At what temp will stainless glow red?

[DavidV]

Laying on the couch last night I was getting the stove going and had the door cracked. Hed filled it with some long flat thin splits. Some were as thin as 1/2 inch. I noticed it was getting pretty loud and went over to check the stove and the stainless offset was glowing red on one side. I shut the door and pushed the damper(cat bypas) in and it stopped almost immediately. after it cooled off a bit I pulled the damper back open, as my front temp was still only showing about 3250-300. Since I had a "slam " installation before I have never seen anything like that. This is my first year with a liner and I didn't put eh surround back on after installation.

Anyone else have similar experiences?

 

[elkimmeg]

Well you learned to pay more attention to what is going on with your stove. You can't leave the door open with smaller splits.
the reason the pipe got red and the stove not getting that hot ,all the heat was going up that connector pipe.
I think glowing red is around 1200 degrees

 

[Corey]

Doesn't really matter what the emitter is...stainless steel, cast iron, tungsten in your light bulb, the temps are about the same for a given color. Generally accepted colors/temps are:

C F Color

400 752 Red heat, visible in the dark
474 885 Red heat, visible in the twilight
525 975 Red heat, visible in the daylight
581 1077 Red heat, visible in the sunlight
700 1292 Dark red
800 1472 Dull cherry-red
900 1652 Cherry-red
1000 1832 Bright cherry-red
1100 2012 Orange-red


But, hey...at least that section of flue is clean!

Corey

 

[Rhone]

This once again makes me wonder about secondary burn. When I turn my air down to as low as possible, my burn tubes don't glow like, at all. If the gases have to reach 1100F+ to ignite am I wrong to say you need your burn tubes glowing to achieve secondary burn?

There's a difference in my secondary burn when my tubes are glowing red vs. when I turn the air down for an overnight burn and they're not glowing. If only I knew how to edit movies I took a video of the difference but my wife was yelling at me during them so, if only there was a way to remove sound I'd post them!

 

[Andre B.]

but my wife was yelling at me during them so, if only there was a way to remove sound I'd post them!

Need to clean off my monitor now, Dr Pepper makes a mess when it comes out thru your nose.

 

[Corey]

This once again makes me wonder about secondary burn. When I turn my air down to as low as possible, my burn tubes don't glow like, at all. If the gases have to reach 1100F+ to ignite am I wrong to say you need your burn tubes glowing to achieve secondary burn?

There's a difference in my secondary burn when my tubes are glowing red vs. when I turn the air down for an overnight burn and they're not glowing. If only I knew how to edit movies I took a video of the difference but my wife was yelling at me during them so, if only there was a way to remove sound I'd post them!

This is a good question [borders on hijacking this thread, so maybe we should start new] but...

I think the key here is that it is the 'gasses' that need to be at 1100F for the secondary burn. Not necessarily the metal of the stove or the burn tubes. The warm air comes out of the burn tubes and mixes with the hot (1100F+) gasses from the fire it can still ignite secondary combustion.


Corey

 

[webbie]

I concur with cozy - it is possible for the temp outside the tubes to be hotter than the tubes themselves

 

[Turner-n-Burner]

What I learned in my heat transfer and thermal design classes would suggest that that is not a sustainable scenario. At some point the tubes should approach the temperature of the surrounding gasses.... Right?

Though I suppose that depends on what is in the tubes... Is there outside air in tubes? Where does that come from? I haven't looked to closely, but I thought the air control fed the "shoe" at the front center of the stove....

 

[saichele]

I'm not sure I buy that as a long-term thing - Sure over short periods, and mabe rhone's only watching for a few minutes after he hits the damper, but if you have metal tubes a few inches (or less) from gasses that are 1100+ for a prolonged period, I hav a hard time believing they aren't going into one of the 'glowing' ranges. Maybe the cooler gasses coming through keep them somewhat lower, but they'd have to be in the 800+ range I would think.

Steve

 

[webbie]

What I learned in my heat transfer and thermal design classes would suggest that that is not a sustainable scenario. At some point the tubes should approach the temperature of the surrounding gasses.... Right?

Though I suppose that depends on what is in the tubes... Is there outside air in tubes? Where does that come from? I haven't looked to closely, but I thought the air control fed the "shoe" at the front center of the stove....

Nah....

