Desa CERAMIC PLAQUE User manual

SERVICE MANUAL
GRH/PV 005
VANGUARD FRONT
Do not store or use gasoline or other
flammable vapors and liquids in the
vicinity of this or any other appliance.
FOR YOUR SAFETY
FOR YOUR SAFETY
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.
WARNING: Improper installation, ad-
justment, alteration, service or mainte-
nancecancauseinjuryorpropertydam-
age. Refer to this manual for correct
installationandoperationalprocedures.
Forassistance oradditional information
consult a qualified installer, service
agency or the gas supplier.
D
E
S
I
G
N
C
O
M
P
L
I
E
S
W
I
T
H
N
N
A
A
T
T
I
O
N
A
L
S
A
F
E
E
T
Y
S
S
T
A
N
D
D
A
R
D
S
C
E
R
T
I
I
F
I
E
A
M
C
R
I
A
S
O
C
I
A
O
G 009
N
Save this manual for future reference.
CERAMIC PLAQUE MODELS
VENT-FREE GAS HEATERS

2
VENT-FREE GAS HEATER SERVICE MANUAL
TABLE
OF
CONTENTS
Section 1 - Safety Information
Safety Requirements .............................................................................................. 3
Warnings................................................................................................................. 3
Section 2 - Introduction
Technical Service Department ............................................................................... 4
Product Features .................................................................................................... 4
Accessories ............................................................................................................ 4
Section 3 - General Operation and Component Descriptions
General Operation .................................................................................................. 5
Burner Assembly .................................................................................................... 5
Ignition System ....................................................................................................... 5
Control Valve .......................................................................................................... 6
Gas Regulator ........................................................................................................ 6
Oxygen Depletion System ...................................................................................... 6
Section 4 - Tools and Equipment ................................................................................. 7
Section 5 - Installation
Gas Type ................................................................................................................ 8
Location: Safety Precautions .................................................................................. 8
Gas Supply Installation ........................................................................................... 9
Propane Installation ................................................................................................ 10
External Regulators ................................................................................................ 10
Section 6 - Test Procedures
Testing Gas Supply Line Connections ................................................................... 11
Testing Heater Gas Connections ........................................................................... 11
Correcting Leaks .................................................................................................... 11
Testing Control Valve and Thermocouple .............................................................. 12
Section 7 - Specifications............................................................................................. 13
Section 8 - Troubleshooting
Ignition Problems
No Spark................................................................................................................. 14
Ignitor Sparks, But Pilot Will Not Light .................................................................... 15
Pilot Lights, But Will Not Stay Lit ............................................................................ 16,17
Main Burner Does Not Light (pilot stays lit) ........................................................... 18
Delayed Ignition Of Main Burner ............................................................................ 18
Combustion Problems
Backfiring During Operation ................................................................................... 19
Smoke or Unwanted Odors .................................................................................... 19
Gas Odor ................................................................................................................ 19
Service Information ...................................................................................................... Back Page

3
VENT-FREE GAS HEATER SERVICE MANUAL
SECTION SAFETY INFORMATION
1
DANGER
Carbon monoxide poisoning may lead to death!
This service manual is intended for use by
individuals with adequate electrical and me-
chanical skills. Attempts to repair this heater by
!
WARNING ICON G 001
WARNINGS
IMPORTANT: Read the 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
fire, explosion, electrical shock, electrocution, and carbon monoxide poisoning.
Early signs of carbon monoxide poisoning resemble the flu, with headaches, dizziness, and/or
nausea. If you have these signs, the heater may not be working properly. Get fresh air at once!
Haveheater serviced.Some people such as pregnant women, personswith heartor lungdisease,
persons with anemia, those under the influence of alcohol, and those at high altitudes are more
affected by carbon monoxide than others. Make certain you read and understand all Warnings.
KeeptheOwner’s Manualfor reference. Itis your guideto safeandproper operationof this heater.
1. Use only propane gas for models designated as propane.
2. Use only natural gas for models designated as natural.
3. If using propane model, do not place propane supply tank inside any structure. The
propane supply tank must be located outdoors.
4. If you smell gas
• Shut off gas supply.
• Do not try to light any appliance.
• Do not touch any electrical switch; do not use any phone in your building.
• Immediately call your gas supplier from a neighbor’s phone. Follow the gas supplier’s
instructions.
• If you cannot reach your gas supplier, call the fire department.
5. Never install the heater
• in sleeping quarters, a mobile home, or 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
6. Always run heater at LOW, THERMOSTAT/MEDIUM, or HIGH locked positions. Never set
controlknobbetweenlockedpositions.Poorcombustionandhigherlevelsofcarbonmonoxide
may result.
7. Open window to admit fresh, outside air when using heater. Open window one (1) or two (2)
inches. When used without fresh, outside air, heater may give off carbon monoxide gas.
8. Never run heater in small, closed room. Open door into next room to help ventilate.
9. If heater shuts off, do not relight until you provide fresh, outside air. If heater keeps shutting
off, have it serviced.
10. Do not run heater
• where flammable liquids or vapors are used or stored
• under dusty conditions
11. Never place any objects on the heater.
12. Surface of heater becomes very hot when running heater. Keep children and adults away
from hot surface. Heater will remain hot for a time after shutdown. Allow surface to cool
before touching.
13. Make sure grill guard is in place before running heater.
14. Do not alter heater or its controls. Any change may create a safety hazard.
15. Make sure heater is turned off, unplugged, and cool before servicing.
!
WARNING ICON G 001
Safety Requirements
individuals without those skills can result in
personal injury as well as property damage.

