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DESA INTERNATIONAL

UNVENTED (VENT-FREE)

NATURAL GAS LOG HEATER

Variable Manually-Controlled Models Also Design-Certified As Vented

Decorative Appliances

OWNER’S OPERATION AND INSTALLATION MANUAL

This appliance may be installed in an aftermarket* manufactured (mobile) home, where not prohib-
ited by state or local codes.

* Aftermarket: Completion of sale, not for purpose of resale, from the manufacturer

Save this manual for future reference.

WARNING: If the information in this
manual is not followed exactly, a fire or
explosion may result causing property
damage, personal injury, or loss of life.

— Do not store or use gasoline or other

flammable vapors and liquids in the
vicinity of this or any other appliance.

— WHAT TO DO IF YOU SMELL GAS

• Do not try to light any appliance.
• Do not touch any electrical switch; do

not use any phone in your building.

• Immediately call your gas supplier

from a neighbor’s phone. Follow the
gas supplier’s instructions.

• If you cannot reach your gas sup-

plier, call the fire department.

— Installation and service must be per-

formed by a qualified installer, ser-
vice agency, or the gas supplier.

WARNING: Improper installation, ad-
justment, alteration, service, or main-
tenance can cause injury or property
damage. Refer to this manual for cor-
rect installation and operational proce-
dures. For assistance or additional in-
formation consult a qualified installer,
service agency, or the gas supplier.

WARNING: This appliance is for instal-
lation only in a solid-fuel burning ma-
sonry or UL127 factory-built fireplace,
or in an approved ventless firebox. It is
design-certified for these installations
in accordance with ANS Z21.11.2.
Exception: Do not install this appli-
ance in a factory-built fireplace that
includes instructions stating it has not
been tested or should not be used with
unvented gas logs.

WARNING: This is an unvented gas-fired heater. It uses air (oxygen) from the room in
which it is installed. Provisions for adequate combustion and ventilation air must be
provided. Refer to 

Air for Combustion and Ventilation section on page 4 of this manual.

®

LO

PILOT

OFF

HI

18", 24", and 30"

(“C” Models) Variable

Manually-Controlled,

and (“B” Models)

Thermostatically-

Controlled

Summary of Contents for VS18NTB

Page 1: ...l the fire department Installation and service must be per formed by a qualified installer ser vice agency or the gas supplier WARNING Improper installation ad justment alteration service or main tenance can cause injury or property damage Refer to this manual for cor rect installation and operational proce dures For assistance or additional in formation consult a qualified installer service agenc...

Page 2: ...ate this heater with glass doors closed If you operate heater with doors closed heat buildup inside fireplace will cause glass to burst Also if fireplace open ing has vents at the bottom you must open the vents before operating heater 7 You must operate this heater with a fire place screen in place Make sure fire place screen is closed before running heater 8 This log heater is designed to be smok...

Page 3: ... and approved to ANS Z21 11 2 stan dard for unvented heaters State and local codes in some areas prohibit the use of vent free heaters This heater may also be oper ated as a vented decorative ANS Z21 60 product by opening the flue damper non thermostat models only SAFETY DEVICE This heater has a pilot with an Oxygen Detection Safety Pilot System ODS The ODS pilot is a required feature for vent fre...

Page 4: ...air for these appliances This will insure proper venting of vented fuel burning appliances WARNING This heater shall notbeinstalledinaconfinedspace or unusually tight construction unless provisions are provided foradequatecombustionandven tilation air Read the following in structions to insure proper fresh air for this and other fuel burning appliances in your home PROVIDING ADEQUATE VENTILATION T...

Page 5: ... vent draws combustion air from the outdoors and vents to the outdoors 4 Compare the maximum Btu Hr the space can support with the actual amount of Btu Hr used _______________ Btu Hr maximum the space can support _______________ Btu Hr actual amount of Btu Hr used Example 51 200 Btu Hr maximum the space can support 73 000 Btu Hr actual amount of Btu Hr used Thespaceintheaboveexampleisaconfinedspac...

Page 6: ... within 12 of the ceiling and one within 12 of the floor Connect these items directly to the outdoors orspacesopentotheoutdoors Thesespaces include attics and crawl spaces Follow the National Fuel Gas Code NFPA 54 ANS Z223 1 Section5 3 AirforCombustionand Ventilation for required size of ventilation grills or ducts IMPORTANT Do not provide openings for inlet or outlet air into attic if attic has a...

Page 7: ...riable Manually Controlled models only in a recreational vehicle where curtains furniture clothing or other flammable objects are less than 42 inches from the front top or sides of the heater in high traffic areas in windy or drafty areas CAUTION This heater cre ates warm air currents These currents move heat to wall sur faces next to heater Installing heater next to vinyl or cloth wall coverings ...

