Heatilator ST42A User manual

1
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): • 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.
Owner’s Manual
Operation and Care
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.
NOTICE: DO NOT discard this manual!
Contact your dealer with questions on installation, operation, or service.
Installation and service of thisappliance should be performed by
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22
ST42A

2
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 Welcome
A. Congratulations 3
B. LIMITED LIFETIME WARRANTY 4
2 Product Specic and General Information
A. Appliance Certication 6
B. Vented Gas Log Sets, Unvented Gas Log Sets,
Gas Inserts, Gas Log Lighters
and Wood-burning Inserts 6
3 Important Safety and Operating Information
A. Fireplace Safety 7
1. Clear Space 7
2. Grate 8
3. Refractory 8
4. Firescreen 8
5. Flue Damper 8
6. Glass Doors 8
7. Over-Firing Your Fireplace 8
8. Chimney Fire 8
B. General Operating Parts 9
1. Flue Damper 10
2. Outside Air (Optional) 10
3. Glass Doors 10
C. Fuel 10
1. Hardwood vs. Softwood 10
2. Moisture content 11
3. Seasoning 11
4. Storing Wood 11
5. Burning Process 12
6. Creosote Formation 12
7. Processed Solid Fuel Firelogs 12
D. First Fire 12
E. Lighting Instructions 12
4 Maintenance and Service
A. Chimney Inspection 13
B. Creosote (Chimney) Cleaning 13
C. Grate 14
D. Glass Cleaning 14
E. Ash Removal 14
F. Refractory/Firebrick 14
5 Troubleshooting
A. FAQs 16
6 Reference Materials
A. Service Parts 18
B. Accessories 19
C. Contact Information 20
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22
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3
Read this manual before installing or operating this replace.
Please retain this owner’s manual for future references.
A. Congratulations
Listing Label Information/Location The model information regarding your specic replace can be found on
the rating plate usually located in the control area of the replace.
1 Welcome
Brand: ________________________________________________ Model Name: ___________________________
Serial Number:__________________________________________ Date Installed: __________________________
Fireplace Information:
Local Dealer Information
DEALER: Fill in
your name, address,
phone and e-mail
information here and
replace information
below.
Dealer Name: ________________________________________________________
Address: ____________________________________________________________
____________________________________________________________
Phone: _____________________________________________________________
E-mail: _____________________________________________________________
Grate
Fireplace
Model
Serial
Number
SERIAL NO./NUMERO DESERE
MODEL/MODELE
MFG. DATE
WARNING: RISK OF FIRE DAMAGE. REPLACE GRATE WITH HEARTH & HOME TECHNOLOGIES
FIREPLACE ALSO FOR USE IN
MANUFACTURED/MOBILE HOMES
WITH SOLID FUEL ONLY
YES NO
CLEARANCE TO
COMBUSTIBLES:
FIREBOX/
FOYER
IN.
MIN.
FAN KIT/
KIT DU VENTILATUER
MODEL NO.
AMP.
IF INSTALLATION OR OPERATING INSTRUCTIONS ARE MISSING CONTACT:
HEARTH & HOME TECHNOLOGIES,
7571 215th Street West, Lakeville, MN 55044.
P.N. 4021-954C
FIRE CHAMBER INTENDED FOR USE WITH HEARTH & HOME TECHNOLOGIES
LISTED FIREPLACE PARTS AND GLASS DOOR KITS. SEE INSTALLATION AND
OPERATING INSTRUCTIONS FOR THIS MODEL.
GRATE MODEL/GRILLE MODELE
DEGAGEMENT DES
MATEIAUX COMBUSTIBLES:
MM
MIN.
AVERTISSEMT:RISQUE DE DOMMAGE PARINCENDIE, REMPLACEZ LA GRILLE AVEC
HEARTH & HOME TECHNOLOGIES
CHIMNEY/CHEMNEE
2 IN. MIN.
51 MM
RATED AT/CAPACITE
115 VOLTS, 50/60 HZ
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22
Congratulations on selecting a Heatilator wood burning
replace. The Heatilator replace you have selected is
designed to provide the utmost in safety and reliability.
As the owner of a new replace, you'll want to read and
carefully follow all of the instructions contained in this
Owner's Manual. Pay special attention to all Cautions and
Warnings.
This Owner's Manual should be retained for future refer-
ence. We suggest that you keep it with your other impor-
tant documents and product manuals.
Your new Heatilator wood burning replace will give you
years of durable use and trouble-free enjoyment. Wel-
come to the Heatilator family of replace products!
Heatilator is a registered trademark of Hearth & Home
Technologies.