4
VENT-FREE GAS HEATER SERVICE MANUAL
NOTE:ThisnumberisONLYfortechnicalserv-
iceassistance and CANNOT be usedfor order-
ingparts,billingquestions,orderstatus,etc.For
salesdepartmentandpartsordering,call1-502-
781-9600.
2
SECTION Technical Service Department
The Technical Service Department, located in
Bowling Green, Kentucky, is committed to as-
sistingourAuthorizedServiceCentersandDeal-
ers to provide prompt, efficient service. If you
needassistanceorhavequestionsaboutservic-
ing problems, please call DESA International’s
Technical Service Department at 1-800-323-
5190.
INTRODUCTION
For accessories, contact authorized dealers of this product. If they are unable to supply
accessory parts, call DESA International at 1-502-781-9600.
Figure 1. Optional Fan Kit Figure 2. Optional Floor Mounting Stand
A 007FAN ACCESSORY-GRH
A 005
OPTIONAL FLOOR MOUNT-GRH
Accessories
The following accessories are available from
DESA International:
1. Fan Kit GA2100A. The fan accessory pro-
vides better heat distribution in the room.
2. Floor Mounting Stand GA4000 (3-plaque
models) and GA4010 (5-plaque models).
The floor stand allows the heater to be
installed away from a wall.
Product Features
The ceramic plaque heaters covered by this
servicemanual havemany features that assure
customer satisfaction and comfort.
• Infra-red Heat: The glowing ceramic burner
plaquesgiveoffinfra-redradiantlightwhich
travels through the air and heats nearby
objects.
• Variable Heat Output: The non-thermostat
heaters can be adjusted to one of three
alternative heat settings to provide user
comfort. The thermostat heaters can be
adjusted to the desired heat setting to per-
miteconomicaluse.Intheeventofapower
outage, the heater can be operated manu-
ally on high or low.
•
Piezo Electric Ignition: The heater can be
started and operated without matches or
otherexternalmeans.Thepilotisignitedby
asparkcreatedfromthepiezoignitorwhen
thecontrolknobisdepressedandturnedto
the “PILOT”position.
• Oxygen Depletion System: The heater is
designed to shut off if the oxygen level in
the room falls to an unacceptable level.

5
VENT-FREE GAS HEATER SERVICE MANUAL
SECTION
3GENERAL OPERATION AND COMPONENT DESCRIPTIONS
“PILOT”position so that the heater is ready to
use.
Turning the control knob operates the control
valve and directs the flow of gas to the pilot and
the burner plaques. The gas is mixed with air
andisinjectedintotheburnerchambersthrough
tubes in the bottom of the burner. The air/gas
mixture burns on the surface of the ceramic
burnerplaques,causingtheceramicplaquesto
glow with a radiant orange color. With proper
careandservicing,theheatershouldgivemany
years of satisfactory use to the customer. Be
sure to inspect and service the heater at least
annually.
General Operation
NOTE: See Owner’s Manual for operating
procedure.
The heater is operated by the control knob
locatedonthetopoftheheater.Besurethatthe
servicesupplyvalveisopenandthatthemanual
shut-off valve (Figure 8, page 9) is fully open.
Depressingthecontrolknobandturningittothe
“PILOT”position will direct gas to the pilot and
provide a spark to light the pilot. The control
knob must be held down (at least 10 seconds)
untilthe thermocouple is heated enoughto hold
the valve open. Once the pilot flame is
established, the control knob can be released
and turned to any of the operating position
settings.The control knob can also be left in the
Ignition System
The ignitor assembly utilizes a piezo electric
ignitionsystem.Thespark gen-
erator is built into the con-
trol valve and will pro-
vide a spark to the pi-
lot when the control
knob is fully de-
pressed and turned
fromthe “OFF”position to the “PILOT”position.
The resulting high voltage spark ignites the gas
atthepilottube.Thepilotflamewill
in turn light the main burners
when the control knob is
rotated to the desired
heat setting.
Burner Assembly
The burner assembly is constructed of a plated
steel burner case with ceramic plaques ce-
mented into the face. A metal frame assures
uniform spacing between the plaques. The gas
orificesaremountedat thebottomofthe air/gas
inlet tubes. The air/gas mixture is distributed to
the plaques through the steel burner chambers
and through the small holes in the ceramic
plaques. The air/gas mixture burns near the
surface of the ceramic plaques, resulting in the
production of both radiant and convected heat.
GRH/P027
IGNITION SYSTEM
Figure 3. Ignition System
Pilot
Control
Valve

