Desa VN20BT Original instructions

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WARNING: If the information in this manual is not fol-
lowed 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 quali-
fied installer, service agency or the gas supplier.
MODELS VN20BT, VP20BT VN30BT AND VP30BT
UNVENTED (VENT-FREE) BLUE FLAME GAS HEATER
SAFETY INFORMATION AND INSTALLATION MANUAL

www.desatech.com 107886-01J2
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. Provi-
sions 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,* per-
manently located, manufactured (mobile) home, where
not prohibited by local codes.
This appliance is only for use with the type of gas indi-
cated on the rating plate. This appliance is not convert-
ible 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
Unpacking ........................................................... 4
Product Information ............................................. 4
Product Features ................................................. 4
Air For Combustion and Ventilation ..................... 5
Installation ........................................................... 7
Operating Heater ............................................... 14
Inspecting Heater .............................................. 15
Cleaning and Maintenance ................................ 16
Specifications .................................................... 17
Service Hints ..................................................... 17
Technical Service .............................................. 17
Service Publications .......................................... 17
Troubleshooting ................................................. 18
Replacement Parts ............................................ 21
Accessories ....................................................... 21
Illustrated Parts Breakdown and Parts List ....... 22
Warranty Information ...........................Back Cover
State of Massachusetts: The installation must be made by a licensed plumber or gas fitter in the
Commonwealth of Massachusetts.
Sellers of unvented propane or natural gas-fired 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 bedroom and bathroom installation in the Common-
wealth of Massachusetts.

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107886-01J 3
SAFETY INFORMATION
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 flu, 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 influence
of alcohol and those at high altitudes.
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 traffic and away from furniture
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
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 flam-
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 (propane/LP models only).
3. 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
neighborʼs phone. Follow the gas supplierʼs
instructions
• if you cannot reach your gas supplier, call
the fire department
4. This heater shall not be installed in a bedroom
or bathroom.
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.

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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 flammable liquids or vapors are used
or stored
• under dusty conditions
9. 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.
10. Turn off and let cool before servicing. Only
a qualified service person should service and
repair heater.
11. Operating heater above elevations of 4,500
feet could cause pilot outage.
12. To prevent performance problems, do not use
propane/LP fuel tank of less than 100 lbs.
capacity (propane/LP models only).
13. 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
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 return to dealer
where you bought heater.
SAFETY INFORMATION
Continued
Figure 1 - Vent-Free Gas Heater
Ignitor
Button
Heater
Cabinet
Front Panel
Glass Panel
Grill Guard
Control
Knob
PRODUCT INFORMATION
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.
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 great-
est heater comfort. This can also result in lower
gas bills.

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107886-01J 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 insure
proper fresh air for this and
other fuel-burning appliances
in your home.
Todayʼs 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 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 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
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 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
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 unconfined 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
unconfined 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 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.
(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. (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 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 unconfined
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 unconfined.
If the actual Btu/Hr used is less than the maximum
Btu/Hr the space can support, the space is an uncon-
fined 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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107886-01J 7
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 openings:
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-
controlled power vent. Heated air entering the attic
will activate the power vent.
Figure 3 - Ventilation Air from Outdoors
Figure 2 - Ventilation Air from Inside
Building
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.
Outlet
Air
Ventilated
Attic
Outlet
A
ir
Inlet
Air
Inlet Air Ventilated
Crawl Space
To
Crawl
Space
To Attic
Or
Remove
Door into
Adjoining
Room,
Option 3
Ventilation Grills
Into Adjoining Room,
Option 2
12"
12"
Ventilation
Grills
into Adjoining
Room,
Option 1

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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
• test gauge connection*
• sediment trap
• tee joint
• pipe wrench
* A CSA design-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 21.
LOCATING HEATER
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 the floor, away from a
wall. A wall mounting bracket and floor base stand
are included with this heater. Determine which
method is best for your application.
INSTALLATION
Continued WARNING: Never install the
heater
• in a bedroom or bathroom
• 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
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.
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 21. If planning to use fan,
locate heater near an electrical outlet.
Figure 4 - Mounting Clearances As
Viewed From Front of Heater
Minimum
From
Sides Of
Heater
36"
2"
FLOOR
CEILING
Minimum
Minimum To
Top Surface
Of Carpeting,
Tile Or Other
Combustible
Material
6"
Left
Side
Right
Side

