Flexible Duct in Narrow Crawlspace

[porkweez]

The previous owner attempted to run flexible duct to the original portion of house in crawlspace. He never connected it up; and left rigid duct end capped and vent boots covered. The old flexible is in bad shape so I want to run new 25' lengths where needed. Since the crawlspace is tight, I wonder if I can connect the new flex to the old, pull the other end, and let the new flex follow the path until I finish pulling. Will flex stand up to that, or is there a better way?

 

[WorthFlorida]

It all depends on how the old flex is supported, if at all unless it is laying on the ground.

http://www.greenbuildingadvisor.com/blogs/dept/building-science/should-flex-duct-be-banned