Dunkirk PVSB - Fresh Air for Combustion; Boiler Located in Unconfined Space; Fresh Air Duct Capacities; Boiler Located in Confined Space

Provisionfor combustionandventilationair mustbe in accordancewithSection5.3, Airfor CombustionandVentilation,of I
the National Fuel Gas Code, ANSIZ223.1-1atest revision, or applicable provisions of the local building codes.
i
WARNING
Be sure to provide enough fresh air for combustion.
Enough air insures proper combustion and assures that
no hazard will develop due to the lack of oxygen.
NOTE
if you use a fireplace or a kitchen or bathroom exhaust
fan, you should install an outside air intake. These
devices will rob the boiler and water heater of combus-
tion air.
Youmustprovideforenoughfreshairtoassurepropercombustion.Thefire
in theboilerusesoxygen.It musthavea continuoussupply.Theairin a
housecontainsonlyenoughoxygento supplytheburnerfor ashorttime.
Outsideair mustenterthehousetoreplacethatusedbytheburner.Study
followingexamples1and2todetermineyourfreshairrequirements.
EXAMPLE1: BoilerLocatedin UnconfinedSpace
Anunconfinedspaceis definedasa spacewhosevolumeis notlessthan
50cubicfeetper1,000Btuperhourofthetotalinputratingofallappliances
installedinthatspace.
Ifyourboileris inanopenarea(unpartitionedbasement)in aconventional
house,theairthatleaksthroughthecracksarounddoorsandwindowswin
usuallybeadequateto provideairforcombustion.Thedoorsshouldnotfit
tightly.Donotcaulkthecracksaroundthewindows.
Equipmentlocatedinbuildingsof unusuallytightconstructionshallbepro-
videdwithairforcombustion,ventilation,anddilutionoffluegasesusing
themethodsdescribedinexample2Borshallbespeciallyengineered.The
authorityhavingjurisdictionmustapprovespeciallyengineeredinstalla-
tions.
EXAMPLE2: BoilerLocatedin ConfinedSpace
A.All Air fromInsidethe Building:Theconfinedspaceshallbepro-
videdwithtwopermanentopeningscommunicatingdirectlywithanaddi-
tionalroom(s)of sufficientvolumeso thatthecombinedvolumeof al!
spacesmeetsthecriteriaforanunconfinedspace.Thetotalinputof all
gasutilizationequipmentinstalledinthecombinedspaceshallbecon-
sideredin makingthisdetermination.Eachopeningshallhavea mini-
mumfreeareaofonesquareinchper1,000Btuperhourofthetotalinput
ratingof al!gasutilizationequipmentintheconfinedspace,butnotless
that100squareinches.Oneopeningshallbewithin12inchesofthetop
andonewithin12inchesof thebottomoftheenclosure.Theminimum
dimensionofairopeningsshallnotbetessthan3 inches.
B.AllAirfromOutdoors:Theconfinedspaceshallcommunicatewiththe
outdoorsinaccordancewithmethods1or2.Theminimumdimensionof
airopeningsshallnotbelessthan3 in.Whereductsareused,theyshall
beofthesamecross-sectionalareaasthefreeareaoftheopeningsto
whichtheyconnect.
1.Twopermanentopenings,onecommencingwithin12 inchesof the
top,andonecommencingwithin12inchesofthebottom,oftheenclo-
sureshallbeprovided.Theopeningsshallcommunicatedirectly,orby
theducts,withtheoutdoorsorspaces(crawlorattic)thatfreelycom-
municatewiththeoutdoors.
a)Wheredirectlycommunicatingwiththeoutdoorsorwherecommu-
nicatingtotheoutdoorsthroughverticalducts,eachopeningshall
haveaminimumfreeareaof1sq.in.per4000Btuperhouroftotal
inputratingof allequipmentintheenclosure.(SeeFigure3A.)
b)Wherecommunicatingwiththeoutdoorsthroughhorizontalducts,
eachopeningshallhaveaminimumfreeareaof1sq.in. per2000
Btuperhouroftotalinputratingofallequipmentintheenclosure.
(SeeFigure3B.)
2.Onepermanentopeningcommencingwith12inchesofthetopofthe
enclosure,shallbepermittedwheretheequipmenthasclearanceof at
least1inchfromthesidesandbackand6 inchesfromthefrontof the
appliance.Theopeningshalldirectlycommunicatewiththeoutdoors
orshaltcommunicatethroughaverticalorhorizontalductto theout-
doorsorspaces(crawlorattic)thatfreelycommunicatewiththeout-
doors,andshallhaveaminimumfreeareaof:
a)1sq.inchper3000Btuperhourof thetotalinputofallequipment
locatedintheenclosure(SeeFigure4),and
b)Notlessthanthesumoftheareasofallventconnectorsinthecon-
finedspace.
1
Figure 3A - FRESH AIR DUCT CAPACITIES (Btuh) I
FreshAir
Duct Size
3"x 12"
8" x 8"
8"x 12"
= 1 tt
18Y2 x 16"
1 Square Inch per 4,000 Btuh
100% Free 75% Free
Area Area
1/4"Wire Metal
Mesh Louvers
144,000 108,000
256,000 192,000
384,000 288,000
5t2,000 384,000
25% Free
Area
Wood
Louvers
36,000
64,000
96,000
128,000
Figure 3B- FRESH AIR DUCT
1SquareInchper2,000Btuh
Fresh Air
Duct Size
3" x 12"
8" x 8"
8" x 12"
81/2"x 16"
100% Free
Area
1/4"Wire
Mesh
72,000
128,000
192,000
256,000
CAPACITIES (Btuh) I
75% Free
Area
Metal
Louvers
54,000
96,000
144,000
192,000
25%Free
Area
Wood
Louvers
18,000
32,000
48,O0O
64,000
Figure 4 - FRESH AIR DUCT CAPACITIES (Btuh)
1Squaretnch per3,000Btuh
100%Free 75% Free 25% Free
Area Area Area
FreshAir 1/4"Wire Metal Wood
Duct Size Mesh Louvers Louvers
3"x !2" 108,000 81,000 27,000
8" x8" 192,000 144,000 48,000
8"x 12" 288,000 216,000 72,000
8½"x 16" 384,000 288,000 96,000
I
7,_8 4