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107886-01J 9
THERMOSTAT SENSING BULB
The thermostat sensing bulb has been placed
below the heater.
1. Place clamp on thermostat sensing bulb as
shown in Figure 5. Clamp is provided in
hardware 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
thermostat sensing bulb is pointing up.
Figure 5 - Attaching Thermostat Sensing
Bulb
Clamp
Thermostat
Sensing Bulb
Figure 6 - Mounting Bracket
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
Removing Front Panel Of Heater
1. Remove the four painted screws, two on each
side of front panel.
2. Pull bottom of front panel 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 are 14
inches apart from their centers. 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 minimum
clearances shown in Figure 8. If
you can, provide greater clearanc-
es from floor and joining wall.
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.
Figure 8 - Mounting Bracket Clearances
18 3/4"
Min.
12"
Min.
14"
18 3/4"
Min.
8"
Min.
Adjoining Wall
14"
Adjoining Wall
Only Insert Mounting
Screws Through Last
Hole On Each End
Only Insert Mounting
Screws Through Last
Hole On Each End
Floor Floor
18 3/4"
Min.
12"
Min.
14"
18 3/4"
Min.
8"
Min.
Adjoining Wall
14"
Adjoining Wall
Only Insert Mounting
Screws Through Last
Hole On Each End
Only Insert Mounting
Screws Through Last
Hole On Each End
Floor
Floor
Models VN30BT & VP30BT
Models VN20BT & VP20BT
INSTALLATION
Continued

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INSTALLATION
Continued
Attaching Mounting Bracket To Wall
Note: Wall anchors, mounting screws and spacers
are in hardware package. The hardware package
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 (see Figure 10).
IMPORTANT: Do not hammer key!
For thick walls (over 1/2" thick) or solid walls,
do not pop open wings.
Figure 9 - Folding Anchor
Figure 11 - Mounting Heater Onto
Mounting Bracket
Stand-
Out Tab
Figure 10 - Popping Open Anchor Wings
For Thin Walls
Mounting Bracket (attached to wall)
Horizontal Slots
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.
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.
Installing Bottom Mounting Screws
1. Locate two bottom mounting holes. These
holes are near bottom on back panel of heater
(see Figure 12).
2. Mark screw locations on wall.
3. Remove heater from mounting bracket.
Figure 12 - Installing Bottom Mounting
Screws
Side View
Front View
Wall
Spacer
Heater

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107886-01J 11
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 firmly
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 (see pages 11
through 13).
MOUNTING HEATER TO FLOOR
Mounting Base Feet to Heater
1. Lay heater cabinet on its back on a table with
the heater bottom overhanging the table edge.
2. Align holes in base foot with mounting holes
on bottom of cabinet (see Figure 13).
3. Secure base foot to heater using sheet metal
screws.
4. Repeat for other side.
INSTALLATION
Continued
Figure 13 - Installing Base Feet
Sheet Metal Screw
Base Foot
Wood
Screw
Mounting Base Feet to Floor (Where
required by local code)
1. Remove front cover (see Removing Front
Panel of Heater, page 9).
2. Position heater with base feet in desired loca-
tion. Mark holes for drilling. Remove heater
with base.
3. For carpeted floors, make a small cut with a
sharp knife at marked locations prior to drill-
ing. If mounting base to a wood floor, drill 1/8
inch diameter hole, 3/4 inch deep. (Do not use
anchors in wood floors).
If mounting base to a concrete floor, drill
with 1/4 inch diameter concrete drill bit, 13/8
inches into floor. Insert anchors completely
into holes.
4. Reposition heater with base feet over holes.
Secure base to floor with wood screws. See
Figure 13.
CONNECTING TO GAS SUPPLY
WARNING: This appliance
requires a 3/8" NPT (National
Pipe Thread) inlet connection to
the pressure regulator.
WARNING: A qualified 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 com-
monly 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 inches of
water. If gas line pressure is higher, heater regula-
tor damage could occur.
CAUTION: For propane/LP
gas, never connect heater directly
to the propane/LP supply. This
heater requires an external regu-
lator (not supplied). Install the
external regulator between the
heater and propane/LP supply.
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 14, page 12. Pointing the vent
down protects it from freezing rain or sleet.

