Desa Comfort Glow CGD3930N Quick start guide

Save this manual for future reference.
WARNING: If the information in this
manual is not followed exactly, a fire or
explosion may result causing property
damage, personal injury, or loss of life.
— Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other appliance.
— WHAT TO DO IF YOU SMELL GAS
• Do not try to light any appliance.
• Do not touch any electrical switch;
do not use any phone in your build-
ing.
• Immediately call your gas supplier
fromaneighbor’sphone.Followthe
gas supplier’s instructions.
• If you cannot reach your gas sup-
plier, call the fire department.
— Installation and service must be per-
formedbyaqualifiedinstaller,service
agency, or the gas supplier.
WARNING:Improperinstallation,adjust-
ment,alteration,service,ormaintenance
can cause injury or property damage.
Refertothismanualforcorrectinstalla-
tion and operational procedures. For
assistance or additional information
consult a qualified installer, service
agency, or the gas supplier.
WARNING:This gaslogsetisforinstal-
lation in a masonry solid fuel burning
fireplace or a U.L. listed manufactured
solid fuel burning fireplace.
WARNING: This is an unvented gas-
fired heater. It uses air (oxygen) from
the room in which it is installed. Provi-
sionsforadequatecombustionandven-
tilation air must be provided. Refer to
AirforCombustionandVentilation sec-
tion in this manual.
18", 24", and
30"Variable
Manually-
Controlled
Models
CGD3018N
CGD3924N
CGD3930N
®
YELLOW FLAME DESIGN
UNVENTED (VENT-FREE)
NATURAL GAS LOG HEATER
(Manually-Controlled Models Also Designed Certified as Vented Decorative Appliance)
This appliance may be installed in an aftermarket* manufactured (mobile) home, where
not prohibited by state or 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
OWNER’S OPERATION AND INSTALLATION MANUAL
24"
Thermostatically-
Controlled Model
CGD3924NT

2
102990
CONTENTS SECTION PAGE
SAFETY
INFORMATION WARNINGS
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 headaches, dizziness, or nausea. If you have these signs, the heater may not
be working properly. Get fresh air at once! Have heater serviced. Some people are more
affected by carbon monoxide than others. These include pregnant women, people with
heart or lung disease or anemia, those under the influence of alcohol, and those at high
altitudes.
NaturalGas:Naturalgasisodorless.Anodor-makingagentisaddedtothegas.Theodor
helpsyoudetectagasleak.However,theodoraddedtothegascanfade.Gasmaybepresent
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 heater.
Safety Information continues on next page
Safety Information................................................................................... 2
Product Identification .............................................................................. 4
Local Codes ............................................................................................. 4
Unpacking................................................................................................ 4
Product Features ...................................................................................... 4
Air for Combustion and Ventilation........................................................ 5
Installing .................................................................................................. 8
Check Gas Type ............................................................................... 8
Installation and Clearances (Vent-Free Operation Only)................. 9
Installing Damper Clamp Accessory for Vented Operation ............ 13
Installing Heater Base Assembly ..................................................... 14
Connecting to Gas Supply................................................................ 16
Checking Gas Connections .............................................................. 17
Installing Logs.................................................................................. 19
Operating Heater (Manually-Controlled Models) ................................... 20
Operating Heater (Thermostatically-Controlled Model)......................... 22
Inspecting Burners................................................................................... 24
Cleaning and Maintenance ...................................................................... 25
Troubleshooting....................................................................................... 25
Optional Positioning of Thermostat Sensing Bulb .................................. 29
Technical Service .................................................................................... 31
Specifications .......................................................................................... 31
Service Hints ........................................................................................... 31
Replacement Parts ................................................................................... 32
Parts Central ............................................................................................ 32
Accessories .............................................................................................. 33
Illustrated Parts Lists ............................................................................... 34
Warranty Information .............................................................................. Back Cover

