Desa RH125TH User manual

IMPORTANT: Read and understand this manual before assembling, starting or servicing
heater.Improperuseofheatercancauseseriousinjury.Keepthismanualforfuturereference.
Heater Size: 125,000 Btu/Hr
Kerosene/Diesel Heater with Built-in Thermostat
PORTABLE FORCED
AIR HEATER
OWNER’S MANUAL
TABLE OF CONTENTS
SAFETY INFORMATION ............................................................ 2
PRODUCT IDENTIFICATION ..................................................... 3
UNPACKING ............................................................................... 3
FUELS......................................................................................... 3
VENTILATION............................................................................. 3
THEORY OF OPERATION ......................................................... 4
ASSEMBLY ................................................................................. 4
OPERATION ............................................................................... 5
OPERATION WITH PORTABLE GENERATOR.......................... 5
STORING, TRANSPORTING, OR SHIPPING............................ 5
PREVENTATIVE MAINTENANCE SCHEDULE ......................... 6
TROUBLESHOOTING ................................................................ 7
SERVICE PROCEDURES .......................................................... 8
SPECIFICATIONS .................................................................... 13
REPLACEMENT PARTS .......................................................... 13
TECHNICAL SERVICE ............................................................. 13
ACCESSORIES ........................................................................ 13
ILLUSTRATED PARTS BREAKDOWN AND PARTS LIST ....... 14
WHEELS AND HANDLE PARTS LIST...................................... 16
WIRING DIAGRAM ................................................................... 16
OWNER'S REGISTRATION FORM .......................................... 17
WARRANTYAND REPAIR SERVICE ...................................... 20
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Fill In For Your Records
Model No. ___________________
(Located on side panel)
Serial No. ___________________
(Located on fuel tank)
Date of Purchase: ______________

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SAFETY INFORMATION
WARNING:Thisproductcontainsand/orgenerates
chemicals known to the State of California to cause
cancer or birth defects, or other reproductive harm.
IMPORTANT: Read this owner’s manual carefully and
completely before trying to assemble, operate, or ser-
vice 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, and/or nau-
sea.Ifyouhavethesesigns,theheatermaynotbeworkingproperly.
Getfreshairatonce!Haveheater serviced.Some peopleare more
affected by carbon monoxide than others. These include pregnant
women, persons with heart or lung disease or anemia, those under
the influence of alcohol, and those at high altitudes.
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.
• Use only kerosene, #1/#2 diesel/fuel oil, JET A or JP-8 fuels
to avoid risk of fire or explosion. Never use gasoline, naphtha,
paint thinners, alcohol, or other highly flammable fuels.
• Fueling
a) Personnel involved with fueling shall be qualified and thor-
oughly familiar with the manufacturer's instructions and ap-
plicableregulationsregardingthesafefuelingofheatingunits.
b) Only the type of fuel specified on the heater's data plate
shall be used.
c) All flame, including the pilot light, if any, shall be extin-
guished and the heater allowed to cool, prior to fueling.
d) During fueling,allfuel lines andfuel-line connections shall
be inspected for leaks.Any leaks shall be repaired prior to
returning the heater to service.
e) At no time shall more than one day's supply of heater fuel
be stored inside a building in the vicinity of the heater.
Bulk fuel storage shall be outside the structure.
f) All fuel storage shall be located a minimum of 25 feet
(762cm) from heaters, torches, welding equipment, and
similar sources of ignition (exception: the fuel reservoir
integral with the heater unit).
g) Whenever possible, fuel storage shall be confined to ar-
eas where floor penetrations do not permit fuel to drip
onto or be ignited by a fire at lower elevation.
h) Fuel storage shall be in accordance with the authority hav-
ing jurisdiction.
• Use only the electrical voltage and frequency specified on
model plate.
• Heater must be grounded. Use only a properly grounded three-
wire extension cord. Plug into grounded outlet only.
• Use only in areas free of flammable vapors or high dust content.
• Minimum clearance from any combustible materials: 8 feet
(244 cm) from hot air outlet; 6 feet (183 cm) from top; and 4
feet (120 cm) from sides and inlet.
• Locate heater on a stable and level surface while hot or operat-
ing or a fire may occur.
• Use only in well-vented areas. Before using heater, provide at
least a three-square-foot (2800 square cm) opening of fresh,
outside air for each 100,000 Btu/Hr (30 kw) of rating.
• Keep children and animals away from heater at all times.
• Never start heater when combustion chamber is hot or if fuel
has accumulated in combustion chamber.
• When used with thermostat, heater may start at anytime.
• When heater is moved or stored, it must be in a level position
or fuel spillage may occur.
• Use heater only in accordance with local ordinances and codes.
• Never use gasoline, crankcase drainings, naphtha, paint
thinners, alcohol, or other highly flammable fuels.
• Never use heater where gasoline, paint thinner, or other highly
flammable vapors are present.
• Never use heater in living or sleeping areas.
• Never leave a heater plugged in without adult supervision if
children or animals are likely to be present.
• Never move, handle, refuel, or service a hot, operating, or
plugged-in heater.
• Never attach duct work to front or rear of heater.
• Never attach heater to external fuel tank.
• Heaters used in the vicinity of tarpaulins, canvas, or similar
enclosure materials shall be located a safe distance from such
materials. The recommended minimum safe distance is 10 feet
(304.8 cm). It is further recommended that these enclosure ma-
terials be of a fire retardant nature. These enclosure materials
shall be securely fastened to prevent them from igniting or
from upsetting the heater due to wind action.
• Unplug heater when not in use.
• Never block air inlet (rear) or air outlet (front) of heater.
SAFETY INFORMATION

