5
AIRFORCOMBUSTION
ANDVENTILATION
PROVIDINGADEQUATE
VENTILATION
Thefollowing areexcerptsfrom
National Fuel Gas Code. NFPA
54/ANSIZ223.1, Section 5.3. Air for
Combustionand Ventilation. All
spaces inhomes fall intooneof
thethreefollowingventilation
classifications:
1.UnusuallyTightConstruction
2.UnconfinedSpace
3.ConfinedSpace
The informationonpages5
through6willhelpyouclassify
yourspaceand provideadequate
ventilation.
WARNING:Thisheater shall
notbe installedinaconfined
spaceorunusuallytightconstruc-
tion unless provisionsarepro-
videdforadequatecombustion
andventilationair. Readthe
following instructionstoinsure
proper fresh air forthisandother
fuel-burning appliancesinyour
home.
Confinedand
UnconfinedSpace
TheNationalFuelGasCode
ANSIZ223.1 definesaconfined
spaceas aspace whosevolume
islessthan 50cubicfeet per1,
000Btuper hour(4.8m3perkw) of
theaggregateinputratingofall
appliances installedinthatspace
andan unconfined space asa
spacewhosevolumeisnotless
than 50cubicfeet per1,000 Btu
perhour(4.8m3 perkw)ofthe
aggregateinput ratingof all
appliances installedinthatspace.
Roomscommunicatingdirectlywith
the spaceinwhichtheappliances
areinstalled*,through openings not
furnishedwithdoors,areconsid-
eredapartoftheunconfined
space.
Thisheatershall notbeinstalledin
aconfined spaceorunusuallytight
construction unless provisionsare
providedforadequatecombustion
andventilationair.
*Adjoining roomsarecommunicat-
ingonlyif therearedoorlesspassage-
waysor ventilation grillsbetweenthem.
UnusuallyTightConstruction
Theairthat leaks around doorsand
windowsmayprovideenoughfresh
airforcombustionand ventilation.
However, inbuildingsofunusually
tightconstruction, youmustprovide
additionalfreshair.
Unusuallytightconstructionis
defined as constructionwhere:
a.Wallsand ceilingsexposedtothe
outsideatmospherehave acon-
tinuouswatervaporretarderwitha
rating ofoneperm(6×10-11 kgper
pa-sec-m2)orless withopenings
gasketedorsealedand
b.Weatherstrippinghasbeen
addedonopenablewindowsand
doors and
c.Caulkingorsealantsareapplied
toareas such as jointsaround
windowanddoorframes,between
soleplates andfloors,between
wall-ceiling joints,betweenwall
panels,atpenetrationsforplumbing,
electrical,and gas lines,andat
other openings. Ifyourhomemeets
all ofthe three criteriaabove, you
mustprovide additionalfreshair.
See Ventilation AirFrom
Outdoors,page 6.
If your homedoesnot meetallofthe
three criteriaabove,see Determin-
ingFresh-AirFlowfor Heater
Location,page5.
DETERMINING FRESH-AIRFLOWFORHEATERLOCATION
Determining if you haveaConfined orUnconfined Space*
Usethisworksheet todetermine if youhave aconfinedorunconfinedspace.
Space: Includesthe roominwhichyouwillinstallheaterplus anyadjoiningroomswithdoorlesspassageways
or ventilation grillsbetweentherooms.
1. Determinethe volumeofthespace(length×width×height).
Length×Width×Height= cu.ft. (volumeofspace)
Example: Spacesize20ft. (length)×16ft.( width)×8ft. (ceiling height)=2560cu. ft. (volumeof space)
If additionalventilationtoadjoiningroomissupplied withgrillsoropenings,addthevolumeoftheserooms
tothe totalvolumeofthespace.
2.Dividethespacevolumeby50 cubicfeettodeterminethemaximumBtu/Hrthespacecansupport.
(volumeof space) 50 cu. ft.=(MaximumBtu/Hr thespacecansupport)
Example: 2560 cu. ft. (volumeof space) 50 cu.ft.=51.2or 51.200(maximumBtu/Hr thespacecansupport)
