Desa CSG3924NTA Quick start guide

For more information, visit www.desatech.com
WARNING: If the information in this manual is not
followed 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.
UNVENTED (VENT-FREE) GAS LOG HEATER
OWNER’S OPERATION AND INSTALLATION MANUAL
24" THERMOSTAT MODELS
CSG3924NTA AND CSG3924PTA

www.desatech.com 123551-01D2
SAFETy
WARNING: Improper
installation, adjustment,
alteration, service or
maintenance can cause
injury or property dam-
age. Refer to this manual
for correct installation
and operational proce-
dures. For assistance or
additional information
consult a qualified in-
staller, service agency or
the gas supplier.
WARNING: This is an
unvented gas-red heat-
er. It uses air (oxygen)
from the room in which
it is installed. Provisions
for adequate combustion
and ventilation air must
be provided. Refer to Air
for Combustion and Ven-
tilation section on page 6
of this manual.
WARNING: This ap-
pliance is for installation
only in a solid-fuel burning
masonry or UL127 factory-
built replace or in a listed
ventless firebox enclo-
sure. It is design-certied
for these installations in
accordance with ANSI
Z21.11.2. Exception: Do
not install this appliance
in a factory-built replace
that includes instructions
stating it has not been test-
ed or should not be used
with unvented gas logs.
This appliance may be in-
stalled in an aftermarket,*
permanently located,
manufactured (mobile)
home, where not prohib-
ited by local codes.
This appliance is only for
use with the type of gas
indicated on the rating
plate. This appliance is
not convertible for use
with other gases.
* Aftermarket: Completion of sale, not for
purpose of resale, from the manufacturer
TABLE OF CONTENTS
Safety .................................................................. 2
Product Identication........................................... 5
Local Codes......................................................... 5
Unpacking............................................................ 5
Product Features................................................. 6
Air For Combustion and Ventilation ..................... 6
Installation ........................................................... 9
Operation........................................................... 18
Inspecting Burners............................................. 20
Cleaning and Maintenance................................ 20
Troubleshooting................................................. 22
Optional Positioning of Thermostat Sensing Bulb... 26
Specications .................................................... 27
Parts .................................................................. 27
Replacement Parts............................................ 30
Service Hints ..................................................... 30
Technical Service............................................... 30
Accessories ....................................................... 30

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123551-01D 3
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, op-
erate or service this replace.
Improper use of this replace
can cause serious injury or
death from burns, re, explo-
sion, 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 headaches, dizziness or nausea. If you
have these signs, the replace may not be
working properly. Get fresh air at once! Have
replace serviced. Some people are more af-
fected 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.
Natural and Propane/LP Gas: Natural and
propane/LP gases are odorless. An odor-
making agent is added to these gases. The
odor helps you detect a gas leak. However,
the odor added to the gas can fade. Gas may
be present even though no odor exists.
Make certain you read and understand all
warnings. Keep this manual for reference. It
is your guide to safe and proper operation of
this replace.
WARNING: Any change to
this heater or its controls can
be dangerous.
SAFETy
Continued
WARNING: Do not use a
blower insert, heat exchanger
insert or other accessory not ap-
proved for use with this heater.
WARNING: This appliance is
for installation only in a solid-fu-
el burning replace or approved
ventless rebox enclosure.
WARNING: Do not allow fans
to blow directly into the replace.
Avoid any drafts that alter burner
ame patterns. Ceiling fans can
create drafts that alter burner
ame patterns. Altered burner
patterns can cause sooting.
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.
Heater base assembly 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
shutdown. Allow surface to cool
before touching.
Carefully supervise young chil-
dren when they are in the room
with heater.

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SAFETy
Continued
8. To prevent the creation of soot, follow the
instructions in Cleaning and Maintenance,
page 20.
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. This heater needs fresh, outside air ven-
tilation 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 6. If heater keeps shutting off, see
Troubleshooting, page 22.
11. Do not run heater
• where ammable liquids or vapors are
used or stored
• under dusty conditions
12. Do not use this heater to cook food or burn
paper or other objects.
13. Do not use heater if any part has been ex-
posed to or 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.
14. Do not operate heater if any log is broken.
Do not operate heater if a log is chipped
(dime-sized or larger).
15. Turn heater off and let cool before servic-
ing, installing or repairing. Only a qualied
service person should install, service or
repair heater.
16. Operating heater above elevations of
4,500 feet could cause pilot outage.
17. To prevent performance problems with
propane/LP models, do not use propane/
LP fuel tank of less than 100 lb. capacity.
18. Provide adequate clearances around air
openings.
You must operate this heater
with a replace screen in place.
Make sure replace screen is
closed 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)
inside any structure. Locate propane/LP
supply tank(s) outdoors (propane/LP units
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 neighbor’s phone. Follow the gas sup-
plier’s instructions
• if you cannot reach your gas supplier,
call the re department
4. This heater shall not be installed in a
bedroom or bathroom.
5. Before installing in a solid fuel burning re-
place, the chimney ue and rebox must
be cleaned of soot, creosote, ashes and
loose paint by a qualied chimney cleaner.
Creosote will ignite if highly heated. A dirty
chimney ue may create and distribute
soot within the house. Inspect chimney
ue and rebox for damage. If damaged,
repair ue before operating heater.
6. Do not burn solid-fuel in a masonry or
UL127 factory-built replace in which a
vent-free room heater is installed.
7. If replace has glass doors, never operate
this heater with glass doors closed. If you
operate heater with doors closed, heat
buildup inside replace will cause glass to
burst. Make sure there are no obstructions
across openings of replace.