www.desatech.com 107886-01J12
IMPORTANT: Hold the pressure regulator with
wrench when connecting it to gas piping and/or
fittings. Do not over tighten pipe connection to
regulator. The regulator body could be damaged.
CAUTION: Use only new, black
iron or steel pipe. Internally-tinned
copper tubing may be used in cer-
tain 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 Diameters
VN20BT, VP20BT - 3/8" or greater
VN30BT, VP30BT - 1/2" 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 15).
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 15. 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.
Figure 14 - External Regulator With Vent
Pointing Down
External
RegulatorPropane/LP
Supply Tank
Vent
Pointing
Down
INSTALLATION
Continued
* A CSA design-certified equipment shutoff valve
with 1/8" NPT tap is an acceptable alternative to
test gauge connection. Purchase the optional CSA
design-certified equipment shutoff valve from your
dealer. See Accessories, page 21.
Figure 15 - Gas Connection
Pressure
Regulator
Tee Joint
Reducer
Bushing
to 1/8"
NPT
1/8" NPT
Plug Tap
Tee Joint
Pipe
Nipple
Cap
3/8" NPT
Pipe Nipple
Heater Cabinet
Sediment Trap
Equipment
Shutoff
Valve *
3" 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)
Ground Joint
Union
Note: Burner
bracket not
shown for clarity
Test Gauge Connection*
CHECKING GAS CONNECTIONS
WARNING: Test all gas piping
and connections for leaks after
installing or servicing. Correct
all leaks at once.
WARNING: Never use an
open flame to check for a leak.
Apply a noncorrosive leak detec-
tion fluid to all joints. Bubbles
forming show a leak. Correct all
leaks at once.

www.desatech.com
107886-01J 13
INSTALLATION
Continued
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 fluid 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 fit-
tings for leaks.
Test Pressures Equal To or Less Than 1/2
PSIG (3.5 kPa)
1. Close equipment shutoff valve (see Figure 16).
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 17) or propane/LP supply tank for
propane/LP gas, to equipment shutoff valve (see
Figure 18). Apply a noncorrosive leak detection
fluid to all joints. Bubbles forming show a leak.
4. Correct all leaks at once.
Figure 16 - Equipment Shutoff Valve
Equipment
Shutoff
Valve
Figure 18 - Checking Gas Joints for
Propane/LP Gas
Propane/LP
Supply Tank
Thermostat
Gas Valve
Figure 17 - Checking Gas Joints for
Natural Gas
Equipment Shutoff Valve
Gas
Meter
Thermostat Gas
Valve
Open
Closed
Equipment Shutoff Valve
PRESSURE TESTING HEATER GAS
CONNECTIONS
1. Open equipment shutoff valve (see Figure 16).
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 17 or 18).
Apply a noncorrosive leak detection fluid 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. Replace front panel.

www.desatech.com 107886-01J14
5. Turn control knob counterclockwise
to the PILOT position. Press in control
knob for five (5) seconds (see Figure 19).
Note: You may be running this heater for
the first time after hooking up to gas sup-
ply. If so, the control knob may need to be
pressed in for 30 seconds or more. This will
allow air to bleed from the gas system.
• If control knob does not pop up when
released, contact a qualified service person
or gas supplier for repairs.
6. With control knob pressed in, push down
and release ignitor button. This will light
pilot. The pilot is attached to the front of
burner. The pilot can be seen through the
glass panel. If needed, keep pressing ignitor
button until pilot lights.
Note: If pilot does not stay lit, refer to
Troubleshooting, page 18. Also contact a
qualified 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 15.
7. 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
released, contact a qualified service person
or gas supplier for repairs.
Note: If pilot goes out, repeat steps 3
through 7. This heater has a safety inter-
lock system. Wait one (1) minute before
lighting pilot again.
Figure 19 - Control Knob In The OFF
Position
O
F
F
P
I
L
O
T
Ignitor Button Control Knob
Figure 20 - Pilot (actual pilot may vary)
Ignitor Electrode
Pilot Burner
Thermocouple
OPERATING HEATER
FOR YOUR SAFETY
READ BEFORE LIGHTING
WARNING: If you do not fol-
low these instructions exactly,
a fire 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 floor because some gas is heavier than
air and will settle on the floor.
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 neighborʼs phone. Follow the gas
supplierʼs instructions.
• If you cannot reach your gas supplier, call
the fire 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, donʼt
try to repair it, call a qualified service tech-
nician or gas supplier. Force or attempted
repair may result in a fire or explosion.
D. Do not use this appliance if any part has
been under water. Immediately call a
qualified service technician to inspect the
appliance and to replace any part of the
control system and any gas control which
has been under water.
LIGHTING
INSTRUCTIONS
1. STOP! Read the safety information
above.
2. Make sure equipment shutoff valve is
fully open.
3. Turn control knob clockwise to the
OFF position.
4. Wait five (5) minutes to clear out any gas.
Then smell for gas, including near the floor.
If you smell gas, STOP! Follow “B” in the
safety information above. If you donʼt smell
gas, go to the next step.