6
VENT-FREE GAS HEATER SERVICE MANUAL
GRH/P 029
O.D.S.
GAS REGULATOR GRH/P 032
GRH/P028
Gas Valve
Oxygen Depletion System (O.D.S.)
The pilot burner is designed to produce a preci-
sionflamewhichwillliftoffofthepilot
thermocouple if the oxy-
gen content of the sur-
roundingairistoolow.
Theresultingcooling
of the pilot thermo-
Figure 6. Oxygen Depletion System
Control Valve
The control valve directs the flow of gas to the
pilot burner and the main burners. The con-
trol knob should be slightly depressed and
rotatedto select the appropriateheatset-
ting, the “PILOT”setting or to turn the
heater off.
The control valve will maintain gas
flow to the main burner and the pilot
burner only if the thermocouple which
is mounted on the pilot burner is suffi-
ciently heated. The heated thermo-
coupleprovidesalowlevelelectriccurrenttoan
electromagnetic plunger in the control valve.
This low level electric current keeps the
plunger open allowing gas to flow to the
pilotandthemainburner.Ifthepilot
flame is extinguished, or if the
pilot flame lifts off of the
thermocouple due to lack of
oxygen,theelectriccurrentto
thevalve will be reduced and the plunger will
close,shuttingoffallgasflowtotheheater.
Gas Regulator
Thegasregulatorisusedtoreducetheincoming
gaspressuretotheappropri-
ate pressure for proper op-
eration of the heater. The
regulator pressure is preset
and cannot be adjusted.
NOTE: Propane heaters also require an exter-
nal regulator (11"-14" W.C.) be in-
stalled. The external regulator is not
supplied with the heater.
Figure 4. Control Valve
Figure 5. Gas Regulator
couple will cause the control valve to close,
shutting off all gas flow to the
heater.The oxygendeple-
tionsystemisrequired
onallmodelsofvent-
freeheaterscovered
by this manual.
Pilot
Control
Valve

7
VENT-FREE GAS HEATER SERVICE MANUAL
4
SECTION Tools You May Need
Phillips Screwdriver
Slotted Screwdriver
1/4 inch (Socket) Nutdriver
5/16 inch (Socket) Nutdriver
5/16 inch Open End Wrench
5/8 inch Open End Wrench
7/8 inch Open End Wrench
9 mm Open End Wrench
10 mm Open End Wrench
11 mm Open End Wrench
13 mm Open End Wrench
15/64 inch Ignition Wrench (Orifices)
1/16 inch Punch
Needle Nose Pliers
Equipment
The following items are recommended for
servicing, troubleshooting, or installing vent-
free gas heaters:
Source Information
Controls, Inc.
P.O. Box 52275
Raleigh, North Carolina
1-800-334-5886
Item: ESL-16
Approximate Cost: $14.00
DESA International
P.O. Box 90004
Bowling Green, KY 42102-9004
502-781-9600
Item: GA5000
Controls, Inc.
P.O. Box 52275
Raleigh, North Carolina
1-800-334-5886
Item: 78060
Approximate Cost: $40.00
DESA International
P.O. Box 90004
Bowling Green, KY 42102-9004
502-781-9600
Item: GA5010
TOOLS AND EQUIPMENT
Item
1. Water Manometer
(For Inlet and Mani-
fold Pressure Testing)
2. BASO Millivolt Test Kit.
(For Testing Valves
and Thermocouples)
3. Low Pressure Test Set
(For Leak Testing Gas
Supply Line To Heater)
4. Manual Shutoff Valve With
1/8" NPT Tap. (For
Installing Heater To Gas
Supply)

8
VENT-FREE GAS HEATER SERVICE MANUAL
5
SECTION INSTALLATION
For detailed installation instructions, see the
Owner’sOperation and InstallationManual that
is packaged with the heater.
*AvailablefromtheAmericanNationalStandards
Institute, Inc., 1430 Broadway, New York, NY
10018 or from the National Fire Protection
Association Inc., Batterymarch Park, Quincy,
MA 02269.
Before servicing the heater, be sure that the
installationconformstolocalcodesandallsafety
precautions outlined in the Owner’s Operation
and Installation Manual. In the absence of local
codes, the installation must conform with the
National Fuel Gas Code, ANSI Z223.1 1984,
and ADDENDA Z223.1a-1987 also known as
NFPA 54*. Only qualified (licensed or trained)
persons should install the product.
Location: Safety Precautions
Be sure that the following safety precautions
have been followed for locating the heater:
1. DONOTinstalltheheaterinsleepingquar-
ters,mobilehomesorrecreationalvehicles.
2. DO NOT install heater as afireplace insert.
3. The heater should be located to give easy
accessfor operation,servicing and inspec-
tion.
4. DO NOT install in areas where curtains,
drapes,clothingorotherflammablemateri-
alsarewithin36inchesofthe front, topand
sides of the heater.
5. This heater has been designed for wall
mounting. The clearances from the heater
to combustible surfaces MUST NOT be
less than shown in Figure 7. These are
absolute minimum clearances. Greater
clearances should be allowed if possible.
The heater can also be mounted to an
optional floor mounting base that is sold as
a separate accessory. If a base accessory
is used, be sure the base is securely at-
tached to the floor.
If the heater is installed in a residential garage,
the following precautions should be taken:
1. The heater pilot and burners must be at
least 18 inches above the floor.
2. The heater must be located or reasonably
protected, so as not to be subjected to
damage by a moving vehicle.
Wall or Base Mounting
SeeOwner’sManualfordetailedinstructionsfor
wall or base mounting.
Gas Type
Be sure that the type of gas supplied to the
heater is the same as that indicated on the
heater data plate. If you observe that the gas
supply is different than that specified on the
heater data plate, DO NOT operate the heater
until the correct gas supply is installed. Verify
that the regulator, burner orifices, and pilot as-
semblyareforthesamegastypeasisindicated
on the heater data plate (see
“SPECIFICA-
TIONS”
, page 13). DO NOT attempt to convert
a heater from one gas type to another (i.e.,
PropanetoNatural Gas or vice versa). Ifneces-
sary,replacetheheaterwithamodelsuitablefor
the type of gas being supplied.
Minimum
From
Sides Of
Heater
GRH/PV 011
L
EARANCE
36"
3"
FLOOR
CEILING
Minimum
Minimum To Top Surface
Of Carpeting, Tile Or Other
Combustible Material
6"
Left
Side Right
Side
Figure 7. Mounting Clearances As Viewed
From Front of Heater

