Desa 10542 Original instructions

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WARNING: If the information in this manual is not followed
exactly, a fire or explosion may result causing property
damage, personal injury, or loss of life.
— Do not store or use gasoline or other flammable vapors and
liquids in the vicinity of this or any other appliance.
— WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any phone in
your building.
• Immediately call your gas supplier from a neighbor’s phone.
Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the fire department.
— Installation and service must be performed by a qualified
installer, service agency, or the gas supplier.
MANUAL 10,000 BTU - 10542 AND 10543
THERMOSTAT 10,000 BTU - 10544 AND 10545
THERMOSTAT 20,000 BTU - 10546 AND 10547
THERMOSTAT 30,000 BTU - 10548 AND 10549
UNVENTED (VENT-FREE) BLUE FLAME GAS HEATER
SAFETY INFORMATION AND INSTALLATION MANUAL

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2
WARNING: Improper installation, adjustment, altera-
tion, service, or maintenance can cause injury or prop-
erty damage. Refer to this manual for correct installation
and operational procedures. For assistance or addi-
tional information consult a qualified installer, service
agency, or the gas supplier.
WARNING: This is an unvented gas-fired heater. It uses
air (oxygen) from the room in which it is installed.
Provisions for adequate combustion and ventilation air
must be provided. Refer to Air for Combustion and
Ventilation section on page 5 of this manual.
This appliance may be installed in an aftermarket,*
permanently located, manufactured (mobile) home,
where not prohibited by local codes.
This appliance is only for use with the type of gas
indicated on the rating plate. This appliance is not
convertible for use with other gases.
* Aftermarket: Completion of sale, not for purpose of resale, from the
manufacturer
TABLE OF CONTENTS
Safety Information ............................................... 3
Local Codes ........................................................ 4
Product Identification .......................................... 4
Unpacking ........................................................... 4
Product Features ................................................ 4
Air For Combustion And Ventilation .................... 5
Installation ........................................................... 7
Operating Heater .............................................. 15
Inpecting Heater ................................................ 18
Cleaning and Maintenance ............................... 19
Troubleshooting ................................................ 20
Specifications .................................................... 24
Service Hints ..................................................... 25
Technical Service .............................................. 25
Service Publications .......................................... 25
Replacement Parts ........................................... 25
Illustrated Parts Breakdown and Parts List ....... 26
Accessories ....................................................... 30
Parts Centrals ................................................... 31
Warranty Information .......................... Back Cover

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113680-01A 3
SAFETY INFORMATION
IMPORTANT: Read this owner’s
manual carefully and completely
before trying to assemble, oper-
ate, or service this heater. Im-
proper use of this heater can
cause serious injury or death
from burns, fire, explosion, elec-
trical shock, and carbon mon-
oxide poisoning.
DANGER: Carbon monoxide
poisoning may lead to death!
Carbon Monoxide Poisoning: Early signs of car-
bon monoxide poisoning resemble the flu, with
headaches, dizziness, or nausea. If you have these
signs, the heater may not be working properly. Get
fresh air at once! Have heater serviced. Some
people are more affected by carbon monoxide than
others. These include pregnant women, people with
heart or lung disease or anemia, those under the
influence of alcohol, and those at high altitudes.
Natural and Propane/LP Gas: Natural and pro-
pane/LP gases are fuel gases. Fuel gases are odor-
less.An odor-making agent are added to fuel gases.
The odor helps you detect a fuel gas leak. How-
ever, the odor added to fuel gas can fade. Fuel gas
may be present even though no odor exists.
Make certain you read and understand all warn-
ings. Keep this manual for reference. It is your
guide to safe and proper operation of this heater.
WARNING: Any change to
this heater or its controls can be
dangerous.
WARNING: Do not use a
blower insert, heat exchanger
insert or other accessory not
approved for use with this heater.
Due to high temperatures, the
appliance should be located out
of traffic and away from furni-
ture and draperies.