www.desatech.com
107886-01J 15
BURNER FLAME PATTERN
WARNING: If yellow tipping
occurs, your heater could pro-
duce increased levels of carbon
monoxide.
NOTICE: Do not mistake orange
flames with yellow tipping. Dirt
or other fine particles enter the
heater and burn causing brief
patches of orange flame.
OPERATING HEATER
Continued
8. Turn control knob counterclockwise
to desired heating level. The main burner
should light. Set control knob to any heat
level between 1 and 5.
CAUTION: Do not try to ad-
just heating levels by using the
equipment shutoff valve.
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
thermostats simply turn on and off the burner.
The thermostat used on this heater senses the
room temperature. The thermostat adjusts the
amount of gas flow to the burner. This increases
or decreases the burner flame 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.
Note: The thermostat sensing bulb measures
the temperature of air near the heater cabinet.
This may not always agree with room tem-
perature (depending on housing construction,
installation location, room size, open air tem-
peratures, etc.). Frequent use of your heater will
let you determine your own comfort levels.
MANUAL LIGHTING
PROCEDURE
1. Remove front panel (see Figure 7, page 9).
2. Follow steps 1 through 5 under Lighting
Instructions, page 14.
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 8, under
Lighting Instructions, pages 14 and 15.
5. Replace front panel.
INSPECTING HEATER
Check pilot flame pattern and burner flame pat-
tern often.
PILOT FLAME PATTERN
Figure 21 shows a correct pilot flame pattern. Figure
22 shows an incorrect pilot flame pattern. The incor-
rect 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 flame pattern is incorrect, as shown in
Figure 22
• turn heater off (see To Turn Off Gas to Appli-
ance)
• see Troubleshooting, page 18
Note: The pilot flame on natural gas units will
have a slight curve, but flame should be blue and
Figure 22 - Incorrect Pilot Flame Pattern
Figure 21 - Correct Pilot Flame Pattern
Thermocouple
Pilot Burner
Pilot Burner
Thermocouple
Blue Flame
Yellow Flame

www.desatech.com 107886-01J16
Figure 23 - Correct Burner Flame Pattern
Yellow Tipping
Figure 24 - Incorrect Burner Flame
Pattern
1/2 Glass
Height
Blue
Flame
1/2 Glass
Height
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
qualified 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.
Figure 25 - Pilot Inlet Air (Propane/LP
Pilot Shown)
Pilot Assembly
Pilot Air Inlet
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 flame. 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 qualified 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. You can use a
vacuum cleaner in the blow position. If using com-
pressed air in a can, please follow the directions on
the can. If you donʼt follow directions on the can,
you could damage the pilot assembly.
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 pi-
lot flame indicates dust and dirt in the pilot assembly.
There is a small pilot air inlet about two inches from
where the pilot flame comes out of the pilot assembly
(see Figure 25). With the unit off, lightly blow air
through the air inlet. You may blow through a drink-
ing straw if compressed air is not available.
INSPECTING HEATER
Continued
CABINET
Air Passageways
Use a vacuum cleaner or pressurized air to clean.
Exterior
Use a soft cloth dampened with a mild soap and
water mixture. Wipe the cabinet to remove dust.
Figure 23 shows a correct burner flame pattern. Fig-
ure 24 shows an incorrect burner flame pattern. The
incorrect burner flame pattern shows yellow tipping
of the flame. It also shows the flame higher than 1/2
the glass panel height.
If burner flame pattern is incorrect, as shown in
Figure 24
• turn heater off (see To Turn Off Gas To Appli-
ance, page 15
• see Troubleshooting, page 18

www.desatech.com
107886-01J 17
SPECIFICATIONS
VN20BT VN30BT
Btu (Variable) 10,000/20,000 15,000/30,000
Type Gas Natural Natural
Ignition Piezo Piezo
Pressure Regulator Setting 3" W.C. 3" W.C.
Inlet Gas Pressure (in. of water)
Maximum 10.5" 10.5"
Minimum 4" 4"
Dimensions, Inches (H x W x D)
Heater (Includes knobs & grill) 24.25 x 18.25 x 7 24.25 x 25.75 x 7
Carton 26.25 x 21.25 x 9 26.25 x 29 x 9
Weight (pounds)
Heater 20 28
Shipping 25 33
VP20BT VP30BT
Btu (Variable) 10,000/20,000 15,000/30,000
Type Gas Propane/LP Propane/LP
Ignition Piezo Piezo
Pressure Regulator Setting 8" W.C. 8" W.C.
Inlet Gas Pressure (in. of water)
Maximum 14" 14"
Minimum 11" 11"
Dimensions, Inches (H x W x D)
Heater (Includes knobs & grill) 24.25 x 18.25 x 7 24.25 x 25.75 x 7
Carton 26.25 x 21.25 x 9 26.25 x 29 x 9
Weight (pounds)
Heater 20 28
Shipping 25 33
SERVICE HINTS
When Gas Pressure Is Too Low
• pilot will not stay lit
• burner will have delayed ignition
• heater will not produce specified heat
• propane/LP gas supply may be low
You may feel your gas pressure is too low. If so, con-
tact your local natural or propane/LP gas supplier.
TECHNICAL SERVICE
You may have further questions about installation,
operation or troubleshooting. If so, contact DESA
Heating Productsʼ Technical Service Department
at 1-866-672-6040. When calling please have your
model and serial numbers of your heater ready.
You can also visit DESA Heating Productsʼ techni-
cal service web site at www.desatech.com.
SERVICE PUBLICATIONS
You can purchase a service manual from the
address listed on the back page of this manual.
Send a check for $5.00 payable to DESA Heat-
ing Products.