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123551-01D 5
LOCAL CODES
PRODUCT IDENTIFICATION
Figure 1 - Product Identication
Log Set (Varies
According to Model)
Base
Assembly
Front and Rear
Burner Control Knob
Piezo
Ignitor
Burner
Control
Knob
Grate
Install and use heater with care. Follow all
local codes. In the absence of local codes,
use the latest edition of The National Fuel
Gas Code ANSI Z223/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 installa-
tion must be made by a licensed plumber
or gas fitter 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
bedroom and bathroom installation in the
Commonwealth of Massachusetts.
UNPACkING
CAUTION: Do not remove the
data plates from the grate as-
sembly. The data plates contain
important warranty and safety
information.
1. Remove logs and heater base assembly
from carton.
Note: Do not pick up heater base as-
sembly by burners. This could damage
heater. Always handle base assembly by
the sides of assembly.
2. Remove all protective packaging applied
to logs and heater for shipment.
3. Check heater for any shipping damage. If
heater is damaged call DESA Heating, LLC
at 1-866-672-6040 for replacement parts
before returning to dealer.

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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.
OPERATION
This heater is clean burning. It requires no
outside venting. There is no heat loss out a
vent or up a chimney. Heat is generated by
both realistic ames and glowing coals. This
heater is designed for vent-free operation
with ue damper closed. It has been tested
and approved to ANSI Z21.11.2 standard
for unvented heaters. State and local codes
in some areas prohibit the use of vent-free
heaters.
AIR FOR COMBUSTION AND VENTILATION
WARNING: This heater shall
not be installed in a room or
space unless the required vol-
ume of indoor combustion air
is provided by the method de-
scribed in the National Fuel Gas
Code, ANSI Z223.1/NFPA 54, the
International Fuel Gas Code, or
applicable local codes. 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 ap-
pliances 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 in-
sure proper venting of vented fuel-burning
appliances.
PROVIDING ADEQUATE VENTILATION
The following are excerpts from National Fuel
Gas Code. ANSI Z223.1/NFPA 54, Air for
Combustion and Ventilation.
All spaces in homes fall into one of the three
following ventilation classications:
1. Unusually Tight Construction
2. Unconned Space
3. Conned Space
The information on pages 6 through 8 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 un-
usually tight construction, you must provide
additional fresh air.
Unusually tight construction is dened 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 oors, 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 8.
If your home does not meet all of the
three criteria above, proceed to Determin-
ing Fresh-Air Flow For Heater Location,
page 7.

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123551-01D 7
AIR FOR COMBUSTION AND VENTILATION
Continued
40,000
31,500
71,500
Conned Space 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/hr (4.8 m3per 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/hr (4.8 m3per kw) of the ag-
gregate input rating of all appliances installed
in that space. Rooms communicating directly
with the space in which the appliances are
installed*, through openings not furnished
with doors, are considered a part of the un-
conned space.
* Adjoining rooms are communicating only if
there are doorless passageways or ventilation
grills between them.
DETERMINING FRESH-AIR FLOW
FOR FIREPLACE 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
replace plus any adjoining rooms with door-
less passageways 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) = 2,560 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 = (Maxi-
mum Btu/Hr the space can support)
Example: 2,560 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 replace __________ 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.
Direct-vent draws combustion air from the
outdoors and vents to the outdoors.
Example:
Gas water heater __________ Btu/Hr
Vent-free replace + __________ Btu/Hr
Total = __________ Btu/Hr
4. Compare the maximum Btu/Hr the space
can support with the actual amount of Btu/
Hr used.
______ Btu/Hr (maximum space can support)
______ Btu/Hr (actual amount of Btu/Hr
used)
Example: 51,200 Btu/Hr (maximum the
space can support)
79,000 Btu/Hr (actual amount of
Btu/Hr used)
The space in the example is a conned space
because the actual Btu/Hr used is more than the
maximum 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
adjoining room. If the extra space provides
an unconned space, remove door to adjoin-
ing room or add ventilation grills between
rooms. See Ventilation Air From Inside
Building, page 8.
B. Vent room directly to the outdoors. See
Ventilation Air From Outdoors, page 8.
C. Install a lower Btu/Hr replace, if lower Btu/
Hr size makes room unconned.
If the actual Btu/Hr used is less than the maxi-
mum Btu/Hr the space can support, the space is
an unconned space. You will need no additional
fresh air ventilation.

