Desa LSL18NT Original instructions

18,000 BTU THERMOSTAT MODELS
LSL18NT, LSL18PT, SL18NT, SL18PT, VSL18NT AND VSL18PT
UNVENTED (VENT-FREE) BLUE FLAME GAS HEATER
SAFETY INFORMATION AND INSTALLATION MANUAL
For more information, visit www.desatech.com
WARNING: If the information in this manual is not fol-
lowed exactly, a re or explosion may result causing
property damage, personal injury or loss of life.
— Do not store or use gasoline or other ammable
vapors and liquids in the vicinity of this or any other
appliance.
— WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any
phone in your building.
• Immediately call your gas supplier from a neighbor’s
phone. Follow the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the re
department.
— Installation and service must be performed by a quali-
ed installer, service agency or the gas supplier.
INSTALLER: Leave this manual with the appliance.
CONSUMER: Retain this manual for future reference.

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SAFETY INFORMATION
WARNING: Improper in-
stallation, adjustment, al-
teration,serviceormainte-
nance can cause injury or
property damage. Refer to
this manual for correct in-
stallation and operational
procedures. For assis-
tance or additional infor-
mation consult a qualied
installer, service agency or
the gas supplier.
WARNING: This is an
unvented gas-red heater.
It uses air (oxygen) from the
room in which it is installed.
Provisions for adequate
combustion and ventila-
tion air must be provided.
RefertoAir for Combustion
and Ventilation section on
page 5 of this manual.
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.
This appliance may be in-
stalled in an aftermarket,*
permanently located,
manufactured (mobile)
home, where not prohib-
ited by local codes.
* Aftermarket: Completion of sale, not for
purpose of resale, from the manufacturer
WARNING: This product con-
tains and/or generates chemicals
known to the State of California
to cause cancer or birth defects
or other reproductive harm.
IMPORTANT: Read this owner’s
manual carefully and completely
before trying to assemble,
operate or service this heater.
Improper use of this heater can
cause serious injury or death
from burns, fire, explosion,
electrical shock and carbon
monoxide poisoning.
DANGER: Carbon monoxide
poisoning may lead to death!
Carbon Monoxide Poisoning: Early signs of carbon
monoxide poisoning resemble the u, with head-
aches, 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 inu-
ence of alcohol and those at high altitudes.
TABLE OF CONTENTS
Safety Information ............................................... 2
Local Codes......................................................... 4
Product Identication........................................... 4
Unpacking............................................................ 4
Product Features................................................. 4
Air For Combustion And Ventilation..................... 5
Installation ........................................................... 7
Operating Heater............................................... 14
Inspecting Heater ............................................. 16
Cleaning and Maintenance................................ 17
Troubleshooting................................................. 18
Specications .................................................... 22
Wiring Diagrams................................................ 22
Accessories ....................................................... 23
Technical Service............................................... 23
Service Publications .......................................... 23
Replacement Parts............................................ 23
Service Hints ..................................................... 23
Illustrated Parts Breakdown and Parts List........ 24
Parts Centrals.................................................... 26
Warranty Information ......................................... 28

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116292-01E 3
Natural and Propane/LP Gas: Natural and
propane/LP gases are fuel gases. Fuel gases are
odorless. An odor-making agent are added to fuel
gases. The odor helps you detect a fuel gas leak.
However, 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 ap-
proved for use with this heater.
Due to high temperatures, the
appliance should be located out
of trafc and away from furniture
and draperies.
Do not place clothing or other
ammable 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
remain hot for a time after shut-
down. Allow surface to cool
before 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 am-
mable vapors and liquids.
1. 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.
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 bathroom
or 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 re department
5. This heater needs fresh, outside air ventilation
to run properly. This heater has an Oxygen
Depletion Sensing (ODS) safety shutoff
system. The ODS shuts down the heater if
not enough fresh air is available. See Air for
Combustion and Ventilation, page 5.
6. Keep all air openings in front and bottom of
heater clear and free of debris. This will insure
enough air for proper combustion.
7. If heater shuts off, do not relight until you
provide fresh, outside air. If heater keeps
shutting off, have it serviced.
8. Do not run heater
• where ammable 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 qualied 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 qualied service person should service and
repair heater.
SAFETY INFORMATION
Continued