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PRODUCT IDENTIFICATION
PRODUCT IDENTIFICATION
UNPACKING
FUELS
VENTILATION
UNPACKING
1. Remove all packing items applied to heater for shipment.
2. Remove all items from carton.
3. Check items for any shipping damage. If heater is damaged,
promptly inform dealer where you bought heater.
Figure 1 - 125TH Model
FUELS
Use only kerosene, #1/#2 diesel/fuel oil, JET A or JP-8 fuels.
Heavier fuels such as No. 2 fuel oil or No. 2 diesel fuel may also be
used but will result in:
• noticeable odor
• additional fuel filter maintenance
• the need for nontoxic, anti-icer additives in very cold weather
Do not use fuels heavier than No. 2 grade or heavy oils such as oil
drained from crankcases. These heavy oils will not ignite properly
and will contaminate the heater.
IMPORTANT: UseaKEROSENEONLY(blue)orDIESELONLY
(yellow)storagecontainer.Besurestoragecontainerisclean.Foreign
matter such as rust, dirt, or water will cause the ignition control
assembly to shut down heater. Foreign matter may also require
heater's fuel system to be frequently cleaned.
WARNING: Use only kerosene, #1/#2 diesel/fuel
oil, JET A or JP-8 fuels to avoid risk of fire or explo-
sion. Never use gasoline, oil drained from crank-
cases,naphtha,paintthinners,alcoholorotherhighly
flammable fuels.
VENTILATION
WARNING: Provide a fresh air opening of at least
three square feet (2,800 square cm) for each 100,000
BTU/HRrating.Provideextrafreshairifmoreheaters
are being used. The minimum ventilation require-
ments must be followed to avoid risks associated
withcarbonmonoxidepoisoning.Makecertainthese
requirements are met prior to operating heater.
Example: A 125,000 Btu/Hr (36.6kw) heater requires one of the
following:
• a two-car garage door [16 feet (4.88 meter) opening] raised
3 inches (7.6 cm)
• a single-car garage door [9 feet (2.74 meter) opening] raised 5
inches (12.7 cm)
• two, 30 inch (76.2 cm) windows raised 9 inches (22.9 cm)
Lower
Shell
Hot Air
Outlet
Control
Cover
Fuel Cap/
Gauge
Upper Shell
Ignition Control Assembly
(On Inside of Control Cover)
Fan
Guard
Fuel Tank
Thermostat Knob
ON/OFF
Switch
Shroud
Rear Panel
Handle
Extension
Cord Wrap

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Figure 2 - Cross Section Operational View
THEORY OF OPERATION
ASSEMBLY
ASSEMBLY
These models are furnished with wheels and a rear handle. Wheels,
handle,andthemountinghardwarearefoundintheshippingcarton.
Tools Needed
• Medium Phillips Screwdriver
• Rubber Mallet/Hammer
• Flat Blade Screwdriver
1. Apply a couple drops of oil in shroud axle holes. Slide axle
through shroud with a twisting motion. Install washers and
wheels on axle as shown in Figure 3.
IMPORTANT: When installing wheels, point extended hub of
wheels toward shroud (see Figure 3).
2. Place cap nuts on axle ends. Gently tap with hammer to secure.
3. Install extension cord wraps into handle.
4. Slide handle onto shroud leaving a one inch gap between parts.
5. Place washers onto screws and insert screws into holes in
handles.
6. Visually confirm that all six screws are threaded into nuts in
the shroud. Push the handle completely into the shroud.
7. Tighten all scews.
THEORY OF OPERATION
TheFuel System: Theair pump forcesair throughthe air line.The
airisthenpushedthroughthenozzle.Thisaircausesfueltobelifted
from the tank. A fine mist of fuel is sprayed into the combustion
chamber.
The Air System: The motor turns the fan. The fan pushes air into
andaroundthecombustionchamber.Thisairisheatedandprovides
a stream of clean, hot air.
The Ignition System: The ignition control assembly provides
powertotheignitor.Thisignitesthefuel/air mixtureinthecombus-
tion chamber.
The Flame-Out Control System: This system causes the heater to
shut down if the flame goes out.
Clean
Heated
Air Out
Fuel Filter Air Line
To Burner
Air
Output
Filter
Air Pump
Air Intake
Filter
Cool
Air In
Fan
Combustion Chamber
Ignitor Motor
Ignition
Control
Assembly
Air For Fuel System Air For Combustion
And Heating Fuel
Fuel
Tank Nozzle
Figure 3 - Wheel and Handle Assembly
Axle
Extension
Cord Wrap
Air Inlet Rear Panel
Hot Air Outlet
Wheel
Handle Screw
Washer
Extended Hub
Washer
Shroud
Cap Nut
Shroud
Axle Hole