Do not place clothing or other
flammable material on or near
the appliance. Never place any
objects on the heater.
Surface of heater becomes very
hot when running heater. Keep
children and adults away from
hot surface to avoid burns or
clothing ignition. Heater will re-
main hot for a time after shut-
down. Allow surface to cool be-
fore touching.
Carefully supervise young chil-
dren when they are in the same
room with heater.
Make sure grill guard is in place
before running heater.
Keep the appliance area clear
and free from combustible ma-
terials, gasoline and other flam-
mable vapors and liquids.
1. This appliance is only for use with the type of
gas indicated on the rating plate. This appli-
ance is not convertible for use with other gases.
2. Do not place propane/LP supply tank(s) in-
side any structure. Locate propane/LP supply
tank(s) outdoors.
3. This heater shall not be installed in a bath-
room. 20,000 and 30,000 Btu/Hr heater mod-
els shall not be installed in a bedroom.
4. If you smell gas
• shut off gas supply
• do not try to light any appliance
• do not touch any electrical switch; do not
use any phone in your building
• immediately call your gas supplier from a
neighbor’s phone. Follow the gas supplier’s
instructions
• if you cannot reach your gas supplier, call
the fire department
5. This heater needs fresh, outside air ventila-
tion to run properly. This heater has an Oxy-
gen Depletion Sensing (ODS) safety shutoff
system. The ODS shuts down the heater if not
enough fresh air is available. See Air for Com-
bustion and Ventilation, page 5.

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6. Keep all air openings in front and bottom of
heater clear and free of debris. This will in-
sure enough air for proper combustion.
7. If heater shuts off, do not relight until you pro-
vide fresh, outside air. If heater keeps shut-
ting off, have it serviced.
8. Do not run heater
• where flammable liquids or vapors are used
or stored
• under dusty conditions
9. Before using furniture polish, wax, carpet
cleaner, or similar products, turn heater off. If
heated, the vapors from these products may
create a white powder residue within burner
box or on adjacent walls or furniture.
10. Do not use heater if any part has been under
water. Immediately call a qualified service
technician to inspect the room heater and to
replace any part of the control system and any
gas control which has been under water.
11. Turn off and let cool before servicing. Only a
qualified service person should service and
repair heater.
12. Operating heater above elevations of 4,500
feet could cause pilot outage.
13. To prevent performance problems, do not use
propane/LP fuel tank of less than 100 lbs.
capacity.
14. Provide adequate clearances around air
openings.
LOCAL CODES
Install and use heater with care. Follow all local
codes. In the absence of local codes, use the latest
edition of National Fuel Gas Code, ANSI Z223.1/
NFPA 54*.
*Available from:
American National Standards Institute, Inc.
1430 Broadway
New York, NY 10018
National Fire Protection Association, Inc.
Batterymarch Park
Quincy, MA 02269
SAFETY INFORMATION
Continued
UNPACKING
1. Remove heater from carton.
2. Remove all protective packaging applied to
heater for shipment.
3. Check heater for any shipping damage. If
heater is damaged, promptly inform dealer
where you bought heater.
PRODUCT FEATURES
SAFETY DEVICE
This heater has a pilot with an Oxygen Depletion
Sensing (ODS) safety shutoff system. The ODS/
pilot is a required feature for vent-free room heat-
ers. The ODS/pilot shuts off the heater if there is
not enough fresh air.
PIEZO IGNITION SYSTEM
This heater has a piezo ignitor. This system re-
quires no matches, batteries, or other sources to
light heater.
THERMOSTATIC HEAT CONTROL
Thermostat models have a thermostat sensing bulb
and a control valve. This results in the greatest
heater comfort. This can also result in lower gas
bills.
PRODUCT
IDENTIFICATION
Figure 1 - Vent-Free Gas Heater
Ignitor Button
Control Knob
Heater
Cabinet
Front
Panel
Glass
Panel
Grill Guard

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113680-01A 5
AIR FOR COMBUSTION
AND VENTILATION
WARNING: This heater shall
not be installed in a confined
space or unusually tight con-
struction unless provisions are
provided for adequate combus-
tion and ventilation air. Read
the following instructions to in-
sure proper fresh air for this
and other fuel-burning appli-
ances in your home.
