New duct work creaking/popping

[Tracs]

I have a old house with poor duct work. I had to rip the floor out of my bathroom for a cast iron stack replacement. While I had it open I installed a new 6" round supply run to my bedroom. It runs 15' from the plenumn, through the main floor, 10' up the wall to the second floor, and across through the joist space 15' to a 4x10 register.

It is so noisy it is driving me insane. I cannot leave it like this.

It is only the vertical run up to the second floor and across to the register that is expanding/contracting making all the noise.

Everything is still exposed.

What can I do to stop the noise?

Due to sliding the pipe across the floor in 2.5" lengths there are lots of joints. I had to install the angle boot first and then slide the pipe through the floor space, I could only get 2 screws per joint in because I couldn't rotate the pipe enough. I was thinking of taking it out and putting foil tape on each joint?

Is it a symptom of the ductwork being to tight or loose?

 

[The Cobbler]

the creaking is the duct rubbing on something while it expands/contracts from the heat. find out where it's rubbing & cushion it.
that seems like a long run for 6". how is the airflow at the end? just curious

 

[Tracs]

the creaking is the duct rubbing on something while it expands/contracts from the heat. find out where it's rubbing & cushion it.
that seems like a long run for 6". how is the airflow at the end? just curious

The airflow is good, hopefully enough. 6" is as big as I could go. I took off right from the plenum for maximum flow. The room is 15x9. It and 3 other rooms were fed from a single 5" take off from the trunk that went to large brass wall registers. The flow was about as hard as me blowing. Heating isn't a concern, its the summer cooling I need. It's a 100 year old 1 1/2 story house.

 

[harley jim]

Wrap it with some foil wrap and see if that will stop it. The thin insulation wrap used on ductwork.

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[lilredex]

Try pushing half a brick along the horizontal length until you find the sweet spot. Keep a string on it so you can pull it out if no success.

Did this with my cold air return duct....it oil canned every time you walked over it.

 

[Kensico]

I had the same problem, it was right before the register, I spray foamed all around where it was flexing and it solved the problem for me.

 

[Bert_]

Do some of the run with flex.

 

[Tracs]

There are 2- 90* elbows twisted to make the turn into the second floor joist space.

I moved them around and put a work glove under the pipe to stop them from rubbing on the ceiling drywall. It has taken away 98% of the noise. I will have to trim a bit more drywall away and hopefully that takes care of things.

 

[harley jim]

If you tape all of the joints with foil tape it will help.

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[LS6 Tommy]

In terms of noise, square duct would have been a little more rigid and possibly less noisy, but I'm glad you got it figured out.

Tommy