Panting oven

[Wiley]

Tonite for the second time I have had my oven "pant". Unfortunately I didn't have a big enough card in my camera to record the video and by the time I installed the 4 gig card it had stopped but I now know the "setting" of the draft door and hopefully can replicate the "pant". Had anyone else experienced their oven panting?

OK, for those unfamiliar with the term "pant".... one can see it in movies of old steam locomotives when they are laboring for instance going up a grade. The chimney puffs smoke at intervals and in the cab the stoker door has a momentary back blast of exhaust followed by an intake or inhale. The stack/chimney has a blast of smoke followed by a pause then another blast. The period of the pant varies but my oven pants at about every second or slightly less. Quite cool looking but I'm not sure it is good for an oven. On my oven it is not so evident in the exhaust from the chimney but there is an audible puff and with it a short blast of smoke out the slot in the draft door followed by and intake of all the expelled smoke which is followed shortly by another out blast. The smoke puffed out the slot in the draft door is sucked back into the oven and then the process is repeated. This went on long enough for me to decide that I should be recording it and run for a camera. By the time I had finished messing about with the new card etc. it had stopped.

Honest, I didn't have anything to drink (yet) and only the oven was smoking!

Bests,
Wiley

[Les]

Re: Panting oven

Wiley - I haven't seen that. Mine just seems to be an even flow. Are you making the fires of hell? It does sound like a fun thing to watch!.

Les...

[Wiley]

Re: Panting oven

Quite the contrary, I'm not one of those who want to see the Fires of Hades. I've seen ovens that were burned up, I don't care to build it twice.

It happened just after the fire caught and starting to go well, and once the oven got hot the panting stopped. We had neighbors over for pizza and the Mister said that he used to have that happen often when he had wood fired ceramic ovens. He said his ovens used to back blast out 4 inches (while mine was barely an inch or an inch and a half). He said it happened in his oven when the atmosphere in the oven was switching from a reducing atmosphere to an oxidizing one (ie not enough oxygen to too much (or sufficient) oxygen. But what do I know? He might be feeding me a line although he used to make his living from pottery.
Wiley

[arevalo53anos]

Re: Panting oven

I have never seen that!
Just a shot...figuring out...
If the relationship between the heights of door and dome is lower than 63%, there be not fully combusted gases on top of the inner dome, because the incoming fresh gases are ‘sealing’ the exhaust gases path.
When the top of the inner dome reach the temperature to burn these ‘not fully combusted’ gases, the higher pressure produced by these gases combustion, push them through the door, stopping the exhaustion of fresh air. From there you could see a black smoke going out of the oven door.
With the dome gases fully combusted, the inner top is ‘empty’ and ‘cool’ how to receive ‘rare’ gases again and the cycle continues...
In short, in a well-balanced dome-door oven, the fresh air enters by the ‘lower half door space’, ignited on the hearth, fluxing combusted on flames through the dome and exhausted by the ‘higher half door space’.
Is there any sense?

Luis

[egalecki]

Re: Panting oven

With the dome gases fully combusted, the inner top is ?empty? and ?cool? how to receive ?rare? gases again and the cycle continues...
In short, in a well-balanced dome-door oven, the fresh air enters by the ?lower half door space?, ignited on the hearth, fluxing combusted on flames through the dome and exhausted by the ?higher half door space?.
Is there any sense?

Luis

Makes a lot of sense to me. The panting must have been pretty cool in a kind of worrying way!

[Wiley]

Re: Panting oven

OK, like the saying goes: "I might not be good, but I am slow".... I have finally captured and uploaded a video of my oven panting. In the usual firing the period of the panting lasts only a few minutes and the period (cycle) of the pant can be slightly adjusted by moving the draft door in or out.

In order to get this video I built a smaller fire and so the pant lasted longer as the oven took longer to heat. I couldn't see more than a slight variance of smoke out the chimney top with each pant. I suppose one could build a chimney stack shaped like on an old time steam locomotive (cone with restriction at top) where the smoke collected momentarily. However, I think it would look pretty strange on my WFO. For those curious to see the pant, here's the link:

YouTube - Panting Wood Fired Oven

Wiley

[brickie in oz]

Re: Panting oven

That is so cool.....

[PizzaPolice]

Re: Panting oven

Cool my A$$! Son, you have the makings of a back draft! DO NOT try to replicate that.

[brickie in oz]

Re: Panting oven

Cool my A$$! Son, you have the makings of a back draft! DO NOT try to replicate that.

Settle down.....

[texassourdough]

Re: Panting oven

It looks like your door is too small for your oven volume and you are addumulating unburned gases which .... burn and create the pant.

Wierd!
Jay

[Wiley]

Re: Panting oven

Jay, the strange thing is that as the WFO heats up the panting stops and settles into a constant deep intake and the fire acts like someone was constantly blowing on it. Like I said, on a regular fire the panting only lasts for a minute or so, I managed to get this one to linger by building a smaller fire, which I suspect simply slowed the time for the oven to heat up.

Steam engines in particular steam locomotives were known for their pant. It was part of what made them seem alive. Here's a youtube of a train panting up a grade.

YouTube - Steam locomotive train 353 chugs up hill rollag engine Soo

Wiley

[Rastys]

Re: Panting oven

Wiley,
an interesting comparison with the steam train sounds.
The 'panting' of the steam train changes in rhythm with the speed that it is doing. As the train goes faster. so is the panting increasing. This does not seem to be in rhythm with the steam cylinders working which drive the wheels, also I remember as a a child that once a steam loco is idle, as when in a station or when it is stationary, the panting is slower but quite consistent.
My uncle was a valued worker on and literally inside the boilers of the old locos and he would have the answers but unfortunately he passed away a couple of years ago.
Try contacting the local steam society and see if they can throw some light on the theory behind it.

Rastys.

[texassourdough]

Re: Panting oven

Hi Wiley!

Given your additional comments... it could just be a phenomenon related to oven volume/height/door dimensions....

As the oven gets hotter the "driving force" for convection (cool air in the bottom/hot out the top) increases. The pant probably reflects an inadequate driving force to create steady flow. When the oven gets hot enough the density difference of the air is enough to provide steady flow...

Only thing that really makes sense to me...

Cool film!
Jay

[BrianShaw]

Re: Panting oven

Settle down.....

Actually, brickie, PizzaPolice has a good point. Whilst an interesting phenomenon it is probably about as safe as automobile exhaust system "backfire" (remember how much fun that was... both to make happen and watch peoples stunned reactions, and later to repair the exhaust system after it splits the tubing or muffler?) and chimney flue fires. There appears to be something wrong with the combustion design that could be dangerous.

[acbova]

Re: Panting oven

I thought you were supposed to not use the door when starting the fire?