Laserfiche WebLink
Directions-The Minnesota Fuel 6as Code method to calculate to size of a required combusiion air opening,is called the Known Air <br /> Infiltration Rate Method. For new consiruction,4b of step 4 is required ta be filted out. <br /> IFGC Appendix E,Worksheet E-1 <br /> Residential Combustion Air Calculation Method <br /> (for Furnace,Boiler,and/or water Heater in the Same Space) <br /> Step 1:Complete vented combustion appiiance information. <br /> Fumace/Boiler. ) <br /> _Dreft Hood _ Fan Assisted �Direct Vent Input:�iJ`� Btu/hr <br /> or Power Vent <br /> Water Heater: � <br /> _Draft Hood � Fan Assisted _Direct Vent Input: ���etu/hr <br /> or Power Vent <br /> Step 2:Calculate the volume of the Combustion Appliance Space(CAS)containing combustion appliances. // <br /> The CAS includes all spaces tonnected to one another by code compliant openings. CAS volume: � �/�� ft' <br /> LxWxH L W H <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 /> If the year 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 /> 4a.Standard Method <br /> Total Btu/hr input of all combustion appliances Input: Btu/hr <br /> Use Standard Method column in Table E 1 to find Total Required TRV: ft3 <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 5. <br /> 4b.Known Air Infiitration Rate(KAIR)Method(DO NOT COUNT DIRECT VENT APPLIANCES) <br /> Total Btu/hr input of all fan-assisted and power vent appliances Input: '��� BtuJhr <br /> Use Fan-Assisted Appliances column in Table E-1 to find RVFA: ��J� ft' <br /> Required Volume Fan Assisted(RVFA) <br /> _ Totat etu/hr input of all Natural dreft appliances Input: � Btu/hr <br /> Use Natural draft Appliances column in Table E-1 to find RVNFA: �'C ft' <br /> Required Volume Natural draft appliances(RVNDA) <br /> Total Required Volume(TRV)=RVFA+RVNDA TRV= ��J J + � - �',J TRV ft' <br /> If CAS Volume(from Step 2)is greater ihan TRV then no outdoor openings are needed. <br /> If CAS Volume(From Step 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. <br /> Ratio=GAS Volume(from Step 2)divided by TRV(from Step 4a or Step 4b) ,/ �-- <br /> Ratio= `���� / �/�J= � <br /> Step 6:Calculate Redudion Factor(RP). <br /> RF=1 minus Ratio Rf=1- • �� _ � O °J� <br /> Step 7:Calculate single outdoor opening as if all combustion air is from outside. <br /> Total Btu/hr input of all Combustion Appliances in the same CAS Input: ��fl�� Btu/hr <br /> �EXCEPT OIRECT VENT) <br /> COmbustion Air Opening Area(CAOA): <br /> Total Btu/hr divided by 3000 Btu/hr per inz CAOA= ��� /3000 Btu/hr per in2= �J in2 <br /> Step 8:Calculate Minimum CAOA. � <br /> Minimum CAOA=CAOA multiplied by RF Minimum CAOA= �-� x • �� _ �.�-� inZ <br /> Step 9:Calculate Combustion Air Opening Diameter(CAOD) <br /> CAOD=1.13 multiplied 6y the square root of Minimum CAOA �AOD=1.13 J Minimum CAOA= �'� in.diameter <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.Foilow procedures in Section <br /> G304. <br /> Page 5 of 6 <br />