Page 8: ... the fireplace hood accessory 24 and 30 models only See Figure 5 for minimum clearances IMPORTANT If you cannot meet these minimum clearances you must operate heater with chimney flue damper open Go to Installing Damper Clamp Accessory for Vented Operation page 10 NOTICE Manual control heaters maybeusedasaventedproduct If so you must always run heater with chimney flue damper open If running heate...

Page 9: ...etween mantel shelf and top of fireplace opening a hood is not required see Figure 6 Determining Minimum Mantel Clearance When Using a Hood If minimum clearances in Figure 6 are not met you must have a hood When using a hood there are still certain minimum mantel clearancesrequired Followminimumclear ances shown in Figure 7 when using hood Continued Minimum Non Combustible Material 8 Min 12 15 18 ...

Page 10: ...r2aboveapplytoyou you must permanently open chimney flue damper You must install the damper clamp accessory to order see Accessories page 28 This will insure vented operation see Figure 10 The damper clamp will keep damper open Installation instructions are included with clamp accessory See chart below for minimum permanent flue opening you must provide Attach damper clamp so the minimum permanent...

Page 11: ...est gauge connection Pur chase the optional A G A design certified manual shutoff valve from your dealer See Accessories page 28 CAUTION Use only new black iron or steel pipe Inter nally tinned copper tubing may be used in certain areas Check your local codes Use pipe of 1 2 diameter or greater to allow proper gas volume to heater If pipe is too small undue loss of pressure will occur Installation...

Page 12: ... 14 Manual Shutoff Valve ON POSITION OFF POSITION Open Closed Manual Shutoff Valve Figure 15 Checking Gas Joints Gas Meter Manual Shutoff Valve Thermostat Gas Valve or Control Valve Location TestPressuresEqualToorLessThan 1 2 PSIG 1 Close manual shutoff valve see Fig ure 14 2 Pressurize supply piping system by ei ther using compressed air or opening main gas valve located on or near gas meter 3 Ch...

Page 13: ...e sure the grooves in the bottom of the log fit over the grate Bring the log forward next to the metal posts The cut out on the middle log must be on top see Figure 17 3 Slide the grooves in the back of the rear log 3 against the rear grate prongs Make sure the peg on the log is on top see Figure 18 4 Place the crossover log 4 on the back log and the middle log Make sure the peg on the rear log is...

Page 14: ...t buildup inside fireplace will cause glass to burst Also if fireplace opening has vents at the bottom you must open the vents before operating heater You must operate this heater withafireplacescreeninplace Make sure fireplace screen is closed before running heater NOTICE During initial operation of new heater burning logs will give off a paper burning smell Orange flame will also be present Open...

Page 15: ...the OFF position Shutting Off Burners Only pilot stays lit Turn control knob clockwise Clockwise to the PILOT position THERMOSTAT CONTROL OPERATION Thethermostatcontrolknobcanbesetto anycomfortlevelbetweenHiandLo The thermostat will gradually modulate the heatoutputandflameheightfromhigher to lower settings or pilot in order to maintain the comfort level you select The ideal comfort setting will v...

Page 16: ...he control knob clockwise Clockwise to the HIGH position 2 Press in and turn control knob clock wise Clockwise to the pilot position Thermocouple Ignitor Electrode Pilot Burner OPERATING HEATER Continued 4 Wait five 5 minutes to clear out any gas Then smell for gas including near the floor If you smell gas STOP Follow B in the safety in formation page 15 column 2 If you don t smell gas go to the n...

Page 17: ...INSPECTING BURNERS Check pilot flame pattern and burner flame patterns often PILOT FLAME PATTERN Figure 24 shows a correct pilot flame pat tern Figure 25 shows an incorrect pilot flame pattern The incorrect pilot flame is not touching the thermocouple This will cause the thermocouple to cool When the thermocouple cools the heater will shut down If pilot flame pattern is incorrect as shown in Figur...

Page 18: ... ware store or home center may carry com pressed air in a can You can use a vacuum cleaner in the blow position If using com pressed air in a can please follow the direc tions on the can If you don t follow direc tionsonthecan youcoulddamagethepilot assembly 1 Shut off the unit including the pilot Allow the unit to cool for at least thirty minutes 2 Inspect burner pilot and primary air inlet holes...

Page 19: ...Thermocouple damaged 8 Control valve damaged REMEDY 1 Reconnect ignitor cable 2 Free ignitor cable if pinched by any metal or tubing Keep ignitor cable dry 3 Tighten nut holding piezo ignitor to base panel of log set Nut is located behind base panel 4 Replace ignitor cable 5 Replace piezo ignitor 6 Replace ignitor 7 Replace ignitor 1 Turn on gas supply or open manual shutoff valve 2 Turn control k...

Page 20: ...or 1 Problem will stop after a few hours of operation 1 Turn control knob to LO position and let warm up for a minute 2 Operate burners until air is removed from line Have gas line checked by lo cal natural gas company 3 Observe minimum installation clear ances see pages 7 through 9 4 Clean burners see Cleaning and Main tenance page 18 or replace burner orifice s 1 Refer to Air for Combustion and ...