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12. Operating heater above elevations of 4,500
feet (1,371 m) could cause pilot outage.
13. To prevent performance problems, do not use
propane/LP fuel tank of less than 100 lbs. (45 kg)
capacity.
14. Provide adequate clearances around air
openings.
LOCAL CODES
Install and use heater with care. Follow all lo-
cal 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
State of Massachusetts: The installation must
be made by a licensed plumber or gas tter in
the Commonwealth of Massachusetts.
Sellers of unvented propane or natural gas-red
supplemental room heaters shall provide to
each purchaser a copy of 527 CMR 30 upon
sale of the unit.
Vent-free gas products are prohibited for bed-
room and bathroom installation in the Com-
monwealth of Massachusetts.
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.
SAFETY INFORMATION
Continued
Figure 1 - Vent-Free Gas Heater
Ignitor
Control Knob
(under door)
Heater Cabinet
Glass Panel
PRODUCT
IDENTIFICATION
PRODUCT FEATURES
SAFETY DEVICE
This heater has a pilot with an Oxygen Deple-
tion Sensing (ODS) safety shutoff system. The
ODS/pilot is a required feature for vent-free room
heaters. The ODS/pilot shuts off the heater if there
is not enough fresh air.
IGNITION SYSTEM
This heater has either a piezo ignitor or electronic
ignitor to light heater fuel supply.
THERMOSTATIC HEAT CONTROL
Thermostat models have a thermostat sensing
bulb and a control valve. This results in the great-
est heater comfort. This can also result in lower
gas bills.

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116292-01E 5
AIR FOR COMBUSTION
AND VENTILATION
WARNING: This heater shall
not be installed in a conned
space or unusually tight con-
struction unless provisions are
provided for adequate combus-
tion and ventilation air. Read the
following instructions to insure
proper fresh air for this and
other fuel-burning appliances
in your home.
Today’s homes are built more energy efcient
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 ef-
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, replaces, clothes dryers and fuel
burning appliances draw air from the house to
operate. You must provide adequate fresh air for
these appliances. This will insure proper venting
of vented fuel-burning appliances.
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 classications:
1. Unusually Tight Construction
2. Unconned Space
3. Conned 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 windows
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 dened as con-
struction where:
a. walls and ceilings exposed to the outside
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 areas such
as joints around window and door frames,
between sole plates and floors, between
wall-ceiling joints, between 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 Ventila-
tion 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.
Conned and Unconned Space
The National Fuel Gas Code, ANSI Z223.1/NFPA
54 denes a conned space as a space whose
volume is less than 50 cubic feet per 1,000 Btu
per hour (4.8 m3 per kw) of the aggregate input
rating of all appliances installed in that space and
an unconned space as a space whose volume is
not less than 50 cubic feet per 1,000 Btu per hour
(4.8 m3 per kw) of the aggregate input rating of
all appliances installed in that space. Rooms com-
municating directly with the space in which the
appliances are installed*, through openings not
furnished with doors, are considered a part of the
unconned space.
* Adjoining rooms are communicating only if
there are doorless passageways or ventilation grills
between them.

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AIR FOR COMBUSTION
AND VENTILATION
Continued
DETERMINING FRESH-AIR FLOW
FOR HEATER LOCATION
Determining if You Have a Conned or
Unconned Space
Use this work sheet to determine if you have a con-
ned or unconned 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. (6.1 m) (length) x 16
ft. (4.88 m)(width) x 8 ft. (2.44 m) (ceiling height)
= 2560 cu. ft. (72.49 m3) (volume of space)
If additional ventilation to adjoining room is
supplied 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. (72.49 m3) (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 replace 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
18,000
58,000
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)
58,000 Btu/Hr (actual amount of
Btu/Hr used)
The space in the above example is a conned space
because the actual Btu/Hr used is more than the maxi-
mum Btu/Hr the space can support. You must provide
additional fresh air. Your options are as follows:
A. Rework worksheet, adding the space of an adjoin-
ing room. If the extra space provides an unconned
space, remove door to adjoining room or add
ventilation grills between rooms. See Ventilation
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 unconned.
If the actual Btu/Hr used is less than the maximum
Btu/Hr the space can support, the space is an uncon-
ned space. You will need no additional fresh air
ventilation.
WARNING: If the area in
which the heater may be oper-
ated is smaller than that dened
as an unconned 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/NFPA54 Section 5.3
or applicable local codes.

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116292-01E 7
Figure 3 - Ventilation Air from Outdoors
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining un-
conned space. When ventilating to an adjoining
unconned space, you must provide two perma-
nent openings: one within 12" (30.4 cm) of the
ceiling and one within 12" (30.4 cm) of the oor
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.
Figure 2 - Ventilation Air from Inside
Building
Or
Remove
Door into
Adjoining
Room,
Option 3
Ventilation Grills
Into Adjoining Room,
Option 2
12"
(30.4 cm)
Ventilation
Grills
into Adjoining
Room,
Option 1
12"
(30.4 cm)
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 qualied 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.
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.
WARNING: This appliance
is equipped for natural or pro-
pane/LP gas. Field conversion
is not permitted.
Ventilation Air From Outdoors
Provide extra fresh air by using ventilation grills
or ducts. You must provide two permanent open-
ings: one within 12" (30.4 cm) of the ceiling and
one within 12" (30.4 cm) of the oor. 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-
controlled power vent. Heated air entering the attic
will activate the power vent.