Today’s homes are built more energy efficient than
ever. New materials, increased insulation, and new
construction methods help reduce heat loss in
homes. Home owners weather strip and caulk
around windows and doors to keep the cold air out
and the warm air in. During heating months, home
owners want their homes as airtight as possible.
While it is good to make your home energy effi-
cient, your home needs to breathe. Fresh air must
enter your home. All fuel-burning appliances need
fresh air for proper combustion and ventilation.
Exhaust fans, fireplaces, clothes dryers, and fuel
burning appliances draw air from the house to
operate. You must provide adequate fresh air for
these appliances. This will insure proper venting
of vented fuel-burning appliances.
PROVIDING ADEQUATE
VENTILATION
The following are excerpts from National Fuel
Gas Code, ANSI Z223.1/NFPA 54, Section 5.3, Air
for Combustion and Ventilation.
All spaces in homes fall into one of the three fol-
lowing ventilation classifications:
1. Unusually Tight Construction
2. Unconfined Space
3. Confined Space
The information on pages 5 through 7 will help you
classify your space and provide adequate ventilation.
Unusually Tight Construction
The air that leaks around doors and win-
dows may provide enough fresh air for
combustion and ventilation. However, in
buildings of unusually tight construction,
you must provide additional fresh air.
Unusually tight construction is defined as
construction where:
a. walls and ceilings exposed to the out-
side atmosphere have a continuous
water vapor retarder with a rating of
one perm (6x10-11 kg per pa-sec-m2)
or less with openings gasketed or
sealed and
b. weather stripping has been added on
openable windows and doors and
c. caulking or sealants are applied to ar-
eas such as joints around window and
door frames, between sole plates and
floors, between wall-ceiling joints, be-
tween wall panels, at penetrations for
plumbing, electrical, and gas lines, and
at other openings.
If your home meets all of the three criteria
above, you must provide additional fresh
air. See Ventilation Air From Outdoors ,
page 7.
If your home does not meet all of the three
criteria above, proceed to Determining
Fresh-Air Flow For Heater Location , page 6.
Confined and Unconfined Space
The National Fuel Gas Code, ANSI Z223.1/NFPA
54 defines a confined space as a space whose vol-
ume is less than 50 cubic feet per 1,000 Btu per
hour (4.8 m3per kw) of the aggregate input rating
of all appliances installed in that space and an un-
confined space as a space whose volume is not
less than 50 cubic feet per 1,000 Btu per hour (4.8
m3per kw) of the aggregate input rating of all ap-
pliances installed in that space. Rooms communi-
cating directly with the space in which the appli-
ances are installed*, through openings not fur-
nished with doors, are considered a part of the
unconfined space.
*Adjoining rooms are communicating only if there
are doorless passageways or ventilation grills be-
tween them.

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AIR FOR COMBUSTION
AND VENTILATION
Continued
DETERMINING FRESH-AIR FLOW
FOR HEATER LOCATION
Determining if You Have a Confined or
Unconfined Space
Use this work sheet to determine if you have a con-
fined or unconfined space.
Space: Includes the room in which you will install
heater plus any adjoining rooms with doorless pas-
sageways or ventilation grills between the rooms.
1. Determine the volume of the space (length x
width x height).
Length x Width x Height =__________cu. ft.
(volume of space)
Example: Space size 20 ft. (length) x 16 ft.
(width) x 8 ft. (ceiling height) = 2560 cu. ft. (vol-
ume of space)
If additional ventilation to adjoining room is sup-
plied with grills or openings, add the volume of
these rooms to the total volume of the space.
2. Multiply the space volume by 20 to determine
the maximum Btu/Hr the space can support.