www.desatech.com 123551-01D8
AIR FOR COMBUSTION AND VENTILATION
Continued
Figure 2 - Ventilation Air from Inside
Building
Figure 3 - Ventilation Air from Outdoors
Outlet
Air
V e ntilated
Attic
Outlet
A
ir
Inlet
Air
Inlet Air V e ntilated
Crawl Space
T o
Crawl
Space
T o Attic
Or
Remove
Door into
Adjoining
Room,
Option
3
Ve ntilation Grills
Into Adjoining Room,
Option 2
Ve ntilation
Grills Into
Adjoining
Room,
Option 1
12"
12"
WARNING:Iftheareainwhich
the heater may be operated does
not meet the required volume for
indoor combustion air, combus-
tion and ventilation air shall be
provided by one of the methods
described in the National Fuel
Gas Code,ANSI Z223.1/NFPA54,
the International Fuel Gas Code,
or applicable local codes.
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining
unconned space. When ventilating to an
adjoining unconned space, you must provide
two permanent openings: one within 12" of the
ceiling and one within 12" 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, 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 perma-
nent openings: one within 12" of the ceiling
and one within 12" 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, 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 thermo-
stat-controlled power vent. Heated air entering
the attic will activate the power vent.

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123551-01D 9
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: Installation and
repair should be done by a
qualied service person. The
appliance should be inspected
before use and at least annu-
ally by a professional service
person. More frequent cleaning
may be required due to exces-
sive lint from carpeting, bedding
material, etc. It is imperative that
control compartments, burners
and circulating air passageways
of the appliance be kept clean.
WARNING: Before installing
in a solid fuel burning replace,
the chimney ue and rebox
must be cleaned of soot, creo-
sote, ashes and loose paint by
a qualified chimney cleaner.
Creosote will ignite if highly
heated. A dirty chimney ue may
create and distribute soot within
the house. Inspect chimney ue
and rebox for damage. If dam-
aged, repair ue before operat-
ing heater.
WARNING: Seal any fresh
air vents or ash clean-out doors
located on oor or wall of re-
place. If not, drafting may cause
pilot outage or sooting. Use a
heat-resistant sealant. Do not
seal chimney ue damper.
WARNING: Never install the
heater
• in a recreational vehicle
• where curtains, furniture, cloth-
ing or other ammable objects
are less than 36" from the front
and 42" from the top of rebox
opening. For side clearances
see Figure 4, page 10
• in high trafc 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 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 Ventila-
tion, page 6.

www.desatech.com 123551-01D10
Figure 4 - Minimum Clearance for
Combustible to Wall
*Minimum 16" from Side Wall
*
Example
Minimum Noncombustible Material
Clearances
If Not Using Mantel
Note: If using a mantel, proceed to If Using
Mantel below. If not using a mantel, follow the
information below.
You must have noncombustible material(s)
above the replace opening. Noncombustible
materials (such as slate, marble, tile, etc.)
must be at least 1/2" thick. With sheet metal,
you must have noncombustible material be-
hind it. Noncombustible material must extend
at least 8" up. If noncombustible material is
less than 12", you must install the replace
hood accessory. See Figure 5, page 11, for
minimum clearances.
If Using Mantel
You must have noncombustible material(s)
above the replace opening. Noncombustible
materials (such as slate, marble, tile, etc.)
must be at least 1/2" thick. With sheet metal,
you must have noncombustible material be-
hind it. Noncombustible material must extend
at least 8" up. If noncombustible material is
less than 12", you must install the replace
hood accessory. Even if noncombustible
material is more than 12", you may need
the hood accessory to deflect heat away
from your mantel shelf. See Figures 5 and 6,
page 11 and Figure 7 page 12, for minimum
clearances.
INSTALLATION
Continued
Note: When installing your gas logs into
a manufactured rebox, follow rebox
manufacturer’s instructions for minimum
clearances to combustible materials.
B. Clearances from top of replace opening
to ceiling should not be less than 42".
CHECK GAS TYPE
Use only the correct gas type (natural or pro-
pane/LP) for your unit. If your gas supply is not
correct, do not install heater. Call dealer where
you bought heater for proper type heater.
WARNING: This appliance is
equipped for either natural gas
or propane/LP gas but not both.
Gas type is indicated on the rat-
ing plate. Field conversion is not
permitted.
INSTALLATION AND CLEARANCES
(Vent-Free Operation Only)
WARNING: Maintain the
minimum clearances. If you
can, provide greater clearances
from oor, ceiling and adjoining
wall.
LOG SIZING REQUIREMENTS
Minimum Firebox Size
Log
Size Height Depth
Front
Width
Rear
Width*
24" 17" 14" 28" 20 1/4"
30" 17" 14" 34" 22 3/8"
*Measured at 14" Depth
Carefully follow the instructions below. This
will ensure safe installation into a masonry,
UL127-listed manufactured replace or certi-
ed vent-free rebox.
Minimum Clearances For Side
Combustible Material, Side Wall and
Ceiling
A. Clearances from the side of the replace
cabinet to any combustible material and
wall should follow diagram in Figure 4.
Example: The face of a mantel, bookshelf,
etc. is made of combustible material and
protrudes 3 1/2" from the wall. This com-
bustible material must be 4" from the side
of the replace cabinet (see Figure 4).