Monessen Hearth DFX24C User manual

VENT-FREE FIREPLACE SYSTEMS
INSTALLATION AND OPERATING INSTRUCTIONS
READ AND SAVE THESE INSTRUCTIONS
MODELS
DFX24C
DBX24C*
DFX32C
Natural Gas or
Propane/LPG
Manual or Milli-Volt
*Thermostat Control Only
This is an unvented gas-red heater. It
uses air (oxygen) from the room in which
it is installed. Provisions for adequate
combustion and ventilation air must be
provided. See page 9.
WARNINGS
If the information in this manual is not followed
exactly, a re or explosion may result causing
property damage, personal injury or loss of
life.
– Do not store or use gasoline or other ammable
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 supplier, call the re
department.
– Installation and service must be performed by
a qualified installer, service agency or the gas
supplier.

2 33D4047
CONTENTS
Important Safety Information .....................................3
Product Features .......................................................5
Product Features and Specications .........................6
Getting Started ..........................................................7
General Installation Information ................................8
Location of Fireplace ..............................................16
Clearances and Height Requirements ....................17
Fireplace Framing ...................................................18
Connecting the Gas ................................................20
Checking Gas Pressure ..........................................21
Electrical Wiring (Milli-volt) ......................................22
Log Placement ........................................................24
Flame Appearance ................................................. 26
Installing Rock Wool and Checking Burner Flame ..27
Operating Instructions ............................................29
For Your Safety Read Before Lighting ...............29
Manual Control Lighting Instructions ................30
Thermostat Control Lighting Instructions ..........31
Milli-Volt Control Lighting Instructions .............. 32
Match Lighting Instructions ...............................33
Cleaning and Servicing ...........................................34
Blower and Optional Equipment ..............................34
Illustrated Parts
Cabinet Accessories ..........................................35
DFX24C Milli-Volt, DFX24C Manual..................36
DFX32C Milli-volt, DFX32C Manual ..................38
DBX24C T-stat ..................................................40
Troubleshooting ......................................................42
Warranty .................................................. Back Cover
DFX24C and DFX32C gas log appliances described in this manual feature the
TRIPLE PLAY BURNER SYSTEM® technology
with exclusive triple effect technology
producing a full random yellow ame, full depth ember bed and glowing logs.

33D4047 3
9. This unit complies with ANSI Z21.11.2 unvented heaters
standard.
10. Do not install the DFX Model in a bathroom or bedroom.
The DBX Model may be installed in a bedroom, but not
in a bathroom.
11. Correctinstallationoftheceramicberlogs,properloca-
tionoftheheater,andannualcleaningarenecessaryto
avoidpotentialproblemswithsooting.Sooting,resulting
from improper installation or operation, can settle on sur-
facesoutsidethereplace.Seelogplacementinstructions
for proper installation.
12. Avoidanydraftsthatalterburneramepatterns.Donot
allowfanstoblowdirectlyintoreplace.Donotplace
ablowerinsideburnareaofrebox.Ceilingfansmay
createdraftsthatalterburneramepatterns.Sootingand
improperburningwilloccur.
13. CAUTION: Candles, incense, oil lamps, etc. produce
combustionby-productsincludingsoot.Vent-freeappli-
anceswillnotlterorcleansootproducedbythesetypes
of products. In addition, the smoke and/or aromatics
(scents) may be reburnt in the vent-free appliance which
can produce odors. It is recommended to minimize the
use of candles, incense, etc. while the vent-free appliance
is in operation.
14. Anunventedgas-redheaterusesair(oxygen)fromthe
room in which it is installed. Provisions for adequate
combustion and ventilation air must be provided. See
installationguidelines.
IMPORTANT
Read these instructions carefully before installing or trying to operate a vent-free gas heater in this rebox.
IMPORTANT SAFETY INFORMATION
1. Due to high temperatures, the appliance be
locatedoutoftrafcandawayfromfurnitureand
draperies.
2. Children and adults should be alerted to the hazard
ofhighsurfacetemperatureandshouldstayaway
toavoidburnsorclothingignition.
3. Youngchildrenshouldbecarefullysupervisedwhen
they are in the same room with the appliance.
4. Donotplaceclothingorotherammablematerial
on or near the appliance.
5. Anysafetyscreenorguardremovedforservicing
anappliance, mustbe replacedprior tooperating
the heater.
6. Installationandrepairshouldbedonebyaqualied
service person.
7. Topreventmalfunctionand/orsooting,anunvented
gas heater should be cleaned before use at least
annually by a professional service person. More
frequentcleaningmayberequiredduetoexcessive
lint from carpeting, bedding material, etc. It is
imperative that control compartments, burners and
circulatingairpassagewaysbekeptclean.
8. CARBON MONOXIDE POISONING: Earlysignsof
carbonmonoxidepoisoning aresimilarto theuwith
headaches, dizziness and/or nausea. If you have these
signs,obtainfreshairimmediately.Havetheheaterser-
vicedasitmaynotbeoperatingproperly. Continued on page 4
WARNING
• Any change to this heater or its controls can be dangerous.
• Improper installation or use of the heater can cause serious injury or death from
re, burns, explosion or carbon monoxide poisoning.
• Do not allow fans to blow directly into the replace. Avoid any drafts that alter burner
ame patterns.
• Do not use a blower insert, heat exchanger insert or other accessory, not approved
for use with this heater where applicable.
INSTALLER
Please leave these instructions with the appliance.
OWNER
Please retain these instructions for future reference .