_______ (volume of space) x 20 = (Maximum
Btu/Hr the space can support)
Example: 2560 cu. ft. (volume of space) x 20 =
51,200 (maximum Btu/Hr the space can support)
3. Add the Btu/Hr of all fuel burning appliances in
the space.
Vent-free heater ______________ Btu/Hr
Gas water heater* ______________ Btu/Hr
Gas furnace ______________ Btu/Hr
Vented gas heater ______________ Btu/Hr
Gas fireplace logs ______________ Btu/Hr
Other gas appliances* + __________ Btu/Hr
Total = __________ Btu/Hr
* Do not include direct-vent gas appliances. Di-
rect-vent draws combustion air from the outdoors
and vents to the outdoors.
Example:
Gas water heater ______________ Btu/Hr
Vent-free heater + _____________ Btu/Hr
Total = _____________ Btu/Hr
40,000
20,000
60,000
4. Compare the maximum Btu/Hr the space can
support with the actual amount of Btu/Hr used.
______________ Btu/Hr (maximum the space
can support)
______________ Btu/Hr (actual amount of
Btu/Hr used)
Example:
51,200 Btu/Hr (maximum the space can support)
60,000 Btu/Hr (actual amount of Btu/Hr used)
The space in the above example is a confined space
because the actual Btu/Hr used is more than the maxi-
mum Btu/Hr the space can support. You must pro-
vide additional fresh air. Your options are as follows:
A. Rework worksheet, adding the space of an ad-
joining room. If the extra space provides an un-
confined space, remove door to adjoining room
or add ventilation grills between rooms. See Ven-
tilation Air From Inside Building, page 7.
B. Vent room directly to the outdoors. See Ventila-
tion Air From Outdoors, page 7.
C. Install a lower Btu/Hr heater, if lower Btu/Hr size
makes room unconfined.
If the actual Btu/Hr used is less than the maximum Btu/
Hr the space can support, the space is an unconfined
space. You will need no additional fresh air ventilation.
WARNING: If the area in
which the heater may be oper-
ated is smaller than that defined
as an unconfined space or if the
building is of unusually tight
construction, provide adequate
combustion and ventilation air
by one of the methods described
in the National Fuel Gas Code,
ANSI Z223.1/NFPA 54 Section
5.3 or applicable local codes .

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113680-01A 7
Figure 3 - Ventilation Air from Outdoors
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining un-
confined space. When ventilating to an adjoining
unconfined space, you must provide two perma-
nent openings: one within 12" of the ceiling and
one within 12" of the floor on the wall connecting
the two spaces (see options 1 and 2, Figure 2).
You can also remove door into adjoining room (see
option 3, Figure 2). Follow the National Fuel Gas
Code, ANSI Z223.1/NFPA 54, Section 5.3, Air for
Combustion and Ventilation for required size of
ventilation grills or ducts.
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation grills
or ducts. You must provide two permanent open-
ings: one within 12" of the ceiling and one within
12" of the floor. Connect these items directly to
the outdoors or spaces open to the outdoors. These
spaces include attics and crawl spaces. Follow the
National Fuel Gas Code, ANSI Z223.1/NFPA 54,
Section 5.3, Air for Combustion and Ventilation
for required size of ventilation grills or ducts.
IMPORTANT: Do not provide openings for inlet
or outlet air into attic if attic has a thermostat-con-
trolled power vent. Heated air entering the attic
will activate the power vent.
Figure 2 - Ventilation Air from Inside
Building
Or
Remove
Door into
Adjoining
Room,
Option 3
Ventilation Grills
Into Adjoining Room,
Option 2
12"
12"
Ventilation
Grills
into Adjoining
Room,
Option 1
Outlet
Air
Ventilated
Attic
Outlet
A
ir
Inlet
Air
Inlet Air Ventilated
Crawl Space
To
Crawl
Space
To Attic
AIR FOR COMBUSTION
AND VENTILATION
Continued
INSTALLATION
NOTICE: This heater is intended
for use as supplemental heat.