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Figure 5 - Installing Glass Panel
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 CSA design-certied equipment shutoff valve
with 1/8" NPT tap is an acceptable alternative to
test gauge connection. The optional CSA design-
certied equipment shutoff valve can be purchased
from your dealer. See Accessories, page 23.
REMOVING FRONT PANEL OF
HEATER
1. Remove and discard shipping screw from back
panel of heater (see Figure 4).
2. Remove the four screws, two on each side of
front panel. Set aside.
3. Pull front panel forward from the bottom, then
lift panel up to remove. If ignitor is installed,
pull front panel forward only 2" to 3" (5 to 7.6
cm) away from back panel. Reach into lower
right side of heater and disconnect ignitor
wire. Set front panel aside.
4. Remove any remaining packaging materials.
INSTALLATION
Continued
Installing Glass Panel
Items needed from hardware packet:
1 - Bushing
4 - Black spacers
4 - Retaining clips
4 - 1.5" long screws
4 - Screw covers
1. Locate hardware packet and dark acrylic glass.
2. Peel protective coating from both sides of glass.
3. Snap bushing into center front hole of front
panel (see Figure 5).
4. Turn front panel face down. Gently press onto
a hard surface to snap bushing into hole. Turn
panel back over, face up.
5. Place spacers over 4 holes on front panel as
shown in Figure 5.
6. Position glass on top of spacers, aligning holes.
Note: If glass gets scratched or marred from
normal use, it may be reversed on heater.
7. Place 4 retaining clips on glass over holes.
8. Install screws in each hole, but do not tighten
at this time.
9. Square glass up with top front surface of front
panel. Tighten screws.
10. Snap screw covers over retaining clips.
Glass Panel
Screw Cover
Front
Panel
Spacer
Screw
Retainer Clip
Figure 4 - Removing Front Panel Of Heater
Screw
Front Panel Ignitor
Wire
Bushing
Shipping
Screw
Location
INSTALLING IGNITOR
1. Locate ignitor in hardware bag. Determine if
your heater is equipped with piezo ignitor or an
electronic ignitor (see Figures 6 and 7, page 9.
2. For Piezo Ignitor, snap ignitor into hole
located on right side of heater as shown in
Figure 6, page 9.
3. For Electronic Ignitor, install ignitor through
hole located on right side of heater as shown
in Figure 7, page 9.

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116292-01E 9
LOCATING HEATER
This heater is designed to be mounted on a wall.
WARNING: Maintain the
minimum clearances shown
in Figure 8. If you can, provide
greater clearances from oor,
ceiling and joining wall.
WARNING: Never install the
heater
• in a bathroom or a bedroom
• in a recreational vehicle
• where curtains, furniture, cloth-
ing or other ammable objects
are less than 36" (92 cm) from the
front, top or sides of the heater
• as a replace insert
• in high trafc areas
• in windy or drafty areas
INSTALLATION
Continued
Figure 8 - Mounting Clearances As
Viewed From Front of Heater
Minimum
From
Sides Of
Heater
36"
(91.4 cm)
Minimum
2" (5.1 cm)
FLOOR
CEILING
Minimum To
Top Surface
Of Carpeting,
Tile Or Other
Combustible
Material
Left
Side
Right
Side
6" (15.2 cm)
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 u-
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 benecial, 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 hu-
midity is experienced, a dehumidier 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" (45.7 cm) above
oor
• locate heater where moving
vehicle will not hit it
For convenience and efciency, install heater
• where there is easy access for operation, inspec-
tion and service
• in coldest part of room
Locate heater near a 120V 60Hz electrical outlet
(normal household voltage).
4. For both ignitors, install ignitor wire only
when replacing front panel of heater after
connecting to gas supply and checking gas
connections (see pages 11 through 13). With
bottom of front panel only 2" to 3" (5 to 7.6
cm) away from back panel, reach into lower
right corner of heater to connect ignitor wire
to ignitor terminal (see Figure 4, page 8).
Side View
Figure 6 - Installing Piezo Ignitor
Piezo
Ignitor
Right Side
of Heater
Figure 7 - Installing Electronic Ignitor
Right Side
of Heater
Electronic Ignitor
Battery

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INSTALLATION
Continued
Figure 11 - Folding Anchor
Figure 12 - Popping Open Anchor Wings
For Thin Walls
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
rmly 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 11.
3. Insert wall anchor (wings rst) into hole. Tap
anchor ush to wall.
4. For thin walls [1/2" (1.3 cm) 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" (1.3 cm) 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.
13" (33 cm)
11"
(27.9 cm)
Min.
12"
(30.4
cm)
Min.
Adjoining Wall
Only Insert Mounting
Screws Through Last
Hole On Each End
Floor
Figure 10 - Mounting Bracket Clearances
INSTALLING HEATER TO WALL
Mounting Bracket
Locate mounting bracket that has been taped to
back panel of heater for shipping. Remove mount-
ing bracket from back panel of heater.
Figure 9 - Mounting Bracket
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" (33 cm) apart. 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 to Wall 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.
Either 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 Figure
10. If you can, provide greater
clearances from oor and join-
ing wall.
2. Mark screw locations on wall (see Figure 10).
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.
Attaching Mounting Bracket To Wall
Note: Wall anchors, mounting screws and spacers
are in hardware package. The hardware package
is provided with heater.