4
B. LIMITED LIFETIME WARRANTY
Hearth & Home Technologies LLC
LIMITED LIFETIME WARRANTY
Hearth & Home Technologies LLC (“HHT”) extends the following warranty for HHT gas, wood, pellet and electric hearth appliances
(each a “Product” and collecvely, the “Product(s)”) and certain component parts set forth in the table below (“Component Part(s)”)
that are purchased from a HHT authorized dealer or distributor.
WARRANTY COVERAGE:
HHT warrants that the Products and their Component Parts will be free from defects in materials and workmanship for the applicable
period of Warranty coverage set forth in the table below (“Warranty Period”). If a Product or Component Parts are found to be
defecve in materials or workmanship during the applicable Warranty Period, HHT will, at its opon, repair the applicable Component
Part(s), replace the applicable Component Part(s), or refund the purchase price of the applicable Product(s). The maximum amount
recoverable under this Warranty is limited to the purchase price of the Product. This Warranty is transferable from the original purchaser
to subsequent owners, but the Warranty Period will not be extended in duraon or expanded in coverage for any such transfer. This
Warranty is subject to condions, exclusions, and limitaons as described below.
WARRANTY PERIOD:
Warranty coverage begins at the date of installaon. In the case of new home construcons, Warranty coverage begins on the date of
rst occupancy of the dwelling or six months aer the sale of the Product(s) by an independent, authorized HHT dealer or distributor,
whichever occurs earlier. However, the Warranty coverage shall commence no later than 24 months following the date of Product
shipment from HHT, regardless of the installaon or occupancy date.
The term “Lifeme” in the table below is dened as: 20 years from the beginning date of warranty coverage for gas appliances, 10 years
from the beginning date of warranty coverage for wood and pellet appliances, and 5 years from the beginning of warranty coverage
for standalone gas log sets. These me periods reect the minimum expected useful lives of the designated Component Parts under
normal operang condions.
Page 1 of 2
4021-645M 9/21
Component
Parts Labor Gas Pellet Wood Electric Venting Component Parts Covered by this Warranty
XAll parts except as covered by Warranty Conditions,
Warranty Exclusions, and Warranty Limitations listed
X X Igniters, Auger Motors, Electronic Components, and
Glass
X
Electrical components limited to modules, remotes/wall
switches, valves, pilots, blowers, junction boxes, wire
harnesses, transformers and lights (excluding light bulbs)
X X Molded Refractory Panels, Glass Liners
X
Burners and logs for standalone gas log sets
(Vented and Vent Free gas log sets not sold as
components of the fireplace or stove)
X
Vent Free Burners and Vent Free Log components of
HHT manufactured fireplaces or stoves
X X Castings, Medallions and Baffles
6 years 3 years XCatalysts
7 years 3 years X X Manifold tubes, HHT Chimney and Terminations
10 years 1 year X
Burners, logs and refractory components of HHT
manufactured fireplaces or stoves
Limited
Lifetime 3 years XXX Firebox and heat exchanger, FlexBurn®System
(engine, inner cover, access cover and fireback)
1 Year None XXXXX All purchased replacement parts
Warranty Period HHT Manufactured Appliances and Venting
All parts including handles, external enameled
components and other material except as covered by
Warranty Conditions, Warranty Exclusions, and
Warranty Limitations listed
2 years
X
1 Year X X X
2 Years
5 years 1 year
Firepots, burnpots, mechanical feeders/auger
assemblies
3 years X
5 years
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22
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5
WARRANTY CONDITIONS:
• Because HHT cannot control the quality of any Products sold by unauthorized sellers, this Warranty only covers Products that are
purchased through an HHT authorized dealer or distributor unless otherwise prohibited by law; a list of HHT authorized dealers
is available on the HHT branded websites.
• This Warranty is only valid while the applicable Product remains at the site of original installaon.
• This Warranty is only valid in the country in which the HHT authorized dealer or distributor that sold the applicable Product is
authorized to sell applicable Product.
• Contact your installing distributor or dealer for Warranty service. If the installing dealer or distributor is unable to provide
necessary parts, contact the nearest HHT authorized dealer or supplier. Addional service fees may apply if you are seeking
Warranty service from a dealer other than the dealer from whom you originally purchased the applicable Product.
• No HHT consumer should bear cost of warranty service or costs incurred while servicing warranty claims (i.e., travel, gas, or
mileage) when the service is performed within the terms of this Warranty. Check with your dealer or distributor in advance for
any costs to you when arranging a warranty call. Travel and shipping charges for parts are not covered by this Warranty.
WARRANTY EXCLUSIONS:
This Warranty does not cover the following:
• Changes in surface nishes as a result of normal use. As a heang appliance, some changes in color of interior and exterior surface
nishes may occur. This is not a aw and is not covered under the Warranty.
• Damage to printed, plated, or enameled surfaces caused by ngerprints, accidents, misuse, scratches, melted items or other
external sources and residues le on the plated surfaces from the use of abrasive cleaners or polishes.
• Repair or replacement of parts that are subject to normal wear and tear during the Warranty Period are not covered. These parts
include: paint, wood and pellet gaskets, rebricks, grates, ame guides, baeries and the discoloraon of glass.
• Minor expansion, contracon, or movement of certain parts causing noise. These condions are normal and complaints related to
this noise are not covered by this Warranty.
• Damages resulng from: (1) failure to install, operate, or maintain the applicable Product in accordance with the installaon
instrucons, operang instrucons, and lisng agent idencaon label furnished with the applicable Product; (2) failure to
install the applicable Product in accordance with local building codes; (3) shipping or improper handling; (4) improper operaon,
abuse, misuse, connued operaon with damaged, corroded or failed components, accident, or improperly/incorrectly performed
repairs; (5) environmental condions, inadequate venlaon, negave pressure, or draing caused by ghtly sealed construcons,
insucient make-up air supply, or handling devices such as exhaust fans or forced air furnaces or other such causes; (6) use of fuels
other than those specied in the operaon instrucons; (7) installaon or use of components not supplied with the applicable
Product or any other components not expressly authorized and approved by HHT; (8) modicaon of the appliance not expressly
authorized and approved by HHT in wring; and/or (9) interrupons or uctuaons of electrical power supply to the applicable
Product.
• Non-HHT venng components, hearth connecons or other accessories used in conjuncon with the applicable Product.
• Any part of a pre-exisng replace system in which an insert or a decorave gas applicable Product is installed.
• HHT’s obligaon under this Warranty does not extend to the Product’s capability to heat the desired space. Informaon is provided
to assist the consumer and the dealer in selecng the proper Product for the applicaon. Consideraon must be given to the
Product locaon and conguraon, environmental condions, insulaon and air ghtness of the structure.
This warranty is void if:
• The applicable Product has been over-red, operated in atmospheres contaminated by chlorine, uorine, or other damaging
chemicals. Over-ring can be idened by, but not limited to, warped plates or tubes, deformaon/warping of interior cast iron
structure or components, rust colored cast iron, bubbling, cracking and discoloraon of steel or enamel nishes.
• The applicable Product is subjected to prolonged periods of dampness or condensaon.
• There is any damage to the applicable Product due to water or weather damage which is the result of, but not limited to, improper
chimney or venng installaon.
LIMITATIONS OF REMEDIES AND LIABILITY:
• EXCEPT TO THE EXTENT PROVIDED BY LAW, HHT MAKES NO EXPRESS WARRANTIES OTHER THAN THE WARRANTY SPECIFIED
HEREIN. The owner’s exclusive remedy and HHT’s sole obligaon under this Warranty or in contract, tort or otherwise, shall be
limited to replacement of the Component Part(s), repair of the Component Part(s), or refund of the original purchase price of the
applicable Product(s), as specied above; provided, however, that (i) if HHT is unable to provide replacement of the Component
Part(s) and repair of the Component Part(s) is not commercially praccable or cannot be mely made, or (ii) the customer is
willing to accept a refund of the purchase price of the applicable Product(s), HHT may discharge all such obligaons by refunding
the purchase price of the applicable Product. In no event will HHT be liable for any incidental or consequenal damages caused
by defects in the applicable Product. Some States do not allow the exclusion or limitaon of incidental or consequenal damages,
so the above limitaon or exclusion may not apply to you. This Warranty gives you specic legal rights and you may also have
other rights which vary from State to State. THE DURATION OF ANY IMPLIED WARRANTY IS LIMITED TO DURATION OF THE
EXPRESSED WARRANTY SPECIFIED ABOVE FOR THE APPLICABLE PRODUCT. Some States do not allow limitaons on how long an
implied warranty lasts, so the above limitaon may not apply to you.
Page 2 of 2
4021-645M 9/21
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