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OPERATION
OPERATION WITH PORTABLE GENERATOR
STORING, TRANSPORTING, OR SHIPPING
TO START HEATER
1. Follow all ventilation and safety information.
2. Locate heater to provide maximum circulation of the heated
air. Follow all location requirements noted in Safety Informa-
tion, page 2.
3. Fill fuel tank with fuel. Use only kerosene, #1/#2 diesel/fuel
oil, JETAor JP-8 fuels to avoid risk of fire or explosion. Never
use gasoline, naphtha, paint thinners, alcohol, or other flam-
mable fuels.
4. Attach fuel cap/gauge.
5. Plug heater’s power cord into approved, grounded, three-wire
extension cord. Extension cord must be at least six feet (1.8
meters) long.
Extension Cord Size Requirement
6 to 10 feet (1.8 to 3 meters) long, use 18 AWG (0.75 mm2)
rated cord
11 to 100 feet (3.3 to 30.5 meters) long, use 16AWG (1.0 mm2)
rated cord
101to 200 feet (30.8 to 61meters) long, use 14AWG (1.5mm2)
rated cord
6. Plug extension cord into standard 120 volt/60 hertz, 3-prong
grounded outlet.
7. Turn thermostat knob to the right (clockwise) to the warmest
position.
8. Push ON/OFF switch to the ON (|) position. Light will come on.
Note: Ignitor will preheat for five seconds, then heater will start.
9. After heater is running, adjust thermostat knob to the desired
setting. Note: A cold heater may affect the thermostat setting.
This thermostat is a general-heating control. It is not intended
for precise temperature control.Adjust thermostat until heater
cycles at the desired setting.
TO STOP HEATER
Push ON/OFF switch to the OFF (O) position.
TO RESET HEATER
1. Push ON/OFF switch to the OFF (O) position and wait 10 sec-
onds. (Wait two minutes if heater has been running.)
2. Repeat steps under To Start Heater.
OPERATION
IMPORTANT: Review and understand the warnings
in the
Safety Information section, page 2. They are
needed to safely operate this heater. Follow all local
ordinances and codes when using this heater. WARNING: Before operating heater or any appli-
ance from a portable generator, verify that generator
has been properly connected to earth ground. Im-
proper grounding or failure to ground generator can
result in electrocution if a ground fault occurs. Refer
to owner’s manual supplied by generator manufac-
turer for proper grounding procedures.
The operating voltage range of the heater is 108 to 132 Volts (120
Volts +/- 10%). Prior to plugging heater into generator the output
voltageshouldbeverified(ifgeneratorisequippedwiththeautomatic
idlefeature,theoutputvoltageshouldbemeasuredwiththegenerator
runningatfullspeed).Ifthevoltagedoesnotmeasureinthisrangethe
heater should not be plugged into the generator.
Refer to Operation for starting, stopping, and resetting heater
procedures.
STORING, TRANSPORTING,
OR SHIPPING
Note: Ifshipping,transportcompaniesrequirefueltankstobeempty.
1. Remove drain plug from bottom side of fuel tank and drain
all fuel.
2. Replace drain plug.
3. If any debris is noted in old fuel, add 1 or 2 quarts of clean
kerosene to tank, stir, and drain again. This will prevent ex-
cess debris from clogging filters during future use.
4. Properly dispose of old and dirty fuel. Check with local auto-
motive service stations that recycle oil.
5. If storing, store heater in dry place. Make sure storage place is
free of dust and corrosive fumes.
IMPORTANT: Do not store kerosene over summer months for use
during next heating season. Using old fuel could damage heater.
OPERATION WITH PORTABLE
GENERATOR
Figure 4 - Typical Generator Grounding Method (Generator
construction may vary from that shown)
Ground Lug
Ground Wire (#10 AWG -
Stranded-Copper)
Alternator Copper or Brass
Grounding Point

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PREVENTATIVE MAINTENANCE SCHEDULE
PREVENTATIVE MAINTENANCE SCHEDULE
How To
See Storing, Transporting, or Shipping, page 5
See Air Output, Air Intake, and Lint Filters, page 8
See Air Output, Air Intake, and Lint Filters, page 8
See Fuel Filter, page 9
See Fan, page 8
WARNING: Never service heater while it is plugged in, operating, or hot. Severe burns and electrical shock
can occur.
Item
Fuel tank
Air output and lint filters
Air intake filter
Fuel filter
Ignitor
Fan blades
Motor
How Often
Flushevery150-200hoursofoperationorasneeded
Replaceevery 500hours ofoperation oronce ayear
Wash and dry with soap and water every 500 hours
of operation or as needed
Clean twice a heating season or as needed
No maintenance required
Clean every season or as needed
Not required/permanently lubricated

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REMEDY
1. Check circuit breaker in electrical panel
2. Verify the ON/OFF switch is in ON (|)
position and light is on
3. Turn thermostat knob to a higher setting
4. Check all electrical connections. See Wir-
ing Diagram, page 16
5. If fan doesnot turnfreely, see Pump Rotor,
page 12
6. See Ignition Control Assembly, page 12
7. Replace ignition control assembly
8. Replace motor
1. Fill tank with kerosene
2. See Pump Pressure Adjustment, page 9
3. See Fuel Filter, page 9
4. See Nozzle Assembly, page 11
5. Drain and flush fuel tank with clean kero-
sene. See Storing, Transporting, or Ship-
ping, page 5
6. Check electrical connections. See Wiring
Diagram, page 16
7. Replace ignitor, see page 10
8. Replace ignition control assembly
1. See Pump Pressure Adjustment, page 9
2. See AirOutput,Air Intake, and LintFilters,
page 8
3. See Fuel Filter, page 9
4. See Nozzle Assembly, page 11
5. Make sure photocell boot is properly
seated in bracket
6. Clean photocell lens
7. Check electrical connections. See Wiring
Diagram, page 16
8. Replace photocell
9. Replace ignition control assembly
POSSIBLE CAUSE
1. No power to heater
2. ON/OFF switch not in the ON (|) position
3. Thermostat setting is too low
4. Bad electrical connection between motor
and ignition control assembly or ignition
control assembly and power cord
5. Binding pump rotor
6. Blown fuse (GMA 10A) on ignition con-
trol assembly
7. Defective ignition control assembly
8. Defective motor
1. No fuel in tank
2. Pump pressure incorrect
3. Dirty fuel filter
4. Obstruction in nozzle
5. Water in fuel tank
6. Bad electrical connection between igni-
tor and ignition control assembly
7. Defective ignitor
8. Defective ignition control assembly
1. Pump pressure incorrect
2. Dirty air intake, air output, and/or
lint filter
3. Dirty fuel filter
4. Obstruction in nozzle
5. Photocell assembly not properly installed
(not seeing the flame)
6. Dirty photocell lens
7. Bad electrical connection between pho-
tocell and ignition control assembly
8. Defective photocell
9. Defective ignition control assembly
FAULT CONDITION
Motor does not start five seconds after
heater is plugged in
Motor starts and runs but heater does not
ignite
Heater ignites but ignition control assem-
bly shuts heater off after a short period of
time
TROUBLESHOOTING
WARNING: Neverserviceheaterwhileitisplugged
in, operating, or hot. Severe burns and electrical
shock can occur.
WARNING: High voltage!
WARNING: High voltage!
WARNING: High voltage!
TROUBLESHOOTING