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116292-01E 11
Side View
Front View
Figure 14 - Installing Bottom Mounting
Screws
Wall
Spacer
Heater
Installing Bottom Mounting Screws
1. Locate two bottom mounting holes. These
holes are near bottom on back panel of heater
(see Figure 14).
2. Mark screw locations on wall.
3. Remove heater from mounting bracket.
4. If installing bottom mounting screws into
hollow or solid wall, install wall anchors.
Follow steps 1 through 4 under Attaching To
Wall Anchor Method, page 10.
If installing bottom mounting screw into wall
stud, drill holes at marked locations using
9/64" drill bit.
5. Replace heater onto mounting bracket.
6. Place spacers between bottom mounting holes
and wall anchor or drilled hole.
7. Hold spacer in place with one hand. With other
hand, insert mounting screw through bottom
mounting hole and spacer. Place tip of screw
in opening of wall anchor or drilled hole.
8. Tighten both screws until heater is rmly
secured to wall. Do not over tighten.
Note: Do not replace front panel at this time.
Replace front panel after making gas connec-
tions and checking for leaks.
INSTALLATION
Continued
Figure 13 - Mounting Heater Onto
Mounting Bracket
Mounting Bracket
(attached to wall)
Horizontal Slots
Stand-Out Tab
CONNECTING TO GAS SUPPLY
WARNING: This appliance
requires a 3/8" NPT (National
Pipe Thread) inlet connection to
the pressure regulator.
WARNING: A qualied service
person must connect heater to gas
supply. Follow all local codes.
WARNING: For natural
gas, never connect heater to
private (non-utility) gas wells.
This gas is commonly known
as wellhead gas.
IMPORTANT: For natural gas, check gas line
pressure before connecting heater to gas line. Gas
line pressure must be no greater than 10.5" of wa-
ter. If gas line pressure is higher, heater regulator
damage could occur.
CAUTION: For propane/LP
gas, never connect heater di-
rectly to the propane/LP supply.
This heater requires an external
regulator (not supplied). Install
the external regulator between the
heater and propane/LP supply.
6. Insert mounting screws through bracket and
into wall anchors.
7. Tighten screws until mounting bracket is
rmly fastened to wall.
Placing Heater On Mounting Bracket
1. Locate two horizontal slots on back panel of
heater.
2. Place heater onto mounting bracket. Slide
horizontal slots onto stand-out tabs on mount-
ing bracket.

www.desatech.com 116292-01E12
Tee Joint
Reducer
Bushing to
1/8" NPT
1/8" NPT
Plug Tap
Test Gauge Connection*
Heater
Cabinet
Equipment
Shutoff
Valve *
3"
(7.6 cm)
Min. Natural Gas
From Gas Meter (4" W.C.
to 10.5" W.C. Pressure)
Propane/LP
From External Regulator
(11" W.C. to 14" W.C.
Pressure)
Tee Joint
Pipe
Nipple
Cap
Sediment Trap
Figure 16 - Gas Connection
INSTALLATION
Continued
Pressure
Regulator
* A CSA design-certied equipment shutoff valve
with 1/8" NPT tap is an acceptable alternative to
test gauge connection. Purchase the optional CSA
design-certied equipment shutoff valve from your
dealer. See Accessories, page 23.
For propane/LP gas, the installer must supply an
external regulator. The external regulator will
reduce incoming gas pressure. You must reduce
incoming gas pressure to between 11 and 14 inches
of water. If you do not reduce incoming gas pres-
sure, heater regulator damage could occur. Install
the external regulator with the vent pointing down
as shown in Figure 15. Pointing the vent down
protects it from freezing rain or sleet.
CAUTION: Use only new,
black iron or steel pipe. Inter-
nally-tinned copper tubing may
be used in certain areas. Check
your local codes. Use pipe of
large enough diameter to allow
proper gas volume to heater. If
pipe is too small, undue loss of
volume will occur.
Typical Inlet Pipe Diameter - 3/8" (9.5 mm) or
greater
Installation must include equipment shutoff valve,
union and plugged 1/8" NPT tap. Locate NPT tap
within reach for test gauge hook up. NPT tap must
be upstream from heater (see Figure 16).
IMPORTANT: Install an equipment shutoff valve
in an accessible location. The equipment shutoff
valve is for turning on or shutting off the gas to
the appliance.
Apply pipe joint sealant lightly to male NPT
threads. This will prevent excess sealant from
going into pipe. Excess sealant in pipe could result
in clogged heater valves.
WARNING: Use pipe joint
sealant that is resistant to liquid
petroleum (LP) gas.
Install sediment trap in supply line as shown in
Figure 16. Locate sediment trap where it is within
reach for cleaning. Locate sediment trap where
trapped matter is not likely to freeze. A sediment
trap traps moisture and contaminants. This keeps
them from going into heater controls. If sediment
trap is not installed or is installed wrong, heater
may not run properly.
IMPORTANT: Hold the pressure regulator with
wrench when connecting it to gas piping and/or
ttings. Do not over tighten pipe connection to
regulator. The regulator body could be damaged.
3/8" NPT
Pipe Nipple
Figure 15 - External Regulator With Vent
Pointing Down
External
Regulator
Propane/LP
Supply Tank
Vent
Pointing
Down
CHECKING GAS CONNECTIONS
WARNING: Test all gas piping
and connections, internal and
external to unit, for leaks after
installing or servicing. Correct
all leaks at once.

