Originally Posted By: mlong This post was automatically imported from our archived forum.
Yes, I’ve seen this a number of times. It’s not uncommon for this type of ductwork. The reasons for it could be several. Age, for one, even though the house may be only 10 years old, the tape does dry out after a time. Could be improper application. The original HVAC guy may not have wrapped it well enough, or wrapped it enough times. It looks from the picture that there was only one wrap. I could be mistaken, but I think usually most duct guys will wrap it down the middle of the joint, then at least once on either side, and then perhaps down the middle again. In the one picture it looks as if the duct has dropped. The duct should not have been relying on the tape to hold it up in place. The straps should be doing that.
Regardless of what actually caused it, however, a recommendation should be made to have a qualified HVAC person repair it, or else the heat will continue to dump under the floor.
Originally Posted By: Lee Hammerstein This post was automatically imported from our archived forum.
I have installed this type of duct. It’s called “duct board”.
We would staple the joints together with a stapler. I stapler was called a "bag stapler". The stapler would spread the staples in opposite directions. Then we would wrap the joint with tape.
The duct must be supported better than metal duct as the joints, even when properly installed, are not as strong as with metal duct.
Originally Posted By: dedwards This post was automatically imported from our archived forum.
Couple of things going on here. This is called duct board and duct components are constructed either on site or at the shop where the HVAC contractor can build up the ductwork prior to installation. The other thing that jumps out at me is the joints are “butt joints” not keyed or interlocking as required to give a good airtight seal. Another thing that I noticeed is the tape. It isn’t “code” tape. Code tape is printed with writting on the outside surface. This looks like plain old foil tape. While it is pretty good it isn’t up to the standards of code tape. The writting on code tape is usually red. Code tape has to be “wiped” or pressed into the ductboard quickly which warms up the glue backing. This creates a very tight permanent bond between the tape and board. The tape will almost disappear into the ductboard. You literally have to cut the tape if you ever want to open the seam. This was a poor installation from the git go. The support mentioned is another reason for premature failure. A lot of companies put their junior personel on the duct crew until they learn the ropes. It is hot as hell in an attic as we can all attest to so…sometimes short cuts are taken and you end up with something like this. The staples mentioned is also just one more step omitted. We always used staples and lots of them. Some good companies even go so far as to hardcast all the seams with Mastic to form a hard shell coating that is superior to other installations.
Originally Posted By: bemelander This post was automatically imported from our archived forum.
Thanks for the replies, by the way central air conditioning was installed recently. Could this have anything to do with this. It is not known when this happened.
Originally Posted By: dedwards This post was automatically imported from our archived forum.
Had a similar situation once. The landlord has a friend who was in the HVAC business go to a house to fix the AC because it wasn’t cooling the home. They replaced almost every single mechanical component one item at a time. Multiple visits and the tenants kept telling them there wasn’t any air coming out of the vents but you could feel cool air coming out of electrical outlets. When they had completely replaced the mechanicals for the system and it didn’t fix the problem they finally got up into the attic and every “end cap” was standing straight out when the AC was running. Someone had used cloth duct tape on every joint. Duct tape is not worth a flip in a hot attic. Shortly after the glue gets warm it turns loose. You can probably think of occasions where you have seen duct tape hanging loose from the ductwork. They were very embarrassed because they had been told all along by the tenants that they thought there was a leak in the ductwork. Could have saved alot of money and time by simple troubleshooting and investigating. Why did I bring up this tale. That may have been why the AC was replaced in this case. Poor performance doesn’t always necessarily mean the AC is at fault. More often than not it is due to poor installation practices and poor maintenance. Cut down on air flow and everything goes south.
Originally Posted By: wcottrell This post was automatically imported from our archived forum.
The installers should have used mastic over every taped seam, especially where high moisture is to be expected. Well this is the common practice used by professionals in the South anyway.
Originally Posted By: jkormos This post was automatically imported from our archived forum.
Recommend repair or replacement by a licensed and insured HVAC contractor. And definitely not supported properly to begin with, substandard installation practices were used by the installing contractor.