Fireplacetobackwall 1/2in.(13mm)
Fireplacetosidewall 1/2in.(13mm)
Topstandoffstoheader 0in.(0mm)
Dooropeningtosidewall 12in.(305mm)
MANTEL
Mantelminimumheight 421/2in.(1079mm)
Maximummanteldepth 12in.(305mm)
(roof)
(insulation)
0 in. to level
of standoffs
Attic
Insulation
Shield
(ceiling)
(attic)
(ceiling)
Offset/Return (secured
with hanger straps)
Storm Collar
Roof Flashing
3/4 in. (19 mm) to back &
sides of appliance
(except at nailing flanges
where it is 1/2 in. [13 mm])
Must have 2 in. (51 mm)
minimum clearance
to header
0 in.
to floor
2 in. (51 mm) min.
Shaded areas
represent
2 in. (51 mm) min.
air space clearance
required around pipe
Combustible Object
48 in.
1219 mm
Adapter
Ceiling Firestop
Note: Chimneyairkit and11-10
in./279-254 mm adapter are
not shown, but are required in
Canada.

11
Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
C. Construct the Chase
Achaseisaverticalboxlikestructurebuilttoenclosethe
replaceand/oritsventsystem.Verticalchimneysthat
runontheoutsideofabuildingmustbeinstalledinsidea
chase.
Incoldclimates,Hearth&HomeTechnologiesrecom-
mendsthatthechasebewellinsulatedusingbatttype
insulationbetweenthejoists.
Constructionofthechasemayvarywiththetypeofbuild-
ing.Theseinstructionsarenotsubstitutesfortherequire-
mentsoflocalbuildingcodes.LocalbuildingcodesMUST
bechecked.
Chasesshouldbeconstructedinthemannerofalloutside
wallsofthehometopreventcoldairdraftingproblems.
Thechaseshouldnotbreaktheoutsidebuildingenvelope
inanymanner.Allouterwallsneedtobeinsulated.
Buildingcodesrequirefalseceilingandceilingrestops/
atticshieldsateachoorofthechaseorevery10ft(3048
mm)ofclearspacetocontrolspreadofre.
Walls,ceiling,baseplateandcantileveroorattherst
levelofthechaseshouldbeinsulated(seeFigure3.3.)
Vaporandairinltrationbarriersshouldbeinstalledinthe
chaseasperregionalcodesfortherestofthehome.Ad-
ditionally,Hearth&HomeTechnologiesrecommendsthat
theinsidesurfacesbedrywalledandtaped(ortheuseof
anequivalentmethod)formaximumairtightness.
Holesandotheropeningsshouldbecaulkedwithhigh
temperaturecaulkorstuffedwithunfacedberglassinsu-
lation.
Ceiling
Firestop
Metal Chase Top
Round Termination Cap
False Ceiling
Insulation in the
outside walls
of the chase
Attic
Insulation
Shield
Chimney
Ceiling
Firestop
Tabs
False Ceiling
False Ceiling
Insulation
Insulation
Figure 3.3 Chase Assembly
12
1. Chimney offset through exterior wall and
enclosed in chase.
2. Chase constructed on roof.
Figure 3.4 Chase Constructions
• Thechaseisconstructedusingframingmaterialsmuch
thesameasthewallsinyourhome.Avarietyofsiding
materials may be used including brick, stone, veneer
brick,orstandardsidingmaterials.
• In constructing the chase, several factors must be
considered:
- Maintain a 2 in. (51 mm) air space around the
chimney.
- The chase top must be constructed of non-
combustiblematerial.
- Incoldclimates,arestopspacerandatticinsulation
shieldshouldbeinstalledinaninsulatedfalseceiling
at the 8 ft. (2438 mm) level above the replace
assembly.Thisreducesheatlossthroughthechase.
- Incold climates, the walls of the chase should be
insulatedtothelevelofthefalseceilingasshownin
Figure3.3.Thiswillhelpreduceheatlossfromthe
homearoundthereplace.
ExamplesofchaseapplicationsareshowninFigure3.4.