6
2 Product Specic and General Information
Warning! Risk of Fire!
For use with solid wood fuel only.
Other fuels may overre and generate poisonous gases
(i.e. carbon monoxide).
B. Vented Gas Log Sets, Unvented Gas Log
Sets, Gas or Wood Inserts and Gas Log
Lighters
• Optional
• Gas log sets, gas or wood inserts, or gas log-lighters
can be installed in this replace. Follow the instructions
provided with the accessory for operation.
Unvented Gas Logs
CAUTION! If an unvented gas appliance is installed in
the replace, the gas appliance must only be operated
with the replace glass door fully open (if included).
Only unvented gas log sets which have been found to
comply with the standard for unvented room heaters,
ANSI Z211.11.2, are to be installed in this replace. If
an unvented gas appliance is installed it must incorpo-
rate an automatic shuto󰀨 device, and must be installed
in accordance with the National Fuel Gas Code Z223.1,
Latest edition.
WARNING! Do Not operate an unvented gas log set in this
replace with the chimney removed.
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22
A. Appliance 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 log set, gas
insert 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 ac-
cordance with UL 127 and CAN/ULC-S610 standards by
Underwriters Laboratories Inc. for installation and opera-
tion in the United States and Canada.

7
A. Fireplace Safety
Most problems are caused by improper installation and op-
eration of the replace. To provide reasonable re safety,
the following should be given serious consideration:
• The re should be supervised whenever the replace is
in use.
• An annual inspection should be performed on the
replace system.
• Install at least one smoke detector on each oor of your
home to ensure your safety.
• Install a conveniently located Class A re extinguisher
near the replace.
• Devise a practiced evacuation plan, consisting of at least
two escape routes.
• Devise a plan to deal with a chimney re:
- Evacuate.
- Notify the re department.
3 Important Safety and Operating Information
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:
• operate damaged replace
• modify replace
• overre
• install any unvented gas log set
• install any component not approved by Hearth & Home
Technologies
• install parts or components not Listed or approved
• operate the fireplace without fully assembling all
components
Improper installation, adjustment, alteration, service or
maintenance can cause injury or property damage.
1. Clear Space
Combustible materials must not be stored on the hearth
extension. Room furnishings such as drapes, curtains,
chairs or other combustibles must be at least 4 ft
(1219 mm) from the front of the replace.
Combustible materials are materials made of or sur-
faced with any of the following materials:
- Wood - Compressed paper
- Plant bers - Plastic
- Plywood/OSB - Drywall
- Any material that can ignite and burn, ame proofed
or not, plastered or un-plastered.
WARNING! Risk of Fire! Keep combustible materials,
gasoline and other ammable vapors and liquids clear of
the replace.
DO NOT:
• store ammable materials close to the replace
• use gasoline, lantern fuel, kerosene, charcoal lighter
uid or similar liquids to start or “freshen up” a re in this
replace.
24 in. (610 mm)
Clear Space
Sides of Fireplace Opening
48 in. (1219 mm)
Clear Space
Front of Fireplace
63-3/4 in. (1619 mm)
Clear Space
Bottom of Fireplace to
Lower Edge of
Mantel or Trim
Figure 3.1 Clear Space
Non-combustible materials are materials which will not
ignite and burn, composed of any combination of the
following:
- Steel - Iron
- Brick - Tile
- Concrete - Slate
- Glass - Plasters
WARNING: This product and the fuels
used to operate this product (wood and
wood pellets), and the products of combus-
tion of such fuels, can expose you to chemi-
cals including carbon black, which is known
to the State of California to cause cancer
and carbon monoxide, which is known to
the State of California to cause birth defects
or other reproductive harm. For more infor-
mation go to: www.P65Warnings.ca.gov.
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