www.desatech.com
116292-01E 13
WARNING: Never use an open
ame to check for a leak. Apply a
noncorrosive leak detection uid
to all joints. Bubbles forming show
a leak. Correct all leaks at once.
CAUTION: For propane/LP
gas, make sure external regula-
tor has been installed between
propane/LP supply and heater.
See guidelines under Connect-
ing to Gas Supply, page 11.
PRESSURE TESTING GAS SUPPLY
PIPING SYSTEM
Test Pressures In Excess Of 1/2 PSIG
(3.5 kPa)
1. Disconnect appliance with its appliance main
gas valve (control valve) and equipment
shutoff valve from gas supply piping system.
Pressures in excess of 1/2 psig will damage
heater regulator.
2. Cap off open end of gas pipe where equipment
shutoff valve was connected.
3. Pressurize supply piping system by either
opening propane/LP supply tank valve for
propane/LP gas or opening main gas valve
located on or near gas meter for natural gas
or using compressed air.
4. Check all joints of gas supply piping system.
Apply a noncorrosive leak detection uid to
all joints. Bubbles forming show a leak.
5. Correct all leaks at once.
6. Reconnect heater and equipment shutoff
valve to gas supply. Check reconnected t-
tings for leaks.
Test Pressures Equal To or Less Than 1/2
PSIG (3.5 kPa)
1. Close equipment shutoff valve (see Figure 17).
2. Pressurize supply piping system by either
opening propane/LP supply tank valve for
propane/LP gas or opening main gas valve
located on or near gas meter for natural gas
or using compressed air.
3. Check all joints from gas meter for natural gas
(see Figure 18) or propane/LP supply tank for
propane/LP gas, to equipment shutoff valve
(see Figure 19). Apply a noncorrosive leak
detection uid to all joints. Bubbles forming
show a leak.
4. Correct all leaks at once.
Figure 19 - Checking Gas Joints for
Propane/LP Gas
Propane/LP
Supply Tank
Figure 18 - Checking Gas Joints for
Natural Gas
Equipment
Shutoff Valve
Gas
Meter
INSTALLATION
Continued
PRESSURE TESTING HEATER GAS
CONNECTIONS
1. Open equipment shutoff valve (see Figure 17).
2. For natural gas open main gas valve located
on or near gas meter. For propane/LP gas open
propane/LP supply tank valve.
3. Make sure control knob of heater is in the OFF
position.
4. Check all joints from equipment shutoff valve
to thermostat gas valve (see Figure 18 or 19).
Apply a noncorrosive leak detection uid to
all joints. Bubbles forming show a leak.
5. Correct all leaks at once.
6. Light heater (see Operating Heater, page 14).
Check all other internal joints for leaks.
7. Turn off heater (see To Turn Off Gas to Appli-
ance, page 15).
8. Connect ignitor wire and replace front panel.
Figure 17 - Equipment Shutoff Valve
Open
Closed
Equipment
Shutoff Valve
Equipment
Shutoff Valve

www.desatech.com 116292-01E14
OPERATING HEATER
FOR YOUR SAFETY READ
BEFORE LIGHTING
WARNING: If you do not fol-
low these instructions exactly,
a re or explosion may result
causing property damage, per-
sonal injury or loss of life.
A. This appliance has a pilot which must be
lighted by hand. When lighting the pilot,
follow these instructions exactly.
B. BEFORE LIGHTING smell all around the
appliance area for gas. Be sure to smell next
to the oor because some gas is heavier than
air and will settle on the oor.
WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electric 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 re department.
C. Use only your hand to push in or turn the
gas control knob. Never use tools. If the
knob will not push in or turn by hand,
don’t try to repair it, call a qualied service
technician. Force or attempted repair may
result in a re or explosion.
D. Do not use this appliance if any part has
been under water. Immediately call a
qualied service technician to inspect the
appliance and to replace any part of the
control system and any gas control which
has been under water.
INSTALLATION
Continued
CONNECTING TO ELECTRICAL
SUPPLY
WARNING: Fan accessory
must be grounded. Fan comes
with a three-prong, grounding
plug as shown in Figure 20. The
plug is your protection against
electrical shock. Plug it into a
standard, three-hole, grounded,
outlet. If cord needs replacing,
use only a cord with a three-
prong, grounding plug.
CAUTION: Label all wires
prior to disconnection when
servicing controls. Wiring errors
can cause improper and danger-
ous operation (see page 22).
Grounding Plug
Grounded Outlet
Figure 20 - Grounding Plug
EXTENSION CORD
Use extension cord if needed. The cord must have
a three-prong, grounding plug and a three-hole re-
ceptacle. Make sure cord is in good shape. It must
be heavy enough to carry the current needed. An
undersized cord will cause a drop in line voltage.
This will result in loss of power and overheating.
Use a No. 16 AWG cord for lengths less than 50
feet (15.24 m) .
CAUTION: Verify proper op-
eration after servicing.
Operating Fan
The blower is connected to a thermostat. When unit
heats up, the fan will operate. A few minutes after
unit cycles off or is turned off, the fan will shut
off. The fan will cycle on and off in this manner.
Note: If you have a heater with a thermostat, the
heater and fan will not turn off and on at exactly
the same time. Fan cycle times will vary with the
heat setting selected.

