Furnace duct noise

[coreyleiper]

Hi there...

With the change in climate here in Eastern Ontario I have noticed two things:

When my furnace comes on I hear a banging type sound coming from the duct-work when the furnace first comes on. It lasts for maybe two or three minutes (I'm guessing until they heat up) and then it starts again after the furnace goes off. Same thing -- it seems after the furnace has been off for maybe two or three minutes it starts banging again. It lasts for at least ten minutes and again, I'm guessing it's the duct-work cooling back down.

Any thoughts? I'm no HVAC pro by any means, but this is the the best guess I can muster at this point.

So, here's what I need:

Advice on cause (If my diagnosis is wrong) A possible solution...?

Thanks a lot -- as you can imagine it's driving me mad and keeping me awake at night. Oh yeah -- the house is less than a year old also if that's relevant.

Corey

[HeatMan]

And the ductwork may be undersized....

[Amun]

As the house is less than a year old,...you simply had a bad installation, as there is no excuse for ducts to be making a banging noise. Depending on the run lengths there should be allowances made for expected expansion and contraction.

One other poster here suggested too small ducts which also could be possible

Either get your builder in (if home was bought with new home warranty) or your heating contractor. Send a written letter and keep a copy, in case you need to go after them later

Let them deal with it. If they don't call in the building inspector that approved the system.

AMUN

[Dr. Hardcrab]

This is called the oil can affect (or is that effect). It won't hurt anything, but can be annoying, especially in the middle of the night. One thing you can check: make sure all of your vents are open AND make sure your filter is clean. Both can cause the ductwork to expand/contact more than it should.