www.desatech.com 107886-01J18
TROUBLESHOOTING
WARNING: Turn off and unplug heater and let cool before servicing.
Only a qualified 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 piezo 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 piezo 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 Clean-
ing and Maintenance, page
16) or replace ODS/pilot as-
sembly
7. Replace gas regulator

www.desatech.com
107886-01J 19
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 flame 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 orifice is clogged
2. Inlet gas pressure is too low
1. Manifold pressure is too low
2. Burner orifice is clogged
1. Burner orifice is clogged or
damaged
2. Burner damaged
3. Gas regulator defective
1. Not enough air
2. Gas regulator defective
3. Clogged or dirty burner
1. Residues from manufacturing
processes
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 backfiring during
combustion
Yellow flame during burner
combustion
Slight smoke or odor during initial
operation
REMEDY
1. Press in control knob fully
2. After ODS/pilot lights, keep con-
trol 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 16) or replace ODS/pilot
assembly
7. Replace pilot assembly
8. Replace control valve
1. Clean burner (see Cleaning
and Maintenance, page 16) or
replace burner orifice
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 16) or
replace burner orifice
1. Clean burner (see Cleaning
and Maintenance, page 16) or
replace burner orifice
2. Replace burner
3. Replace gas regulator
1. Check burner for dirt and
debris. If found, clean burner
(see Cleaning and Mainte-
nance, page 16)
2. Replace gas regulator
3. Clean burner (see Cleaning
and Maintenance, page 16)
1. Problem will stop after a few
hours of operation
TROUBLESHOOTING
Continued

www.desatech.com 107886-01J20
TROUBLESHOOTING
Continued
WARNING: 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. Fol-
low the gas supplier’s instructions.
• If you cannot reach your gas supplier, call the fire department.
IMPORTANT: Operating heater where impurities in air exist may create odors. Cleaning supplies,
paint, paint remover, cigarette smoke, cements and glues, new carpet or textiles, etc., create fumes.
These fumes may mix with combustion air and create odors.
POSSIBLE CAUSE
1. Turning control knob to posi-
tion 5 when burner is cold
2. Air in gas line
3. Air passageways on heater
blocked
4. Dirty or partially clogged
burner orifice
1. When heated, vapors from
furniture polish, wax, carpet
cleaner, etc., may turn into
white powder residue
1. Metal expanding while heating
or contracting while cooling
1. Heater burning vapors from
paint, hair spray, glues, etc.
(see IMPORTANT statement
above)
2. Low fuel supply (propane/LP
gas only)
3. Gas leak. See Warning
statement above
1. Not enough fresh air is
available
2. Low line pressure
3. ODS/pilot is partially
clogged
OBSERVED PROBLEM
Heater produces a whistling noise
when burner is lit
White powder residue forming
within burner box or on adjacent
walls or furniture
Heater produces a clicking/tick-
ing noise just after burner is lit
or shut off
Heater produces unwanted
odors
Heater shuts off in use (ODS
operates)
REMEDY
1. Turn control knob to position 1
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 4, page 8)
4. Clean burner (see Cleaning
and Maintenance, page 16)
or replace burner orifice
1. Turn heater off when using
furniture polish, wax, carpet
cleaners or similar products
1. This is common with most heat-
ers. If noise is excessive, contact
qualified service person
1. Ventilate room. Stop using
odor causing products while
heater is running
2. Refill supply tank
3. Locate and correct all leaks
(see Checking Gas Connec-
tions, page 12)
1. Open window and/or door for
ventilation
2. Contact local natural or pro-
pane/LP gas company
3. Clean ODS/pilot (see Cleaning
and Maintenance, page 17)