9
VENT-FREE GAS HEATER SERVICE MANUAL
GRH/P 001A
GAS CONNECTION
Gas Supply Installation
1. Use only new, black iron or steel pipe.
Copper tubing may be acceptable in some
areas but should be internally tinned or
equivalently treated to resist corrosion by
sulphur compounds. CHECK LOCAL
CODES.
2. The gas supply line shall be sized and
installed to provide a sufficient supply of
gas to meet the maximum demand of the
heater without undue loss of pressure.
Model Installed Supply Line
3-Plaque Models 3/8 inch or greater
5-Plaque Models 1/2 inch or greater
3. The sealant used on the threaded joints of
the gas pipe must be the specific type
resistant to the action of liquid petroleum
(LP) gas. Apply sealant lightly to the male
threads to ensure excess sealant does not
enterthelines.Anyexcesssealantcouldbe
forced into the pipe and result in clogged
valves.
IMPORTANT: Pressure regulator
must be held with wrench when
connecting gas piping and/or fittings
to pressure regulator.
External Regulator
(For LP Heaters Only)
Drip Leg
(Trap)
Figure 8. Gas Connection
Manual Shut-off
Valve
Union
1/8" NPT Plug Tap
4. The supply system must include a manual
shut-off valve, a union in the line and a
plugged 1/8 inch NPT tap. The tap should
be accessible for test gauge connections
upstream of the gas supply connection to
the heater.
5. Include a drip leg (trap) in the supply line.
The purpose of the drip leg is to prevent
moisture and contaminants in the gas sup-
ply from entering the heater controls. The
drip leg should be within reach to permit
cleaning or emptying. A drip leg should not
be located where condensation is likely to
freeze.Failuretouseadriplegcanresultin
operational difficulties with the heater.
The gas supply to the heater must be regulated
to maintain the inlet pressure within the follow-
ing limits:
Models Gas Pressure
(Inches W.C.)
Natural Gas 7" Min. / 10.5" Max.
Propane 11" Min. / 14" Max.

10
VENT-FREE GAS HEATER SERVICE MANUAL
REGULATOR INSTALLATION GRH/PV 018
Propane Installations
CAUTION: Propane models require an
external regulator (not supplied with heater).
The external regulator must be connected be-
tween the heater and the propane supply tank.
Thisregulator mustreduce the incoming supply
pressure to a maximum of 14" W.C. Under no
circumstances should this heater ever be con-
nected directly to a propane supply tank.
A typical propane installation is shown (below
right)in Figure 9.For details concerning tank or
cylinder location and installation, refer to NFPA
Pamphlet No. 58 and the laws in your locality.
External Regulators - Vents
External regulators should be installed with the
vent pointing down as shown in Figure 9. Some
regulators have a so-called “drip lip”surround-
ing the vents which acts as a shield for the
recessed vent opening. This lip makes it more
difficult for freezing rain or sleet to plug a vent
that has been installed pointing down. Older
style vents may not have the lip and are far less
resistanttofreeze-up problems (see Figure10).
A regulator with the drip lip design installed
outdoors does not require additional protection
if the vent is pointing down, unless subjected to
upward splatter from rain.
Older regulators with the non-drip lip vent con-
structionrequireadditionalprotection,suchasa
hood, cover, encasement, etc. The external
regulatorshouldbeinstalledhighenoughabove
ground level (at least 18 inches) so that rain
splatter does not block or freeze the vent. Extra
protection for the vent may be needed in areas
where there is heavy snow fall.
Be sure the external regulator is installed in
accordance with NFPA No. 58 and any other
applicable local regulations, as well as the
manufacturer’s instructions.
DRIP LIP
GRH/P 026
Figure 9. Typical Propane Installation
Drip Lip No Drip Lip
Figure 10. Regulator Vent Drip Lips
3 FT
MIN
3 FT
MIN
3 FT
MIN
CYLINDER LOCATION GRH/PV 016
Supply
Tank
Regulator
!
WARNING ICON G 001
Manual Shutoff Valve
With 1/8" NPT Tap