Page 21: ...valve defective 1 Foreign matter between control valve and burner 2 Gas leak SeeWarning statement at top of page 1 Thermostat sensing bulb needs to be re positioned OBSERVED PROBLEM Heater produces a clicking ticking noise just after burners are lit or shut off Heater produces unwanted odors Heater shuts off in use ODS operates Gas odor even when control knob is in OFF position Gas odor during com...

Page 22: ... Masonry Fireplace Thermostat Sensing Bulb Adhesive backed Mounting Clip Thermostat Sensing Bulb Figure 34 Locating Thermostat Sensing Bulb on Factory built Metal Fireplace Capillary Q Q Q Q Q Q Q Q Q Q Q Q Q Adhesive backed Mounting Clip Glass Doors Figure35 InstallingThermostatSensing Bulb behind Glass Doors Thermostat Sensing Bulb Capillary Thermostat Sensing Bulb Do Not Crimp Capillary Adhesiv...

Page 23: ... 800 337 2564 You can also visit DESA International s Technical Services web site at www desatech com 18 Thermostat 24 Thermostat 30 Thermostat Controlled Controlled Controlled Btu Variable 16 000 26 000 20 000 33 000 21 500 36 000 Type Gas Natural Gas Only Natural Gas Only Natural Gas Only Ignition Piezo Piezo Piezo Manifold Pressure 3 4 W C 3 4 W C 3 4 W C Inlet Gas Pressure in of water Maximum ...

Page 24: ...AL GAS LOG HEATER ILLUSTRATED PARTS BREAKDOWN VARIABLE MANUALLY CONTROLLED SPLIT OAK MODELS VS18NVC CFS18NVC VS24NVC CFS24NVC VS30NVC CFS30NVC 17 19 18 25 24 20 20 26 27 5 6 7 28 28 24 9 8 10 11 12 14 21 22 26 1 26 2 23 6 1 6 2 13 15 16 4 3 2 1 ...

Page 25: ...Screw 2 13 101011 01 101011 02 101011 03 Inlet Tube 1 14 098354 01 098354 01 098394 01 Control Knob 1 15 098462 03 098462 03 098462 03 Control Rod 1 16 098325 01 098325 01 098325 01 Roll Pin 1 17 098508 01 098508 01 098508 01 Valve Retainer Nut 1 18 102568 01 102568 01 102568 01 Gas Valve 1 19 101005 01 101005 01 101005 01 Valve Bracket 1 20 M11084 26 M11084 26 M11084 26 Screw 4 21 101004 11 10100...

Page 26: ...UNVENTED NATURAL GAS LOG HEATER ILLUSTRATED PARTS BREAKDOWN THERMOSTAT CONTROLLED SPLIT OAK MODELS VS18NTB VS24NTB VS30NTB 30 5 24 5 6 7 8 9 10 7 7 28 12 11 12 13 14 15 17 16 18 23 25 26 6 1 6 2 28 21 22 20 27 19 29 9 1 9 2 4 3 2 1 ...

Page 27: ... 102445 01 Piezo Ignitor 1 14 098867 09 098867 09 098867 09 Gas Regulator 1 15 M11084 38 M11084 38 M11084 38 Screw 2 16 102810 01 102810 02 102810 03 Inlet Tube 1 17 098354 01 098354 01 098354 01 Control Knob 1 18 098462 03 098462 03 098462 03 Control Rod 1 19 100000 01 100000 01 100000 01 Cotter Pin 1 20 101053 01 101053 01 101053 01 Adapter 1 21 099211 01 099211 01 099211 01 Screw 1 22 098544 01...

Page 28: ...8NV B CFS18PV B VENT FREE LOGMATE FIREBOXES Not Shown Available in 32 36 and42 models May be paired with the logs listed below Circu lating fireboxes feature louvers and an op tionalblower Non circulating smoothface models are ideal for custom trim applica tions such as stone or marble ACCESSORIES Purchasetheseheateraccessoriesfromyour local dealer If they can not supply these accessories callDESA...

Page 29: ...____________________ _______________________________________________________________________________________________ _______________________________________________________________________________________________ _______________________________________________________________________________________________ ___________________________________________________________________________________________...

Page 30: ...ring a defective heater will be the responsibility of the owner TO THE FULL EXTENT ALLOWED BY THE LAW OF THE JURISDICTION THAT GOVERNS THE SALE OF THE PRODUCT THIS EXPRESS WARRANTY EXCLUDES ANY AND ALL OTHER EXPRESSED WARRANTIES AND LIMITS THE DURATION OF ANY AND ALL IMPLIED WARRANTIES INCLUDING WARRANTIES OF MERCHANTA BILITY AND FITNESS FOR A PARTICULAR PURPOSE TO FOUR 4 YEARS ON ALL COMPONENTS A...

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