White smoke at 700 degrees?

[mnowaczyk]

Is it normal to have white smoke out the chimney top when running at 700 degrees (on the stove front)? I thought everything should burn clear at that temperature. Is this just moisture, not smoke?

(The stove has been up and running at good temps for less than an hour.)

 

[Pagey]

In very cold weather you will see white steam exiting the flue.

 

[ROBERT F]

I usually only see white smoke with less than steller wood. And then its hard to pull 700 degree stove temps. Steam or moisture looks similar to smoke but smoke is a little more grey than steam.

 

[mnowaczyk]

I guess it's steam then. I took a video on my blackberry. Now if I can just figure out how to post it.

 

[Pagey]

If what you see is white, very "light" and whispy in appearance and dissipates within a few feet of the stack, it's steam. If it's blue/grey and "heavier" and thus lingers lower and longer, it is smoke.

I get steam off a fresh load in very cold weather. I was cruising at 650F this morning and had steam for about 10 or 15 minutes, but it was about 8F so it was to be expected.

 

[mnowaczyk]

Here's a video (if this might help confirm this is steam... which would be good, right?)



http://www.youtube.com/watch?v=5qr65hjk_Nw

 

[3fordasho]

I get steam off a fresh load in very cold weather. I was cruising at 650F this morning and had steam for about 10 or 15 minutes, but it was about 8F so it was to be expected.

+1 on the steam. The colder the outside temp is the more noticable it will be. We've had some -25f mornings here, steam lasts for up to an hour on a fresh load at those temps. Wood is at least two years seasoned, and in a wood shed to boot.

 

[Danno77]

hard to tell, but my guess is that it's steam (based on your video)

 

[SlyFerret]

It's steam.

-SF

 

[fossil]

Actually, it's condensate. Steam (water vapor) is invisible. The steam begins to condense immediately upon contacting the cold air as the flue gases exit the chimney top. Yeah, I'm being picky/nerdy/dorky...I'm an Engineer. You're just making little clouds, is all. Rick

 

[ccwhite]

Steam .... er ... uh... What Rick said.

 

[Danno77]

Actually, it's condensate. Steam (water vapor) is invisible. The steam begins to condense immediately upon contacting the cold air as the flue gases exit the chimney top. Yeah, I'm being picky/nerdy/dorky...I'm an Engineer. You're just making little clouds, is all. Rick

no, this is an important distinction, i wasn't totally aware and am still a little fuzzy. Does this mean, then, that what you are seeing is mostly water from the air formed on a small amount of water (vapor) from the chimney?

 

[fossil]

Get yourself a tea kettle with a nice small diameter spout, fill it with water, and put it on the stove to boil. Don't be hesitant here, turn up the heat to the max. Let the thing get up to as violent a boil as you can, and then very carefully observe at the end of the spout. Immediately away from the end of the spout you see nothing (actually, you're looking at steam). Then, a slight distance away, the stream of fluid becomes visible...this is condensing water vapor (what everybody always calls steam, because we can see it, so it needs a name). It takes very little water to produce a bunch of vapor (steam). At standard temperature & pressure, a given mass of water will produce 1600 times its volume in steam (water vapor). So what you see coming out of a properly operated woodburning appliance chimney on a real cold night is just the little residual moisture from the fuel and the water as a product of combustion. Not much water there at all, but what's there becomes visible as it condenses back from vapor to liquid in the cold outside air. Rick

 

[northwinds]

I see this when it gets below zero.

 

[albertj03]

I see this with my stove when it's really cold as well.

 

[mnowaczyk]

I will take note of what I see above freezing. I think it was a little below freezing this day, but could have been just above freezing too. I doubt that would make a significant difference... unless I was looking to see snow coming out of my shimney... that would be cool, huh?