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1
SERVICE PROCEDURES
WARNING: To avoid risk of burn and electrical
shock, never attempt to service heater while it is
plugged in, operating, or hot.
Figure 5 - Upper Shell Removal
Upper Shell
UPPER SHELL REMOVAL
1. Remove screws along each side of heater using phillips screw-
driver. These screws attach upper and lower shells together.
See Figure 5.
2. Lift upper shell off.
3. Remove fan guard.
Screw
FAN
IMPORTANT: Remove fan from motor shaft before removing
motorfrom heater. Theweight ofthe motor restingon the fancould
damage the fan pitch (see Figure 6).
1. Remove upper shell (see Figure 5).
2. Use 1/8" allen wrench to loosen setscrew which holds fan to
motor shaft.
3. Slip fan off motor shaft.
4. Clean fan using a soft cloth moistened with kerosene or solvent.
5. Dry fan thoroughly.
6. Replace fan on motor shaft. Place fan hub flush with end of
motor shaft (see Figure 7).
7. Place setscrew on flat of shaft.Tighten setscrew firmly (40-50
inch-pounds/4.5-5.6 n-m).
8. Replace upper shell.
AIR OUTPUT, AIR INTAKE AND LINT FILTERS
1. Remove upper shell (see Figure 5).
2. Remove filter end cover screws using 5/16" nut-driver (see
Figure 8).
3. Remove filter end cover.
4. Replace air output and lint filters.
5. Wash or replaceair intakefilter (see Preventative Maintenance
Schedule, page 6).
6. Replace filter end cover.
7. Replace upper shell.
IMPORTANT: Do not oil filters.
Motor
Shaft
Setscrew
Figure 6 - Fan, Motor Shaft,
and Setscrew Location
Motor
Shaft
Fan
Setscrew
Figure 7 - Fan Cross Section
Fan
Flush
Motor
Figure 8 - Air Output, Air Intake, and Lint Filters
Air Intake
Filter Filter End
Cover
Lint Filter
Air Output Filter
SERVICE PROCEDURES

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Upper Fuel Line
Figure 11 - Fuel Filter Removal
PUMP PRESSURE ADJUSTMENT
1. Remove fan guard using medium phillips screwdriver.
2. Remove pressure gauge plug from filter end cover (see Figure 9).
3. Install accessory pressure gauge (part number HA1180).
4. Start heater (see Operation, page 5). Allow motor to reach
full speed.
5. Adjust pressure. Turn relief valve to right to increase pressure.
Turn relief valve to left to decrease pressure. See specifica-
tions below for correct pressure (see Figure 10).
6. Remove pressure gauge. Replace pressure gauge plug in filter
end cover.
SERVICE PROCEDURES
Continued
Figure 9 - Pressure Gauge Plug Removal
Pressure
Gauge
Figure 10 - Adjusting Pump Pressure
Relief
Valve
Pump
Model Pressure
125TH 6.0 PSI
FUEL FILTER
1. Remove controlcoverscrews usingmediumphillips screwdriver.
2. Remove control cover.
3. Pull upper fuel line off fuel filter neck (see Figure 11).
4. Carefully pry bushing, fuel filter, and lower fuel line out of
fuel tank (see Figure 11).
5. Wash fuel filter with clean fuel and replace in tank.
6. Attach upper fuel line to fuel filter neck.
7. Replace control cover.
SERVICE PROCEDURES
Pressure
Gauge
Plug
Fuel Filter, Bushing,
and Lower Fuel Line
Control
Cover
Screw

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CAUTION: Do not bend or strike ignitor element.
Handle with care.
IGNITOR
1. Remove upper shell (See Upper Shell Removal, page 8).
2. Remove fan (see page 8).
3. Remove 2 control cover screws with a phillips screwdriver.
Remove control cover (see Figure 11, page 9).
4. Disconnect ignitor wires from ignition control assembly (see
Figure 12). Pull the ignitor wires up through the hole in the
lower shell.
5. Disconnect fuel line hose and air line hose. Remove photocell
from photocell bracket (see Figure 12).
6. Remove combustion chamber. Stand combustion chamber on
end with nozzle adapter bracket on top (see Figure 13).
7. Remove ignitor screw with a 5/16" nut driver. Carefully re-
move ignitor from nozzle adapter bracket.
8. Carefully remove replacement ignitor from packing.
Figure 12 - Disconnecting Ignitor Wires from Ignition Control
Assembly
Combustion
Chamber
Photocell
Bracket
Photocell
Assembly
Air Line Hose
Fuel Line Hose
Ignitor Wire
Ignitor
Nozzle Adapter
Bracket
Ignition
Control
Assembly
Control Cover
Photocell
Bracket
Ignitor
Nozzle Adapter
Bracket
Ignitor Element
Combustion
Chamber Nozzle Adapter
Bracket Opening
Figure 13 - Ignitor Replacement
SERVICE PROCEDURES
Continued
9. Carefully guide ignitor into opening in nozzle adapter bracket.
Do not strike ignitor element.Attach ignitor to nozzle adapter
bracket with screw using a 5/16" nut driver (see Figure 13).
Torque 8 to 15 in-lbs (.90 to 1.69 N-m) Do not over torque.
10. Replace combustion chamber.
11. Routethe ignitor wiresback down through the hole inthe lower
shell. Connect wires to the ignition control assembly (see Fig-
ure 12).
12. Replace control cover (see Figure 11, page 9).
13. Connect and route fuel line hose and air line hose to nozzle
adapter assembly. See Fuel and Air Line Replacement and
Proper Routing, page 11.
14. Replace photocell in photocell bracket. Route wires as shown
in either Figure 14, page 11.
15. Replace fan (see page 8).
16. Replace upper shell (see page 8).
SERVICE PROCEDURES