WARNING! You must install false ceilings and ceil-
ing restops at each oor of the chase or every 10 ft
(3.05 m) to control spread of re.
WARNING! Risk of Fire! DO NOT sealareabetweenre
stop opening and chimney pipe except where they enter
the attic or leave the warm air envelope of the home (use
600° F sealant).
WARNING! Risk of Fire! Youmustmaintaina minimum
2in.(51mm)airspaceclearancetoinsulationandother
materials surrounding the chimney system.
• Insulationandothermaterialsmustbermlysecuredto
prevent accidental contact with chimney system.
• Thechasemustbeproperlyblockedtopreventblown
insulation or other combustibles from entering and
makingcontactwithreplaceorchimney.
• Failuretoprevent contactbetweeninsulationorother
materials and chimney system may cause overheating
andre.

12 Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
D. Frame the Fireplace
NOTICE: Hearth extension design must be determined
beforeinstallationofreplace.
Ifthereplaceisplacedontheoorthemaximumheight
ofanishedraisedhearthis71/2in.(192mm),ifyou
wantahigherraisedhearththereplacemustbeplaced
onaplatform.
WARNING! Risk of Fire! Youmustcomplywithall
minimum air space clearances to combustibles. DO NOT
packrequiredairspaceswithinsulationorothermateri-
als.
WARNING! Risk of Fire! Comply with all minimum clear-
ancesspecied.
• A minimum 1/2 in. (13 mm) air clearance must be
maintained at the back and sides of the fireplace
assembly.
• Chimneysectionsatanylevelrequirea2in.(51mm)
minimum air space clearance between the framing and
chimney section.
Figure3.5showsatypicalframing(using2x4lumber)
ofthereplace,assumingcombustiblematerialsare
used.Allrequiredclearancestocombustiblesaroundthe
replacemustbeadheredto.SeeFigure3.2.Anyframing
acrossthetopofthereplacemustbeabovethelevelof
thetopstandoffs.(Norecessabovestandoffs.)
The nished cavity depth must be no less than 27 in.
(686mm).Framingmustextendstraightupallthewayto
theceiling.
CAUTION! RiskofCuts/Abrasions.Wearprotectivegloves
and safety glasses during installation. Sheet metal edges
are sharp.
WARNING! Risk of Fire! Prevent contact with sagging,
loose insulation.
• DO NOT install against vapor barriers or exposed
insulation.
• Secureinsulationandvaporbarriers.
• Provideminimumairspaceclearancesatthesidesand
backofthereplaceassembly.
E. Secure and Level the Fireplace
Thisreplacemaybeplacedoneitheracombustible
ornoncombustiblecontinuousatsurface.Followthe
instructionsforframinginSection3.Slidethereplace
intoposition.Besuretoprovidetheminimum1/2in.air
clearanceatthesidesandbackofthereplace.
Thereplaceshouldbepositionedsothefaceofthenon-
combustiblematerialonthereplacewillbeushwiththe
faceofthedrywallonthewalls.
Levelthereplaceandshimasnecessary.
You must maintain
2 in. (51 mm) min. air space
clearance from the
chimney to the
enclosure.
27 in.
(686 mm)
Note: Fireplace
Header cannot be
positioned until after
the fireplace assembly
is in place.
12 in. (305 mm) max.
48 in.
(1219 mm)
Figure 3.5 Framing the Fireplace
1/2 in.
(13 mm)
Fireplace must be set out
1/2 in. (13 mm) in front of
the face of the framing
material.

13
Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
Protective metal strips are placed 2 in. (51 mm) under the
front of the fireplace and must extend beyond the front
and sides of fireplace opening by 2 in. (51 mm).
1 in. (25 mm)
overlap
Raised Platform
Floor
2 in.
(51 mm)
1 in. (25 mm) min.
overlap
2 in.