8
8. Chimney Fire
In the event of a chimney re
• Have the chimney and adjacent structure inspected by
qualied professionals. Hearth & Home Technologies
recommends that NFI or CSIA certied professionals,
or technicians under the direction of certified
professionals, conduct a minimum of an NFPA 211
Level 2 inspection of the chimney.
• Replace components of the chimney and replace
as specied by the professionals.
• Ensure all joints are properly engaged and the
chimney is properly secured.
WARNING! Risk of Fire! A chimney re can perma-
nently damage your chimney system. Failure to re-
place damaged components and make proper repairs
can cause a structure re.
7. Over-Firing Your Fireplace
WARNING! Risk of Fire! Do not over-re.
Over-firing may ignite creosote or will damage the
replace and chimney.
Symptoms of over-ring may include one or more of the
following:
• chimney connector or replace glowing
• roaring, rumbling noises
• loud cracking or banging sounds
• metal warping
• chimney re
To prevent over-ring your replace. DO NOT:
• use ammable liquids
• overload with wood
• burn trash or large amounts of scrap lumber
• permit too much air to the re
2. Grate
This replace is designed to be used with the supplied
grate or one approved by HHT.
WARNING! Risk of Fire! Use only the factory-sup-
plied integral grate.
• Keeps logs in place.
• Allows proper air circulation around the re.
3. Refractory
The refractory is supplied to contain heat and provide
an attractive interior.
It will break down over time and will need occasional
replacement. Small hairline cracks and discoloration
are normal and do not a󰀨ect its safety.
WARNING! Risk of Fire! DO NOT burn replace with-
out refractory. Use only refractory supplied by Hearth &
Home Technologies.
4. Firescreen
The rescreen is provided to control sparks. Keep it
closed when the replace in use.
WARNING! Risk of Fire or Burns!
• Screen will not prevent burning materials from falling
out.
• Screen pulls or handles may be hot.
5. Flue Damper
The ue damper must be in the fully opened position
during operation of the replace.
WARNING! Risk of Fire and Asphyxiation! Open
damper prior to operating replace. A closed damper
overres the replace and spills smoke and ames
into the room.
6. Glass Doors
• Glass doors are optional.
• With certain replace installations, it may be neces-
sary to operate the replace with both glass doors
in the fully open or fully closed position to prevent
smoke spillage into the home.
WARNING! Risk of Fire! Install ONLY doors approved
by Hearth & Home Technologies.
WARNING! Risk of Fire and Smoke! Fireplace
equipped with doors should be operated only with
doors fully open or doors fully closed. If doors are left
partly open, gas and ame may be drawn out of the
replace opening.
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

9
B. General Operating Parts
WARNING! DO NOT operate replace before reading and understanding operating instructions. Failure to operate re-
place according to operating instructions could cause re or injury.
WARNING
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.
HOT SURFACES!
Glass and other surfaces are hot during operation AND cool down.
Damper
Handle
Air Kit Handle Location
(just above stone) open
open
close
close
Figure 3.2 General Operating Parts
CAUTION! If you expect that children may come into contact with this replace, we recommend a barrier such as a decorative
screen. See your dealer for suggestions.
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

10
Refer to Figure 3.2 for location and operation of control.
The outside air kit supplies some combustion air for
your replace. It may help reduce the e󰀨ects of nega-
tive air pressure.
Close the inlet to prevent cold drafts when the replace
is not being used
2. Outside Air (Optional)
CAUTION! Outside air control handle may be warm.
Adjust before lighting re.
3. Glass Doors
• Glass doors are optional.
• Refer to Figure 3.3 for how to properly use them.
• With certain fireplace installations, it may be
necessary to operate the replace with both glass
doors in the opened or closed position to prevent
smoke spillage into the home.
1. Flue Damper
Refer to Figure 3.2 for location and operation of con-
trol.
Before lighting the replace, verify fully open position
by looking up from the inside of the replace.
ONE SIDE OPENED &
ONE SIDE CLOSED
CORRECT
BOTH SIDES OPEN
CORRECT
PARTLY CLOSED/OPENED
INCORRECT
BOTH SIDES CLOSED
CORRECT
Figure 3.3 Operating Positions of Bi-fold Doors
Soft woods Hard woods
• Douglas Fir • Oak
• Pine • Maple
• Spruce • Apple
• Cedar • Birch
• Poplar
• Aspen
• Alder
C. Fuel
1. Hardwood vs. Softwood
Your replace’s performance depends on the quality of
the rewood you use. One species of wood varies very
little to the other in terms of energy content. All sea-
soned wood contains about 8,000 BTU’s per pound.
Hardwoods have a greater density than softwoods; a
piece of hardwood will contain about 60% more BTU’s
than an equal size piece of softwood. A cord of sea-
soned oak (hardwood) would contain about 60% more
potential energy than a cord of seasoned pine (soft-
wood).
Most softwoods are coniferous. These are trees with
needle-like leaves that stay green all year and carry
their seeds exposed in a cone. Examples of conifer-
ous trees are Douglas r, pine, spruce and cedar. Soft-
woods, being more porous, require less time to dry,
burn faster and are easier to ignite than hardwoods.
Hardwoods are deciduous trees, broadleaf trees that
lose their leaves in the fall. Their seeds are usually
found within a protective pod or enclosure. Some ex-
amples of deciduous trees are oak, maple, apple, and
birch. However, it should be noted that there are some
deciduous trees that are denitely not considered hard-
woods such as poplar, aspen and alder. Hardwoods
require more time to season, burn slower and are usu-
ally harder to ignite than softwoods. Obviously, you will
use the type of wood that is most readily available in
your area. However, if at all possible the best arrange-
ment is to have a mix of softwood and hardwood. This
way you can use the softwood for starting the re, giv-
ing o󰀨 quick heat to bring the replace up to operating
temperature. Add the hardwood for slow, even heat and
longer burn time.
WARNING! For use with solid wood fuel only.
Other fuels may overre and generate poisonous gases (i.e.
carbon monoxide).
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

