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• <br /> Directions-The Minnesota Fuel Gos Code method to calculate to size of a required combustion air opening,is called the Known Air. <br /> infiltration Rote Method. For new construction,4b of step 4 Is required to be filled out <br /> iPOC Appy E,WOKE-1 <br /> Residential Combustion Air Calculation Method <br /> (for Furnace,Boiler,* • or Water Heater in the Same ..ce <br /> Step 1:Complete vented combustion appliance information' <br /> _Draft <br /> ora t Hood Fan Assisted .Direct Vent Input:. .{ _-fir <br /> orPowerVentWatet Qeater: � <br /> Draft Hood X Fan Assisted .4-Medi/eat Input:-qW U0� _ <br /> '- or Power VentSpate(CAS)containing appnan <br /> amp 2•Calculate the volume of the Combustion AppRe > volume: /6 <br /> The CAS includes all spaces connected to one another by code compliant opening W H <br /> Step a:Determine Air Changes per Hour(ACH)1 <br /> DefeuitACH values have been Incorporated <br /> into Table E-1 for use with Method 4b(KAIR Method). <br /> If the e r n consequired VolumeikcH for Cambodian Air. NOT COnot known,use method 4a UNT�DiRECT VENT APPLIANCES) <br /> Step 4:Dstarmine Required <br /> 4g,.Standard Method Input Btu/hr <br /> Total Btu/hr lnpUt of as combustion applian it; <br /> Use Standard Method column In Table E-1 to find Total Required <br /> volume(TRV) <br /> If CAS Volume(from Step 2)is greeter than TRV then no outdoor openings are needed. <br /> If CAS Volume(from Step 2)isle sthanTRV then goto STEPS. <br /> 4b.Known Air Infiltration Rate(KAIR)Method(DO NOT COUNT DIRECT vterr APPUA S)�� fir <br /> Total stu/hr input of all fanastiated and pooervent appiWntes 1 ' <br /> Use Fan-AssiSted AppMnces column in Table Ei to find <br /> RVFA: 4-000 its <br /> Required Volume Fan Assisted(RVFA) <br /> Input C Btu/fir <br /> Total Btu/hr Input of all Natural draftappliances CI <br /> Use Natural draft Appliances admen in Table E•1 to fed <br /> avNFA: It' <br /> Required Volume Natural draft appliances(SDA) /�� TRV f <br /> Total Required Volume(TRV)12 TRV <br /> RVFA a3�=---___+ (� <br /> if CAS volume(from Step 211s greater than TRV then no outdoor openings are needed. <br /> If CAS Volume from Step 2 is kw then TRV then to 5115>5. <br /> step 5:Calculate the ratio of available lnterl rvotume to the total required volume. <br /> Ratio a CAS Volume(from Step 21 divided byTRV Groin Step 4g,or Step ab} Ratio= /060 Gds . , 1 11 <br /> Step 6:Calculate Reduction Factor(RF). . 8 a . <br /> RF=1• . 1% <br /> RF=1 minuso as if an combustion aids from outside. <br /> Step 7:Calculate <br /> umte Ingle Outdoor opening latae same CAS Input & 0b Btu/hr <br /> Total eRsjhr input tied Combustion AP 1c� <br /> (EXCEPT DIRECr VENT) r1 y <br /> Combustion Air Opening Area(CAOAI: ar •6 j in' <br /> Total Btu/hr dividpedd' 3000 stulhr• in= CAOA.. SO000 ,�!i ., r tri = <br /> Step 8:tak Minimum CAOA, <br /> Mlnlmum CA0A=CA0 ma' <br /> . RF Minimum CADAa P�a.G/x , ga . () lin int <br /> '' • // `` <br /> step a:Calculate Combustion Air OpeningDlameter(CAOD) Ali b8 V <br /> CAOD-sit multiplied by the squaw tuft ofMinium CAOA <br /> CAOD=1.13 V Minimum CADA=„r». , . <br /> one inch In size If flex duet <br /> 1 If desired,ACM can be determined using ASHRAS piculation or blower doortest.rima procedures In Section <br /> 6304. <br /> Page 5of8 <br />