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119344-01B

4

12. Operating  heater  above  elevations  of 

4,500 feet could cause pilot outage.

13. To prevent performance problems, do not 

use propane/LP fuel tank of less than 100 
lbs. capacity.

14. Provide adequate clearances around air 

openings.

loCAl Codes

Install and use heater with care. Follow all lo

-

cal codes. In the absence of local codes, use 

the latest edition of 

National Fuel Gas Code, 

ANSI Z223.1/NFPA 54

*.

*Available from:

American National Standards Institute, Inc.

1430 Broadway

New York, NY  10018

National Fire Protection Association, Inc.

Batterymarch Park

Quincy, MA  02269

State of Massachusetts:

 The installation 

must  be  made  by  a  licensed  plumber  or 
gas  fitter  in  the  Commonwealth  of  Mas

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sachusetts.
Sellers  of  unvented  propane  or  natural 
gas-fired supplemental room heaters shall 
provide to each purchaser a copy of 527 
CMR 30 upon sale of the unit.
Vent-free  gas  products  are  prohibited  for 

bedroom and bathroom installation in the 

Commonwealth of Massachusetts.

UNPACkING

1.  Remove heater from carton.
2.  Remove all protective packaging applied 

to heater for shipment.

3.  Check heater for any shipping damage. If 

heater is damaged, promptly inform dealer 
where you bought heater.

sAFeTY INFoRMATIoN

Continued

Figure 1 - Vent-Free Gas Heater

Ignitor Button

Control Knob

Heater
Cabinet

Front Panel

Glass Panel

Grill Guard

PRodUCT 

IdeNTIFICATIoN

PRodUCT FeATURes

SAFETY DEvICE

This heater has a pilot with an Oxygen Deple

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tion Sensing (ODS) safety shutoff system. The 
ODS/pilot is a required feature for vent-free 
room  heaters.  The  ODS/pilot  shuts  off  the 
heater if there is not enough fresh air.

PIEzO IGNITION SYSTEM

This heater has a piezo ignitor. This system re

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quires no matches, batteries or other sources 
to light heater.

THERMOSTATIC HEAT CONTROL

Thermostat models have a thermostat sens

-

ing bulb and a control valve. This results in the 
greatest heater comfort. This can also result 
in lower gas bills.

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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