(51 mm)
Top piece must overlap
bottom piece
Figure 3.7 Protect the Front of an Elevated Platform
F. Protective Metal Hearth Strips
Figure 3.6 Position the Protective Metal Hearth Strips
• Locatethefourprotectivemetalhearthstripsmeasuring
approximately26in.x4in.(660mmx102mm)included
withthisreplace.
• Slideeachmetalstrip2in.(51mm)underfrontedgeof
replace.
• Overlapstripsinthemiddleofreplaceopeningby1in.
(25mm)minimum.
• Metal strips must extend beyond the front and sides
of the replace opening by at least 2 in. (51 mm),
Figure3.6).
• Protectthefrontofaplatformelevatedabovethehearth
extensionwithmetalstrips(notincludedwithreplace)
per Figure 3.6. See Section 7 for hearth extension
instructions.
WARNING! Risk of Fire! Protective metal hearth
strips MUST be installed on combustible surfaces. DO
NOT cover metal strips with combustible materials.
Sparksorembersmayigniteooring.
WARNING! Risk of re! Hightemperatures,sparks,
embers or other burning material falling from the
replacemayigniteooringorconcealedcombustible
surfaces.
• ProtectivemetalhearthstripsMUSTbeinstalled.
• Hearth extensions MUST be installed exactly as
specied.

14 Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
G. Outside Air Kit
Whenyouinstalltheoutsideairkit,Hearth&Home
Technologiesrecommendsyouutilizetheshortestduct
runtooptimizetheperformanceoftheoutsideairkit.The
outsideairinlethoodshouldbepositionedinamanner
thatwillnotallowsnow,leaves,etc.toblocktheinlet.In
someinstallationstheairductmayneedtoberunverti-
cally.Insuchaninstallation,a3ft(914mm)heightdiffer-
encemustbemaintainedfromthetopoftheuppermost
chimneysectiontotheoutsideairinlethood.
RefertoFigures3.8and3.9whenplacingtheoutsideair
inlethood.
AK17 Installation
• Removethecoverplatefromthesideofthereplaceand
replaceitwithoutsideairplateassemblyusingexisting
screws.
• Markandcutouta41/2in.(114mm)diameterholein
thebuildingsideforairentry.Thisholeshouldallowfor
someframing(twosides)sotheoutsideairinlethood
maybenailedintoposition,ushwithbuilding’soutside.
• Secureexibleduct(notsupplied)totheplateassembly.
• Feed duct through hole to the outside, fasten to the
outsideairinlethood.
• Fastenoutsideairinlethoodassemblytothestructure
withscrews.
• Seal between the wall and the pipe with silicone to
preventmoisturepenetrationandairleaks.
• Sealbetweentheoutsideairinlethoodandthehouse
withsiliconetopreventairinltration.
CAUTION! Risk of Cuts/Abrasions. Wearprotective
gloves and safety glasses during installation. Sheet metal
edges are sharp.
CAUTION! Risk of Fire or Asphyxiation! DO
NOT draw outside combustion air from wall,
oororceilingcavity,orenclosedspacessuch
as an attic or garage.
• DO NOT place outside air inlet hood close to
exhaust vents or chimneys. Fumes or odor
could be drawn into the room through the
replace.
• Locate outside air inlet hood to prevent
blockage from leaves, snow/ice, or other
debris.Blockagescouldcausecombustion
air starvation.
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3 ft min. from
top of uppermost
chimney section
to air inlet.
Figure 3.8 Outside Air Inlet Locations
Outlet placed
higher than 3 ft
below the
termination cap
Attic space
Garage or
combustible
liquids storage
Outlet blocked by
snow, leaves, etc.
Clear area
outside
house or in
ventilated
crawl space
YES
NO
NO
NO
NO
Factory-built
fireplace
• Use UL181 Class 0 or Class 1 rigid or flexible ducting.
• Install with short run or mainly straight duct, except small
dip for cold air trap which will help prevent flow of cold air.
• Secure flex duct with metal tape, screws or wire ties.
Figure 3.9 Outside Air Installation
Note: Chimneyairkitand
11-10 in./279-254 mm
adapter are not shown,
butarerequiredinCanada.

