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Brad White
Brad White Member Posts: 2,398
To my thinking. I do not have the actual UL listing numbers but your code may dictate in stronger language than any referenced standard. Here in MA one needs at least 2 inches clear between masonry chimneys and combustibles (surrounding framing in particular). I have to imagine bare hot (140F) sheetmetal would require more.

IIRC, the standard was that after firing for a period of time to steady state equilibrium, the surface of the combustible material could not be higher than so many degrees above ambient. I forget the numbers, but you may try a UL search or contact a local code authority.
"If you do not know the answer, say, "I do not know the answer", and you will be correct!"

-Ernie White, my Dad


  • R. Day
    R. Day Member Posts: 1
    Fire safety

    Whatis a minimum distance for a wood beam (2x10) from a plenum of an oil fired furnace? Mine are within 1"
  • lchmb
    lchmb Member Posts: 2,997

    It depend's on the make. I have seen a number of them that only require 1". Check the web site for the unit you have...
  • jp_2
    jp_2 Member Posts: 1,935
    got a picture?

    I general consider a plenum more of a hot air duct/return, and a 'furnace exhaust vent' aa a flue?

    since you state "mine are" a plural form suggests you are talking about 'many' plenums? so I am confused my your actual meaning.
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