4 33D4047
IMPORTANT SAFETY INFORMATION
This appliance may be installed in an aftermarket,
permanently located, manufactured (mobile)
home, where not prohibited by local codes.
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.
15. Keep room area clear and free from combustible materi-
als,gasolineandotherammablevaporsandliquids.
16. Unvented gas heaters are a supplemental zone heater.
They are not intended to be a primary heating appli-
ance.
17. Unventedgasheatersemitmoistureintothelivingarea.
Inmosthomesofaverageconstruction,thisdoesnotpose
a problem. In houses of extremely tight construction,
additional mechanical ventilation is recommended.
18. Duringmanufacturing,fabricatingandshipping,various
components of this appliance are treated with certain oils,
lmsorbondingagents.Thesechemicalsarenotharmful
butmayproduceannoyingsmokeandsmellsastheyare
burnedoffduringtheinitialoperationoftheappliance;
possiblycausingheadaches,oreyeorlungirritation.This
is a normal and temporary occurrence.
The initial break-in operation should last two to three
hours with the burner at the highest setting. Provide
maximumventilationbyopeningwindowsordoorsto
allowodorstodissipate.Anyodorsremainingafterthis
initialbreak-inperiodwillbeslightandwilldisappear
with continued use.
19. Input ratings are shown in BTU per hour and are for
elevations up to 2,000 feet. For elevations above 2,000
feet,inputratingsshouldbereduced4percentforeach
1,000 feet above sea level. Refer to the National Fuel Gas
Code.
20. Theapplianceanditsappliancemaingasvalvemustbe
disconnectedfromthegassupplypipingsystemduring
anypressure testingofthat systemat testpressuresin
excessof1/2psig(3.5kPa).
21. Theappliancemustbeisolatedfromthegassupplypiping
systembyclosingitsequipmentshutoffvalveduringany
pressuretestingofthegassupplypipingsystemattest
pressuresequaltoorlessthan1/2psig(3.5kPa).
22. Do not use this room heater if any part has been under
water.Immediatelycallaqualied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.
23. Neverburnsolidfuelsinareplacewhereaunvented
room heater is installed.
24. Alwayshaveareplacescreeninplacewhentheappli-
ance is in operation, and unless other provisions for
combustion air are provided, the screen shall have an
opening(s)forinductionofcombustionair.
25. Donotllspacesaroundthereboxwithinsulationor
other materials. These spaces must be maintained to pre-
ventthereboxfromcomingincontactwithcombustible
materials.

33D4047 5
Piezo
Ignition
Fireplace Screen
Control
Knob
PRODUCT FEATURES
Yourvent-freereplacemustbemountedontheoororontheoptionalreplacehearth.
OPERATION
Thisunventedgasheaterrequiresnooutsideventingandburnscleanlywithhighheatingefciency.
Thiszero-clearanceunventedgasheatercanbeinstalledagainst(orrecessedinto)anywallthatisaccessibletoagasline.
Figure 1 - Unvented Gas Heater
(Control Access Door Shown Open)
On/Off
Switch

6 33D4047
NATURAL GAS
Manual and T-Stat Pressure
Regulator Pressure Setting 4 in. w.c.
Gas Inlet Pressure: Max. 10.5 in. w.c.
Min. 5 in. w.c.
PRODUCT FEATURES and SPECIFICATIONS
IGNITION CONTROLS
Piezoignitorallowsignitionofthepilotwithouttheuseofmatchesorbatteries.
Manual control has four (4) positions:
OFF - Allgastothegaslogsisshutoffatthevalve.
IGN - Valvepositiontolight/maintainastandingpilot.
ON - ValvepositiontoturnON/OFFlogsetwithremoteswitch/thermostat.
LOW/HI - Variablepositiontocontrolameheight(heatoutput).Bothfrontandrearburnersareinoperationto
providerealisticglowandyellowame.
Thermostat control has three (3) positions:
OFF - Allgastothegaslogsisshutoffatthevalve.
IGN - Valvepositiontolight/maintainastandingpilot.
LOW/HI - Variablepositioncorrespondingtodesiredtemperature.
Continued
Model Number Type Gas Rate Number of
Burners
Max BTU/Hr Min BTU/Hr
DFX24PMC Manual 22,000 17,000 1
DFX24PVC Milli-Volt 22,000 17,000 1
DFX32PMC Manual 26,000 15,000 1
DFX32PVC Milli-Volt 26,000 20,000 1
DBX24PTC T-Stat 10,000 — 1
Milli-Volt Pressure
Regulator Pressure Setting 3.5 in. w.c.
Pilot Regulator 3.5 in. w.c.
Gas Inlet Pressure: Max. 10.5 in. w.c.
Min. 5 in. w.c.
PROPANE / LPG
Note: An external regulator is required to reduce supply pressure to a maximum of 13" w. c.
T-Stat, Manual and Milli-Volt Pressure
Regulator Pressure Setting 10 in. w.c.
Gas Inlet Pressure: Maximum 13 in." w.c.
Minimum 11 in. w.c.
Model Number Type Gas Rate Number of
Burners
Max BTU/Hr Min BTU/Hr
DFX24NMC Manual 22,000 15,000 1
DFX24NVC Milli-Volt 22,000 17,000 1
DFX32NMC Manual 26,000 15,000 1
DFX32NVC Milli-Volt 26,000 20,000 1
DBX24NTC T-Stat 10,000 — 1

33D4047 7
PILOT
Thegaslogheateristtedwithaspeciallydesignedsafetypilotlightwhichsensestheamountofoxygenavailableinthe
roomandshutsthegaslogheateroffiftheoxygenlevelbeginstodropbelowasatisfactorylevel.Thepilotcanonlyberelit
when adequate fresh air is available.
THERMAL GENERATOR
The milli-volt gas log pilot is tted with a milli-volt generator to provide power for remote activation.
GETTING STARTED
Make sure you have received all parts:
Checkyourpackinglisttoverifythatalllistedpartshavebeenreceived.Youshouldhavethefollowing:
 • Unventedgasheater •Two(2)90°-anglebrackets • Trimkit
 • Installation/operatinginstructions •Canopyandthree(3)screws • Two(2)anchoringscrews
 • Ceramicberlogs •Four(4)blackscrews
MillivoltcontrolledheaterdesignedtobeoperatedwithoptionaldevicesforON/OFFfunctions.
 • HandheldRemotewithreceiver • WallT-statwith20'wire
 • Wallswitchwith20'wire • HandheldThermostatRemotew/receiver
PRODUCT SPECIFICATIONS and GETTING STARTED
Carefullyinspectthecontentsforshippingdamage.Ifanypartsaremissingordamaged,immediatelyinformthedealer
from whom you purchased the appliance. Do not attempt to install any part of the appliance unless you have all parts
in good condition.
Whatyouwillneedforinstallation:
Youmusthavethefollowingitemsavailablebeforeproceedingwithinstallation:
 • Externalregulator(forpropane/LPGonly) • Manualshutoffvalve
 • Pipingwhichcomplieswithlocalcodes • Sedimenttrap
• Phillips head screwdriver • Tee joint.
 • Pipesealantapprovedforusewithpropane/LPG • Pipewrench
(Resistant to sulfur compounds)
CAUTION
• Handle the gas log burner assembly by the grate only. Do not pick the unit up by
the burners.
• Gloves are recommended when handling ceramic ber logs to prevent skin irritation
from loose bers. Logs are fragile — handle with care.
Milli-Volt control has four (4) positions:
OFF - Allgastothegaslogsisshutoffatthevalve.
IGN - Valvepositiontolight/maintainastandingpilot.
ON - ValvepositiontoturnON/OFFlogsetwithremoteswitch/thermostat.
LOW/HI - Variablepositiontocontrolameheight(heatoutput).Bothfrontandrearburnersareinoperationto
providerealisticglowandyellowame.