3
102990
SAFETY
INFORMATION
Continued
WARNINGS Continued
WARNING: Any change to this heater or its controls can be dangerous.
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. If you smell gas
• shut off gas supply
• do not try to light any appliance
• do not touch any electrical switch; do not use any phone in your building
• immediately call your gas supplier from a neighbor’s phone. Follow the gas
supplier’s instructions
• if you cannot reach your gas supplier, call the fire department
3. This heater shall not be installed in a bedroom or bathroom.
4. Never install the heater
• 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
• in high traffic areas
• in windy or drafty areas
5. Beforeinstallingin asolid fuel burningfireplace, the chimneyflue and fireboxmust be
cleanedofsoot,creosote,ashesandloosepaintbyaqualifiedchimneycleaner.Creosote
willigniteifhighlyheated.Inspectchimneyfluefordamage.Ifdamaged,operateheater
with flue damper closed.
6. If fireplace has glass doors, never operate this heater with glass doors closed. If you
operateheaterwith doors closed,heatbuildup inside fireplacewill cause glasstoburst.
Also if fireplace opening has vents at the bottom, you must open the vents before
operating heater.
7. Youmustoperatethisheaterwithafireplacescreeninplace.Makesurefireplacescreen
is closed before running heater.
8. Thislogheaterisdesignedtobesmokeless.Iflogseverappeartosmoke,turnoffheater
andcallaqualifiedserviceperson.
Note: Duringinitialoperation,slightsmokingcould
occur due to log curing and heater burning manufacturing residues.
9. Do not allow fans to blow directly into the fireplace. Avoid any drafts that alter burner
flame patterns. Ceiling fans can create drafts that alter burner flame patterns. Altered
burner patterns can cause sooting.
10. Do not use a blower insert, heat exchanger insert or other accessory not approved for
use with this heater.
11. Thisheaterneedsfresh,outsideairventilationtorunproperly.Thisheaterhasanoxygen
depletionsensor(ODS) pilot lightsafetysystem. The ODSshutsdown the heaterifnot
enough fresh air is available. See Air for Combustion and Ventilation, pages 5 through
7. If heater keeps shutting off, see Troubleshooting, pages 25 through 28.
12. Do not run heater
• where flammable liquids or vapors are used or stored
• under dusty conditions
13. Do not use this heater to cook food or burn paper or other objects.
14. Never place any objects on the heater.
15. Heaterbase assemblybecomes veryhot whenrunningheater.Keepchildrenandadults
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.
16. Carefully supervise young children when they are in the room with heater.
17. Do not use heater if any part has been exposed to or 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.
18. Donotoperateheaterifanylogisbroken.Donotoperateheaterifalogischipped(dime-
sized or larger).
19. Turn heater off and let cool before servicing. Only a qualified service person should
service and repair heater.
20. Operating heater above elevations of 4,500 feet could cause pilot outage.

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102990
PRODUCT
IDENTIFICATION
Figure 1 - Vent-Free Gas Log Heater
LOCAL CODES 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, also
known as 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
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 realistic dancing, yellow flames. This
heater is designed for vent-free operation with flue damper closed. State and local
codes in some areas prohibit the use of vent-free heaters. You can operate heater as
a vented product by opening flue damper.
Safety Device
This heater has a pilot with an Oxygen Depletion Sensor Shutoff System (ODS).
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 requires no matches, batteries, or other
sources to light heater.
1. Remove logs and heater base assembly from carton.
Note: Do not pick up
heater base assembly by burners. This could damage heater. Always handle
base assembly by grate.
2. Remove all protective packaging applied to logs and heater for shipment.
3. Check all items for any shipping damage. If damaged, promptly inform dealer
where you bought heater.
UNPACKING
PRODUCT
FEATURES
Front Log
Control Knob
Back Log
Base Grate
Burner
Piezo
Ignitor
Crossover Log
Middle Log
Note: Where listed vented decorative logs are required, thermostat operation is not
permitted.