www.desatech.com
116292-01E 15
LIGHTING
INSTRUCTIONS
1. STOP! Read the safety information, page 14.
2. Make sure equipment shutoff valve is fully
open.
3. Turn off any electric power to the appliance
if service is to be performed.
4. Turn control knob clockwise to the
OFF position.
5. Wait ve minutes to clear out any gas. Then
smell for gas, including near the oor. If you
smell gas, STOP! Follow “B” in the safety
information, page 14. If you don’t smell gas,
go to the next step.
6. Turn control knob counterclockwise
to the PILOT position. Press in control knob
for ve (5) seconds.
7. With control knob pressed in, push down and
release ignitor button. This will light pilot. The
pilot is attached to the front of burner. Note:
You may be running this heater for the rst time
after hooking up to gas supply. If so, you may
need to press in control knob for 30 seconds or
more. This will allow air to bleed from the gas
system. If needed, keep pressing ignitor button
until pilot lights. If ignitor does not light pilot,
refer to Troubleshooting, page 18 or contact
a qualied service person or gas supplier for
repairs. Until repairs are made, light pilot with
match. To light pilot with match, see Manual
Lighting Procedure, page 16.
8. Keep control knob pressed in for 30 seconds
after lighting pilot. After 30 seconds, release
control knob.
• If control knob does not pop up when re-
leased, contact a qualied service person or
gas supplier for repairs.
Note: If pilot goes out, repeat steps 4 thru 7.
Thermostat models have a safety interlock
system. Wait one (1) minute before lighting
pilot again.
9. Turn control knob counterclockwise to
desired heating level. The main burner should
light.
WARNING: Always operate
manual control heaters at the
locked positions. Operation
between these positions may
create a possible health hazard
if used in a poorly ventilated
room. Read owner’s manual for
complete instructions.
O
F
F
P
I
L
O
T
Figure 21 - Control Knob In The OFF
Position
Piezo Ignitor
Figure 23 - Pilot (actual pilot may vary)
OPERATING HEATER
Continued
Ignitor Electrode
Pilot Burner
Thermocouple
TO TURN OFF GAS
TO APPLIANCE
Shutting Off Heater
1. Turn control knob clockwise to the
OFF position.
2. Turn off all electric power to the appliance if
service is to be performed.
Shutting Off Burner Only (pilot stays lit)
Turn control knob clockwise to the PILOT
position.
THERMOSTAT CONTROL
OPERATION
The thermostatic control used on these models
differs from standard thermostats. Standard ther-
mostats simply turn on and off the burner. The
thermostat used on this heater senses the room
temperature. The thermostat adjusts the amount of
gas ow to the burner. This increases or decreases
the burner ame height. At times the room may
exceed the set temperature. If so, the burner will
shut off. The burner will cycle back on when room
temperature drops below the set temperature. The
control knob can be set to any heat level between 1
and 5. Selecting the 5 setting will cause the burner
to remain fully on without modulating down in
most cases.
OFF
O
F
F
P
I
L
O
T
Electronic Ignitor
Figure 22 - Ignitor Buttons
CAUTION: Do not try to ad-
just heating levels by using the
equipment shutoff valve.

