# Ducting questions on new owner/builder construction.



## pauldana (7 mo ago)

The picture posted in my garage, where the HVAC unit is located. 
I need to go up the wall (~20') over to the left about 15' and then up into the 3rd story/attic
The right side of the AC unit is where the return line will be.

1. can I use A/C insulated flexible round ducting?
2. what size do i have to use for code (Kalifornia)
3. Can I go tin? if so, what is the minimum size?
4. got another idea?  
5. any difference coming from bottom or side for return air?


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## channellxbob (Sep 27, 2020)

Too many variables. What size unit, volume airflow, where are these ducts going, what size room or area. You need to lay it out on paper with measurements and calculate available static pressure and work out duct sizing. A run that far would likely require very large flex. I would go metal if at all possible, especially where enclosed in walls.


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