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Old 04-30-2012, 09:37 AM   #1
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Trunk line design in Attic

Contractor started on HVAC install today and told me best location for trunkline is near apex of roof line in middle of attic, taking up 18" of my precious 111" total attic height. This unit is for downstairs. Attic conversion will be at end of 2012. At this time, a 2nd Unit will be installed for attic itself. Attic is currently not insulated and not vented. Intend to use spray foam at end of the year.
My question: Since the duct will start at this apex and shoot out parallel and next to the uninsulated roof, would it not take on heat in summer and cold in winter, making my AC costs higher? I asked contractor to come up with alternatives but they said this is the best way and that the impact if any will not be noticeable in my bill. Is the contractor correct?


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Old 04-30-2012, 03:04 PM   #2
as seen on tv
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If it is designed correctly for an unconditioned space should have little impact on operating cost. There are materials designed for that application


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Old 04-30-2012, 05:19 PM   #3
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That's the way it's supposed to be installed unless you have a crawlspace or basement. If you do he could install the equipment there and leave the attic alone if your going to complete attic renovations in a couple years.
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Old 04-30-2012, 06:24 PM   #4
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I'd suggest getting the foam done first. The way you are doing it the duct needs to be insulated because it's an unconditioned space. Once the roof deck is foamed then your attic can be classified as a conditioned space. No sense paying for insulation twice and foaming the roof will be a whole lot easier without duct in the way.
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