11
WARNING! Risk of Fire!
• DO NOT burn wet or green wood.
• Wet, unseasoned wood can cause accumulation of
creosote.
2. Moisture content
The majority of the problems replace owners expe-
rience are caused by trying to burn wet, unseasoned
wood. Freshly cut wood can be as much water as it is
wood, having a moisture content of around 50%. Imag-
ine a wooden bucket that weighs about 8 pounds. Fill it
with a gallon of water, put it in the rebox and try to burn
it. This sounds ridiculous but that is exactly what you
are doing if you burn unseasoned wood. Dead wood
lying on the forest oor should be considered wet, and
requires full seasoning time. Standing dead wood can
be considered to be about two-thirds seasoned, if cut at
the dry time of the year.
Burning wet, unseasoned wood will produce less heat
output because it requires energy in the form of heat
to evaporate the water trapped inside. This is wasted
energy that should be used for heating your home. This
moisture evaporates in the form of steam which has
a cooling e󰀨ect in your rebox and chimney system.
When combined with tar and other organic vapors from
burning wood it will form creosote which condenses in
the relatively cool rebox and chimney.
Even dry wood contains at least 15% moisture by
weight, and should be burned hot enough to keep the
chimney hot for as long as it takes to dry the wood out
- about one hour. To tell if wood is dry enough to burn,
check the ends of the logs. If there are cracks radiating
in all directions from the center, it is dry. If your wood
sizzles in the re, even though the surface is dry, it may
not be fully cured.
3. Seasoning
Seasoned rewood is nothing more than wood that is
cut to size, split and air dried to a moisture content of
around 20%. The time it takes to season wood varies
from around nine months for soft woods to as long as
eighteen months for hardwoods. The key to seasoning
wood is to be sure it has been split, exposing the wet
interior and increasing the surface area of each piece.
A tree that was cut down a year ago and not split is
likely to have almost as high a moisture content now as
it did when it was cut.
To season wood:
• Cut logs to size
• Split to 6 in. (152 mm) or less
• Air dry to a moisture content of around 20%
- Soft wood - about nine months
- Hard wood - about eighteen months
NOTICE: Seasoning time may vary depending on drying
conditions.
4. Storing Wood
Splitting wood before it is stored reduces drying time.
The following guideline will ensure properly seasoned
wood:
• Stack the wood to allow air to circulate freely around
and through the woodpile.
• Elevate the woodpile o󰀨 the ground to allow air
circulation underneath.
• The smaller the pieces, the faster the drying process.
Any piece over 6 in. (152 mm) in diameter should be
split.
• Wood should be stacked so that both ends of each
piece are exposed to air, since more drying occurs
through the cut ends than the sides. This is true even
with wood that has been split.
• Store wood under cover, such as in a shed, or covered
with a tarp, plastic, tar paper, sheets of scrap plywood,
etc., as uncovered wood can absorb water from rain
or snow, delaying the seasoning process. Avoid
covering the sides and ends completely. Doing so
may trap moisture from the ground and impede air
circulation.
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