15
Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
d & g
Ceiling Firestop h
i
58-7/8 in.
(1495 mm)
Effective
Height
a,b,c,f
11-10 in. (279-254 mm)
adapter required in
Canada.
Figure 4.1 Chimney Requirements
NOTICE: Amaximumoftwopairsofoffsetsandreturns
may be used.
WARNING! Risk of Fire! Youmustmaintain2in.(51mm)
air space clearance to insulation and other combustible
materials around the chimney system. Failure to do so
maycauseoverheatingandre.
NOTICE: You must provide support for the pipe during
constructionandchecktobesureinadvertentloadinghas
notdislodgedthechimneysectionfromthereplaceorat
any chimney joint.
A. Chimney Requirements
Verticaldistancesaremeasuredfromthebaseofthe
replaceasshowninFigure4.1.
4 Chimney and Termination Requirements
Table 4.2 Chimney Component Dimensions
Table 4.1 Chimney Requirements
ft meters
a. Minimumoverallstraightheight 14.0 4.27
b. Minimumheightwithoffset/return 16.5 5.03
c. Maximumheight 90.0 27.43
d. Maximumchimneylengthbetweenanoffsetand
return
20.0 6.1
e. Maximumdistancebetweenchimneystabilizers 35.0 10.67
f. Doubleoffset/returnminimumheight 22.0 6.71
g. Maximumunsupportedchimneylengthbetweenthe
offsetandreturn
6.0 1.83
h. Maximumunsupportedchimneyheightabovethe
replace
35.0 10.67
i. Maximumunsupportedchimneyaboveroof 6.0 1.83
HEIGHT OF CHIMNEY COMPONENTS in. mm
US Canada ONLY
Chimney Stabilizer
SL11 SL4 4-3/4 121
Offsets/Returns
SL1130 SL430 14-1/2 368
Chimney Sections*
SL1106 SL406 4-3/4 121
SL1112 SL412 10-3/4 273
SL1118 SL418 16-3/4 425
SL1136 SL436 34-3/4 883
SL1148 SL448 46-3/4 1187
n/a SLA10 16-3/4 425
*Dimensionsreecteffectiveheight.

16 Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
B. Offsets/Returns
• Useanoffset/returntobypassoverheadobstructions.
• Anoffsetandreturncanbeusedasasingleentityorseparatedbychimneysection(s).
WARNING! Risk of Fire! DO NOT useoffset/returnsgreaterthan30°.Chimneydraftwillberestrictedandcouldcause
overheatingandre.Secureoffsetswithscrews(nottoexceed1/2”/13mminlength)Securereturnswithstrapping.
Straight chimney sections may be secured with screws. Keep chimney sections from separating or twisting.
• Measuretheshiftneededtoavoidtheoverheadobstruction.RefertodimensionAinFigure4.2.
• FindtheappropriateAdimensionlistedinTable4.3.TheBdimensioncoincidingwiththeAdimensionmeasurementin
Table4.3representstherequiredverticalclearanceneededtocompletetheoffset/return.
• Readacrossthecharttondthenumberofchimneysections/modelnumbersneededbetweentheoffsetandreturn.
A
B
1-1/4 in. (32 mm)
OVERLAP
Figure 4.2 Chimney Offset/Return
Table 4.3 Offset Dimensions
Example:
Your“A”dimensionfromFigure4.2is141/2in.
(368mm).UsingTable4.3thedimensionclosestto,but
notlessthan141/2in.(368mm)is153/4in.(400mm)
usinga30°offset/return.
Youdeterminedfromthetablethatyouwouldneed36-
5/8in.(930mm)(Dimension“B”)betweentheoffsetand
return.
Thechimneycomponentthatbesttsyourapplicationis
twoSL1112s.
Note: SL400seriespipeavailable
forCanadaONLY.
