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Ivue <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 Rate Method. For new construction,4b of step 4 is required to be filled out. <br /> FFurnace/Boiler. <br /> Appendix E,Worksheet E-1,1346.6012 <br /> dential Combustion Air Calculation Method <br /> Furnace,Boiler,and/or Water Heater in the Same S 1:Complete vented combustion appliance information. <br /> Btu/hr <br /> raft HOOd _ Fan Assisted erect Vent Input <br /> or Power Vent <br /> Water Heater: W� Btu/hr <br /> _Draft Hood Fan Assisted _Direct Vent Input: <br /> or Power Vent <br /> Step 2:Calculate the volume of the Combustion Appliance Space(CAS)containing combustion appliances. <br /> CAS volume: O <br /> The CAS includes all spaces connected to one another by code compliant openings. W H X <br /> LxWxH <br /> Step 3:Determine Air Changes per Hour(ACH)1 <br /> Default ACH values have been incorporated into Table E-1 for use with Method 4b(KAIR Method). <br /> lithe ear of construction or ACH is not known,use method 4a(Standard Method). <br /> Step 4:Determine Required Volume for Combustion Air.(DO NOT COUNT DIRECT VENT APPLIANCES) <br /> aa.Standard Method Btu/hr <br /> Total Btu/hr input of all combustion appliances Input: <br /> Use Standard Method column in Table E-1 to find Total Required <br /> TRV: <br /> Volume(TRV) <br /> If CAS Volume(from Step 2)is greater than TRV then no outdoor openings are needed. <br /> If CAS Volume(from Step 2)Is less than TRV then go to STEP S. <br /> 4b.Known Air Infiltration Rate(KAIR)Method(DO NOT COUNT DIRECT VENT APPLIAN ES) gtu/hr <br /> Total Btu/hr input of all fan-assisted and power vent appliances Input: )Y <br /> Use Fan-Assisted Appliances column in Table E-1 to find <br /> RVFA: <br /> Required Volume Fan Assisted(RVFA) s`^I� <br /> Total Btu/hr input of all Natural draft appliances input: V Btu/hr <br /> RVNFA: ft' <br /> Use Natural draft Appliances column in Table E-1 to find <br /> Required Volume Natural draft appliances(RVNOA) <br /> Ste Q = 5�� TRV ft' <br /> Total Required Volume(TRV)=RVFA+RVNDA TRV=� <br /> If CA5 Volume(from Step 2)is greater than TRV then no outdoor openings are needed. <br /> If CAS Volume(from Ste 2)is less than TRV then go to STEP 5. <br /> Step 5:Calculate the ratio of available interior volume to the total required volume. 2 c/ <br /> Ratio=CAS Volume(from Step 2)divided by TRV(from Step 4a or Step 4b) Ratio= J S8'a <br /> Step 6:Calculate Reduction Factor(RF). <br /> RF=1- <br /> RF=1 minus Ratio <br /> Step 7:Calculate single outdoor opening as if all combustion air is from outside. Input. 76 V Btu/hr <br /> Total Btu/hr input of all Combustion Appliances in the same CAS <br /> (EXCEPT DIRECT VENT) <br /> Combustion Air Opening Area :CAOA) j 3,j z <br /> Toni Btu/hr divrded b 3000 Btu/hrr in= CAOA= ! /3000 Btu hr r int_ in <br /> Step 8:Calculate Minimum CAOA. <br /> _ 16, WMinimum CAOA=CAOA multiplied by RF Minimum CAOA= 25r33X r " <br /> Yr/ <br /> Step 9:Calculate Combustion Air Opening Diameter(CAOD) o3 <br /> in.diameter <br /> CAOD=1.13 multiplied by the square root of Minimum CAOA CAOD-1.13-4 Minimum CADA= <br /> go up one inch in size if using flex duct <br /> 1 If desired,ACH can be determined using ASHRAE calculation or blower door test.Follow procedures in Section G304. <br /> I:\Building\SafetyPoliaesinformation\Current\2016\VentMakupCombAirCa1s2016.docx <br /> Page 5 of 6 <br />