11
VENT-FREE GAS HEATER SERVICE MANUAL
6
SECTION
!
WARNING ICON G 001
Testing Heater Gas Connections
1. Remove the front panel of the heater by
removing the two screws near the bottom
cornersand pullingthe bottom of the panel
forward and then downward. Turn heater
control knob to the “OFF”position. Open
the manual shut-off valve (see Figure 8,
page 9). Apply solution of liquid detergent
andwatertoallconnectionsfromthesupply
line to control valve. Bubbles forming indi-
cate leaks that must be corrected.
2. Light the heater and check all remaining
internalconnectionsforleakswiththeliquid
detergent and water solution.
Correcting Leaks
1. To correct a leak on flared tubing, first try
tightening the connection. If this doesn’t
work, reflare or replace the section of tub-
ing.
2. On threaded piping, try tightening or re-
doping first. If the leak continues, take the
connectionapartandinspectthethreads.If
necessary, cut new threads or replace the
section of piping.
3. If steps 1 and 2 fail to correct the problem,
look for pinholes in the pipe or fittings and
check for splits in the tubing. Replace ma-
terials or fittings that are defective.
Testing Gas Supply Line Connections
WARNING: All gas piping and connec-
tionsmustbetestedforleaksafterinstallationor
servicing. All leaks must be corrected immedi-
ately.
WARNING: NEVER USE AN OPEN
FLAME TO CHECK FOR A LEAK. Apply a
solution of liquid detergent and water to all
connections. The formation of bubbles indicate
leaks that must be corrected.
Pressure Testing Supply Line
1. The heater and its control valve must be
disconnected from the gas supply piping
systemduringanytestingofthegas supply
piping system when test pressures are in
excess of 14" W.C. (1/2 PSIG).
2. The heater must be isolated from the gas
supply piping system by closing its individ-
ual manual shut-off valve during any pres-
suretestingofthegassupplypipingsystem
when pressures are equal to or less than
14" W.C. (1/2 PSIG).
TEST PROCEDURES
Testing Gas Supply Piping System
1. Inspectallconnectionsfromthegassupply
tothemanual shut-off valve tobesurethey
are tight or closed.
2. Connect a low pressure gauge to the 1/8
inch NPT pressure tap (see “Equipment” ,
page 7). The manual shut-off valve should
be closed.
3. Open the gas supply service valve to pres-
surize the system. Close the service valve
tightly.
4. The low pressure gauge should read at
least 11 inches W.C. Bleed off pressure by
slowly opening the manual shut-off valve
to vent enough gas to reduce the pressure
to exactly 10 inches W.C.
5. If the pressure remains at 10 inches W.C.
for 10 minutes, you can assume the gas
supply system is leak tight. If the pressure
drops, apply a solution of liquid detergent
and water to all connections and observe
carefullyforformingandexpandingbubbles.
Bubbles forming indicate a leak that must
be corrected.
!
WARNING ICON G 001

12
VENT-FREE GAS HEATER SERVICE MANUAL
Testing Control Valve and Thermocouple
The following procedure can be used to deter-
mine if the valve and thermocouple meet speci-
fication. This procedure requires a BASO milli-
volt tester. See Equipment, page 7.
PROCEDURE
1. Connectthevalveattachmenttothecon-
trol valve in place of the thermocouple.
2. Plugthevalveattachmentconnectorinto
the BASO millivolt tester as shown in
Figure11. SetBASO to 0-500 Milliamps.
3. Adjust the current to 80 ma (if using dry
cell batteries, set the current level by
adjusting the rotary volume knob).
4. Turn control knob from the OFF position
tothePILOTposition. Checktoseeif the
control valve holds in satisfactory.
5. If the control valve does not hold in,
increase current levels by 10 ma and
repeat step 4. Repeat by 10 ma incre-
ments until the valve holds in. Note re-
sult.
6. Gradually reduce
ma level until the con-
trol valve drops out. Note result.
Hold-incurrent specification: 230ma maximum
Drop-out current specification: 80 ma minimum
Ifthecontrolvalveoperatescorrectlyduringthe
above test, it is likely that the problem is the
result of a bad thermocouple.
7. Connect the thermocouple attachment
to the thermocouple as shown in Figure
12.Besure the redclipis attachedtothe
outer (copper) thermocouple sheathing.
Set BASO to 0-500 Millivolts.
8. Lighttheburnerpilotandcontinuetohold
thecontrolknobdowntokeepthecontrol
valveopen,orremovethethermocouple
and hold it over an open flame (a BIC
lighter can be used).
Thermocouple output specification: 20-28 mv
If the thermocouple millivolt output is below
specification, replace the thermocouple.
ADJUST
500
300
100
10
20
0
700
30
40
900
50
DC MILLIVOLT 0-50
MILLIVOLTS MILLIAMPS
MILLIAMPS
0-500
GRH/OV 032
0-1000
MILLIVOLTS
BASO
Milivolt Tester
ADJUST
500
300
100
10
20
0
700
30
40
900
50
DC MILLIVOLTS 0-1000
MILLIVOLTS MILLIAMPS
MILLIAMPS
0-500
GRH/OV 031
0-50
MILLIVOLTS
BASO
Milivolt Tester
Figure 12. Testing Thermocouple With BASO Milivolt Tester
Thermocouple
Attachment
Thermocouple
Attachment
Figure 11. Testing Control Valve With
BASO Milivolt Tester
Valve
Attachment
Control
Valve