12
WARNING! Risk of Fire! Keep combustible materials,
gasoline and other ammable vapors and liquids clear of
the replace.
DO NOT:
• store ammable materials close to the replace
• use gasoline, lantern fuel, kerosene, charcoal lighter
uid or similar liquids to start or “freshen up” a re in this
replace.
E. Lighting Instructions
NOTICE: You must establish a good draft to prevent smoke
spillage into the room.
The rst three or four res should be of moderate size to
allow the oils and binders to be burned from the replace
and the refractory and paint to cure. You may notice an in-
dustrial odor the rst few res. This is considered normal.
Use well-seasoned wood.
• Open the ue damper to a fully open position.
• Place crumpled or twisted paper under the replace
grate.
• Loosely arrange kindling or small pieces of wood to form
a ‘tent’ on the replace grate.
• Pre-warm the ue to establish a draft to help reduce
smoke spillage during start-up. Hold a rolled up piece
of burning newspaper under the ue damper for a few
moments.
• Light the crumpled paper to ignite the kindling.
• Add small pieces of wood until a hot bed of embers has
been established.
• Add a minimum of three average size pieces of split
rewood, placed to allow combustion air and ames
between them.
5. Burning Process
Fire requires fuel, air and heat. If heat is robbed from
the replace during the drying stage, the new load of
wood has reduced the chances for a good clean burn.
Always burn dry, seasoned rewood.
6. Creosote Formation and Need For Removal
When wood is burned slowly, it produces tar and other
organic vapors which combine with expelled moisture
to form creosote. The creosote vapors condense in
the relatively cool chimney ue of a newly-started or
a slow-burning re. As a result, creosote residue ac-
cumulates on the ue lining.
When ignited, creosote creates an extremely hot re
which may damage the chimney or even destroy the
house.
The chimney shall be inspected at least annually be-
fore lighting, or once every two months during heating
season.
When creosote has accumulated it shall be removed to
reduce the risk of a chimney re.
D. First Fire
Before lighting your rst re in the replace, make certain
that:
• refractory is in place
• all labels have been removed
7. Processed Solid Fuel Firelogs
Manufactured relogs may be used with this replace.
Hearth & Home Technologies recommends the use of
ANSI/CAN/UL/ULC 2115 processed solid fuel relogs
and restarters. Follow the manufacturer’s lighting and
safety instructions.
Using relogs may require more frequent chimney in-
spections and cleaning.
Do not poke or stir the logs while they are burning. Use
only relogs that have been evaluated for the appli-
cation in manufactured replaces and refer to relog
warnings and caution markings on packaging prior to
use.
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

13
4 Maintenance and Service
WARNING! Hot Surfaces!
Glass and other surfaces are hot during operation AND cool
down. DO NOT clean replace until it is cooled.
Installation and repair should be done by a qualied
service technician only. The replace should be inspected
before use and at least annually by a professional service
person.
The following tasks may be performed annually by the
homeowner. If you are uncomfortable performing any of
the listed tasks, please contact your dealer for a ser-
vice appointment.
A. Chimney Inspection
Frequency: As necessary; at least annually before
lighting replace, or once every two months during
heating season.
By: Homeowner/Chimney Sweep
• Confirm that termination cap remains clear and
unobstructed.
• Inspect for blockages such as bird nests, leaves, etc.
• Inspect for corrosion or separation.
• Inspect for creosote and remove as needed, at least
every two months during the heating season.
• Inspect the system at the replace connection and
at the chimney top.
WARNING! Risk of Asphyxiation and Fire! Annual
inspection by qualied technician recommended.
Check:
• condition of doors, surrounds and fronts
• condition of glass and glass assembly
• obstructions of combustion and ventilation air
• obstructions of termination cap
Clean:
• glass
• air passageways, grilles
In the event of a chimney re, Hearth & Home Tech-
nologies recommends replacement of the chimney and
inspection of the adjacent structure to the provisions of
NFPA Level III inspection criteria.
WARNING! Risk of Fire! Ignited creosote is extremely
HOT. Prevent creosote buildup.
B. Creosote (Chimney) Cleaning
Frequency: As needed; at least annually before light-
ing, or once every two months during heating season.
When creosote has accumulated it shall be removed
to reduce the risk of a chimney re.
By: Chimney Sweep
Tools Needed: Brush, Phillips screwdriver
• When wood is burned slowly, it produces tar and
other organic vapors, which combine with expelled
moisture to form creosote. The creosote vapors
condense in the relatively cool chimney ue of a
slow-burning fire. As a result, creosote residue
accumulates on the ue lining. When ignited, this
creosote makes an extremely hot re.
• Remove all ash from the rebox and extinguish all
hot embers before disposal. Allow the replace to
cool completely.
• Close the door tightly.
• Remove the top of the termination cap as shown in
Figure 4.1 to clean the cap and chimney.
• The creosote or soot should be removed from the
chimney with a brush specically designed for the
size of chimney in use.
• Reinstall termination cap.
• Clean out fallen debris from the rebox.
Figure 4.1 Chimney & Termination Cap Cleaning
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22
Chimney
Remove 4 screws
and lift top pan off.
Cap
Slip
Section
ST1175
ST475
Square Termination Cap
Cap
Remove screws,
lift top cover.
Top Cover
TR11/TR11T
TR444/TR442
Round Termination Cap
TCT1175
Terra Cotta
Termination Cap
Available US only
Remove 2 screws from
the front and back and
lift the top off.
1. REMOVE (8) SCREWS
2. LIFT TOP
TOP TOP
SCREW
SCREW
DT SERIES

14
F. Refractory/Firebrick
Frequency:
By:
Tools Needed:
• Inspect condition of brick. Replace if crumbly or
otherwise deteriorated, or if cracks exceed 1/4 in.
(6 mm).
C. Grate
Frequency: After each ash removal
By: Homeowner
Inspect grate for:
• Warping or sagging 1-1/2 in. (38 mm) or more
• Broken welds
• Burn-through of grate bars
For safe operation, replace only with the approved grate
from Hearth & Homes Technologies.
E. Ash Removal
Frequency: As necessary
By: Homeowner
Tools Needed: Covered metal container, metal
shovel, replace broom
WARNING! Risk of Fire! DO NOT remove ashes until
the re is out and the replace is cold.
• Ashes should be placed in metal container with tight
tting lid.
• The closed container of ashes should be placed
on a noncombustible oor or on the ground, well
away from all combustible materials, pending nal
disposal.
• If the ashes are disposed of by burial in soil or
otherwise locally dispersed, they should be retained
in the closed container until all cinders have
thoroughly cooled.
D. Glass Cleaning
Frequency: As necessary
By: Homeowner
Tools Needed: Vinegar or glass cleaner, soft towel
• Clean glass with a non-abrasive glass cleaner. Use a
damp cloth dipped in wood ashes or a commercially
available oven cleaner. Remove any oven cleaner
residue with a glass cleaner or soap and water.
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