www.desatech.com 116292-01E16
Figure 26 - Correct Burner Flame Pattern
Yellow
Tipping
Figure 27 - Incorrect Burner Flame
Pattern
1/2
Deector
Height
Blue
Flame
1/2
Deector
Height
Note: The thermostat sensing bulb measures the
temperature of air near the heater cabinet. This
may not always agree with room temperature
(depending on housing construction, installation
location, room size, open air temperatures, etc.).
Frequent use of your heater will let you determine
your own comfort levels.
MANUAL LIGHTING
PROCEDURE
1. Remove front panel (see Figure 4, page 8).
2. Follow steps 1 through 7 under Lighting
Instructions, page 15.
3. With control knob pressed in, strike match.
Hold match to pilot until pilot lights.
4. Keep control knob pressed in for 30 seconds
after lighting pilot. After 30 seconds, release
control knob. Now follow step 9, under Light-
ing Instructions, page 15.
5. Replace front panel.
INSPECTING HEATER
Check pilot ame pattern and burner ame pat-
tern often.
PILOT FLAME PATTERN
Figure 24 shows a correct pilot ame pattern.
Figure 25 shows an incorrect pilot ame pattern.
The incorrect pilot flame is not touching the
thermocouple. This will cause the thermocouple
to cool. When the thermocouple cools, the heater
will shut down.
If pilot ame pattern is incorrect, as shown in
Figure 25
• turn heater off (see To Turn Off Gas to Appliance,
page 15)
• see Troubleshooting, page 18
Note: The pilot ame on natural gas units will
have a slight curve, but ame should be blue and
have no yellow or orange color.
Figure 25 - Incorrect Pilot Flame Pattern
Figure 24 - Correct Pilot Flame Pattern
Thermocouple
Pilot
Burner
Thermocouple
Blue Flame
Yellow Flame
Pilot
Burner
OPERATING HEATER
Continued
BURNER FLAME PATTERN
WARNING: If yellow tipping
occurs, your heater could pro-
duce increased levels of carbon
monoxide.
NOTICE: Do not mistake orange
ames with yellow tipping. Dirt
or other ne particles enter the
heater and burn causing brief
patches of orange ame.
Figure 26 shows a correct burner ame pattern.
Figure 27 shows an incorrect burner ame pattern.
The incorrect burner ame pattern shows yellow
tipping of the ame. It also shows the ame higher
than 1/2 the deector panel height.
If burner ame pattern is incorrect, as shown in
Figure 27
• turn heater off (see To Turn Off Gas To Appli-
ance, page 15)
• see Troubleshooting, page 18

www.desatech.com
116292-01E 17
CLEANING AND
MAINTENANCE
WARNING: Turn off heater
and let cool before cleaning.
CAUTION: You must keep
control areas, burner and circu-
lating air passageways of heater
clean. Inspect these areas of
heater before each use. Have
heater inspected yearly by a
qualied service person. Heater
may need more frequent clean-
ing due to excessive lint from
carpeting, bedding material, pet
hair, etc.
WARNING: Failure to keep
the primary air opening(s) of
the burner(s) clean may result in
sooting and property damage.
ODS/PILOT AND BURNER
Use a vacuum cleaner, pressurized air or small,
soft bristled brush to clean.
BURNER PILOT AIR INLET
The primary air inlet holes allow the proper
amount of air to mix with the gas. This provides a
clean burning ame. Keep these holes clear of dust,
dirt and lint. Clean these air inlet holes prior to each
heating season. Blocked air holes will create soot.
We recommend that you clean the unit every three
months during operation and have heater inspected
yearly by a qualied service person.
We also recommend that you keep the burner
tube and pilot assembly clean and free of dust and
dirt. To clean these parts we recommend using
compressed air no greater than 30 PSI. Your local
computer store, hardware store or home center may
carry compressed air in a can. If using compressed
air in a can, please follow the directions on the can.
If you don't follow directions on the can, you could
damage the pilot assembly.
Figure 28 - Pilot Inlet Air - Propane/LP
Pilot Shown (Actual Pilot May Vary from
Illustration)
Pilot Air Inlet
1. Shut off the unit, including the pilot. Allow
the unit to cool for at least thirty minutes.
2. Inspect burner, pilot for dust and dirt.
3. Blow air through the ports/slots and holes in
the burner.
4. Never insert objects into the pilot tube.
Clean the pilot assembly also. A yellow tip on the
pilot ame indicates dust and dirt in the pilot as-
sembly. There is a small pilot air inlet about two
inches from where the pilot ame comes out of
the pilot assembly (see Figure 28). With the unit
off, lightly blow air through the air inlet. You may
blow through a drinking straw if compressed air
is not available.
Pilot Assembly
CABINET
Air Passageways
Use pressurized air to clean.
Exterior and Dark Acrylic Front Glass
Use a soft cloth dampened with a mild soap and
water mixture. Wipe the cabinet to remove dust.

