10Interior Wall Materials:
Wallmaterials, such as drywall, should be set ush with
theroughfront faceofthe Vent-Freereplace.Thiswill allow
forplacementofrequirednon-combustiblesurroundmaterialin
suchawaythat thesurroundmaterial canlayatagainst the
nishedwallsurfaceandalsoalignwiththeleadingedgeofthe
rebrickinterioroftheVent-Freereplace(seeFigure 15).
Trim Facings:
Partsof the combustible mantle assembly located along
thesidesofthe reboxopening,whichproject morethanone
andone-halfinches(1-1/2”)fromthefaceofthereplace,shall
bekeptatleasteightinches(8”)fromthereboxopening.
Adjoining Room Walls:
Interiorwall surfaces of adjoining room walls must be at a
minimumhorizontalmeasureoftwenty fourinches(24”)away
fromthenishedopeningoftheVent-Freereplace.
D1W
1-1/2”
8”MIN.NON-COMBUSTIBLEMATERIAL
FRAMING
Figure 14
Model W D1
MM39VF 43” 73-1/2”
MM44VF 48” 77”
MM49VF 53” 80-1/2”
1-1/2”
8”MIN
20”
MIN
8”MIN.NON-COMBUSTIBLEMATERIAL
FRAMING
Figure 15
Air for Combustion and Ventilation
Energyefcienthomesrequire homestobeairtight butatthe
sametime provide sufcient fresh air to breathe. Fresh air
entersthe home through air conditioning duct vents, around
doorsandwindowsbutalsomust provideenoughfreshairfor
propercombustiononallfuel-burningappliancesinthehome.
Exhaust fans, replaces, clothes dryers, and fuel-burning
appliancesdrawairfromthehousetooperate.Youmustprovide
adequatefreshairfortheseappliances.Thiswillinsureproper
ventingofventedfuel-burningappliances.
Non-combustible
FlexHose
Figure 16 Exterior
Providing Adequate Ventilation
InaccordancewiththeNationalFuelGasCodeNFPA54/ANSI
Z223.1,Section 5.3, Air for Combustion and Ventilation, all
spacesinhomesfallinto oneofthethreefollowing ventilation
classications:
1.UnusuallyTightConstruction
2.UnconnedSpace
3.ConnedSpace
Thefollowinginformationwillhelpyouclassifyyourspaceand
provideadequateventilation.
Unusually Tight Construction
 Theairthatleaksaround doorsandwindowsmay provide
enough fresh air for combustion and ventilation. However,
in homes of unusually tight construction, you must provide
additionalfreshair. Unusually tight construction is dened as
constructionwhere:
a.Wallsandceilingsexposedtotheoutside atmospherehave
acontinuouswatervaporretarderwitharatingofoneperm*
orlesswithopeningsgasketedorsealedand...
b.Weatherstrippinghasbeenaddedonopenablewindowsand
doorsand...
c.Caulking or sealants are applied to areas such as joints
aroundwindowand doorframes,between soleplates and
oors,between wall-ceiling joints, between wall panels, at
penetrations for plumbing, electrical, and gas lines, and
otheropenings.
*Apermis aunitof permeanceorwater vaportransmission,
theUSperm-inchisdenedasthepassageof1grainofvapor
through1squarefootof1inchthickmaterialin1hourundera
pressuredifferenceof1inchofmercury.
Ifyourhomemeetsallthethreecriteriaabove,youmustprovide
additionalfreshair.