Loud Bang each night, got videos!

[metaljay]

Had our log burner fitted a few months, the installer said he doesn’t know what is causing it but to me I can only guess it’s the twin wall pipe expanding and then contracting at such a rate it makes a load bang.
Sometimes happens multiple times in the night. Only occurs after having a fire.

Any thoughts?
Few photos of the install as it was being done.

Video of the bang below:

 

[DAKSY]

Watched it 3x but didn't hear the "bang."
The loud "bangs" I have encountered, don't come from the pipe.
They come from the expansion of the large flat piece of shell in
the rear of the unit.
It's referred to as "Oil Canning."

 

[metaljay]

It happens 2-3 seconds in, I can’t time stamp it. It’s almost like a load knock

Here’s a video of it from the outside too, this is right next to the external flue

 

[Dan Freeman]

Sounds like a contraction of metal to me.

 

[metaljay]

Sounds like a contraction of metal to me.

Any ways to reduce or stop this? Sometimes it goes off at 2am and wakes the house up.

 

[EatenByLimestone]

Its expansion/contraction of a metal joint.

 

[Dan Freeman]

Any ways to reduce or stop this? Sometimes it goes off at 2am and wakes the house up.

Doesn't sound that loud to me, but I'm not in your house to really hear how loud it is. My stove makes cracking noises as the temp goes up and comes down. (My stove is plate steel.) Someone with more knowledge that I have will come along with help for you in this thread.

 

[kennyp2339]

Any ways to reduce or stop this? Sometimes it goes off at 2am and wakes the house up.

Dont burn as low, keep the fire hotter, then the bang time will shift from 2am to 4am... closer to waking up

 

[metaljay]

Dont burn as low, keep the fire hotter, then the bang time will shift from 2am to 4am... closer to waking up

Haha love this, but not sustainable - any actual ways to reduce this?

 

[kennyp2339]

You can try to put a blower on the stove or point a large fan at the stove to take away the heat that gets built up in the alcove , that might keep the metal from getting to that hot expanding point.

 

[clancey]

My stove exhaust sometimes flaps up top in the wind and it sounds just like that..clancey

 

[metaljay]

Its expansion/contraction of a metal joint.

Any suggestions on how to reduce the noise? Fire cement?

 

[rwhite]

Is there a block off plate installed in the alcove? It almost sounds like sheet metal that is a bit tight and popping up and down as it cools.

 

[metaljay]

Is there a block off plate installed in the alcove? It almost sounds like sheet metal that is a bit tight and popping up and down as it cools.

Yes we have a block plate, it doesn’t appear to move, should there be clearance all round?

 

[rwhite]

Yes we have a block plate, it doesn’t appear to move, should there be clearance all round?

They don't need clearance all around but it should fit correct without being forced. It sounds as if the plate is so tight it might have a slight bow in it that is popping up and down. Almost as if they made it a 1/8" to large and forced it in. Try pushing up and down on it and see if it makes a similar noise?

 

[EatenByLimestone]

I'd start puffing graphite into every joint. Metal is going to move, your just trying to get it to move easier.

 

[rwhite]

If it is sheet metal that's banging you may be able to add some rock wool insulation if there isn't any. The added weight alone may keep it from flexing, or deaden the noise?

 

[snobuilder]

Is your wife still trying to get out?



Sorry just had to,

 

[rwhite]

If it is sheet metal that's banging you may be able to add some rock wool insulation if there isn't any. The added weight alone may keep it from flexing, or deaden the noise

 

[metaljay]

Fairly confident this is not the actual fire or the metal plate above the stove, it’s in fact the twin wall outside that’s echoing inside.

Is it normal for twin walls pop?

 

[rwhite]

Possible. All metal tends to pop a bit as it heats and cools but that doesn't sound like anything I have ever heard a stove or pipe make. ???

 

[EatenByLimestone]

Fairly confident this is not the actual fire or the metal plate above the stove, it’s in fact the twin wall outside that’s echoing inside.

Is it normal for twin walls pop?

I can't say it's normal, but I've seen a few threads on it over the years. Pull the pipe, lube the connections with graphite, and reinstall. Maybe that'll stop it.

 

[Tar12]

Never heard of this...it would drive me nuts!

 

[coaly]

Are there screws at each section of pipe? In the US, 3 are required at each joint. This may make it solid on the outside without enough room to move at joints for expansion and contraction with such a short distance. (The longer the run, the more joints, and the less movement at each joint)

Do you know if it bangs on heating from expansion, or cooling with contraction, or both?

I would remove screws for a night. If this allows the expansion and contraction to move without sound, moving all at once, you know it is the pipe. Process of elimination. No screws allows it to move freely, or compress farther together, allowing it to be shorter without the screws holding at the same length. Maybe the pipe is too long, so it is tight when cold and can't expand. Just loosening the screws could make a difference. If so, remove each one and drill the hole in outer pipe larger so the screw shank can move within the hole. This would be like a elongated hole or slotted hole to allow for movement.