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Old 08-25-2010, 08:53 AM   #1
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flex duct turns


Should I have solid 90"S and 45's at the bends in my flex duct off the distribution box, and in the ceiling registers?
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Old 08-27-2010, 07:22 PM   #2
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flex duct turns


Although not absolutely necessary, I would recommend it. I have seen too many installations where the flex duct has nearly collapsed into itself on bends. A hard elbow is clearly better.
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Old 08-27-2010, 08:40 PM   #3
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flex duct turns


Care must be taken not to kink the flex when making turns/bends.

If you really want to use hard pipe ells, nothing wrong with that.
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Old 08-27-2010, 09:20 PM   #4
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flex duct turns


I would avoid flex where you can, in permanent setups. Think of how much more dust they will collect over time due to how they are made.
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Old 08-28-2010, 05:58 AM   #5
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flex duct turns


If you are making bends or connecting flex to register boots make sure you use a wide radius when making the turns and support them if needed.

No sharp bends.
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Old 08-28-2010, 06:40 PM   #6
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flex duct turns


so how much diffrence does it make how tight the turn is into the register box? All mine are laying on the insulation on the attic floor and the just 90 down into the register box.
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Old 08-28-2010, 08:02 PM   #7
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flex duct turns


The tighter the 90, the more restricted the air flow is.

Hop in your car. Drive around the block. The first 2 turns, make them wide. Make the next 2 turns very tight. Feel the difference. It has the same effect on air. Throws more air to the one side, and slows it down.
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Old 08-28-2010, 09:27 PM   #8
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flex duct turns


I would. You should be one size bigger on the straight runs: http://rockwallcontrols.com/Resident...ag=air-ducting

Pressure losses: http://www.mmmfg.com/pdfs/True_Cost_...x_10-27-06.pdf

http://www.thefreelibrary.com/Pressu.....-a0201591046

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