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www.desatech.com

119344-01B

3

Natural and Propane/LP Gas: 

Natural and pro

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pane/LP gases are fuel gases. Fuel gases are 
odorless. An odor-making agent is added to 
fuel gases. The odor helps you detect a fuel 
gas  leak.  However,  the  odor  added  to  fuel 
gas can fade. Fuel gas may be present even 
though no odor exists.
Make  certain  you  read  and  understand  all 
warnings. Keep this manual for reference. It 
is your guide to safe and proper operation of 
this heater.

  WARNING:  Any  change  to 

this  heater  or  its  controls  can 

be dangerous.

  WARNING:  Do  not  use  a 

blower  insert,  heat  exchanger 

insert or other accessory not ap

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proved for use with this heater.

Due  to  high  temperatures,  the 

appliance should be located out 

of traffic and away from furniture 

and draperies.

Do not place clothing or other 

flammable  material  on  or  near 

the appliance. Never place any 

objects on the heater.

Surface of heater becomes very 

hot when running heater. Keep 

children and adults away from 

hot  surface  to  avoid  burns  or 

clothing  ignition.  Heater  will 

remain hot for a time after shut-

down.  Allow  surface  to  cool 

before touching.

Carefully supervise young chil

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dren when they are in the same 

room with heater.

Make sure grill guard is in place 

before running heater.

Keep  the  appliance  area  clear 

and free from combustible ma

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terials, gasoline and other flam

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mable vapors and liquids.

1.  This appliance is only for use with the type 

of gas indicated on the rating plate. This 
appliance  is  not  convertible  for  use  with 
other gases. 

2.  Do not place propane/LP supply tank(s) 

inside any structure. Locate propane/LP 
supply tank(s) outdoors.

3.  This  heater  shall  not  be  installed  in  a 

bedroom or bathroom.

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.  This heater needs fresh, outside air ventila

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tion to run properly. This heater has an Oxy

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gen Depletion Sensing (ODS) safety shutoff 
system. The ODS shuts down the heater if 
not enough fresh air is available. See 

Air for 

Combustion and Ventilation,

 page 5.

6.  Keep all air openings in front and bottom 

of heater clear and free of debris. This will 
insure enough air for proper combustion.

7.  If heater shuts off, do not relight until you 

provide fresh, outside air. If heater keeps 
shutting off, have it serviced.

8.  Do not run heater

• where flammable liquids or vapors are 

used or stored

• under dusty conditions

9.  Before using furniture polish, wax, carpet 

cleaner or similar products, turn heater off. If 
heated, the vapors from these products may 
create a white powder residue within burner 
box or on adjacent walls or furniture.

10. Do not use heater if any part has been 

under water. Immediately call a qualified 
service  technician  to  inspect  the  room 

heater  and  to  replace  any  part  of  the 

control system and any gas control which 
has been under water.

11. Turn off and let cool before servicing. Only 

a qualified service person should service 
and repair heater.

sAFeTY INFoRMATIoN

Continued

Summary of Contents for WMN20A

Page 1: ...her 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...

Page 2: ...er or birth defects or other reproductive harm IMPORTANT Read this owner s manualcarefullyandcompletely before trying to assemble operate or service this heater Improper use of this heater can cause s...

Page 3: ...th other gases 2 Do not place propane LP supply tank s inside any structure Locate propane LP supply tank s outdoors 3 This heater shall not be installed in a bedroom or bathroom 4 If you smell gas sh...

Page 4: ...f the unit Vent free gas products are prohibited for bedroom and bathroom installation in the Commonwealth of Massachusetts Unpacking 1 Remove heater from carton 2 Remove all protective packaging appl...

Page 5: ...The air that leaks around doors and windows may provide enough fresh air for combustion and ventilation However in buildings of un usually tight construction you must provide additional fresh air Unus...

Page 6: ...ppliances Direct vent draws combustion air from the outdoors and vents to the outdoors Example Gas water heater _ ____________ Btu Hr Vent free heater _ ___________ Btu Hr Total _ ___________ Btu Hr 4...

Page 7: ...lheatingsystem youmay run system s circulating blower whileusingheater Thiswillhelp circulatetheheatthroughoutthe house In the event of a power outage you can use this heater as your primary heat sour...

Page 8: ...affic areas in windy or drafty areas Figure 4 Mounting Clearances As Viewed From Front of Heater INSTALLATION Continued CAUTION This heater cre ates warm air currents These currents move heat to wall...