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SERVICE PROCEDURES
Continued
NOZZLE ASSEMBLY
1. Remove upper shell (see Upper Shell Removal, page 8).
2. Remove fan (see Fan, page 8).
3. Remove fuel and air line hoses from nozzle assembly (see
Figure 14).
4. Turn nozzle assembly 1/4 turn to left and pull toward motor to
remove (see Figure 15).
5. Place plastic hex-body into vise and lightly tighten.
6. Carefully remove nozzle from the nozzle adapter using 5/8"
socket wrench (see Figure 16).
7. Blow compressed air through face of nozzle. This will free
any dirt in nozzle area.
8. Inspect nozzle sleeve for damage.
9. Replace nozzle into nozzle adapter until nozzle seats. Tighten
1/3 turn more using 5/8" socket wrench 40 to 45 in-lbs (4.5 to
5.1 N-m). See Figure 16.
10. Attachnozzle assemblyto nozzleadapterbracket (seeFigure 15).
11. Attach fuel and airline hoses to nozzle assembly. See Fuel and
Airline Replacement and Proper Routing.
12. Replace fan (see Fan, page 8).
13. Replace upper shell (see Upper Shell Removal, page 8).
Figure 14 - Removing Air and Fuel Line Hoses
Fuel Line Hose
Nozzle/
Adapter
Assembly
Combustion
Chamber
Photocell
Bracket
Air Line
Hose
Nozzle
Adapter
Bracket
Figure 15 - Removing Nozzle/Adapter Assembly
Nozzle/Adapter
Assembly
Combustion
Chamber
Figure 16 - Nozzle and Nozzle Adapter
Nozzle
Face
Nozzle
Nozzle Sleeve
Nozzle Adapter
Air Line Fitting Fuel Line
Fitting
SERVICE PROCEDURES
FUEL AND AIR LINE REPLACEMENT AND
PROPER ROUTING
1. Remove upper shell (see Upper Shell Removal, page 8).
2. Remove control cover screws using phillips screwdriver (see
Figure 11, page 9).
3. Remove control cover.
4. Inspect fuel and air line hoses for cracks and/or holes. If fuel
line hose is damaged, disconnect from nozzle adapter (see Fig-
ure 14) and from fuel filter (see Fuel Filter, page 9). If air line
hose is damaged, disconnect from nozzle adapter (see Figure 14)
and from barb fitting on pump end cover (see Figure 17).
5. Install new air and/or fuel line.Attach one end of air line hose
to barb fitting on pump end cover (see Figure 17) and the other
end to nozzle adapter (see Figure 14). Attach one end of fuel
line hose to fuel filter (see Fuel Filter, page 9) and the other
end to nozzle adapter (see Figure 14).
Note: Routehoses asshown in Figure14. Hoses arenot totouch
photocell bracket.
6. Replace control cover.
7. Replace upper shell (see Upper Shell Removal, page 8).
Figure 17 - Air Hose to Barb Fitting
Barb Fitting
Pump End
Cover
Air Hose

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IGNITION CONTROL ASSEMBLY
WARNING: High voltage!
Fuse
Fuse Cover
Fuse Clips
1. Unplug heater.
2. Remove control cover screws (2) using phillips screwdriver to
expose ignition control assembly (see Figure 11, page 9).
3. Remove fuse cover.
4. Remove fuse from fuse clips.
5. Replace with new fuse (DESA Heating Products part number
105880-02). Do not substitute a fuse with a higher current rat-
ing. Use Bussmann GMA-10 or equivalent.
6. Replace fuse cover.
7. Replace control cover (see Figure 11, page 9).
PUMP ROTOR
(Procedure if Rotor is Binding)
1. Remove upper shell (see Upper Shell Removal, page 8).
2. Remove fan guard.
3. Remove filter end cover screws using 5/16" nut driver (see
Figure 18).
4. Remove filter end cover and air filters.
5. Remove pump plate screws using 5/16" nut-driver.
6. Remove pump plate.
7. Remove rotor, insert, and blades (see Figure 18).
8. Check for debris in pump. If debris is found, blow out with
compressed air.
9. Install insert and rotor.
10. Check gap on rotor. Adjust to .003"/.004" (.076/.101 mm) if
needed (see Figure 19).
Note: Rotate rotor one full turn to ensure the gap is .003"/.004"
(.076/.101 mm) at tightest position.Adjust if needed.
11. Install blades, pump plate, air filters, and filter end cover.
12. Replace fan guard and upper shell (see Upper Shell Removal,
page 8).
13. Adjust pump pressure (see Pump PressureAdjustment, page 9).
Note: If rotor is still binding, proceed as follows.
SERVICE PROCEDURES
Continued
Figure 18 - Rotor Location
Insert
Blade
Rotor
Pump Plate
Air Intake
Filter
Air Output
Filter
Filter End
Cover
Gap Adjusting Screw
Rotor
Blade
.003"/.004"
(.076-.101 mm)
Gap Measured
With Feeler
Gauge
Gap Adjusting Screw
Figure 19 - Gap Adjusting Screw Locations
Sandpaper
Figure 20 - Sanding Rotor
SERVICE PROCEDURES
Figure 21 - Replacing Fuse
14. Perform steps 1 through 6.
15. Place fine grade sandpaper (600 grit) on flat surface. Sand ro-
tor lightly in “figure 8” motion four times (see Figure 20).
16. Reinstall insert and rotor.
17. Perform steps 10 through 12.

