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arrecdOns - The Minnesota Fuel Gas Corse method to-ah;gjatC tq 51>re Of 0 feq(llrely CQf1ibU5C10f? 01f DfJ21J1JJg, 15 r"811ed the ICnolvn /fir <br />in�frafidn note I�et�toor <br />Pop new construction, 4b of step 4;s required to be filled out. <br />IFGCAppendix 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:Com ete vented cumbustdon appliance information. <br />Furnas Boder: — 1 01� G�� <br />Draft Hood Fan Assisted — DirectVenC Input: l Lto/ hr <br />or Power Vent <br />Water Heater; sj <br />_ Draft flood �an Assisted Direct Vent Input: �y,066 Btu/hr <br />or Power Vent <br />Step Z: Calculate the vcfume of the Combustion Appliance Space (CAS) containing combustion appliances. + �� <br />The CAS includes all spaces connected to one another by code compliant openings. CAS volume: f ft3 <br />LXWxH L W H <br />Step 3: Determine Air Changes per Hour (ACH)1 <br />Default ACH values have heen incorporated into Table E-1 for use with Method 4b (KAIR Method). <br />If the year o€construction orACH is not known, use method 4a (Standard Method). <br />Step 4: Determine Required Volume for Combustion Air. (DO NOT COUNT DIRECT VENT APPLIANCFS) <br />4a. Standard Method % r <br />Total Btu/hr input of all combustion appliances Input: 6 606 Btu/hr <br />Use Standard Method column in Table E-1 to find Total Required TRV: ,�� SQ ft' <br />Volume (TRV) <br />If CAS Volume (from Step 2) is greater Chun TRV then no outdoor openings are needed. <br />If CAS Volume (from Step 2) is fess than TRV then go to STEP 5. <br />4b. Known Air Infiltration Rate (KAIR) Method (DO NOT COUNT DIRECT VENT PPLIANCES) <br />Total Btu/hr input of all fan -assisted and power vent appliances I put: 6tu/hr <br />Use Fain -Assisted Appliancescolumn inTable E-ltofind R FA: ft3 <br />Required Volume Fan Assisted (RVFA) <br />Total Btu/hr input of all Natural draft appliances inp t: Btu/hr <br />Use Natural draft Appliances column in Table E-1 to find RVN ft3 <br />Required Volume Natural draft appliances (RVNDA) <br />Total Required Volume MV) = RVFA r RVNDA TRV = + TRV ft3 <br />If CAS Volume (from Step 2) is greater than TRV then no outdoor openings are eeded. <br />If CAS Volume (from Step 2) is less than TRV then go to STEP S. <br />Step S, Calculate the ratio of available interior volume to the total required voi me. <br />Ratio =CAS Volume (from Step 2) divided by TRV (from Step 4a or Step 4b) <br />.tin = / <br />Step 5: Calculate Reduction Factor (RF) - <br />RF =1 minus Ratio RF =1- _ <br />Step 7: Calculate single outdoor opening as if all combustion air is from outsid 2. <br />Total 9tu/hr input of ali Combustion Appliances In the same CAS Input Btu/hr <br />(EXCEPT DIRECT VENT) <br />Combustion Air Opening Area (CAOA): <br />Total Btu/hrdividedby 3000 Btu/hrperin' CADA= I30006tu/hr per irZ= in' <br />Step B. Calculate Minimum CADA. <br />Minimum CADA = CAOA multipliedby RF Minimum CAOA = x - in' <br />Step 9: Calculate Comhustion Air Opening Diameter (CAOD) <br />CAOD =1.13 multiplied by the square root of Minimum CAOA CAO0 L12 V Minimum CADA = 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. Follow procedures in Section <br />G304. <br />Page 5 of 6 <br />