13
VENT-FREE GAS HEATER SERVICE MANUAL
7
SECTION SPECIFICATIONS
MODELS VP1600 VP1600T VP2600 VP2600T
VP1600A VP1600TA VP2600A VP2600TA
VP1600B VP2600B
Gas Type LP Only LP Only LP Only LP Only
Inlet Gas Pressure (Inches W.C.)
Maximum 14" 14" 14" 14"
Minimum 11" 11" 11" 11"
Supply Line 3/8" or greater 3/8" or greater 1/2" or greater 1/2" or greater
Inlet Fitting Size 1/2" NPT 1/2" NPT 1/2" NPT 1/2" NPT
Regulator Pressure (Inches W.C.)
Maximum 8.2" 8.2" 8.2" 8.2"
Minimum 7.8" 7.8" 7.8" 7.8"
Control Valve Type Manual Manual with Manual Manual with
Thermostat Thermostat
Manifold Pressure (Inches W.C.)
Maximum 7.9" 7.9" 7.9" 7.2"
Minimum 7.5" 7.5" 7.5" 6.8"
Burner Orifice Diameter .028" (#70 drill) .028" (#70 drill) .028" (#70 drill) .028 "(#70 drill)
Burner Orifice Diameter (B Model) .042" (#58 drill) .042" (#58 drill)
BTU/HR Output
Maximum 16,000 16,000 26,000 26,000
Minimum 6,000 6,000 6,000 11,000
Fresh Air Opening (Minimum) 16 sq. in. 16 sq. in. 26 sq. in. 26 sq. in.
MODELS VN1800 VN1800T VN3000 VN3000T
VN1800A VN1800TA VN3000A VN3000TA
VN1800B VN3000B
Gas Type Natural Only Natural Only Natural Only Natural Only
Inlet Gas Pressure (Inches W.C.)
Maximum 10.5" 10.5" 10.5" 10.5"
Minimum 7" 7" 7" 7"
Supply Line 3/8" or greater 3/8" or greater 1/2" or greater 1/2" or greater
Inlet Fitting Size 1/2" NPT 1/2" NPT 1/2" NPT 1/2" NPT
Regulator Pressure (Inches W.C.)
Maximum 6.2" 6.2" 6.2" 6.2"
Minimum 5.8" 5.8" 5.8" 5.8"
Control Valve Type Manual Manual with Manual Manual with
Thermostat Thermostat
Manifold Pressure (Inches W.C.)
Maximum 5.5" 5.5" 5.2" 5.2"
Minimum 5.1" 5.1" 4.8" 4.8"
Burner Orifice Diameter .041" (#59 drill) .043" (#57 drill) .043" (#57 drill) .043 "(#57 drill)
Burner Orifice Diameter (B Model) .042" (#58 drill) .042" (#58 drill)
BTU/HR Output
Maximum 18,000 18,000 30,000 30,000
Minimum 6,600 6,600 6,600 12,000
Fresh Air Opening (Minimum) 18 sq. in. 18 sq. in. 30 sq. in. 30 sq. in.

14
VENT-FREE GAS HEATER SERVICE MANUAL
GRH/P 030
I
g
nitor/Pilot
8
SECTION TROUBLESHOOTING
thatitisfree of dust,grease,carbonbuild-
upormoisture.Cleantheignitorwithadry
rag and retest.
3. Inspect the porcelain body of the ignitor
electrode to be sure that it is not cracked.
If the porcelain is cracked, replace the
ignitor electrode.
4. Be sure that the control knob is fully de-
pressed when attempting to ignite the pi-
lot. If necessary, instruct the customer on
properoperating procedure (seeOwner’s
Operation and Installation Manual for
heater in question).
5. If sparking is still not observed after the
abovestepshavebeentaken,replacethe
controlvalveassembly.Besuretoturnoff
the manual shut-off valve before begin-
ning replacement of the control valve.
Ignition Problems
Problem
No Spark
Possible Causes
1. Ignitor cable
2. Ignitor electrode position and/or cleanli-
ness
3. Ignitor electrode body cracked
4. Control knob not fully depressed
5. Control valve malfunction
Procedures
1. Check the ignitor cable at the point of
connection to the ignitor electrode. Be
surethat the cable insulation is not splitor
damagedandthatthecableisfullypressed
onto the serrated point of the ignitor elec-
trode.
2. Inspecttheignitorelectrodetobesurethat
it is properly positioned in the bracket and
Installation and repair should be done by a qualified service person in accordance with local
ordinances and codes. The room heater should be inspected before use and at least annually by
aprofessionalserviceperson.It is importantthatcontrolcompartments,burnersand circulating air
passageways of the room heater be kept clean. More frequent cleaning may be required due to
excessive lint from carpeting, bedding material, etc.
Ignitor Electrode
Porcelain Body
Ignitor cable point of
connection
Cable Insulation
Figure 13. Ignitor Electrode Assembly

15
VENT-FREE GAS HEATER SERVICE MANUAL
PILOT GRH/P 007A
Problem
Ignitor sparks, but pilot will not light
Possible Causes
1. Gas supply is turned off and/or manual
shut-off valve is closed
2. Air in pilot line
3. Dirty pilot assembly
4. Insufficient gas supply pressure
Procedures
1. Checktobesurethatthegassupplytothe
heater is turned on. Be sure the manual
shut-off valve is open.
2. Besurethat the pilot line has been purged
for sufficient time to remove air from the
line.
Thepilot line canbe purgedby turningthe
control knob to the “PILOT”position and
fully depressing the knob. Ignition should
be attempted every 30 seconds until a
correct pilot flame is established. See
Owner’sManualforcorrectignitionproce-
dure.
3. Checkthepilotassemblyfordirt,cobwebs
or other restrictions. Be sure the heater
hasbeenturned off.Firstremove thewire
clip from the bi-metal strip located on the
pilot tube (see Figure 14). Remove the
brass cover and clean any dust or cob-
webs from the air/gas mixing chamber.
Reassemblethe brasscoverwiththewire
clipandretesttoseeifacorrectpilotflame
is established. If the above procedure
does not give satisfactory results, discon-
nectthepilotassemblyandremoveitfrom
the heater. Blow out the pilot tube from
bothdirectionstoremoveanyrestrictions.
Also inspect the pilot line tubing for dirt,
kinks in the line or other restrictions. Re-
place the pilot assembly if necessary.
4. Check gas supply pressure at the pres-
sure tap on the manual shut-off valve
belowtheheaterandatthemanifoldpres-
sure tap next to the control valve (see
Figure21,page17)tobesurethatenough
pressure is available to the system ac-
cording to the
“SPECIFICATIONS” sec-
tion on page 13. If the inlet pressure is
correct and the manifold pressure is low,
replacetheregulator,controlvalveorinlet
tubing as required.
Problem
Bi-metal Strip
Brass Cover
Wire Clip
Figure 14. Ignitor/Pilot Assembly

