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Bringing an Attic Furnace / Air Handler into Conditioned Space

here_to_learn_more | Posted in Building Code Questions on

Want to bring furnace/air combo unit into conditioned space.  It’s a 1950s, 1.5 story, located in zone 5 with furnace/air in third floor attic.  The unit is suspended and close to roof rafters.  The rafters are 2×6, and the roof is vented.  It’d be challenging (and more expensive) to put unit and all ducts into conditioned space by insulating ceilings in entire roughly 40′ length with 5′ and 13′ rafters.  If just bringing the unit into the conditioned space, what is code regarding insulation?  Any recommendations would be appreciated.

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  1. user-2310254 | | #1

    Does the furnace use combustion? If so, is it sealed or atmospheric?

    1. here_to_learn_more | | #3

      Steve, it's a sealed combustion (drawing air from outside).

  2. GBA Editor
    Kiley Jacques | | #2

    This article includes code-related information potentially applicable to your situation as well as a number of useful resources: Creating a Conditioned Attic.

    1. here_to_learn_more | | #4

      Kiley, thanks for the link. I did see this earlier and found it quite useful info. In fact, this article is what caused me to consider the original question. Ideally, I would redo insulation by insulating the entire attic space from the sloped roof. I'm just trying to gather info about around the furnace and weigh all options. Thanks again!

  3. Jon_R | | #5

    Encapsulating attic ducts can "fulfill the DOE Zero Energy Ready Home program requirement that ducts be installed in conditioned space".

  4. Deleted | | #6


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