Duct makes a Thud Sound

Is there anything that can be done to completely stop an annoying, "loud, thud noise" that a duct is making? Repeatedly, about every 10 seconds, there is only one duct in the basement that must be expanding/contracting and then makes a loud thud sound.
The basement is unfinished and it's been difficult to determine exactly which duct is making this noise. The noise is occuring only late at night (and we haven't got a clue why it doesn't happen during the daytime) and the loud noise is quite irritating (there are no ghosts that we know of).
We've checked to make sure that all the basement ducts are fully opened and have also opened all the registers located in the ducts ... at first, these adjustments seemed to lengthen the time between the "loud, thud noise" but it has not entirely stopped the noise.
Closing the register in one of the bedrooms also seemed to helped, but leaving this register closed is not a viable long term option. We suspected this was helping because it is trapping heat for a longer time in the duct, but we don't know for certain.
The home and furnace are 18 years old.
Thanks.
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start by finding the thud.. shouldnt be too hard, you say it happens every 10 seconds...
i suspect the fix will become clear once that is done.
randy

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The most likely place is close to the furnace in the return air duct..especially in the middle of a long duct section. It is referred to as :'Duct Boom' . Usually caused by thinner sheetmetal . Simply push on the center of each long section of return air duct , near the furnace, and duplicate the noise youre hearing. Then add a brace across the entire section of that area and screw it on. This will hopefully stop the duct from vibrating/being sucked in. If for some reason you cant add a brace due to space limitations...then wedge something in there to stop the noise. Good luck.
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I had the same problem, and just wedged something against the duct so it stayed pushed in.
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I too had this problem.
What I did was to get out my SKS, and fire a few rounds into the ducts about every 4 feet. Eventually, I heard a scream, and Bruce Willis came out. He was really pissed, but I told him: Look man, if you are going to film Die Hard 4 in my house, you should have asked me first. He agreed. Then I got him a band aid to put over the spot where his left leg used to be, and we had a beer. He's really a pretty cool guy.
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'What I did was to get out my SKS, and fire a few rounds into the ducts about every 4 feet. Eventually, I heard a scream, and Bruce Willis came out. He was really pissed, but I told him: Look man, if you are going to film Die Hard 4 in my house, you should have asked me first. He agreed. Then I got him a band aid to put over the spot where his left leg used to be, and we had a beer. He's really a pretty cool guy.'
I hope he had enough courtesy to not go and bleed all over the place :)
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Hey Matt, remind me not to accept an invitation to hang out at your place!....I got a kick out of your post....take care, Ross
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Dude !!!!
You are really confused, man,,, Like I think you done way too many bad drugs.
First you say "there is only one duct in the basement"
Then you say "it's been difficult to determine exactly which duct is making this noise."
OK, if there is ONLY ONE. Why do you have to determine which one it is? DUH !!!!
Like, use your brain, dude..... Get off the crack and the beer for a few hours and take some mind expanding drugs like some acid. Then grab your recliner and put it under that duct and trip out on the sounds it makes. Pretty soon you'll be able to hear all the way thru that duct, all the way to the core of the earth. (Thats where they begin). You'll hear volcanos erupting and then the earth will quake. That's what causes the bang sound. You see, there are earthquakes every 10 minutes or so, deep in the bowels of the earth. Thats what you are hearing. If you are really tripped out, you might even hear people from other countries talking, because their ducts carry their voices to the same place, and if you close your eyes, you could even have a religious miracle and see Jesus walking thru that duct, chasing after the devil because everyone knows that the devil lives in the fires buried deep within the earth, and that is why everyone says hell is down.
Anyhow, when the trip wears off and you are back to doing your usual boring drugs like prozac, caffeine, and alcohol. You'll have a whole new appreciation of those bangs. Instead of being annoying and terrible bangs, they will sound like an orchestra of angels singing in a beautiful choir and you'll remember seeing Jesus chasing the devil out of your house and if you close your eyes, you may even hear the earthquakes thundering at the very core of the earth and for one fraction of a second in space, you will flashback into a deja-vu trip and become one with the universe, before returning to your boring daily routine, which is stressing you out far too much, causing you to experience trauma and elevating your blood pressure, which could lead to a stroke if you do not learn to accept the sounds of nature and hear the birds singing every day no matter what you are doing or where ever you are.
Your current elevation, flat plains, planet earth, cityscape, boringville.
Your destination, soaring like an eagle above the trees surrounded by the sounds of banging birds chirping in the ductwork that connects the planets and holds the entire universe together to warm the hearts of every living being as they all hold hands and sing praises to the almighty one.
It's up to you to accept.
God grant me the serenity to accept the things I cannot change; courage to change the things I can; and wisdom to know the difference.
Have a great day.
Guru Harnishma ------------------------------------

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wrote:

Doesn't sound like the 12 step program is working...
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