8 33D4047
J
K
I
E
CD
A
B
H
L
GN
M
F
Inplanningtheinstallationforthereplaceitisnecessarytodeterminewheretheunitistobeinstalledandwhetheroptional
accessoriesaredesired.Gassupplypipingshouldalsobeplanned.Thefollowingstepsrepresentthenormalsequenceof
installation.Eachinstallationisunique,however,andmightrequireadifferentsequence.
 1.Positionreplacein desiredlocation.SeetheLocation of Fireplace and Clearances and Height Requirements, and
Firebox Framing sections found in this manual.
Note: Be sure all packing material has been removed from underside the unit.
2.Installcanopyandlogsperinstructionsfoundinthismanual.ThecanopyMUSTbeinstalledforsafeoperationofthe
unit.
3. Field wire main power supply to units with fan kit. See the Electrical Section found in this manual. (Electrical connec-
tionsshouldonlybeperformedbyanexperienced,licensedcertiedtradesman).
 4.InstalloptionalON/OFFkitonunitswithmillivoltcontrol.Seeinstallationinstruc-
tions included with the kit and also See the Electrical Wiring section found in this
manual.
 5.Plumbgasline.SeetheConnecting the Gas section found in this
manual.(Gasconnectionsshouldonlybeperformedbyanexperienced,
licensed/certiedtradesman).
 6.Completenishwallmaterialand/orsurround.
Figure 2 - Firebox Dimensions with Screen and Log Sets Removed
GENERAL INSTALLATION INFORMATION
DFX24C/DBX24C DFX32C
A14 213/4
B131/8171/2
C117/8133/8
D9 105/8
E21 27
F47/85
G17 201/4
H1 15/8
I221/2283/4
J1 15/8
K241/232
L45/843/4
M101/212
N261/230

33D4047 9
GENERAL INSTALLATION INFORMATION
ADEQUATE COMBUSTION AND VENTILATION AIR
Thisheater shallnotbeinstalledin aconned spaceor unusuallytight constructionunlessprovisions areprovided for
adequate combustion and ventilation air.
TheNationalFuelGasCodedenesaconnedspaceasaspacewhosevolumeislessthan50cubicfeetper1,000BTUper
hour(4.8m3perkw)oftheaggregateinputratingofallappliancesinstalledinthatspace.Anunconnedspaceisdened
asaspacewhosevolumeisnotlessthan50cubicfeetper1,000BTUperhour(4.8m3perkw)oftheaggregateinputrating
ofallappliancesinstalledinthatspace.Roomscommunicatingdirectlywiththespaceinwhichtheappliancesareinstalled,
throughopeningsnotfurnishedwithdoors,areconsideredapartoftheunconnedspace.
UNUSUALLY TIGHT CONSTRUCTION IS DEFINED AS CONSTRUCTION WHERE…
a) wallsandceilingsexposedtotheoutsideatmospherehaveacontinuouswatervaporretarderwitharatingof1perm(6
x1011kgper-pa-sec-m2)orlesswithopeningsgasketedorsealed,and
b) weatherstripinghasbeenaddedonopenablewindowsanddoors,and
c) caulkingorsealantareappliedtoareassuchasjointsaroundwindowsanddoorframes;betweensoleplatesanddoors;
betweenwall-ceilingjoints;betweenwallpanels;atpenetrationsforplumbing,electrical,andgaslines;andatother
openings.
CODES
Adheretoalllocalcodesor,intheirabsence,thelatesteditionofTHENATIONALFUELGASCODEANSIZ223.1or
NFPA54 which can be obtained from…
American National Standards Institute, Inc.
1430 Broadway
New York, NY 10018
or
National Fire Protection Association, Inc.
Batterymarch Park
Quincy, MA 02269
WARNING
Do not install the heater
• where curtains, furniture, clothing, or other
ammable objects are less than 42" from the front
of the heater.
• in high trafc areas.
• in windy or drafty areas.

10 33D4047
GENERAL INSTALLATION INFORMATION
Figure 3 - Sample Room for Determining the Maximum Heater Rating
WARNING
If the area in which the heater may be operated is smaller than that dened as an
unconned space or if the building is of unusually tight construction, provide adequate
combustion and ventilation air by one of the methods described in the National Fuel
Gas Code, ANSI Z223.1, 1992, Section 5.3 or applicable local codes.
Thefollowingformulacanbeusedtodeterminethemaximumheaterratingperthedenitionofunconnedspace:
BTU/Hr =
(L1 + L2) Ft x (W) Ft x (H) Ft. x1000 BTU/Hr
50
Considertwoconnectingroomswithanopenareabetween,withthefollowingdimensions:
L1= 151/2Ft.,L2=12Ft.,W=12Ft.,H=8Ft.
BTU/Hr = (151/2 + 12) x (12) x (8) x1000=52800 BTU/Hr
50
If there were a door between the two rooms the calculation would be based only on the room with the heater.
BTU/Hr = (151/2) x (12) x (8) x1000=29760 BTU/Hr
50