16
VENT-FREE GAS HEATER SERVICE MANUAL
COLD-START CHOKE ADJUSTMENT GRH/OV 027
Pilot ignites but will not stay lit
Possible Causes
1. Control knob not held down long enough
2. Defective valve or thermocouple
3. Not enough fresh air
4. Wrong air/gas mixture at pilot
Procedures
1. Besure that thecontrol knob isheld down
long enough to get the thermocouple hot.
After lighting the pilot, hold the control
knob down for 10 to 15 seconds before
releasing.
2. Check to be sure that the pilot flame pat-
tern is correct (see Figures 15 & 16).
Figure 15. Correct LP Pilot Flame
Figure 16. Correct Natural Gas Pilot Flame
If the pilot flame appears to be normal,
check the control valve according to the
test procedure outlined on page 12 under
“TestingControlValveandThermocouple” .
Ifthevalvepassesthetesting,thethermo-
couple may be defective and should be
replaced.
3. If the pilot flame is lifting off the thermo-
coupleas shownin Figure 17, check tobe
sure that the room is properly ventilated.
See “SPECIFICATIONS” ,page13,forthe
minimum fresh air openings required. If
necessary,instructtheusertoslightlyopen
a window for proper ventilation.
4. Be sure that strong or gusty drafts are not
blowing on the heater. If necessary, the
GRH/OV 007GOOD PILOT/LP
GRH/OV 009GOOD PILOT
GRH/OV 008BAD PILOT/LP
LP
GRH/OV 010BAD PILOT
Natural Gas
Figure 18. Pilot Barrel Liftoff
LP
Figure 17. Pilot Barrel Liftoff
heater should be relocated to a more
protected area.
If the pilot flame is incorrect as shown in
Figure 18, it is possible that the cold-start
choke is allowing too much air to enter the
pilot tube. Turn the heater off, remove the
frontcoverfromtheheater,andinspectthe
cold-start choke on the pilot tube.
Insert a 1/4 inch diameter rod (i.e., a 1/4
inch drill bit will do) under the bi-metal strip
to adjust the cold-start choke to the nearly
closedposition (seeFigure19).Relightthe
pilot and observe to see if the pilot flame is
more stable. Replace the front cover.
GRH/OV 007AFLAME LIFTING/LP
Liftoff
LP
Figure 19. Cold-Start Choke Adjustment
GRH/OV 009AFLAME LIFTING
Liftoff
Natural Gas
Figure 18. Thermocouple Liftoff
1/4" Rod

17
VENT-FREE GAS HEATER SERVICE MANUAL
2
1
0
1
2
3
4
5
6
GRH/OV 026
5-Plaque
Thermostat
Propane Models
3-Plaque
Thermostat &
Non-Thermostat
Natural Gas
Models
3
4
5
6
7.7"
MANIFOLD PRESSURE-GRH
2
1
0
1
2
3
4
5
6
3
4
5
6
5.3"
2
1
0
1
2
3
4
5
6
3
4
5
6
5.0"
2
1
0
1
2
3
4
5
6
3
4
5
6
7.0"
3-Plaque
Thermostat &
Non-Thermostat
& 5-Plaque
Non-Thermostat
Propane Models
5-Plaque
Thermostat &
Non-Thermostat
Natural Gas
Models
Ifthepilotflameisshortasshown in Figure
20, check for low pressure to the pilot.
First, be sure that the gas supply inlet
pressure to the heater is adequate. Check
the line for proper size.
Second, check manifold pressure with a
manometer to be sure that the regulator is
not defective. See “SPECIFICATIONS” on
page 13 for the model you are servicing.
Third, check the pilot assembly and pilot
line to be sure that a restriction, such as
dustordirt is notpresent. Blow outthepilot
assembly from both directions to remove
any dirt. Replace the pilot assembly if nec-
essary.
Figure 20. Short Flame
GRH/OV 012ASHORT FLAME/LP
3. Read the manometer water level both
above and below the zero (0) mark, then
add the readings to give the correct
manifold pressure.
1. Fill tube with water until you see the water
level off at zero (0) on both sides.
2. Connect rubber hose to the line to be
tested.
How To Use A Manometer
Manifold
Pressure
Tap (1/8" NPT)
Control
Valve
Manometer
Connect Rubber
Hose At Manifold
Pressure Tap
Control
Valve
Figure 21. Measuring Manifold Pressure