 

[Adios Pantalones]

Actually, it's condensate. Steam (water vapor) is invisible. The steam begins to condense immediately upon contacting the cold air as the flue gases exit the chimney top. Yeah, I'm being picky/nerdy/dorky...I'm an Engineer. You're just making little clouds, is all. Rick

You sound like me- ya dork! I wish I wore glasses so's I could push them up my nose before making such proclamations

 

[Pagey]

Get yourself a tea kettle with a nice small diameter spout, fill it with water, and put it on the stove to boil. Don't be hesitant here, turn up the heat to the max. Let the thing get up to as violent a boil as you can, and then very carefully observe at the end of the spout. Immediately away from the end of the spout you see nothing (actually, you're looking at steam). Then, a slight distance away, the stream of fluid becomes visible...this is condensing water vapor (what everybody always calls steam, because we can see it, so it needs a name). It takes very little water to produce a bunch of vapor (steam). At standard temperature & pressure, a given mass of water will produce 1600 times its volume in steam (water vapor). So what you see coming out of a properly operated woodburning appliance chimney on a real cold night is just the little residual moisture from the fuel and the water as a product of combustion. Not much water there at all, but what's there becomes visible as it condenses back from vapor to liquid in the cold outside air. Rick

Well said and very informative, Rick. I will try to remember this distinction when we get the question here in the future.

 

[Wood Duck]

Get yourself a tea kettle with a nice small diameter spout, fill it with water, and put it on the stove to boil. Don't be hesitant here, turn up the heat to the max. Let the thing get up to as violent a boil as you can, and then very carefully observe at the end of the spout. Immediately away from the end of the spout you see nothing (actually, you're looking at steam). Then, a slight distance away, the stream of fluid becomes visible...this is condensing water vapor (what everybody always calls steam, because we can see it, so it needs a name). It takes very little water to produce a bunch of vapor (steam). At standard temperature & pressure, a given mass of water will produce 1600 times its volume in steam (water vapor). So what you see coming out of a properly operated woodburning appliance chimney on a real cold night is just the little residual moisture from the fuel and the water as a product of combustion. Not much water there at all, but what's there becomes visible as it condenses back from vapor to liquid in the cold outside air. Rick

And after a short time, the tiny visible water droplets tend to evaporate back into the air, which is why the 'steam' is visible only for a short distance. You can sometimes notice that on a cool but humid morning when relative humidity is high, the 'steam' stays visible longer than on a cold but dry morning, when relative humidity can be low.

 

[billb3]

Stove fog.

 

[Battenkiller]

So what you see coming out of a properly operated woodburning appliance chimney on a real cold night is just the little residual moisture from the fuel and the water as a product of combustion. Not much water there at all, but what's there becomes visible as it condenses back from vapor to liquid in the cold outside air. Rick

Well, here I go, opening myself up to a beating by them there chemists here, but...

The amount of water as a product of wood combustion isn't trivial. Oxygen combines with volatile gases produced by the gasification of the wood. In theory, every two hydrogen atoms in the fuel will combine with one oxygen molecule to create one water molecule. With a good clean burn, you will get a hell of a lot of water produced. Since wood is primarily cellulose and lignin, an amount probably equal to 60% or more of the dry weight of the fuel - plus the water that was still in the wood when you put it in the stove - goes up the stack.

And after a short time, the tiny visible water droplets tend to evaporate back into the air, which is why the 'steam' is visible only for a short distance. You can sometimes notice that on a cool but humid morning when relative humidity is high, the 'steam' stays visible longer than on a cold but dry morning, when relative humidity can be low.

Ah-ha! That explains a lot. On a particularly warm and drizzly night early in the season, I awoke to the smell of smoke in the house. New stove, so I was a bit concerned. Checked the stove and it was cranking fiercely, but nothing smoky going on there. Opened the basement door and I was greeted by the smell of burning wood. Grabbed my headlamp to take a look at the chimney and there some white "smoke" hitting the foggy air. It appeared to be coming out at a high velocity, then almost hitting a wall at a certain height and falling down to ground level where it seemed to disappear. The stove, apparently, was drawing that air back into the basement, and some of it was rising to the upstairs levels through convection. Couldn't figure it out until just now since I had always associated seeing white water vapor with cold weather. And the stove top thermometer was at about 750ºF. Now I get it. My stove was making that foggy air that was then cooling off and drifting down to the ground where it finally evaporated. No smoke at all, only the smell in the damp air.

 

[Beetle-Kill]

Fire clouds. :cheese: