9
CIRCULATING AIR REQUIREMENTS
WARNING:
Allīsupplyīductsīmustībeīsecuredītoītheīfurnaceī
withīsheetīmetalīscrewsīandīadequatelyīsealed.ī
Whenīsupplyīairīisīprovidedīthroughītheībottomī
ofītheīunit,ītheījointībetweenītheīfurnaceīandī
theīplenumīmustībeīairītight.
Theīsurfaceīthatītheīfurnaceīisīmountedīonīmustī
provideīsoundīphysicalīsupportīofītheīfurnaceī
withīnoīgaps,īcracksīorīsaggingībetweenītheī
furnaceīandītheīīoorīorīplatform.
Supplyī airī ductsī mustī notī beī connectedī toī
anyī otherī heatī producingī deviceī suchī asī aī
ī¬replaceīinsert,īstove,īetc.īThisīmayīresultīinī
ī¬re,ī explosion,ī carbonī monoxideī poisoning,ī
personalīinjury,īorīpropertyīdamage.
Plenumsī&īAirīDucts
This unit is designed only for use with a bottom return
supply duct and must be installed in accordance with
theīstandardsīofītheīNationalīFireīProtectionīAssociationī
Standardī forī Installationī ofī Airī Conditioningī Systemsī
(NFPAī90A),īStandardīforīInstallationīofīResidenceīTypeī
WarmīAirīHeatingīandīAirīConditioningīSystemsī(NFPAī
90B),īandīallīapplicableīlocalīcodes.īNFPAīpublicationsī
areī availableī byī writingī to:ī Nationalī Fireī Protectionī
Association,īBatterymarchīPark,īQuincy,īMEī02269īorīvisitī
www.NFPA.orgīonītheīweb.
ā¢ī Designītheīairīductsīaccordingītoīmethodsīdescribedī
byītheīAirīConditioningīContractorsīofīAmericaī(ACCA).
ā¢ī Airīductsīmustībeīaluminum,ītinīplate,īgalvanizedīsheetī
steel, or other approved materials for outlet or return
airī ducts.ī Snap-Lockī orī Pittsburgh-Lockī seamsī areī
preferred.īAllīotherītypesīofīseamsīmustībeīmadeītightī
to prevent leakage.
ā¢ī Itī isīgoodī practiceītoī sealīallī connectionsīandī jointsī
with industrial grade sealing tape or liquid sealant.
Requirements for sealing ducts vary from region to
region.īConsultīwithīlocalīcodesīforīrequirementsīspeciī¬cī
to your area.
ā¢ī Gasīpipingīmustīnotīrunīinīorīthroughīanyīofītheīairīductī
system.
SupplyīAirīConnections
ā¢ī The supply duct system must be designed so that the
static pressure measured external to the furnace does
not exceed the listed static pressure shown on the
furnace rating plate. The supply air must be delivered
toītheīheatedīspaceībyīduct(s)īsecuredītoītheīfurnaceī
casing, running full length and without interruption.
ā¢ī Ductīsystemīmustībeīdesignedīsoīthatīnoīsupplyīregistersī
are located in duct system directly below the furnace.
Dampers
Anīautomatedīshutīoffīdamperīisīrequiredīwhenītheīhomeī
isī airī conditionedī byī aī self-containedī unit.ī Aī damperī
isī requiredī toī preventī chilledī airī fromī īowingī overī theī
furnace heat exchanger. This damper is designed to ļ¬t
inītheīfeederīductīcavity,īdirectlyīunderītheīfurnace.īForī
proper installation, refer to the instructions provided with
the damper. See replacement parts list provided online.
UnconditionedīSpaces
Allīductīworkīpassingīthroughīunconditionedīspaceīmustī
be properly insulated to minimize duct losses and prevent
condensation. Use insulation with an outer vapor barrier.
Refer to local codes for insulation material requirements
Closet Installations
WARNING:
Failureī toī complyī withī theī theī followingī
instructionsīmayīresultīinīī¬re,īasphyxiationīorī
carbonīmonoxideīpoisoning.
Forī properī airī circulation,ī closetī installationsī requireī
a return air grill installed in the door or side wall that
exchanges with the living area of the home as shown in
Figureī3ī(pageī10).īAīpartiallyīlouveredīdoorīmayīalsoībeī
used across the opening. Return air openings should not
be located to draw air directly from a bathroom. Grilles
placedīinīaīsideīwallīrequireīaī6āīclearanceīfromītheīwallī
to the furnace so that the air may enter the front grille of
the furnace. In addition, all return air systems, including
theī īoorī andīceilingī systems,ī mustī meetītheī followingī
conditions:
ā¢ī Theīreturnīairīopening,īregardlessīofīitsīlocationīinītheī
closet, must not be smaller than size speciļ¬ed on unit
dataīlabel.īIfīlocatedīinītheīīoor,ītheīopeningīmustībeī
provided with a means of preventing its inadvertent
closureībyīīatīobject(s)īplacedīoverītheīopening.
ā¢ī Theīreturn-airīopeningīintoītheīcloset,īregardlessīofīitsī
location, must have an open free area of 200 in
2
ī(1290ī
cm
2
ī)īminimum.
ā¢ī Theīcross-sectionalīareaīofītheīreturnīductīsystemī(inī
īoorīorīceiling)īleadingīintoītheīclosetīmustīnotībeīlessī
than 200 in
2
ī(1290īcm
2
ī).
ā¢ī Theītotalīfreeīareaīofītheīopeningsīinītheīīoorīorītheī
ceiling registers serving the return air duct system must
not be not less than 300 in
2
ī(1935īcm
2
ī).
ā¢ī Materialsīlocatedīinītheīreturnīductīsystemīshallīhaveī
aīīameīspreadīclassiī¬cationīofī200īorīless.
ā¢ī Noncombustibleīpansīhavingīoneīinchīupturnedīīangesī
areī locatedī beneathī openingsī inī aī īoorī returnī ductī
system.
ā¢ī Hollowī spacesī usedī asī ductsī orī plenumsī forī
environmentalīairīmayīcontainīmineral-insulatedīmetalī
sheathed cable, aluminum sheathed cable, electrical
metallicī tubing,ī rigidī metalī conduit,ī īexibleī metalī
conduitī(notītoīexceedī4īft),īorīmetal-cladīcables.īWiringī