A B SL1106
SL406
SL1112
SL412
SL1118
SL418
SL1136
SL436
SL1148
SL448in. mm in. mm
47/8 124 177/8 454 - - - - -
71/4 184 22 559 1- - - -
93/4 248 261/8 664 2 - - - -
101/4 260 271/4 692 - 1- - -
123/4 324 313/8 797 1 1 - - -
131/4 337 323/8 822 - - 1- -
153/4 400 365/8 930 - 2 - - -
181/8 460 403/4 1035 12 - - -
183/4 476 413/4 1060 - 1 1 - -
213/4 552 47 1194 - - 2 - -
221/4 565 48 1219 - - - 1-
243/4 629 521/8 1324 1- - 1-
273/4 705 573/8 1457 - 1-1-
281/4 718 583/8 1483 - - - - 1
303/4 781 621/2 1588 1---1
333/4 857 673/4 1721 - 1- - 1
363/4 933 73 1854 - - 1-1
393/4 1010 781/8 1984 - - - 2 -
411/8 1045 823/8 2092 1- - 2 -
453/4 1162 881/2 2248 - - - 1 1
481/8 1222 923/4 2356 1- - 1 1
513/4 1314 987/8 2511 - - - - 2
Properassemblyofaircooledchimneypartsresultsinanoverlapofchimneyjoints
of1-1/4in.(32mm).Effectivelengthisbuiltintothistable.

17
Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
Slanted Roofs
Flat Roofs
Chimney must
extend 3 ft (.9 m)
above the roof
Chimney must extend 2 ft (.6 m)
above any portion of the roof or
adjacent structures within
10 ft (3 m) of the chimney
Chimney must
extend 3 ft (.9 m)
above the roof
Chimney must extend 2 ft (.6 m)
above any portion of the roof or
adjacent structures within
10 ft (3 m) of the chimney
Multiple Chimney Locations
A B
6 in. (minimum) up to 20 in.
152 mm/508 mm
18 in. minimum
457 mm
20 in. and over 0 in. minimum
Gas, Wood or Fuel Oil
Termination Cap
Wood
Minimum
(See
illustration
above)
B
Gas
Termination
Cap **
A *
Perpendicular Wall
*
If using decorative cap cover(s), this distance may need to be
increased. Refer to the installation instructions supplied with the
decorative cap cover.
**
In a staggered installation with both gas and wood terminations, the
wood termination cap must be higher than the gas termination cap.
Figure 4.3 Multiple Chimney Locations
C. Termination Requirements
• Installacapapprovedandlistedforthisreplacesystem.
• Locatecapwhereitwillnotbecomepluggedbysnoworothermaterials.
• Locatecapawayfromtreesorotherstructures.
• Thebottomoftheterminationcapmustbeatleast3ft(.91m)abovetheroofANDatleast2ft(.61m)aboveanyportion
ofroofwithin10ft(3.05m).
• Thedistancerequiredbetweencapsisshownbelow.

18 Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
5 Chimney Installation
Chimney must extend
beyond combustible
roof structure
Maintain minimum
height of chimney
above roof
Additional
support for
tall chimneys
Install roof flashing
according to minimum
requirements
Maintain minimum
clearances to
combustibles as
specified
Offsets/returns
may not exceed
30° from vertical
Lock chimney
sections together
firmly to resist
movement
Ceiling firestops
are required where
chimney passes
through ceiling or
floor
Support straps for offsets
(not shown) must be
secured to adequate framing
Termination Cap
Storm Collar
Offsets/returns must be
secured with the screws
provided (outer pipe only)
Attic shield
Figure 5.1 Typical Chimney System - Guidelines for Chimney System Installation
NOTICE: Chimney performance may vary.
• Trees,buildings,rooflinesandwindconditionsaffectperformance.
• Chimneyheightmayneedadjustmentifsmokingoroverdraftoccurs.
A. Typical Chimney System

19
Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
C. Install Chimney Air Kit
• RequiredinCanada.
• Followinstructionsincludedwithaccessory.
NOTICE: Chimney sections cannot be disassembled once
lockedtogether.Planahead!
• Lockchimneysectionsand/oroffsets/returnstogetherby
pushingdownwarduntilthetopsectionmeetsthestop
beadonthelowersection.
