Oil furnace makes banging noise when it shuts off. It can be heard from the vents of the house. How to fix?

Hi,





New homeowner question :)


The furnace in our house is not too old, but is not new either. Maybe like 10 yrs old I'd say The filter has been replaced, within the last month, it is in good shape, however, since we moved in I noticed a banging noise (3 separate bangs actually) when the furnace shuts off. They are always the same: first one is the loudest, then less louder, and third one is even less louder (this actually I can take). However, I can't tell where the noise is coming from and what the issue is. It is an oil furnace. I went in the basement, where the furnace is, thinking the noise would originate from there, but it can be barely heard from there, its almost as if the noise is in the walls of the house and it echoes the ';bang'; through the vents in the entire house. It can be heard less in one side of the house actually. If anyone has an idea on where to look for this noise and how to fix it I'd be eternally grateful, as the noise wakes me up everytime it shuts off at night and scares the heck out of me :) Thank you in advance.Oil furnace makes banging noise when it shuts off. It can be heard from the vents of the house. How to fix?
I think what you are hearing is a condition called ';oil canning';. When air is being pushed or pulled through the ducts, the air causes the metal to flex. When the fan turns off, the metal returns to its original position and makes a banging noise. It is not harmful but it can be annoying If you follow the ducts and can find where they are flexing, you can solve the problem by screwing braces to the duct to make them more rigid.Oil furnace makes banging noise when it shuts off. It can be heard from the vents of the house. How to fix?
sometimes the draw from your return air will cause the door to pop in and when the unit kicks off it pops out and is heard mostly through your duct and vents. I've had to take the doors off before and screw a metal brace down the door to eliminate this. But metal duct really magnifies all sounds.
It could possibly the vent/system contracting.Do you notice any similar noises when the furnace is starting up. Regards
Sounds like the exterior vent flap is sticking when it opens and slams shut when it warms up.