www.desatech.com 116292-01E18
TROUBLESHOOTING
WARNING: Turn off and unplug heater and let cool before servicing.
Only a qualied service person should service and repair heater.
CAUTION: Never use a wire, needle or similar object to clean
ODS/pilot. This can damage ODS/pilot unit.
Note: All troubleshooting items are listed in order of operation.
POSSIBLE CAUSE
1. Ignitor electrode positioned
wrong
2. Ignitor electrode broken
3. Ignitor electrode not con-
nected to ignitor cable
4. Ignitor cable pinched or wet
5. Broken ignitor cable
6. Bad ignitor
1. Gas supply turned off or equip-
ment shutoff valve closed
2. Control knob not in PILOT
position
3. Control knob not pressed in
while in PILOT position
4. Air in gas lines when in-
stalled
5. Depleted gas supply (propane/
LP gas only)
6. ODS/pilot is clogged
7. Gas regulator setting is not
correct
OBSERVED PROBLEM
When ignitor button is pressed,
there is no spark at ODS/pilot
When ignitor button is pressed,
there is spark at ODS/pilot but
no ignition
REMEDY
1. Replace pilot assembly
2. Replace pilot assembly
3. Reconnect ignitor cable
4. Free ignitor cable if pinched
by any metal or tubing. Keep
ignitor cable dry
5. Replace ignitor cable
6. Replace ignitor
1. Turn on gas supply or open
equipment shutoff valve
2. Turn control knob to PILOT
position
3. Press in control knob while in
PILOT position
4. Continue holding down con-
trol knob. Repeat igniting op-
eration until air is removed
5. Contact local propane/LP gas
company
6. Clean ODS/pilot (see Cleaning
and Maintenance, page 17) or
replace ODS/pilot assembly
7. Replace gas regulator

www.desatech.com
116292-01E 19
OBSERVED PROBLEM
ODS/pilot lights but flame
goes out when control knob is
released
Burner does not light after
ODS/pilot is lit
Delayed ignition of burner
Burner backring during com-
bustion
REMEDY
1. Press in control knob fully
2. After ODS/pilot lights, keep
control knob pressed in 30
seconds
3. Wait one minute for safety in-
terlock system to reset. Repeat
ignition operation
4. Fully open equipment shutoff
valve
5. Hand tighten until snug, then
tighten 1/4 turn more
6. A) Contact local natural or
propane/LP gas company
B) Clean ODS/pilot (see
Cleaning and Maintenance,
page 17) or replace ODS/pilot
assembly
7. Replace pilot assembly
8. Replace control valve
1. Clean burner (see Cleaning
and Maintenance, page 17)
or replace burner orice
2. Contact local natural or pro-
pane/LP gas company
1. Contact local natural or pro-
pane/LP gas company
2. Clean burner (see Cleaning
and Maintenance, page 17)
or replace burner orice
1. Clean burner (see Cleaning
and Maintenance, page 17)
or replace burner orice
2. Replace burner
3. Replace gas regulator
POSSIBLE CAUSE
1. Control knob not fully pressed in
2. Control knob not pressed in
long enough
3. Safety interlock system has
been triggered
4. Equipment shutoff valve not
fully open
5. Thermocouple connection
loose at control valve
6. Pilot ame not touching ther-
mocouple, which allows ther-
mocouple to cool, causing
pilot flame to go out. This
problem could be caused by
one or both of the following:
A) Low gas pressure
B) Dirty or partially clogged
ODS/pilot
7. Thermocouple damaged
8. Control valve damaged
1. Burner orice is clogged
2. Inlet gas pressure is too low
1. Manifold pressure is too low
2. Burner orice is clogged
1. Burner orice is clogged or
damaged
2. Burner damaged
3. Gas regulator defective
TROUBLESHOOTING
Continued

www.desatech.com 116292-01E20
TROUBLESHOOTING
Continued
OBSERVED PROBLEM
Yellow flame during burner
combustion
Slight smoke or odor during
initial operation
Heater produces a whistling
noise when burner is lit
White powder residue forming
within burner box or on adjacent
walls or furniture
Blower fan does not come on
Heater produces a clicking/tick-
ing noise just after burner is lit
or shut off
POSSIBLE CAUSE
1. Not enough air
2. Gas regulator defective
3. Clogged or dirty burner
1. Residues from manufacturing
processes
1. Turning control knob to 5
position when burner is cold
2. Air in gas line
3. Air passageways on heater
blocked
4. Dirty or partially clogged
burner orice
1. When heated, vapors from
furniture polish, wax, carpet
cleaners, etc. may turn into
white powder residue
1. Power cord not connected
2. No power to electric outlet
3. Time delay for thermal switch
to warm up
4. Bad switch
5. Loose wire connection
1. Metal expanding while heat-
ing or contracting while
cooling
REMEDY
1. Check burner for dirt and
debris. If found, clean burner
(see Cleaning and Mainte-
nance, page 17)
2. Replace gas regulator
3. Clean burner (see Cleaning
and Maintenance, page 17)
1. Problem will stop after a few
hours of operation
1. Turn control knob to 1 posi-
tion and let warm up for a
minute
2. Operate burner until air is
removed from line. Have gas
line checked by local natural
or propane/LP gas company
3. Observe minimum installation
clearances (see Figure 8, page 9)
4. Clean burner (see Cleaning
and Maintenance, page 17)
or replace burner orice
1. Turn heater off when using
furniture polish, wax, carpet
cleaners or similar products
1. Connect power cord to 120V
60Hz outlet
2. Have a qualied service per-
son check for power at outlet
3. Wait 4 to 5 minutes with the
burner on
4. Replace switch
5. Reconnect wires
1. This is normal with most heat-
ers. If noise is excessive, con-
tact qualied service person