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102990
AIR FOR
COMBUSTION
AND
VENTILATION
WARNING
This heater shall not be installed in a confined space unless
provisions are provided for adequate combustion 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 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 efficient, 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.
Continued
Unconfined Space
The National Fuel Gas Code, ANSIZ223.1, 1992, Section 5.3 defines uncon-
fined space as having a minimum air volume of 50 cubic feet (127 cubic cm) for
each 1000 Btu/Hr input rating of all appliances in the space (cubic feet equals
length x width x height of space). Include adjoining rooms only if there are
doorless passageways or ventilation grills between the rooms.
Confined Space
The National Fuel Gas Code, ANSIZ223.1, 1992, Section 5.3 defines confined
space as having an air volume of less than 50 cubic feet (127 cubic cm) for each
1000 Btu/Hr input rating of all appliances in the space (cubic feet equals length
x width x height of space). Include adjoining rooms only if there are doorless
passageways or ventilation grills between the rooms.
PROVIDING ADEQUATE VENTILATION
The following is exerpts from National Fuel Gas Code. NFPA 54/ANSI Z223.1,
Section 5.3, Air for Combustion and Ventilation.
All spaces in homes fall into one of the three following ventilation classifications:
1. Unusually Tight Contruction; 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 outside atmosphere have a continu-
ous water vapor retarder with a rating of one perm or less with open-
ings 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 addi-
tional fresh air. See Ventilation Air From Outdoors , page 7 .
If your home does not meet all of the three criteria above, proceed to page 6.

6
102990
AIR FOR
COMBUSTION
AND
VENTILATION
Continued
DETERMINING AIR FLOW FOR HEATER LOCATION
Determining if You Have a Confined or Unconfined Space
Use this work sheet to determine if you have a confined or unconfined space.
Space: Includes the room in which you will install heater plus any adjoining rooms with
doorless 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) =
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. Divide the space volume by 50 cubic feet to determine the maximum Btu/Hr the space
can support.
____________ (volume of space) ÷50 cu. ft. = (Maximum Btu/Hr
the space can support)
Example: 2560 cu. ft. (volume of space) ÷50 cu. ft. = 51.2 or 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
Example: Gas water heater 40,000 Btu/Hr
Vent-free heater +39,000 Btu/Hr
Total =79,000 Btu/Hr
* Do not include direct-vent gas appliances. Direct-vent draws combustion air from the
outdoors and vents to the outdoors.
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)
79,000 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 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 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 Ventilation Air From Outdoors, page 7.
C. Install a lower Btu/Hr heater, if lower Btu/Hr size makes room unconfined.
If the actual Btu/Hr used is less than the maximum Btu/Hr the space can support, the space
is an unconfined space. You will need no additional fresh air ventilation.

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102990
AIR FOR
COMBUSTION
AND
VENTILATION
Continued
WARNING
If the area in which the heater may be operated is smaller than
that defined as an unconfined space, provide adequate combus-
tion and ventilation air by one of the methods described in the
National Fuel Gas Code, ANSI Z223.1, 1992, Section 5.3.
VENTILATION AIR
Ventilation Air From Inside Building
This fresh air would come from an adjoining unconfined space. When ventilating to an
adjoining unconfined space, you must provide two permanent 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 NFPA 54/ANSI Z223.1, Section 5.3, Air
for Combustion and Ventilation for required size of ventilation grills or ducts.
WARNING
Rework worksheet, adding the space of the adjoining unconfined
space. Thecombinedspacesmusthaveenoughfreshairtosupplyall
appliances in both spaces.
Figure 3 - Ventilation Air from Outdoors
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 floor. Connect
these items directly to the outdoors or spaces open to the outdoors. These spaces include
attics and crawl spaces.
IMPORTANT: Donotprovideopeningsforinletoroutletairintoatticifattichasathermostat-
controlled power vent. Heated air entering the attic will activate the power vent.
Figure 2 - Ventilation Air from Inside Building
Outlet
Air Ventilated
Attic
Outlet
Air
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
Ventilation
Grills
Into Adjoining
Room,
Option 1
12"
12"

