Tapping into existing Duct ?

Old 09-06-08, 02:43 PM
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Tapping into existing Duct ?

2 q's:

1) I am finishing an attic as a walk in closet and running A/C Insulated Flex Tubing into the attic. I will be tapping into my A/C Ducting in my upstairs attic (the two attics connect).

If my Supply duct is a rectange - say 15 feet long by 2 feet wide and 1 foot deep. All of the feeds are off the sides of the ducting (like the legs on a Centipede). For my new feed, do I have to tap into the side of the duct, or can I tap into the end (ie the Head of the Centipede). Also, if I do tap into the side, does it matter that I will be very close to another feed coming out of the same side?

2) I have very small amout of space above the ceiling so I need to use a ceiling box with a side inlet (7" circular inlet) rather then a top inlet. The flex tubing will connect to the side inlet and will have to clear a 2x4 stud (Colar Tie). To clear the studs I would like to extend the box up with some 2x4 wood framing. Can wood be part of the A/C feed, or will condensation rot the wood over time? The flex would feed the metal box. The box would be mounted on the 2x4's, the Ceiling Diffuser would be screwed from below into the 2x4 framing.

Thanks. Steve
Old 09-06-08, 06:00 PM
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Can not tie into end cap. And last take off should be two feet from end of duct. Supply air will have to be duct. Return can be just about any thing (in my area).
Old 09-06-08, 09:04 PM
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Air Conditioning Problems

You should not tap into the end of your trunk line because you will negatively impact your system pressure your new tap will have alot of airflow and the air in the rest of the branch lines will be greatly reduced if you tap into any of the sidewalls you should be fine although you are still altering the system when you finish out the tap you will need to use insulated metal or ductboard if you use wood you will be creating a mold problem

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