15
5 Troubleshooting
Start Fire Problems Possible Cause Solution
Can’t get re started
Excessive smoke or spillage
Burns too slowly
Smolders, sizzles
Not enough kindling/paper or no
kindling/paper
Use dry kindling, more paper. Arrange kindling & wood for
air movement.
Damper closed/not fully open Open damper.
Not enough air for re to ignite Check for restricted cap/shroud.
Open air kit (if installed).
Check for ue blockage.
Pre-warm ue before starting re (refer to starting re
section).
Check for adequate vent height (refer to chimney
assembly section).
Open window below the replace towards the wind.
Wood condition is too wet, too large Use dry, seasoned wood (refer to wood fuel section).
Bed of coals not established before
adding wood
Start with paper & kindling to establish bed of coals (refer
to starting re section).
Flue blockage such as birds’ nests
or leaves in termination cap
Have chimney inspected for creosote and cleaned by a
certied chimney sweep.
Down draft or negative pressure
Competition with exhaust devices
Do not use exhaust fans during start-up (refer to negative
pressure section).
Open window below the replace towards the wind.
Fire burns too fast Extremely dry or soft wood Mix in hardwood.
Mix in less seasoned wood after re is established (refer
to wood fuel section).
No glass doors Add glass doors to slow down air ow.
Overdrafting Check for correct vent height; too much vertical height
creates overdrafting.
Check location of vent termination (refer to chimney
assembly section).
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

16
A. FAQs
If smoke spillage occurs from a replace opening when
the door is open, there is either a leakage in the ue, a
blockage in the ue, or some condition is a󰀨ecting draft
Understanding and di󰀨erentiating the conditions which
can cause each of these kinds of spillage problems is
essential to their solution.
• Flue Leakage
Check for improperly connected flue joints or a
damaged ue joint in the chimney system. Such
leakage would reduce draft (air would be drawn in
through the leaks rather than through the replace).
The result might be difficult start-up and smoky
res that might spill if other adverse draft conditions
accompany this problem.
• Flue Blockage
The damper should be open.
Check for objects that may have fallen down the
chimney.
Be sure you have air available for combustion and that
your rewood is dry and well seasoned. Build your res
properly and according to the instructions given in op-
erating instructions, “Starting a Fire”. Be sure your ue
system is installed correctly and that it is the proper di-
ameter and height. Check for the following:
• All chimney sections are properly installed.
• The chimney is clean and free of creosote or soot
buildup.
• Make sure overhanging trees and branches are cut
back within ten feet of the top of the chimney and the
chimney is free of debris from animals.
• Ensure the chimney cap is clean and free of any
buildup of soot or creosote if cap is equipped with a
spark arrestor screen.
• The wood being used in dry and well seasoned.
If you still suspect you have a low draft problem it may
be necessary to increase the volume of air in your
ue system. Since the diameter of your ue system is
matched with the size of the ue collar and should not
be changed, then the height of the system must be in-
creased. Add chimney sections one at a time until the
draft improves.
In some cases, regardless of what you do, it can still be
di󰀩cult to establish the proper ue draft. This is espe-
cially evident when using an exterior factory-built chim-
ney or exterior masonry chimney. Try holding a burning
rolled up newspaper as close to the ue outlet as pos-
sible for a few minutes, then light the paper under the
kindling. The heat generated from the burning rolled up
newspaper should help get the draft established.
Still other factors can a󰀨ect how well your ue system
performs. Neighboring structures, high winds, tall trees,
even hillsides can a󰀨ect air currents around the chim-
ney. Well designed chimney caps are available that can
help. Your replace dealer is the local expert in your
area. He can usually make suggestions or discover
problems that can be easily corrected allowing your
replace to operate correctly as it has been designed,
providing safe and economical heat for your home.
Flue draft is measured as negative pressure in the
chimney. The amount of negative pressure determines
how strong the draft is. The draft is important because
it draws the combustion air into the replace and pulls
the smoke out of the chimney.
There are three basic criteria essential in establishing
and maintaining ue draft:
• availability of combustion air
• heat generated from the re
• diameter and height of the ue system
These three factors work together as a system to create
the ue draft. Increasing or decreasing any one of them
will a󰀨ect the other two and thus change the amount of
draft in the entire system.
If the re is hard to start and smoke spills out of the re-
place, or you nd it di󰀩cult to establish and maintain a
moderately high burn rate, then the ue draft is too low
and corrective measures must be taken.
Hearth & Home Technologies assumes no responsibil-
ity for the improper performance of the replace sys-
tem caused by inadequate draft due to environmental
conditions, down drafts, tight sealing construction of
the structure, or mechanical exhausting devices which
will create a negative air pressure within the structure
where the replace is located.
Contact your dealer for additional informa-
tion regarding operation and troubleshoot-
ing. Visit www.heatilator.com to nd a
dealer.
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