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102990
INSTALLING NOTICE
Aqualifiedservicepersonmustinstallheater.Followalllocalcodes.
WARNING
Before installing in a solid fuel burning fireplace, the chimney flue
andfireboxmustbecleanedofsoot,creosote,ashesandloosepaint
by a qualified chimney cleaner. Creosote will ignite if highly heated.
Inspect chimney flue for damage. If damaged, operate heater with
flue damper closed.
WARNING
Sealanyfreshairventsorashclean-outdoorslocatedonfloororwall
of fireplace. If not, drafting may cause pilot outage or sooting. Use a
heat-resistant sealant. Do not seal chimney flue damper.
WARNING
Never install the heater
• in a bedroom or bathroom
• in a recreational vehicle
• wherecurtains,furniture,clothing,orotherflammableobjectsare
less than 36 inches from the front, top, or sides of the heater
• in high traffic areas
• in windy or drafty areas
CAUTION
This heater creates warm air currents. These currents move heat
to wall surfaces next to heater. Installing heater next to vinyl or
cloth wall coverings or operating heater where impurities in the air
(such as tobacco smoke) exist, may discolor walls.
CHECK GAS TYPE
Use only natural gas. If your gas supply is not natural gas, do not install heater.
Call dealer where you bought heater for proper type heater.
IMPORTANT: Vent-free heaters add moisture to the air. Although this is benefi-
cial, installing heater in rooms without enough ventilation air may cause mildew to
form from too much moisture. See Air for Combustion and Ventilation, pages 5
through 7.
NOTICE
State or local codes may only allow operation of this appliance in a
vented configuration. Check your state or local codes.

9
102990
INSTALLATION AND CLEARANCES (Vent-Free Operation Only)
WARNING
Maintain the minimum clearances. If you can, provide greater clear-
ances from floor, ceiling, and adjoining wall.
INSTALLING
Continued
Carefully follow the instructions below. This will ensure safe installation into a
masonry or U.L. listed manufactured fireplace.
Minimum Wall and Ceiling Clearances (see Figure 4)
A. Clearances from the side of the fireplace opening to any combustible wall
should not be less than 16 inches.
B. Clearances from the top of the fireplace opening to the ceiling should not be
less than 42 inches.
Figure 4 - Minimum Clearance to Wall and Ceiling
Continued
LOG SIZING REQUIREMENTS
Log Minimum Firebox Size
Size Height Depth Front Width
18" 17" 14" 20"
24" 17" 14" 26"
30" 17" 14" 32"
MINIMUM FIREPLACE CLEARANCE
TO COMBUSTIBLE MATERIALS
Log Size Side Wall Ceiling
18", 24", 30" 16" 42"
42"
16"
Left and Right
Sides

10
102990
INSTALLING
Continued
NOTICE
You may use this heater as a vented product. If so, you must
always run heater with chimney flue damper open. If running
heater with damper open, non-combustible material above fire-
place opening is not needed. Go to Installing Damper Clamp
Accessory for Vented Operation, page 13.
Heat Resistant
Material (A)
Minimum Non Combustible Material Clearances
If Not Using Mantel
Note: If using a mantel, go to page 11. If not using a mantel, follow the informa-
tion on this page.
You must have non combustible material(s) above the fireplace opening. Non
combustible materials (such as slate, marble, tile, etc.) must be at least 1/2 inch
thick. With sheet metal, you must have non combustible material behind it. Non
combustible material must extend at least 8" up (for all models). If non combus-
tible material is less than 12", you must install the fireplace hood accessory (24"
and 30" models only). See chart below and Figure 5 for minimum clearances.
IMPORTANT: If you cannot meet these minimum clearances, you must operate
heater with chimney flue damper open. Go to Installing Damper Clamp Accessory
for Vented Operation, page 13.
Non-Combustible Requirements for
Material Distance (A) Safe Installation
12" or more Non combustible material okay.
Between 8" and 12" 24" or 30" Models: Install fireplace hood acessory
(GA6050 or GA6052, see Accessories, page 33).
18" Model: Non combustible material okay.
Less than 8" Non combustible material must be extended to at
least 8". See Between 8" and 12", above. If you
cannot extend material, you must operate heater
with flue damper open.
Figure 5 - Heat Resistant Material (Slate, Marble, Tile, etc.) Above Fireplace