How to Fix Crumbling Flex Duct Buried in Ceiling


  #1  
Old 10-20-18, 11:28 PM
O
Member
Thread Starter
Join Date: Oct 2018
Location: USA
Posts: 2
Upvotes: 0
Received 0 Upvotes on 0 Posts
How to Fix Crumbling Flex Duct Buried in Ceiling

Hi. I just moved into a house built in 1980 and found that one of the duct runs is flex that is falling apart. Wire separating from plastic. Plastic inner tube crumbling. The big problem is that it's buried in the ceiling between the first and second floor and the only way I can get to it is from the register end. Is it possible to thread a new tube in through the register, or is my only course of action to demo the ceiling in order to replace this ductwork?
 
  #2  
Old 10-21-18, 04:24 AM
P
Group Moderator
Join Date: Mar 2003
Location: NC, USA
Posts: 27,592
Received 2,144 Upvotes on 1,920 Posts
I would get access to both ends of the duct turn. Tie a piece of light string or thread onto the end of big piece of tissue paper. Then use a leaf blower or shop vac exhaust to blow the tissue paper through the duct. Then use the string to pull some para cord through the duct. Now you can attach new duct to the end of the cord. I would also try taping the new duct to the end of the old. Then pull the old duct out while also pulling on the cord trying to get the new duct to follow the old into the cavit.
 
  #3  
Old 10-21-18, 08:11 AM
H
Member
Join Date: Nov 2012
Location: USA
Posts: 2,304
Received 292 Upvotes on 250 Posts
Originally Posted by Pilot Dane
Tie a piece of light string or thread onto the end of big piece of tissue paper. Then use a leaf blower or shop vac exhaust to blow the tissue paper through the duct.
Good suggestion, but two important changes.

First, if the duct is already in bad shape, I'd be careful about a leaf blower, you might blast the brittle plastic apart.

Second, I'd suggest trying to "bridge the gap" by feeding the 2" diameter hose from a swimming pool vacuum as far as possible, from either side. THEN tie a dryer sheet (tougher material than tissue paper) and apply vacuum on one side, positive pressure from a shop vac exhaust on the other.
 
  #4  
Old 10-21-18, 10:44 AM
Marq1's Avatar
Member
Join Date: Sep 2016
Location: USA MI
Posts: 9,745
Received 1,210 Upvotes on 1,098 Posts
Give it a try but I doubt it's going to work.

Trying to pull a flexible duct through floor joists, around corners, with who knows what other types of objects like electrical wires, plumbing, etc compressing the duct while also trying to pull out the original!

Let us know!
 
  #5  
Old 10-21-18, 10:50 PM
O
Member
Thread Starter
Join Date: Oct 2018
Location: USA
Posts: 2
Upvotes: 0
Received 0 Upvotes on 0 Posts
Wow. I'm impressed. Very creative solution. At this point I can only get to one end. However there is a large duct in the garage that is boxed in by drywall. I figure that large duct is the feed that the flex duct branches off of. First step would be to remove the drywall to see what's up. If I get lucky I'll be able to get access to where the flex duct connects to the feed and then do your trick.

The drywall covering the large duct has popcorn all over it. Any tips on removing a section of the drywall without damaging the duct inside?

Thanks!
 
  #6  
Old 10-23-18, 05:43 AM
airman.1994's Avatar
Member
Join Date: Dec 2005
Location: VA
Posts: 5,491
Upvotes: 0
Received 8 Upvotes on 8 Posts
Done by hacks. Flex should only be used in areas it can be gotten to. If you can't pull a new one through you will have to remove the ceiling.
 
 

Thread Tools
Search this Thread
 
Ask a Question
Question Title:
Description:
Your question will be posted in: