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Directions-The Minnesota Fuel Gas Co�method to calculate to size of a required cpmbustion&ir opening,is callerl the Known Air <br /> /nfiltr�tion Rate Method. For new coastr�iction,4b of step 41s requlreat to be filled out. <br /> IFGC ndix E,Wotksheet E-1—Residenti Combustion Air Caicuiation AAetl�od for Fum ,Boiler,ancllor Water Heater in tl�e Same S ce <br /> Step 1:Compiete vented combustion appGa i�ormatfon_ <br /> Fumacei8oiler. <br /> �raft Hood ❑Fan Assisted �irect Vertt Input: ���i��, Btullx <br /> « <br /> or Power Vent <br /> Water Heater: <br /> C3?raR Hood �.Fan Assisted , �ir�d Verit Input: 7�. `t�`J V BtWhr <br /> or Power Vent <br /> Step 2:Calculete the wlume ofi the Comb n Appliance Space(CAS)contaioing combustio appliances.The CAS indudes ati <br /> spaces connected to one anoiher by code compii�nt openings. �3�� x g�� $ <br /> CAS volume: �0 3 v R3 L x W x H L W H <br /> Sbep 3:Deterrnine Air Changes per Hour(AGH)1 <br /> De#autt ACH values have been in�rporated irrto Tab1e E-9 for use with Method 4b(KAIR Me�hod). <br /> If the year of construtxion or ACH is no1 kn ,use method 4a(Standard MeUmd). <br /> Step 4:D�ermine Requit�ed Volume for C ustion Air.(00 NOT COUIVT DIRECT VEM'A PLIANC S) <br /> 4a.Standard Method <br /> Totai Biu/hr input of ali combustion appliances inpu Btumr <br /> Use StandaM Method cokunn in Table E-9 to find Total Required TRV: ft' <br /> Volume(TR�If CAS Volume(from S'tep 2)ia g�aterthan TRV then no outdoor openir�s arq needed.If CAS Vok�me(from Step 2)Is/ess Lhan <br /> TRV then go to STEP 5. <br /> 4b.Knovm Air IM'ilMdtion Rate(KAIR)Method(DO NOT COUNT DiRECT VENT APPLIANCE� <br /> Total Btu/hr input of a11 fan�ssisted and porver verrt apptianoes Inp�R: �$�-� B� <br /> Use Fan-Assisted AppRarx:es column in Table E-9 to find RVRA: g��S ft$ <br /> Required Volume Fan Assisted(RVFA) <br /> Total BtuiF��input of alt Matu►al draft appNances ]np�t: � BtWt�r <br /> Use Plaiural draft Applianoes c�lumn in Ta41e E-1 to find Rv►iFA: � ft' <br /> Required Volume Naturei draR appliances(fd�MDA) <br /> Total Required Volume(TRV)=RYFA+RVNDA TRV= s�S + O = Sb a S TRV ft <br /> If CAS Vol�une from Ste 2 fs t�than tl�en no outdoor o nin s are needed.(f CAS oitxne Ste 2 is/ess than TRV tl�en o to STEP S. <br /> Sbep 5:Calcutate the ratio of availabk rrteribr votume to the total requined volume. <br /> Retio=CAS Votume(from Step 2)dlvldmd 4y TRV(from Step 4a or Step 4b) <br /> Rat;o�'�i 5��'� � 3� <br /> Step 6:Calculate ReducUon Factor{RF�. R =1 mJnus Ratio <br /> RF=1 - � 3� _ � � 1 <br /> 5top 9:Calcuiate single a�tdoor opening as ff ali combustion air is irom outside.Totsl Btufir of ap C�nbustion Appliarwes in the same CAS <br /> ��P�; ��j C�C� 8tultu(EXCEPT RECT VEN� <br /> Combustion Air Opening Area(CAOA):Totel BtWhr divfded by 3000 BtuRu per inZ <br /> CAOA= ��� !3000 Btulhr per in2= o� S in2 � <br /> 3tep 8:Calculate Minimixn CAOA Min�nt�n CAOA=CAOA mu/Hplied by RF <br /> Minimum CAOA= �J x� f �]� _ �� ��2 <br /> Sfiep 9:Calculate Carnbustion Air Opening iameter(CAOD): CAOD=1-13 mulBplled by e squa�e root of Minimum CAOA ,� � _ <br /> � �..f.� <br /> CAOD=1.13� Minlmum CAOA= y � ir►.diameter go up one in in size if using flex duct �� , �� <br /> 1 If desired,ACH can be detem�ined using AShiRAE ralculation or btov�r door tesL Follow p ures in Section G304. <br /> � <br /> I <br />