112865-01A
13
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For more information, visit www.desatech.com
SPECIFICATIONS
Output Rating (Btu/Hr) 125,000
Fuel Use only kerosene, #1/#2 diesel/fuel oil, JET A or JP-8
fuels*
Fuel Tank Capacity (U.S. Gal./Liters) 13.5/51
Fuel Consumption (Gal. Per Hr/Liters Per Hr) .90/3.41
Pump Pressure (psi) 6.0
Electric Requirements 120 V/60 HZ
Amperage (Normal Run) 3.6
Maximum Motor Speed (RPM) 3400
Hot Air Output (CFM) 520
Motor Horsepower 1/5
Shipping Weight 77/34.9
(Approximate Pounds/Kilograms)
Heater Weight without Fuel 69/31.3
(Approximate Pounds/Kilograms)
* Use of #2 diesel/fuel oil will result in noticeable odor and could
require additional fuel filter maintenance. Use in extreme cold
temperatures may require nontoxic anti-icer additives.
SPECIFICATIONS
REPLACEMENT PARTS
TECHNICAL SERVICE
ACCESSORIES
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
originalreplacement part(s), call DESA Heating Products’ Techni-
cal Service Dept. at 1-866-672-6040.
When calling DESA Heating Products, have ready:
• your name
• your address
• model and serial numbers of your heater
• how heater was malfunctioning
• purchase date
Usually, we will ask you to return the part to the factory.
PARTS NOT UNDER WARRANTY
Contactauthorizeddealersofthisproduct.Iftheycan’tsupplyoriginal
replacementpart(s), call DESA Heating Productsat 1-866-672-6040
for referral information. Parts dealers are listed in the Authorized
Service Center booklet supplied with heater.
When calling DESA Heating Products, have ready:
• model and serial numbers of your heater
• the replacement part number
TECHNICAL SERVICE
You may have further questions about installation, operation, or
troubleshooting. If so, contact DESA Heating Products’ 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 Products’ technical services web
site at www.desatech.com.
ACCESSORIES
Purchase accessories and parts from your nearest dealer or
service center. If they can not supply these accessories or parts,
either contact your nearest parts dealer or DESA Heating Prod-
ucts at 1-866-672-6040 for referral information. Parts Centrals are
listed in the Authorized Service Center booklet supplied with
heater.
AIR GAUGE KIT - HA1180
For all models. Special tool to check pump pressure.
IGNITION CONTROL ASSEMBLY/PHOTOCELL
TESTER - HA1170
Specialtoolusedtotesttheignitioncontrolassemblyandphotocell.

112865-01A
14
For more information, visit www.desatech.com
For more information, visit www.desatech.com
ILLUSTRATED PARTS
BREAKDOWN
MODELS
M125TH
RH125TH
ILLUSTRATED PARTS BREAKDOWN
Models M125TH and RH125TH
Motor and Pump Assembly
10-11
10-17
10-16
10-15
10-14
10-18
10-12
10-10
10-1
10-2
10-3
10-4
10-5
10-6
10-7 10-8
10-9
10-13
1
13
3
23 19
910
11
12
15
25
13
24
29
30
31
34
42
32
41
14
36
26
39
13
16
2
43
23
5
46
18
7
8
44
27
20
22
21
28
33
40
37
35
238
7-2
7-1
7-3
7-4
17