Think of a torch - does the nozzle ever approach the temp of the flame? No way....
The tubes have relatively cool air (a couple hundred degrees) passing through them constantly, which helps them stay cooler than the ends of the flames coming out of them. This is also similar to oil or gas burner designs.....

The tubes contain room air that has been heated by the tubes and by other manifolds in the stove. In any case, that air is a lot cooler than the secondary flames. The secondary flames are also headed up the flue quickly, so they can't hang around long enough to heat any metal to the same temp.

I a piece of steel was placed an inch or two in front of the tubes - right at the hottest point of the flame, then it might get to higher temps.

Of course, the tubes are also heated by reflected radiant heat from the fire and firebox.

 

[BrotherBart]

The burn tubes in the Englander have glowed a few times. The most interesting time was when the edges between the ceramic fiber boards in the baffle turned red too. And the stove top was only at 500 at the time.

Even though the tubes have cooler air in them they also have the tube right behind them blasting hot burning gases at them.

 

[Rhone]

Sorry, I removed it here and decided to make this a new post.

 

[BrotherBart]

Laying on the couch last night I was getting the stove going and had the door cracked. Hed filled it with some long flat thin splits. Some were as thin as 1/2 inch. I noticed it was getting pretty loud and went over to check the stove and the stainless offset was glowing red on one side. I shut the door and pushed the damper(cat bypas) in and it stopped almost immediately. after it cooled off a bit I pulled the damper back open, as my front temp was still only showing about 3250-300. Since I had a "slam " installation before I have never seen anything like that. This is my first year with a liner and I didn't put eh surround back on after installation.

Anyone else have similar experiences?

David, did the color of your liner change any after "the blast"?

 

[DavidV]

Yeah, the offset has a slight copper tinge to it. Why do you ask?

 

[BrotherBart]

Yeah, the offset has a slight copper tinge to it. Why do you ask?

When my old stove got so hot it changed the liner to a copper tint also.

 

[DavidV]

Thought you were going to tell me something bad like I had to swap the liner out now. I was gonna flip.
How's the Englander doing for you so far? I am torn between doing a complete rebuild on mine next year of maybe holding off and buying a new one in a year or two.

 

[BrotherBart]

Thought you were going to tell me something bad like I had to swap the liner out now. I was gonna flip.
How's the Englander doing for you so far? I am torn between doing a complete rebuild on mine next year of maybe holding off and buying a new one in a year or two.

Since it was "supposed" to be 24* by sun-up I loaded it last night at eight o'clock for its first official overnight burn. At seven this morning there were more than enough coals for a restart, fan had not shut down yet and the house was 72 upstairs and down with the outside temp at 29. That was loaded North/South and it burns too hot and fast that way. I am going to try E/W for the next one and see how it does.

I think it is a keeper.

 

[BrotherBart]

Since I had a "slam " installation before I have never seen anything like that.

What's a 'slam' installation??

A slam installation is where a insert is installed into a masonry fireplace with no liner and it vents directly into the firebox/chimney.

 

[Turner-n-Burner]

What I learned in my heat transfer and thermal design classes would suggest that that is not a sustainable scenario. At some point the tubes should approach the temperature of the surrounding gasses.... Right?

Though I suppose that depends on what is in the tubes... Is there outside air in tubes? Where does that come from? I haven't looked to closely, but I thought the air control fed the "shoe" at the front center of the stove....

Nah....

Think of a torch - does the nozzle ever approach the temp of the flame? No way....
The tubes have relatively cool air (a couple hundred degrees) passing through them constantly, which helps them stay cooler than the ends of the flames coming out of them. This is also similar to oil or gas burner designs.....

The tubes contain room air that has been heated by the tubes and by other manifolds in the stove. In any case, that air is a lot cooler than the secondary flames. The secondary flames are also headed up the flue quickly, so they can't hang around long enough to heat any metal to the same temp.

I a piece of steel was placed an inch or two in front of the tubes - right at the hottest point of the flame, then it might get to higher temps.

Of course, the tubes are also heated by reflected radiant heat from the fire and firebox.

Yeah, that's what I was thinking *after* I typed my initial response. Guess I'll have to dig out the manual and take a look at the air feed and what is moving through the tubes. Certainly the tube temperature is going to be somewhere in the middle of the temperatures of the air inside the tube and that of the burning gas outside...