Question on extending/relocating ductwork


Old 05-28-08, 08:47 PM
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Question on extending/relocating ductwork

Hi, all -

I *think* I know what needs to be done with this part of our remodel, but would love some expert advice.

My husband and I have gutted our finished attic. It was already finished with 2 bedrooms and a bathroom when we purchased the house, but needed lots of updating so we decided to redo it all. We're down to the studs and have started reframing and preparing for new insulation and drywall.

One of the final tasks we need to complete before we hvae the insulation guys come is to level out our floors. This means moving some ductwork.

We have moved a wall back about 3 feet, so the duct that was previously on the wall is now sticking up in the middle of the room. We've considered just cutting it down and having it be a floor vent, but it still would be about 3 feet in from the wall which isn't ideal.

The duct comes up from the floor below somewhere in the middle of the room, and travels parallel to the floor already, so all we really need to do is extend it back about 3 feet following the exact path it's on already. We think it's a simple as buying an extension of the same size, connecting it to the existing duct, and moving it back to the wall. Am I missing something, or does that sound right?

Note that we have no problem cutting the floorboards to get at the ductwork, since that specific area of floor is unfinished so we need to add some plywood anyway.

Lastly, if we do really just need to extend it back, any tips about how to best seal the connection would be appreciated. I've seen some posts that mention applying mastic - is that the best thing to do?

Thanks in advance,
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Old 05-29-08, 03:33 PM
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No one wants to reply, your question is a tough one. You are obviously not the casual DIY, your skills seem beyond that. But I would leave HVAC to the experts. You could upset the whole balance of the system.

And I hope I am not to critical at this stage of your project, but since you mentioned moving walls, has this been approved by an engineer or your local code authority??? Many will disagree, but they are there for your(and the next owner) protection, not just be a pain in the butt.
Old 07-11-08, 07:32 AM
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Actually, it's not a big deal. Just extend it to the new location if you don't like where it is, trying to keep a straight as run as possible.

It sounds like you have sheet meal instead of flex-duct. connect sheet metal with a few metal screws and then seal with the aluminum duct tape.
Old 07-11-08, 10:22 AM
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Hi, walkman -

That's actually exactly what we ended up doing. Lowe's had some straight duct extensions, and we connected those to the existing ducts with the connectors that we took off of the old connection (it used to connect to a duct going straight up to the wall). We then sealed with aluminum tape to reinforce the connection. It seems to be working well!

Thanks for the reply!

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