Use this heater along with your
primary heating system. Do not
install this heater as your pri-
mary heat source. If you have a
central heating system, you may
run system’s circulating blower
while using heater. This will help
circulate the heat throughout the
house. In the event of a power
outage, you can use this heater
as your primary heat source.
WARNING: A qualified ser-
vice person must install heater.
Follow all local codes.
CHECK GAS TYPE
Use only the correct type of gas (natural or pro-
pane/LP). If your gas supply is not the correct gas
type, do not install heater. Call dealer where you
bought heater for proper type heater.
WARNING: This appliance
is equipped for (natural or pro-
pane/LP) gas. Field conversion
is not permitted.

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8
INSTALLATION ITEMS
Before installing heater, make sure you have the
items listed below.
• for propane/LP gas, external regulator (supplied
by installer)
• piping (check local codes)
• sealant (resistant to propane/LP gas)
• equipment shutoff valve *
• ground joint union
• sediment trap
• tee joint
• pipe wrench
• for natural gas, test gauge connection*
* A CSAdesign-certified equipment shutoff valve
with 1/8" NPT tap is an acceptable alternative to
test gauge connection. The optional CSA design-
certified equipment shutoff valve can be purchased
from your dealer. See Accessories, page 30.
LOCATING HEATER
This heater is designed to be mounted on a wall.
WARNING: Maintain the
minimum clearances shown in
Figure 4. If you can, provide
greater clearances from floor,
ceiling, and joining wall.
You can locate heater on floor, away from a wall.
An optional floor mounting stand is needed. Pur-
chase the floor mounting stand from your dealer.
See Accessories, page 30.
WARNING: Never install the
heater
• in a bathroom
• 20,000 or 30,000 Btu in a bed-
room
• in a recreational vehicle
• where curtains, furniture,
clothing, or other flammable
objects are less than 36 inches
from the front, top, or sides of
the heater
• as a fireplace insert
• in high traffic areas
• in windy or drafty areas
Figure 4 - Mounting Clearances As
Viewed From Front of Heater
INSTALLATION
Continued
CAUTION: This heater cre-
ates warm air currents. These
currents move heat to wall sur-
faces next to heater. Installing
heater next to vinyl or cloth wall
coverings or operating heater
where impurities (such as, but
not limited to, tobacco smoke,
aromatic candles, cleaning flu-
ids, oil or kerosene lamps, etc.)
in the air exist, may discolor
walls or cause odors.
IMPORTANT: Vent-free heaters add moisture to the
air. Although this is beneficial, installing heater in
rooms without enough ventilation air may cause
mildew to form from too much moisture. See Air for
Combustion and Ventilation, page 5. If high humid-
ity is experienced, a dehumidifier may be used to
help lower the water vapor content in the air.
CAUTION: If you install the
heater in a home garage
• heater pilot and burner must
be at least 18 inches above
floor
• locate heater where moving
vehicle will not hit it
For convenience and efficiency, install heater
• where there is easy access for operation, inspec-
tion, and service
• in coldest part of room
An optional fan kit is available from your dealer.
See Accessories, page 30. If planning to use fan,
locate heater near an electrical outlet.
Minimum
From
Sides Of
Heater
36"
2"
FLOOR
CEILING
Minimum
Minimum To
Top Surface
Of Carpeting
,
Tile Or Other
Combustible
Material
Left
Side
Right
Side
6"

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113680-01A 9
INSTALLATION
Continued
THERMOSTAT SENSING BULB
(Thermostat Models Only)
The thermostat sensing bulb has been placed be-
low the heater.
1. Place clamp on thermostat sensing bulb as
shown in Figure 5. Clamp is provided in hard-
ware package.
2. Snap clamp into upper mounting hole as shown
in Figure 5. Mounting hole is located on lower
left edge on back of heater. Make sure the ther-
mostat sensing bulb is pointing up.