• Pullonthetopsectiontomakesureitisfullyengaged
andwillnotseparate.
• Youmayuse#6or#8sheetmetalscrewsnolongerthan
1/2in.(13mm)tofastenchimneysectionstogether.Do
NOTpenetrateinnerue.
WARNING! Risk of Fire! YouMUSTusescrews(pro-
vided)tofastenoffset/returnstochimneysectionsto
keepthechimneypartsfromtwisting.Failuretodoso
couldcausere.
• Fasten offset/returns to chimney sections. Insert the
screws(provided)throughthepredrilledholes.DoNOT
penetrateinnerue.
• Secure chimney returns with hanger straps provided;
fastentostudsorjoists.
• Verticalstraightrunsofchimneymustbesupportedevery
35ft(10.7m).
B. Assemble Chimney Sections
Useonlythosecomponentsdescribedinthismanual.
Substituteordamagedchimneycomponentscouldimpair
safeoperationandcauseoverheatingandre.
Attacheitherastraightchimneysectionoranoffsetto
thetopofthereplace(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ueisplacedtotheinsideoftheuesection
belowit.Theoutercasingisplacedoutsidetheoutercas-
ingofthechimneysectionbelowit.SeeFigure5.2.
WARNING! Risk of Fire! DO NOT install substitute or
damaged chimney components.
Figure 5.2 Assembling Chimney Sections

20 Heatilator • ST42A Installation Manual • 4012-051 • Rev C • 10/03/13
D. Secure Offset/Return
E. Install Ceiling Firestops
CAUTION! Risk of Fire! Ceilingrestopsmustbeused
wheneverthechimneypenetratesaceiling/oor.
• Chaseconstructionrequiresceilingrestopsateach
oororevery10ft.(3.05m)ofclearspace.
• Theceilingrestopslowsspreadofreandreduces
coldairinltration.
• Installaceilingrestopwheneverchimneypenetrates
ceiling/oor.
• MarkandcutanopeninginceilingasshowninFigure5.4.
• Frametheopeningwiththesamesizelumberusedin
theceilingjoists.
• Nailtheceilingrestoptothebottomoftheceilingjoists
whenthereisaroomabove.
• Useanatticinsulationshieldiftheceilingisinsulated.
Theceilingrestopmaythenbeattachedaboveorbelow
thejoists.
ROOM ABOVE (non-insulated ceiling)
ATTIC ABOVE (insulated ceiling)
B
A
Ceilng firestop
attached to bottom
of framing
Ceiling firestop
attached to top of
framing
Note: Use same dimensional lumber for framing
ceiling firestop and joists.
2 in. (51mm)
clearance
2 in. (51mm)
clearance
WARNING! Risk of Fire! DO NOT seal area between
restopopeningandchimneypipeexceptwheretheyen-
ter the attic or leave the warm air envelope of the home
(use 600° F sealant).
Figure 5.4 Installing the Ceiling Firestop
Whenoffsetsandreturnsarejoinedtostraightpipesec-
tions,theymustbelockedintopositionwiththescrews
provided*(outeronly),usingthepredrilledholes.Topre-
ventgravityfrompullingthechimneysectionsapart,the
returnsandthechimneystabilizershavehangerstrapsfor
securingthesepartstojoistsorrafters.SeeFigure5.3.
* Use#6or#8sheetmetalscrew,orlarger,nolonger
than1/2in.(13mm).
WARNING! Risk of Fire!
• Secureoffsetswithscrews(nottoexceed1/2in./13mm
In length).
• Securereturnswithstrapping.
• Straightchimneysectionsmaybesecuredwithscrew
(nottoexceed1/2in./13mmInlength)atthejoints.
• Keepchimneysectionsfromseparatingortwisting.
Ceiling
Firestop
Straps
Optional
Additional
Support
Joint
Band
(Optional)
Figure 5.3 Secure the Chimney
Catalog #
A B
in. mm in. mm
FS538 17 432 17 432
FS540 17 432 26 660