112865-01A
15
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For more information, visit www.desatech.com
PARTS LIST
MODELS
M125TH
RH125TH
Thislistcontains replaceable parts used in your heater. When ordering parts,be sure to
provide the correct model and serial numbers (from the model plate), then the part
number and description of the desired part.
PARTS LIST
M125TH and RH125TH
KEY PART
NO. NUMBER DESCRIPTION QTY.
KEY PART
NO. NUMBER DESCRIPTION QTY.
1 107353-10 Upper Shell (Service Part Will
Be Black) 1
2 108631-01 Screw, #10-16 x 1" 3
3 098512-77 Combustion Chamber 1
4 103154-05 Photocell Bracket 1
5 M10908-2 Screw, #6-32 x 3/8" 2
6 M16656-21 Photocell Assembly 1
7 ∆Burner Head Assembly 1
7-1 HA3027 Nozzle Assembly 1
7-2 102548-08 Ignitor Kit 1
7-3 104054-01 Nozzle Adapter 1
7-4 102336-05 Nozzle Adapter Bracket 1
8 M11084-26 Screw, #10-16 x 3/8" 2
9 097293-01 Fan 1
10 ∆Motor and Pump Assembly 1
10-1 102001-30 Motor 1
10-2 079975-02 Pump Body 1
10-3 FHPF3-5C Screw, #10-32 x 5/8" 2
10-4 M22009* Rotor Insert 1
10-5 M22456-1* Pump Rotor 1
10-6 M50545 Pump End Cover 1
10-7 M12179*** Intake Filter 1
10-8 M16545 Filter End Cover 1
10-9 M8940∞Steel Ball, 1/4" Diameter 1
10-10 M10993-1∞Relief Spring 1
10-11 M27694∞Adjusting Screw 1
10-12 M22997∞Plug 1
10-13 M12461-31 Screw, #10-32 x 1" 4
10-14 M12244-1*** Output Filter 1
10-15 M11637*** Lint Filter 1
10-16 104096-01 Fitting, Straight Nylon Barb 1
10-17 M8643* Blade 4
10-18 M12461-31 Screw, #10-32 x 1" 6
11 M50631 Rubber Bumper 2
12 101206-01 Motor Mounting Bracket 1
13 M11084-29 Screw, #10-16 x 3/4" 11
14 104068-02 Ignition Control Assembly 1
15 NTC-4C Hex Lock Nut, 1/4-20 2
16 108460-01 Fan Guard 1
17 M27417 Drain Plug (Includes “o”Ring) 1
18 108457-01 Shroud 1
19 M51345-12 Fuel Line 1
20 106896-01*** Fuel Filter 1
21 M51151-02 Fuel Line Tube 1
22 M10990-3 Rubber Bushing 1
23 M50814-08 Airline 1
24 107353-11 Lower Shell (Service Part Will
Be Black) 1
25 M50104-06 Bushing 2
26 M50104-01 Bushing 1
27 M12461-51 Screw, #10-16 x 0.38" 1
28 108708-01 Clip Nut 13
29 M10908-14 Screw, #8-32 x 1/4" 1
30 108088-12 Fuel Tank 1
31 097663-03 Fuel Cap/Gauge 1
32 108668-01 P.C. Board Support 5
33 108394-01 ON/OFF Switch 1
34 107994-01 Power Cord 1
35 108461-01 Control Cover 1
36 M9900-170 Wire Assembly, Black 2
37 104460-01 Knob 1
38 104458-01 Thermostat 1
39 108458-01 Rear Panel 1
40 M12461-18 Screw, #8-32 x 7/8" 1
41 097785-08 Foam Gasket 1
42 108739-01 Filler Neck Screen 1
43 097467-02 Button Plug 1
44 M9900-197 Wire Assembly, Green 1
__ 105880-02 Fuse (Not Shown) 1
__ 097785-09 T-stat Foam Gasket (Not Shown) 1
∆Not available as an assembly *** Included in Filter Kit (Part No. HA3017)
* Included in Rotor Kit (Part No. HA3004) ∞Included in Pump Adjustment Kit (Part No. HA3020)

112865-01A
16
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For more information, visit www.desatech.com
KEY PART PART
NO. NUMBER DESCRIPTION QTY.
1 108459-01 Handle/Support 1
2 WP 4C Washer 6
3 108630-01 Screw 6
4 108463-01 Extension Cord Wrap 2
5 M16801-5 Axle 1
6 108468-01 Washer 2
7 107426-01 Wheel Kit (Contains: 2
2 Wheels and Cap Nuts)
8 M28526 Cap Nut 2
WHEELS AND HANDLE
WIRING DIAGRAM
WHEELS AND HANDLE
WHEELS AND HANDLE PARTS LIST
1
2
6
5
7
8
3
4
WIRING DIAGRAM
Power Plug
120V/60Hz
Blue
Blue
White
Photocell
Ignition Control Assembly
Green
Black
Black
Green
Red
Black
White
White
Motor
Thermostat
Photocell
Photocell
Ignitor
Motor Return
AC Neutral (L2)
120V (L1)
Ignitor
Motor
White
ON/OFF Switch
with Light
5
41
Ignitor

1. Who will heater be used by? ❍ Individual ❍ Business
2. Will you use your heater in more than one location? ❍ Yes ❍ No
3. Where will the product be used? (You may select more than one.) ❍ Workshop ❍ Barn ❍ Residential Construction
❍ Commercial Construction ❍ Garage ❍ Factory ❍ Recreation ❍ Warehouse ❍ Utility Shed/Outbuilding
❍ Other ______________________________ (Specify)
4. Cost of product (excluding sales tax)? $________________________________
5. Maintenance/service work will be performed by: ❍ Self ❍ Service Center ❍ Other ___________________________________
6. If you bought this product yourself, did you plan to purchase this type of product before going into the store? ❍ Yes ❍ No
7. Type of store where product was purchased? ❍ Hardware ❍ Propane Dealer ❍ Natural Gas/Utility Co. ❍ Home Center or Builder’s Supply
❍ Farm/Ag. Supply ❍ Auto Parts ❍ Warehouse Club ❍ Industrial/Contractor Supply ❍ Rental Store
❍ Discount Store ❍ HVAC Dealer ❍ Other _________________________________________________
8. What is your primary source of heat? ❍ Propane (LP Gas) ❍ Natural Gas ❍ Kerosene ❍ Diesel ❍ Electric ❍ Other________________
9. What motivated you to buy this product? ❍ Sudden Cold Weather ❍ Replace Older Model ❍ D.I.Y. Home Project ❍ Emergency Back-Up Heat
❍ Heater on Sale ❍ Construction Project ❍ Hard to Heat Location ❍ Other ________________________________
10. How did you learn about this product brand? ❍ Advertisement ❍ Relative or Friend ❍ Co-Worker ❍ Store Representative
❍ Store Display ❍ Previously Owned a Heater ❍ Other _________________________________________________(Specify)
11. What other brands did you consider? ❍ None ❍ Master ❍ Remington ❍ All-Pro ❍ Dayton ❍ Universal ❍ Mr. Heater ❍ L.B.White Tradesman
❍ John Deere ❍ Dyna-Glo ❍ Dura-Heat ❍ Paulin ❍ Coleman ❍ Vogelzang American ❍ Other ___________________________________
12. Who selected the product? ❍Male ❍Female ❍Both
13. Level of Education of Purchaser: ❍ High School ❍ Vocation/Technical School ❍ Some College ❍ Completed College ❍ Graduate School
14. Age of Purchaser: ❍ Under 20 ❍ 20 - 29 ❍ 30 - 39 ❍ 40 - 49 ❍ 50 - 59 ❍ 60 or Over
15. Buyer’s total annual household income: ❍ Under $19,999 ❍ $20,000 to $34,999 ❍ $35,000 to $49,999
❍ $50,000 to $74,999 ❍ $75,000 to $99,999 ❍ $100,000 and Over
16. What is the population of your area? ❍ Under 10,000 ❍ 10,000 to 25,000 ❍25,000 to 50,000 ❍ 50,000 to 100,000
❍ 100,000 to 250,000 ❍ Over 250,000
17. Store where product was purchased:
Name: ______________________________________ City: _____________________________________ State: __________
18. In choosing this product, how important were the following:
Availability
Price
Brand Name
Overall Quality
Heat Output (Btu/Hr Rating)
Variable Heat Output (Btu/Hr)
Made in USA
Warranty
Local Service
Value for Price
19. This question will allow us to better understand the demographic profile of our customers.Which of the following best describes you? (not required)
❍ African American ❍ Asian American ❍ Mexican ❍ Puerto Rican ❍ Cuban ❍ Other Hispanic ❍ White ❍ Other ___________________
Brand: (Reddy Heater, Master, Remington, etc.)
Model: (R60, HD15, etc.)
Date Purchased: Note: Keep receipt for warranty verification.
Serial Number: 7 or 9 digit number located on product or identification tag.
First Name: Last Name:
Address:
City: State: Zip: Country:
Phone: ( ) - E-Mail:
OWNER'S REGISTRATION FORM
Please answer the following questions to register your product with DESA Heating Products:
Complete registration form and mail or complete on-line registration at www.desatech.com within 30 days after purchase.
Not Somewhat Very
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Not Somewhat Very
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Size
Prior Brand Experience
Built-In Thermostat
Ease of Operation
Special Features
Salesperson’s Recommendation
Friend/Relative’s Recommendation
Portability
Quiet Operation