Page 9: ...of front panel forward then out 3 Remove any remaining packaging ma terials Methods For Attaching Mounting Bracket To Wall Only use last hole on each end of mounting bracket to attach bracket to wall...

Page 10: ...cm 5 6 cm 18 3 4 47 6 cm Min 18 3 4 47 6 cm Min Figure 10 Popping Open Anchor Wings For Thin Walls Mounting Bracket attached to wall Horizontal Slots Attaching To Wall Anchor Method For attaching moun...

Page 11: ...lace front panel at this time Replace front panel after making gas connections and checking for leaks see pages 12 through 14 INSTALLATION Continued Mounting heater to floor With optional floor kit Mo...

Page 12: ...ure 14 External Regulator With Vent Pointing Down External Regulator Propane LP Supply Tank Vent Pointing Down CAUTION Use only new black iron or steel pipe Inter nally tinned copper tubing may be use...

Page 13: ...ernal regula tor has been installed between propane LP supply and heater See guidelines under Connect ing to Gas Supply page 12 Pressure Testing Gas Supply Piping System Test Pressures In Excess Of 1...

Page 14: ...tank valve 3 Make sure control knob of heater is in the OFF position 4 Check all joints from equipment shutoff valve to thermostat gas valve see Figure 17 or 18 Apply a noncorrosive leak de tection f...

Page 15: ...losion may result causing property damage per sonal injury or loss of life A This appliance has a pilot which must be lighted by hand When lighting the pi lot follow these instructions exactly B BEFOR...

Page 16: ...temperatures etc Frequent use of your heater will let you determine your own comfort levels MANUAL LIGHTING PROCEDURE 1 Remove front panel see Figure 7 page 9 2 Follow steps 1 through 7 under Lighting...

Page 17: ...eck pilot flame pattern and burner flame pattern often PILOT FLAME PATTERN Figure 22 shows a correct pilot flame pattern Figure 23 shows an incorrect pilot flame pat tern The incorrect pilot flame is...

Page 18: ...ommend that you keep the burner tube and pilot assembly clean and free of dust and dirt To clean these parts we recommend using compressed air no greater than 30 PSI Your local computer store hardware...

Page 19: ...position 4 Air in gas lines when in stalled 5 Depleted gas supply pro pane LP gas only 6 ODS pilot is clogged 7 Gas regulator setting is not correct OBSERVED PROBLEM Whenignitorbuttonispressed there...

Page 20: ...ane LP gas company 1 Contact local natural or propane LP gas company 2 Clean burner see Cleaning and Maintenance page 18 or replace burner orifice 1 Clean burner see Cleaning and Maintenance page 18 o...

Page 21: ...s from furniture polish wax carpet cleaners etc may turn into white powder residue 1 Metal expanding while heat ing or contracting while cooling REMEDY 1 Check burner for dirt and debris If found clea...

Page 22: ...partially clogged 1 Gas leak See Warning statement above 2 Control valve defective 1 Foreign matter between control valve and burner 2 Gas leak See Warning statement above 1 Not enough combustion vent...

Page 23: ...ced under warranty Parts Under Warranty Contact authorized dealers of this product If they can t supply original replacement part s call DESA Heating Products Technical Ser vice Department at 1 866 67...

Page 24: ...119344 01B 24 4 20 4 17 18 19 2 3 5 6 8 16 9 10 11 12 13 14 18 Manual Control Models Only Thermostat Models Only 19 7 1 21 22 15 9 Illustrated Parts Breakdown Models WMN20A WMP20A GWN20TA GWP20TA GWN...

Page 25: ...bly 1 107894 15 Deflector Assembly 1 9 098271 09 Ignitor Cable 1 10 098249 01 Nut 2 11 110803 01 ODS Pilot Assembly 1 110803 02 ODS Pilot Assembly 1 12 103446 02 Burner 1 103447 06 Burner 1 13 099387...

Page 26: ...GA5010 For all models Equipment shutoff valve with 1 8 NPT tap FAN KITS PP100 For all models Provides better heat distri bution Makes heater more efficient Com plete installation and operating instru...

Page 27: ...1 0505 1 800 446 1446 www nbmc com Parts Centrals These Parts Centrals are privately owned businesses They have agreed to support our customer s needs by providing original replacement parts and acces...

Page 28: ...Heating Products who will provide original factory replacement parts Failure to use original factory replacement parts voids this warranty The heater MUST be installed by a qualified installer in acc...

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