What causes the ticking sound in a wood stove?

[Sneaksuit]

wood stove "ticking" sound

I have a question about something I've wondered about since I was a child and possibly someone will know the answer. What causes the "ticking" sound when a wood stove heats up? Those of you who have a wood stove will know what I'm talking about. I'm guessing it might have something to do with the metal expanding?

 

[Palindrom]

I'm just guessing here, but perhaps the outer surface of the metal cracks up because of the expansion?

 

[HallsofIvy]

It's not a matter of a "wood stove". If the stove is burning coal, oil or kerosine the same thing happens: as the metal heats it expands. The clicks you hear are the various pieces of the stove rubbing against each other as they expand. (It isn't necessary that the metal actually "crack up".)

 

[Sneaksuit]

"The clicks you hear are the various pieces of the stove rubbing against each other as they expand. "

Perhaps you might care to elaborate. What peices are you referring to? I suppose I should have asked the "physics" behind it. But I assumed since this was a physics forum I would have gotten a scientific answer regarding the "ticking"(transfer of energy from ? to sound waves).

 

[ObsessiveMathsFreak]

I think the sound you're talking about can also be heard in radiators and pipes which are heating up. This is caused by the metal expanding due to heat. The sound is the metal suddenly snapping as built up stresses due to the expansion are relieved by the metal taking on a new position. These snaps and changes in position are of course minute, but they do result in that quiet ticking or clicking that you hear. This also happens as the metal cools too. You sometimes hear cars ticking after the engine has been turned off. Also houses at night tend to creak, paticularly after hot days, as their materials contract.

 

[krab]

"The clicks you hear are the various pieces of the stove rubbing against each other as they expand. "

Perhaps you might care to elaborate. What peices are you referring to? I suppose I should have asked the "physics" behind it. But I assumed since this was a physics forum I would have gotten a scientific answer regarding the "ticking"(transfer of energy from ? to sound waves).

What's the intent of the last sentence? This is a physics forum. All is voluntary; no one is obliged to give you the answer you want. Someone has generously taken some time to answer you.

Anyway, a stove puts out 10s of kilowatts of energy. The subsequent sound waves constitute maybe 1 milliwatt of energy. That's a ratio of over 10,000,000, so it's no use relating the two.

A testable conclusion from Halls' hypothesis is that a stove made of a single piece of solid metal will be quiet on heating. Has anyone any experience in that regard?

 

[Sneaksuit]

"Anyway, a stove puts out 10s of kilowatts of energy. The subsequent sound waves constitute maybe 1 milliwatt of energy. That's a ratio of over 10,000,000, so it's no use relating the two. "

If there's no relation(indirectly or directly) then why would the ticking start when the stove is heating up? I think ObsessiveMathsFreak's answer sounds right but what do I know.

 

[Cyrus]

Sneaksuit, I think Krab is saying that there is no relation between heat being converved into sound energy as it is dissipated. Thats different from the sound made as the metal pieces expand/contract.

 

[russ_watters]

"Anyway, a stove puts out 10s of kilowatts of energy. The subsequent sound waves constitute maybe 1 milliwatt of energy. That's a ratio of over 10,000,000, so it's no use relating the two. "

If there's no relation(indirectly or directly) then why would the ticking start when the stove is heating up? I think ObsessiveMathsFreak's answer sounds right but what do I know.

The stove makes noise only while heating and cooling (just like your car when you shut it off) because that's when the pieces of the stove are expanding (contracting), rubbing against each other, and thus make noise.

This is unrelated to the output of the stove except in that the output of the stove affects how hot it gets and how fast it heats up. But you can't calculate how much noise it will make, for example, given the output of the stove.

I suppose I should have asked the "physics" behind it. But I assumed since this was a physics forum I would have gotten a scientific answer regarding the "ticking"(transfer of energy from ? to sound waves).

No need for the attitude, people are making a sincere effort to answer you: and that was a physics answer.

 

[physicsisphirst]

The stove makes noise only while heating and cooling (just like your car when you shut it off) because that's when the pieces of the stove are expanding (contracting), rubbing against each other, and thus make noise.

what is curious is that the ticking (woodstove or car) seems to have a fair bit of regularity. can simple expansion or contaction explain this regularity? I'm puzzled by the regularity - i would have thought there would be greater variety (or perhaps it only appears to sound regular).
we got rid of our woodstove (it was really heavy too!), but now i wish i'd paid more attention to it :(
i'm pretty ticked off

A testable conclusion from Halls' hypothesis is that a stove made of a single piece of solid metal will be quiet on heating. Has anyone any experience in that regard?

that would be really neat to know about!
are woodstoves even made of a single piece of metal?
how about an oven? (i'm going to listen in next time!)

edit: actually, just noticed that our electric baseboard heaters do the same thing - they tick regularly heating up and cooling down. i don't see why the ticking should be regular - even if the metal expands uniformly (i'm not sure it does), the construct of the heater should cause variations in the frequency of the ticking shouldn't it?

what is the mechanism of the ticking?
is the ticking caused by say a piece of metal expanding and hitting another piece (which is cool) and then contracting a bit and then expanding again? shouldn't there also be several 'tickers' (possibly at different frequencies)?

 

[Gonzolo]

i don't see why the ticking should be regular - even if the metal expands uniformly (i'm not sure it does), the construct of the heater should cause variations in the frequency of the ticking shouldn't it?

what is the mechanism of the ticking?
is the ticking caused by say a piece of metal expanding and hitting another piece (which is cool) and then contracting a bit and then expanding again? shouldn't there also be several 'tickers' (possibly at different frequencies)?

The ticking is when two distinct pieces of metal suddenly slide against each other after having been compressed against each other. Imagine compressing two pieces of metal together, then forcing them sideways. The sideway motion may be so sudden and fast we hear "tick". The heating is not necessarily uniform, but heat flow T(x,y,z,t) will be the same on any given day, so I suppose the same ticks will happen at the same places and time after heat is turned on at t=0.