17
Another appliance in
home also exhausting
air (furnace, fan,
dryer, etc.)?
Air register from
furnace near
fireplace?
Doors opening
and closing?
Window closed
for start-up?
Outside air
closed?
Overhead fan
operating?
Overhanging
tree?
Bird's nest
or leaves in
termination
cap?
Structural
changes in
chimney area?
Creosote buildup
in flue?
S
t
r
o
n
g
w
i
n
d
s
a
r
o
u
n
d
c
h
i
m
n
e
y
t
e
r
m
i
n
a
t
i
o
n
?
Unsealed
can lights?
Combustion
air control
Figure 5.1 Factory-built Fireplaces: Troubleshooting
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

18
6 Reference Materials
A. Service Parts
Service Parts ST42A 42 in. See-thru Woodburning Fireplace
Beginning Manufacturing Date: Apr 1992
Ending Manufacturing Date: Active
IMPORTANT: THIS IS DATED INFORMATION. Parts must be ordered from a dealer or
distributor. Hearth and Home Technologies does not sell directly to consumers. Provide
model number and serial number when requesting service parts from your dealer or distributor.
Stocked
at Depot
ITEM DESCRIPTION COMMENTS PART NUMBER
1Damper Blade Assembly SRV34487 2Starter Section Assembly 22072B Y
3Top Stando󰀨s Qty 4 req SRV4044-111 4 Smoke Shield Qty 2 req 16829F 5 Refractory - Back Qty 2 req 16672 6 Refractory - Side Qty 4 req 16948A 7**Firescreen Assembly Qty 4 req 26053 Y
Firescreen Handle SRV10002
8 Door Support No longer available 16697D
9 Hearth Refractory 16673A
10 Ashlip Qty 2 req 16674B
11 Grate GR11 Y
12 Damper Control 16663
** Firescreen length changed from 21.69" to 22.12"
Additional service parts on following page. 11/21
2
1
4
10 11
8912
7
6
5
3
Service Parts
IMPORTANT: THIS IS DATED INFORMATION. Parts must be ordered from a dealer or
distributor. Hearth and Home Technologies does not sell directly to consumers. Provide
model number and serial number when requesting service parts from your dealer or distributor.
Stocked
at Depot
ITEM DESCRIPTION COMMENTS PART NUMBER
13 Outside Air Plate Assembly 19081A 14 Long Cable Tie No longer available SRV19954
15 Outside Air Shield SRV33271 Y
Air Kit Fastener Pack 13580 Damper Weight SRV19785 Door Pivot Clip Qty 2 req SRV31527 Door Track (Upper) Qty 2 req SRV15427 Door Track (lower) Qty 2 req 4012-001 Firescreen Rod Qty 4 req SRV12052 Gas Access Panel (for use with Air Kit) 31636 Grate Clip Qty 2 req SRV28062 Nailing Flange Qty 8 req 31190 Overlay
Top SRV16687BK Bottom SRV12848BK Left and Right SRV16689BK
Refractory Bracket No longer available 23959A Refractory Retainer No longer available 16675B Refractory Retainer Qty 4 req SRV11847 Refractory Stando󰀨 Qty 6 req 16678 Smoke Shelf No longer available 16676B Smoke Shield Kit SRV4012-036 Strip Protector Qty 4 req SRV18320 Touch-Up Paint 71479 Installation Manual 4012-051 Owners Manual 4012-050
ST42A
Beginning Manufacturing Date: Apr 1992
Ending Manufacturing Date: Active
(Side of Fireplace)
15
13 14
(Duct not included in kit, sold separately.)
Outside Air Kit
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22
►

19
B. Accessories
Doors
DM1242 Bi-fold Doors with Black Trim
DM1242S Bi-fold Doors with Stainless Steel Trim
Gas Log Sets
Gas Log Lighters
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22

20
C. Contact Information
– NOTES –
Printed in U.S.A. - Copyright 2012
DO NOT DISCARD THIS MANUAL
CAUTION
•Leave this manual with
party responsible for use
and operation.
•Important operating
and maintenance
instructions included.
•Read, understand and follow
these instructions for safe
installation and operation.
This product may be covered by one or more of the following patents: (United States) 5000162, 5016609, 5076254, 5113843,
5191877, 5218953, 5263471, 5328356, 5341794, 5347983, 5413089, 5429495, 5452708, 5542407, 5890485, 5931661, 5941237,
5947112, 5996575, 6006743, 6019099, 6048195, 6053165, 6145502, 6170481, 6237588, 6296474, 6374822, 6413079, 6439226,
6484712, 6543698, 6550687, 6601579, 6672860, 6688302, 6688302B2, 6715724B2, 6729551, 6736133, 6748940, 6748942,
6769426, 6774802, 6796302, 6840261, 6848441, 6863064, 6866205, 6869278, 6875012, 6880275, 6908039, 6919884,7047962,
7216645, D320652, D445174, D462436; (Canada) 1297749, 2195264, 2225408, 2313972; (Australia) 780250, 780403, 1418504 or
other U.S. and foreign patents pending.
Heatilator • ST42A Owner Manual • 4012-050 • Rev K • 02/22
Please contact your Heatilator dealer with any questions or concerns.
For the number of your nearest Heatilator dealer, please visit www.heatilator.com.
Heatilator, a brand of Hearth & Home Technologies
7571 215th Street West, Lakeville, MN 55044
www.heatilator.com