Figure 5 - Attaching Thermostat Sensing
Bulb
INSTALLING HEATER TO WALL
Mounting Bracket
Locate mounting bracket in heater carton. Remove
mounting bracket from heater carton.
Figure 7 - Removing Front Panel Of
Heater
Clamp
Thermostat
Sensing Bulb
Figure 6 - Mounting Bracket
Removing Front Panel Of Heater
1. Remove the two screws, one on each side of
front panel.
2. Pull bottom of front panel up and forward, then
out.
3. Remove any remaining packaging materials.
Methods For Attaching Mounting
Bracket To Wall
Only use last hole on each end of mounting bracket
to attach bracket to wall. These two holes centers are
13 inches apart for the 20,000 and 30,000 Btu/Hr
units and 9 inches apart for the 10,000 Bru/Hr units.
Attach mounting bracket to wall in one of two ways:
1. Attaching to wall stud
2. Attaching to wall anchor
Attaching to Wall Stud: This method provides the
strongest hold. Insert mounting screws through
mounting bracket and into wall studs.
Attaching toWall Anchor: This method allows you
to attach mounting bracket to hollow walls (wall
areas between studs) or to solid walls (concrete or
masonry).
Decide which method better suits your needs. Ei-
ther method will provide a secure hold for the
mounting bracket.
Marking Screw Locations
1. Tape mounting bracket to wall where heater
will be located. Make sure mounting bracket
is level.
WARNING: Maintain mini-
mum clearances shown in Fig-
ure 8, page 10. If you can, provide
greater clearances from floor
and joining wall.

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10
18
3
/
4
"
Min.
12
1
/
2
"
Min.
13"
18
3
/
4
"
Min.
9"
Min.
Adjoining Wall
13"
Adjoining Wall
Only Insert Mounting
Screws Through Last
Hole On Each End
Only Insert Mounting
Screws Through Last
Hole On Each End
Floor
Floor
9"
20
1
/
2
"
Min.
7
1
/
2
"
Min.
Adjoining Wall
Only Insert Mounting
Screws Through Last
Hole On Each End
Floor
INSTALLATION
Continued
30,000 Btu/Hr Model
20,000 Btu/Hr Model
Figure 8 - Mounting Bracket Clearances
Attaching Mounting Bracket To Wall
Note: Wall anchors, mounting screws, and spac-
ers are in hardware package. The hardware pack-
age is provided with heater.
Attaching To Wall Stud Method
For attaching mounting bracket to wall studs
1. Drill holes at marked locations using 9/64"
drill bit.
2. Place mounting bracket onto wall. Line up last
hole on each end of bracket with holes drilled
in wall.
3. Insert mounting screws through bracket and
into wall studs.
4. Tighten screws until mounting bracket is
firmly fastened to wall studs.
Attaching To Wall Anchor Method
For attaching mounting bracket to hollow walls
(wall areas between studs) or solid walls (concrete
or masonry)
1. Drill holes at marked locations using 5/16"
drill bit. For solid walls (concrete or masonry),
drill at least 1" deep.
2. Fold wall anchor as shown in Figure 9.
3. Insert wall anchor (wings first) into hole. Tap
anchor flush to wall.
4. For thin walls (1/2" or less), insert red key
into wall anchor. Push red key to “pop” open
anchor wings.
IMPORTANT: Do not hammer key!
For thick walls (over 1/2" thick) or solid walls,
do not pop open wings.
5. Place mounting bracket onto wall. Line up last
hole on each end of bracket with wall anchors.
6. Insert mounting screws through bracket and
into wall anchors.
7. Tighten screws until mounting bracket is
firmly fastened to wall.
Figure 9 - Folding
Anchor
Figure 10 - Popping
Open Anchor Wings
For Thin Walls
2. Mark screw locations on wall (see Figure 8).
Note: Only mark last hole on each end of
mounting bracket. Insert mounting screws
through these holes only.
3. Remove tape and mounting bracket from wall.
10,000 Btu/Hr Model