2701 Industrial Drive
P.O. Box 90004
Bowling Green, KY 42102-9004
Postage
Required
TAPE
TAPE

WARNING
WARNING
PROPANE FORCED AIR HEATERS
PROPANE TANK TOP HEATERS
PROPANE AND NATURAL GAS
GARAGE HEATERS
PROPANE CONVECTION HEATERS
PORTABLE KEROSENE FORCED
AIR HEATERS
PROPANE
PATIO HEATERS PROPANE AND NATURAL GAS CHIMENEAS
OTHER OUTDOOR HEATING PRODUCTS

112865-01A
20
For more information, visit www.desatech.com
For more information, visit www.desatech.com
WARRANTY AND REPAIR SERVICE
Printed in U.S.A.
WARRANTY INFORMATION
This warranty does not cover damage resulting from misuse, abuse, negligence, accidents, lack of proper maintenance, normal wear, alteration,
modification, tampering, contaminated fuels, repair using improper parts, or repair by anyone other than an authorized dealer or service center.
Routine maintenance is the responsibility of the owner.
THIS EXPRESS WARRANTY IS GIVEN IN LIEU OF ANY OTHER WARRANTY EITHER EXPRESSED OR IMPLIED, INCLUDING
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
DESAHeatingProductsassumesnoresponsibilityfor indirect, incidental or consequential damages. Some states do not allow the exclusion or limitation
of incidental or consequential damages or limitations or exclusions may not apply to you. This limited warranty gives you specific legal rights, which
vary from state to state.
WARRANTY SERVICE
Warranty service is available only through authorized dealers and service centers.
Should your heater require service, return it to your nearest authorized service center. Proof of purchase must be presented with the heater. The heater
will be inspected. Faulty materials or workmanship may cause a defect. If so, DESA Heating Products will repair or replace the heater without charge.
REPAIR SERVICE
Returntheheatertoyournearestauthorizedservicecenter. Eachservicecenteris independentlyownedandoperated. Repairsnotcoveredbythewarranty
will be billed at standard prices. We reserve the right to amend these specifications at any time without notice.
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
andthedatelocatedinthelowerrightcornerofthispage. Aservicemanualcanbepurchasedfromtheaddresslistedbelow.Sendacheckfor$5.00payable
to DESA Heating Products.
When writing for information regarding your heater, be sure to include the model number and serial number as shown on the model plate.
For more information about this warranty, write:
LIMITED LIFETIME WARRANTY
DESA Heating Products warrants the following parts only (no labor) thereof, to be free of defects in materials and workmanship for lifetime from the
date of first purchase when operated and maintained in accordance with instructions. This warranty is extended only to the original retail purchaser,
when proof of purchase is provided. (Excludes Rental Use Applications)
Warranty Covers: Wheels
Fuel Tank
Exterior Plastic Housing Parts:
(Shroud, Rear Panel, Fan Guard, Handle/Support, Extension Cord Wrap Cleats and Control Cover)
Thiswarrantycoversonly thecostofparts(no labor)requiredto restorethe producttoproper operatingcondition. Transportation andincidentalcosts
associated with warranty repairs are not reimbursable under this warranty.
LIMITED 2-YEAR WARRANTY
DESA Heating Products warrants this product and any parts thereof, to be free of defects in materials and workmanship for two (2) years from the
date of first purchase when operated and maintained in accordance with instructions. This warranty is extended only to the original retail purchaser,
when proof of purchase is provided.
Thiswarranty covers only the cost of parts and labor required to restore the product to properoperatingcondition. Transportationandincidentalcosts
associated with warranty repairs are not reimbursable under this warranty.
2701 Industrial Drive
P.O. Box 90004
Bowling Green, KY 42102-9004
www.desatech.com