
CompactUnit/UtilityHeater OperatingInstructionsandOwner’sManual
5
Theseunitsarecertifiedforresidentialapplications.Forinstallation
inaresidentialgarage,theseunitsmustbeinstalledsothat
burnersandignitionsourcearelocatednolessthan18”(457mm)
abovefloor.Heatermustbelocatedorprotectedtoavoidphysical
damagebyvehicles.RefertoCSAB149.1,NaturalGasandPropane
InstallationCodecurrentedition.
INCANADA:Inaconfinedarea,theheatermustbeinstalled
inaccordancewiththeCSAB149.1,NaturalGasandPropane
InstallationCode.Besuretocheckwithlocalcodesand
ordinancesforadditionalrequirements.
UNIT HEATER INSTALLATION
Unitisshippedreadyforinstallation.Unitmaybeinstalledas
showninfigure 1orinverted180odependingondesiredlocation
asgovernedbyclearances,ventconnection,airdirection,gas
supply,electricalsupplyandserviceaccessibility.
1. Ifinstallingunitinaninvertedposition:Removeandretain
screwssecuringdoorandrotatedoor180o.Securewith
retainedscrews.Rotatelouversdirectingairflowasdesired.
2. Chooselocationformountingbrackets.
3. Removeandretainthreescrewsalongtopedge(bottom
edgewheninverted)offrontofunit.
4. Alignscrewholesonmountingbracketwithholesalong
topedge(eitheruprightorinverted)ofunit.Secureone
mountingbrackettofrontofunitwithretainedscrews.
Secureothermountingbrackettobackofunitwithscrews
retainedonthebackofunit.
5. Tosupportunit,securemountingbrackettoceilingjoistor
truss.Unitmayalsohangonrodsasshowninfigure 1.
COMBUSTION AND VENTILATION AIR
Adequatefacilitiesforsupplyingairforcombustionandventilation
mustbeprovidedinaccordancewiththelatesteditionofsection
5.3,AirforCombustionandVentilation,oftheNationalFuel
GasCode,ANSIZ223.1,intheU.S.A.,CSAB149.1NaturalGas
andPropaneInstallationCode,orapplicableprovisionsoflocal
buildingcodes.
Allgasfiredappliancesrequireairtobeusedforthecombustion
process.Inmanybuildingstoday,thereisanegativeindoorair
pressurecausedbyexhaustfans,etc.Ifsufficientquantitiesof
combustionairarenotavailable,theheateroranotherappliance
willoperateinaninefficientmanner,resultinginincomplete
combustionwhichcanresultintheproductionofexcessivecarbon
monoxide.
CAUTION: Insufficientcombustionaircancauseheadaches,
nausea,dizziness,asphyxiationordeath.
Ifindoorairistobeusedforcombustion,itmustbefreeofthe
followingsubstancesorthelifeoftheheatexchangerwillbe
adverselyaffected:chlorine,carbontetrachloride,cleaningsolvent,
halogenrefrigerants,acids,cementsandglues,printinginks,
fluorides,paintremovers,varnishes,oranyothercorrosives.
VENTING
A–GENERALRECOMMENDATIONSAND
REQUIREMENTS
NOTE:Theventisapassageway,verticalornearlyso,usedto
conveyfluegasesfromanappliance,oritsventconnector,tothe
outsideatmosphere.Theventconnectoristhepipeorductthat
connectsafuel-gasburningappliancetoaventorchimney.
Unitheatersmustbeventedincompliancewithalllocalcodes
orrequirementsofthelocalutility,thecurrentstandardsofthe
(American)NationalFuelGasCode,ANSIZ223.1or(Canada)
CSAB149.1NaturalGasandPropaneInstallationCode,andthe
followinginstructions.
Ametalstamped/extrudedtransitionissuppliedwiththiscertified
unit.Itmustnotbemodifiedoralteredandmustbeinstalled
ontheoutletoftheinduceddraftblowerassemblypriortothe
installationoftheventorventconnector.Failuretocomplywith
thisrequirementwillvoidthecertificationoftheunitbythe
approvalagencies.Alljointsshallbesecuredwithatleasttwo
corrosionresistantscrews.Alljointsmustbecheckedforgas
tightnessafterinstallation.
B–VERTICALVENTSUSINGMETALVENT
PIPE–COMMERCIALANDRESIDENTIAL
INSTALLATIONS
MHUcompactunitheatersarelistedasCategoryIappliancesfor
verticalventinstallations.
1. MHUunitheatersaretobeusedwithNFPA-orANSI-
approvedchimneys,U.L.listedtypeB-1gasvents,single wall
metalpipe,orlistedchimneyliningsystemforgas venting
whereapplicable,aswellasthemodificationsand limitations
listedinfigure 2.Sealsinglewallventmaterial accordingto
thesectionA - General Recommendations and
Requirements.
2. Theventdiametershallbe 3" (76mm) or 4" (102mm) for the
50k unit and 4" (102mm) only for the 80k and 125k units.
In all cases, afluetransition piece(supplied)isrequiredtofit
overthe outletofthe induceddraftassemblyonthe
appliance.
3. Keeptheventconnectorrunsasshortaspossiblewith
aminimumnumberofelbows.Refertothe(American)
NationalFuelGasCodeANSIZ223.1or(Canada)CSAB149.1
NaturalGasandPropaneInstallationCodeformaximum vent
andventconnectorlengths.Horizontalrunofthevent
connectorfromtheinduceddraftblowertothechimney/vent
INSTALL UNIT / UTILITY HEATER
SUPPORT
RODS
MOUNTING
BRACKETS (2)
FIGURE 1