18
VENT-FREE GAS HEATER SERVICE MANUAL
Problem
Main burner does not light (pilot stays lit)
Possible Causes
1. Low inlet gas pressure
2. Burner orifice is clogged
3. Burner orifice is not correct
Procedures
1. Besurethatthesupplypressureand line
size to the heater is adequate. Refer to
“SPECIFICATIONS” on page 13 for the
modelyouareservicing.Ifthesupplyline
is the correct size and the supply pres-
sure is low, contact your local gas com-
pany or LP supplier.
Propane (LP) Models Only:
A. Be sure tank is not empty or nearly
empty.
B. Be sure tank is not frozen due to high
usagerateson a small propane cylin-
der. If many appliances or heating
devices are being run off the same
tank,evaporationratescancausethe
remaining liquid to cool and create
GRH/P 031
Burner Orifice
frost or ice on the outside of the tank.
The ice acts as an insulator and can
reduce the evaporation rate and the
pressure to your heater. If an im-
proper tank size is causing a low
supply pressure to the heater, con-
tactthelocalLPgassupplierforproper
tank sizing.
2. Check the burner orifices to be sure that
they are not clogged. Remove the
orifice(s)andexaminefordirtorparticles
which would restrict the flow of gas. DO
NOTattempttocleantheorifice(s)witha
wire. Blow out the orifice(s) or gently
clean. Replace the orifice(s) if neces-
sary.
3. Check the burner orifice size. Refer to
the proper drill size in “SPECIFICA-
TIONS” onpage13forthemodelyouare
servicing. If an orifice is not the correct
size, it should be replaced.
Problem
Delayed ignition of main burner
Possible Cause
1. Low pressure to one or more burner
plaques.
Figure 22. Burner Orifice
Procedure
1. Check for the cause of low pressure by
following procedure number 3 under
“Problem: Gas odor” at the bottom of
page 19.
Burner Orifice (Injector)
Washer
Injector Holder

19
VENT-FREE GAS HEATER SERVICE MANUAL
Problem
Smoke or unwanted odors
Possible Causes
1. Oil or residue from manufacturing proc-
esses
2. Household chemicals
Procedures
1. If oils or residues from manufacturing
processes are present in the heater, the
problemwill usuallybeeliminatedaftera
few hours of operation. If odors persist,
remove the front panel and examine the
inside of the heater cabinet for oil or
foreign material.
2. Some household chemicals, such as
paint, hair spray or glues can produce
unwantedodorswhentheheaterisoper-
ating. Ventilate the room and advise the
user to discontinue using such products
while the heater is operating.
Procedure
1. Inspect the ceramic burner plaques to
see if the plaques are cracked or badly
chipped. If a burner plaque is cracked or
broken, replace the burner.
2 Check for low pressure to the burner by
following procedure number 3 under
“Problem: Gas odor” (bottom of page).
Problem
Backfiring during operation
Possible Causes
1. Burner damaged
2. Low pressure to one or more burner
plaques
Combustion Problems
!
WARNING ICON G 001
Problem
Gas odor
Possible Causes
1. Gas leak
2. Defective control valve
3. Dirt or particles clogging gas line
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. Follow the gas
supplier’s instructions.
•If you cannot reach your gas supplier,
call the fire department.
Procedures
1. Checkallheater and gassupplyconnec-
tions for leaks. See procedures under
“Testing Gas Supply Line Connections”
and “Testing Heater Gas Connections”
on page 11 of this service manual.
2. If all gas connections inside and outside
of the heater have been checked and
found to be free of leaks, check for a
defectivecontrolvalve.Visuallyexamine
thesurfaceofthecontrolvalvetobesure
thatitisnotcracked,dentedordamaged.
Asmall mirror andflashlight maybe nec-
essary to examine the rear of the valve.
Checktobesurethatthevalveismounted
securely in a vertical position, and that
the control knob can be turned to all
positions. If any defect is found, replace
the control valve. Be sure to test all gas
connections for leaks after replacing the
control valve.
3. Low pressure to one or more burner
plaques can result in improper combus-
tion and gas odor. Check burner opera-
tion at the “HIGH”setting to see if all
plaques have the same uniform color.
A. If one plaque is glowing less than the
others, dirt or particles may be clog-
ging the line between the valve and
theburner,ortheburnerpipemaybe
blocked by spider webs or other ob-
structions. Turn off gas to the heater
at the manual shut-off valve below
the heater. Remove the appropriate
gas line(s) to the burner and clean
foreignmatterfromthetubing.Check
theburnerorificesandcleanifneces-
sary.
B. If all plaques do not develop a full
radiance,checkmanifoldpressureat
the 1/8" NPT tap located next to the
control valve. See
“SPECIFICA-
TIONS”
on page 13 for the model of
heater you are servicing. If manifold
pressure is low, check inlet (supply)
pressure to the heater. If the inlet
supply pressure is correct, clean the
inlet tube between the regulator and
valve.Replacetheregulatorandvalve
if necessary.

TECHNICAL SERVICE
You may have further questions about installation, operation, or troubleshooting.
If so, contact DESA International’s Technical Service Department at 1-800-323-5190.
REPLACEMENT PARTS
Note: Use only original replacement parts. This will protect your warranty coverage for parts
replaced under warranty.
Parts Under Warranty
Contact authorized dealers of this product. If they can’t supply original replacement part(s), call
DESA International’s Technical Service Department at 1-800-323-5190.
When calling DESA International, have ready
•your name
•your address
•your heater’s model number
•how heater was malfunctioning
•type of gas used (propane or natural gas)
•purchase date
In most cases, we will ask you to return the defective part to the factory.
Parts Not Under Warranty
Contact authorized dealers of this product. If they can’t supply original replacement part(s), call
DESA International’s Parts Department at [phone].
When calling DESA International, have ready
•your heater’s model number
•the replacement part number
098734-01
Rev. D
12/89
DESA
INTERNATIONAL
Corporate Headquarters
P.O. Box 90004
2701 Industrial Drive
Bowling Green, Kentucky 42102-9004
502-781-9600
R
ILLUSTRATED PARTS LISTS
Illustrated parts lists can be obtained free of charge. Send a self-addressed, stamped envelope
to the address listed below. List the heater model number and the date located in the lower right
corner of this page.