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nfpa 54/common vent sizing

zepfan Member Posts: 312
does anyone know which nfpa 54 table is used to size the common vent flue pipe size for category 1 furnaces? we have a job where we are doing an oil to gas conversion,and would be install five 120 mbh category 1 furnaces,relining the chimney and i need to find out how to size the common vent that the five furnaces would tie into.they give some examples in the book,but i did not see any that had five furnaces.thanks to all


  • Bob Harper
    Bob Harper Member Posts: 862
    common vent sizing

    You use the common vent sizing tables for B-vent with either single walled connectors or under B-vent connector depending upon which you're using. Pay special attention to your manifolding and support as well as the 7x rule.

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