Flex duct angles

[schaefage]

I was just wondering if a 90 degree angle/turn in flex duct is too much.

Thanks,

Kent

[Rich]

It just depends how tight the turn is. It's no problem if you take 4' to make the 90. I would say you wouldn't want to go much less than twice the diameter. 8" duct - make the turn in 16".
The other issue with turning it too sharply is the noise - cavitation for lack of a better word.