To quote myself< "Could the hearth's smoke 'blob' be randomly interfering with the campfire's blob? In effect trying to stuff 2 blobs into a space that can hold only one?"

The smoke blobs can be seen as ball shaped clouds. Sometimes there were gaps between them like this and other times they were bunched up.

https://steamcommunity.com/sharedfiles/filedetails/?id=2799815651

Added a roof tile - no more smoke intrusion from below.

https://steamcommunity.com/sharedfiles/filedetails/?id=2799817916

This one still has me puzzled though:

https://steamcommunity.com/sharedfiles/filedetails/?id=2799469639

Check out this guide on smoke physics if you have not already:
https://www.youtube.com/watch?v=i5wvMTLYxWI

Originally posted by retsam1:

Originally posted by us271934-Слава Україн:

Plenty of smoke exit points. So far putting a barrier between the hearth and campfire is keeping the campfire lit.
https://steamcommunity.com/sharedfiles/filedetails/?id=2799668574

Best way I can explain all this(and some are sorta covering it) is to think of the smoke from a fire as a block of stone. When the fire makes 1 block of smoke every few seconds, it has to move up and away. If it does not, then the game turns off the fire.

If the blocks move but start to accumulate to the point where they can create a traffic jam of blocks that end up backing up to where the fire is, the same stopping of the fire will occur.

The on/off, is due to the blocks eventually dissipating that are older and a new block shifting into its previous place and being checked by the system(usually) to ask the fire to turn on or off.

Building in certain ways then can "guide" the movement of the blocks of smoke. Other wise, they'll pick a direction(or alternate/randomize). This may be why your "barrier" allowed for the smoke to be guided in a different direction.

Looking at your picture, it is very obvious that the roof of that structure is very low for a hearth and why you have to have such ventilation more open and somewhat guided. You can clearly see the smoke blocks accumulating too much and low even with that. Personally I would redesign it to have a much higher roofing with ventilation perhaps.

Thank you, I wanted to say this but couldn't find the words. I believe you are 200% accurate.

i had something similar and i think it was related to smoke being trapped in buildings (cooking stations maybe) close to it... and/or rain or wind coming from the not so optimal chimney... it was actually quite useful because it saved a lot of fuel ;)

Originally posted by us271934-Слава Україн:

Plenty of smoke exit points. So far putting a barrier between the hearth and campfire is keeping the campfire lit.
https://steamcommunity.com/sharedfiles/filedetails/?id=2799668574

Best way I can explain all this(and some are sorta covering it) is to think of the smoke from a fire as a block of stone. When the fire makes 1 block of smoke every few seconds, it has to move up and away. If it does not, then the game turns off the fire.

If the blocks move but start to accumulate to the point where they can create a traffic jam of blocks that end up backing up to where the fire is, the same stopping of the fire will occur.

The on/off, is due to the blocks eventually dissipating that are older and a new block shifting into its previous place and being checked by the system(usually) to ask the fire to turn on or off.

Building in certain ways then can "guide" the movement of the blocks of smoke. Other wise, they'll pick a direction(or alternate/randomize). This may be why your "barrier" allowed for the smoke to be guided in a different direction.

Looking at your picture, it is very obvious that the roof of that structure is very low for a hearth and why you have to have such ventilation more open and somewhat guided. You can clearly see the smoke blocks accumulating too much and low even with that. Personally I would redesign it to have a much higher roofing with ventilation perhaps.

The haunting continues.....after a long time of burning without incident, following the 'fixes' I implemented, the campfire once again went out. In less than a minute it reignited itself. I waited several more minutes and it didn't go out again. So something in the environment was still messing with the smoke flow. If you've watched Firespark81's video on Valheim fire characteristics then you know it behaves like a single blob and not like a bunch of particles.
In the screenshot above that shows the top down view of the campfire it hangs over the edge of the wall. Directly below it is a hearth. The room the hearth is in has a big smoke outlet on one side at the roof line but it also has access to the campfire location.
Could the hearth's smoke 'blob' be randomly interfering with the campfire's blob? In effect trying to stuff 2 blobs into a space that can hold only one?
I then built a barrier wall underneath the campfire that totally separates the hearth room from the tower campfire.
So far so good - lol, we'll see.

(being somewhat of a pyro I'm quite interested in these mechanics

IMO, and I saw the help you got, I believe your building does not have enough airflow.

Plenty of smoke exit points. So far putting a barrier between the hearth and campfire is keeping the campfire lit.
https://steamcommunity.com/sharedfiles/filedetails/?id=2799668574

I disagree with the fire only needs an exit. It is easy to make fires in a building with exits and still have the fires go out.

What do you mean? Is it going out and then reignite? That would be a ventilation issue.

In my experience it is almost always an air flow issue second only to not being fully protected from rain.

Without seeing your roof/chimney it is hard to make a guess.

Try moving the spice rack hanging over it. That should fix the problem of the smoke putting the fire out over and over.

It's haunted...by Valheim physics.
I removed the spice rack - no change
I removed a 1m beam on the wall side of the floor cutout around the fireplace (above left) - no change
I removed the beams supporting the spice rack - no change
I then removed two 1/4 floor boards flanking the notch in the stone wall thinking they might be impinging on the smoke requirement space - success! Even though they were optically not hanging over the edge of the wall notch. I replaced them and the haunted physics kept the fire going. I will say that the floor board placement on top of this tower isn't perfect but the boards were visually flush with the notch, not hanging over. They don't look any different now than when the fire was going out. I bet it was a Wraith!
Anyway thanks for the ideas.
https://steamcommunity.com/sharedfiles/filedetails/?id=2799469270

Bonus screenshot confirming the existence of Valheim physics

https://steamcommunity.com/sharedfiles/filedetails/?id=2799469639

Edit: I forgot to say "no mods"

Just an FYI - the big cooking rack doesn't work over 1 campfire.

Originally posted by us271934-Слава Україн:

It's haunted...by Valheim physics.
I removed the spice rack - no change
I removed a 1m beam on the wall side of the floor cutout around the fireplace (above left) - no change
I removed the beams supporting the spice rack - no change
I then removed two 1/4 floor boards flanking the notch in the stone wall thinking they might be impinging on the smoke requirement space - success! Even though they were optically not hanging over the edge of the wall notch. I replaced them and the haunted physics kept the fire going. I will say that the floor board placement on top of this tower isn't perfect but the boards were visually flush with the notch, not hanging over. They don't look any different now than when the fire was going out. I bet it was a Wraith!
Anyway thanks for the ideas.
https://steamcommunity.com/sharedfiles/filedetails/?id=2799469270

Bonus screenshot confirming the existence of Valheim physics

https://steamcommunity.com/sharedfiles/filedetails/?id=2799469639

Edit: I forgot to say "no mods"

Yea, I agree now. 100% confirmed haunted. ;-)