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chimney liner sizing

gto400_1970 Member Posts: 1
have a potential job with 96,000 btu gas boiler forty gallon hwh gas also 40,000 btus what size liner chimney about 30 ft in height a buddy says 5'' liner is fine to use is this correct have tried to get info from nat grid with no results any help greatly appreciated


  • Tim McElwain
    Tim McElwain Member Posts: 4,487
    Assuming both of these

    appliances are natural draft (no fan assisted) a total of 136,000 BTU's on a Type "B" common vent connector 30 feet high will handle up to 185,000 BTU's on a 5" Type "B" vent. Liners however are 20% less capacity than a "B" vent so a 5" liner would handle 185,000 x 20% = 37,000 subtracted from 185,000 it will handle 148,000 so your buddy is correct.

    I would however double check the charts for the type liner you put in to be accurate.
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