Are my ducts noisy because of heat or too much air?

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You're my neighbor!
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That's where I am too. As I said, one advantage to being a little bigger is that you can heat the house up faster. I can go up about 6 deg an hour. That way if you don't always come home at the same time, you can have it set back and recover faster.
have more, but I

Where is that set? Sounds like at the furnace and you don't have a two stage thermostat? Ideally the thermostat should make the selection because it knows what the temp is and where it needs to go.

Well, it must be an odd thermostat, because every one I've ever seen had it. What about AC? What does it do with AC on, or haven't you had a day where you could try it? On heat the blower should move around 900 -1200 cfm. On fan only typical would be maybe 1400. On AC, 1800-2000.
 I'm going to assume it is temp, and not air

I don't see how the reputation of the HVAC company is a factor. The blowers are what the blowers are. It's not like Rheem is 2000 cfm and Trane is 800. For the same size furnace they are about the same. And going from say a 75K furnace to 110K, doesn't change it all that much either. It is possible that they moved something slightly, or didn't put screws, hangers back where they should be. But I assume the noise isn't near the furnace, right?
You should have a pretty good idea if it's temp or air pressure. You can hear the blower ramp up. If the noise occurs in the first 30 secs or so, it;s likely air pressure, because it's going to take longer than that to heat it up. Also, the bangs I've heard from air pressure occur both when it starts up and when it shuts off. Does it bang right when the blower stops?
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wrote:

Lots of good points, trader4. Btw, I'm from around cherry hill. Now, your points.
The time between the first and second stage is set at the dip switches in the furnace, not the thermostat. I do have a setting for fan only, but nothing turns on when I set it. Time to read the manual, I guess. I didn't start the AC yet, too cold for that. I assumed a good hvac company would not sell me something if they knew the ducts couldn't handle it. No, the noise is not at the furnace, it is at one of the ducts that is farthest from the furnace, and another that is about half that distance from the furnace. No noise at the closest ducts. I assume pressure would get those first. The first bang is well after the start of the ramp up. And I get several bangs long after it stops, never immediately after it stops. Remember too that I was able to get rid of the start up bangs by using heavy duty tape to hold the duct open so to speak.
Thanks for all your help, btw.
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Trader4, I just figured out how to get fan only, and after 5 minutes, no noise. So I guess that clinches it, it's temp and not noise, and I can fix it by getting at least the last foot or so of the duct replaced or strengthened. My confusion on this temp vs pressure issue started because I have the setting at 71/69, and that seems too low to cause the duct to expand and make the REALLY POWERFUL BANG. But then, when I hold my hand to the vent, the air pressure seems pretty low too.
Thanks for everything. I really hope the home improvement guy gets this fixed. I'm going nuts from this noise.
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t>

But the temp in that duct is swinging from 70 to 110 or so, which is plenty to cause enough expansion/contraction. If it runs through any colder areas, it could be even more swing.
 But then,

It should be easy to fix once you have the wall opened up. It sucks though that you have to do that. Here's a thought. You might want to do the opening up part yourself. If you do it, you could open one or two smaller openings where you think the problem is. If you can see it, you might be able to figure out how to shove something in to support it, etc without tearing out a whole wall or ceiling worth of drywall.
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wrote:

net>

It's the ceiling, not the wall, and I expect the home improvement guy will just tear out a small strip to reveal the duct. I imagine I just need a strip of about 1 foot by 3 feet. But we'll see. I'll do anything to get this fixed. I don't see that the whole ceiling needs to come down.
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e.net>

I don't know how you're paying the guy, for the job, by the hour, etc. But for something like this, if you can do the opening up, fiddling around yourself, you might save $$ and have a better result. Like I'm thinking the guy opens up one spot. Then you have to cycle the heat so you can see if it moves. Maybe you can't see it that well, did it really move or not, etc. Now you have to wait for it to cool, cycle it again. Then maybe open up another spot or bigger spot, etc. And if you think you have it fixed, I'd want to wait at least a day or two to make sure before closing it. If you open it and do the fiddling around, it might be better.
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The preferred way is to have a two stage thermostat that makes the selection. In some cases, it may be too difficult to do it that way because it takes one more wire from furnace to thermostat. If an extra wire isn't there and it's not easy to run, then you use the fallback mode of letting the furnace do it.
The advantage is the thermostat knows that if it's 60 and we're going to 70, then we want 2nd stage right away. Conversely, if it's been running for 11 minutes and it's only .5 deg to go, no sense in going to 2nd stage.

Odd, maybe it's not connected.

Your welcome and good luck.
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On 3/25/2013 3:23 PM, Dom wrote:

had an oil furnace, once, with a separate thermostat and it has a little knob in the middle that would turn on the fan.
Paul
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Dom wrote:

Earplugs. Fifty cents.
But I don't suppose I'll get much credit for an economical idea...
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They would have to be the type of earplugs you get at a firing range. Trust me, this is a BANG!
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