04:59AM | 10/27/03
Member Since: 10/26/03
3 lifetime posts
Right before the heat kicks on each time, there is a loud bang that comes from the furnace. I am hoping someone may have an idea about why this is happening and how to stop it. It's loud enough to wake our lighter sleepers up. And there is a new baby coming in a couple of months and you all know we don't want anything avoidable to wake them when they are sleeping. *smile*



07:01AM | 10/27/03
Member Since: 06/06/03
1250 lifetime posts
If your heat is forced air: Does it sound like someone banging on sheet metal? This happens to ours--when the blower turns on, it expands the large ductwork above the plenum, and when it turns off, it pops back into position.

In our case, I tried locating the place and it's pretty much we live with it. Hopefully yours is accessible so you can figure a way to stabilize it--perhaps attach it to house framing better, or something.

Good luck,


09:00AM | 10/27/03
Member Since: 10/26/03
3 lifetime posts
There is a blower on the furnace, so I guess it's forced air. It does sound like someone bangs once on the ductwork when it happens. I hope I can find it too. It's really beginnning to drive us crazy. Thanks for responding!



12:28PM | 10/27/03
Member Since: 06/06/03
1250 lifetime posts
Hopefully HK will respond; he's great! I'd love to hear how the HVAC gurus handle this; I'm sure they get it all the time!

-k2 in CO.


02:21PM | 10/27/03
If it is possible, try to physically locate which section of duct is 'breathing'. If you can, you can use some small, light guage 1 x 1 angle iron and cut it the full width of the duct. Pilot drill several holes in the cut angle. Use hex head self drilling screws to secure it to the duct where it is breathing. Good luck.


05:03PM | 10/28/03
Member Since: 09/10/03
67 lifetime posts
this could be just a pre ignition combustion when the air adjustment is not correct. this is pretty common on L P or propane gases. you can look at the flame when furnace is burning, if lazy yellow flame, the unit is dirty or the air adjustment is incorrectly set. also, there is a possiblity of a hairline crack in the combustion chamaber. i would suggest a tech look at this, as could be a very dangerous situation.


03:58PM | 10/30/03
Member Since: 10/26/03
3 lifetime posts
Well, from what I can tell, the bang is about 10 feet or so away from where the furnace is. So that rules out the ignitor, right? I am hoping to spend time tomorrow cleaning the basement and hopefully I'll be down there when the bang happens. The weather was too warm today for the furnace to kick on. I may have to wait a couple of days, but will get back to you all with any other info I gather. Thanks for your help so far, everyone!



11:55AM | 11/28/03
Member Since: 11/27/03
6 lifetime posts
If there a bang when the furnace turns on it is one of two things. 1. The duct work is undersized and when the blower starts it crates too much static, expands the duct work and creates a bang. 2. The burners are dirty. When the furnace calls for heat, the ignitor is enegized, which in turn tells the gas valve to open and send gas to the burners, the ignitor then light the burners. If the burners are dirty they will delay the burners from being ignited causing the bang. If left unattended, the buildup of gas from not being ignited could cause a problem.


03:10PM | 01/31/10
Member Since: 01/30/10
1 lifetime posts
I awoke to my furnace making repeated loud banging noises prior to lighting the burners. I checked to see if gas was leaking from anything inside. It turned out everything was okay in regards to gas leaks.

In my furnace there are 5 burners. The last burner, I noticed was turned 45 degrees and not aligned with the others. when the furnace burners were tring to light the gap between the last was causing the popping sound. I used metal wire and held the last burner correctly in place using the second to last burner. From that moment on, the furnace did not bang or pop any longer. Check this out, if you are experiencing this problem.


11:28PM | 01/05/13
I believe the guy that said one of two things cause the loud bang when the heater starts.If it is a duct the bang will come from a location other than the heater.If the bang comes from the heater location it is dirty burners.
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