one month old chimney cap black

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LAndrim

Member
Jan 1, 2011
94
Outside of Philly
Been reading recent posts about chimney fires and creosote and getting a little nervous since I'm a newbie and still in learning mode.

Sotve: One month old Lennox Canyon ST301, pretty much running 24/7.

Burning Procedure: I try to start fires small and hot, once going, I then pack a half dozen splits ( mixed hardwoods 1 yr old) and wait till the next cycle to load again.

Temperatures: A little unclear here, but I installed a Condar probe thermometer into double pipe, 18" above stove and I get the internal pipe temp about 600 and then damp it down a bit to around 400.

What am i doing that gives the cap this horrible black? i see some of my neighbors caps, and they are not this black. Normal or do I need to change something? thanks much guys!
 

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It is perfectly normal for the cap and part of the top section of stainless to get discolored over time. I will qualify that by saying that at some point you will want to get up there and confirm that it is only discoloration and not creosote.
 
Ditto what Pagey said, and I'll add that you could run the flue hotter. Damped down temp could be 500-600.
My external therm., is showing about 350 right now, and I believe that translates to an internal temp of about 600.
Cap gets dirty. It's going to, and will get some creosote buildup, but if you burn hotter, that will minimize it.
Check the cap and flue f you can get to it. First time burners might do well to check once/month or so to see how things are going, then adjust that routine once familiar with things.
What's the stove temp when burning?
 
Thanks Papa Dave and Pagey,

I only have the Condar probe thermometer and it runs 400-600. From what I've read in the forums I'm trying to "read" the stove and flames since the thermometers tend to not be that accurate.

My concern is it's just about a month of burning and should I have that much creosote?? Seems abnormal to me, but if you guys think it's OK, I'll get a cup of coffee and stop worrying!
 
Is your probe on double or single wall pipe.

If that's on double wall pipe you are on the low side of things but OK.

If that's 400-600 on single wall pipe you are burning too low.

pen
 
the probe is in double wall pipe...

what would you suggest as optimal temperature for internal probe on double wall? thanks much!
 
Pen, if it's a probe, wouldn't it read the same on either pipe, since it's inside both? Am I missing something?
Anyway, Jamison, at least you noticed. Good job keeping an eye on things.
 
that stuff won't stay shiny forever... looks like normal disoloration from smoke and moisture to me.
 
No surprise on the darkening of the cap.. You may notice it gets cleaner when we have a rain or a hard snow. Not a bad idea to get up there when you can but this does not seem out of normal. I would raise burning temps a bit as well.
 
Well I can tell you this much, my cap gets black (block chimney) and stains the chimney (never had this before) and I run the flue way hotter than the old stove, I looked at the chimney last week and it has a very thin layer of loose material on it, not sure why my cap get so black.
 
Jamison I am a newbie burning 1 month --also had the same exact feeling at 2 weeks(cap looked black and dirty) so went up on roof, did my first cleaning and only had about 1-2 tablespoons of waste . but it gave me peace of mind and wanted to get the lesson of cleaning 1st time under my belt-- plus had to take advantage of a break in weather as roof was cleared . The way winter has gone in your neck of the woods -well wait to June LOL. definetlely get up when safe to have a look you will feel more confident about your situation. Keep stuffing the wood and flipping off the gas man!!
 
PapaDave said:
Pen, if it's a probe, wouldn't it read the same on either pipe, since it's inside both? Am I missing something?
Anyway, Jamison, at least you noticed. Good job keeping an eye on things.

If you read back a page in the posts you'll see a thread w/ the title "Is 1200 degree flue temp too high" check that out or do a search for "flue temp probe full of it" if you want more info on recent discussions.

What many of us are finding is that condar flue temp probes are ok on double wall (as far as believing the values for a normal burn vs too hot) but are inaccurate on single wall due to the extra radiant heat.

pen
 
I agree with Pen,,,think your burning a little on the cool side. Also agree with the condition of the pipe, its not gonna stay nice and shiny forever. Get a look at the pipe over the next couple of months, its appearance will change once its been out in the weather.
 
For what it's worth here's my 2 cents...

When I light my fires I get the flu temperature to 500 degrees. I have a probe thermometer that is installed 18 inches above my stove. I then cut it down and it cruises at 375-425. That is plenty hot. My opinion is that any warmer and you are wasting too much heat by pumping it outdoors.

It is normal for a cap to become black. When it is damp out, relatively mild, the sun warms the cap, etc the first 5 minutes of fire will darken the cap. However it is good to check for creosote buildup. From what you mentioned above, I seem to heat the same way you do.

Andrew
 
And, of course, any time you see that one has to question the wood. I agree the cap will turn black but that much after only a month seems extreme. I also agree it seems you might be running a bit too cool. I'd still think strongly on the wood.
 
Swedishchef said:
For what it's worth here's my 2 cents...

When I light my fires I get the flu temperature to 500 degrees. I have a probe thermometer that is installed 18 inches above my stove. I then cut it down and it cruises at 375-425. That is plenty hot. My opinion is that any warmer and you are wasting too much heat by pumping it outdoors.

It is normal for a cap to become black. When it is damp out, relatively mild, the sun warms the cap, etc the first 5 minutes of fire will darken the cap. However it is good to check for creosote buildup. From what you mentioned above, I seem to heat the same way you do.

Andrew
Your flue temps seem low to me also if you are using a probe.
 
Thanks everybody...your insights as usual are much appreciated. It is impossible for me to get up and look at the cap even when weather breaks (pitch and height of roof are far too scary). I'll call a chimney sweep in Spring.

One final question on temperature:

1. Everyone seems to agree that for double pipe, a 400-600 degree probe reading is too cool.
So what should my probe thermometer be reading for as good, safe temperature? (Condar's thermometer shows 400-800 as "good").

Again, you all are such a font of wisdom..very reassuring for a newbie!
 
Hey guys

Well, maybe I do run it a bit cool. To tell the truth, you're right I do. I can't run my flue temps any hotter. If I do, my stove top temps reach 800-900 degrees!!!!

At initial light up, my temps are at 400-500 and then I turn it down. I often cruise at 400. Creosote buildup is at 250 or less. BY the time my stack temps reach 250, there is no offgassing by the wood inside (after about 1 hr). My stove company recommends flu gas temps between 250 and 500 degrees.

I am gonna get my chimney swept in a week or so. I guess then I will be able to tell if I am either doing it right, or wrong.

Now I am paranoid. LOL.

Andrew

**Edit** I just went outside 15 mins after a reload. My temps were up to 450, turned it down, it's cruising at 400 now. Not a single puff of smoke coming out the stack. I presume that means no creosote formation?
 
Swedishchef said:
Hey guys

Well, maybe I do run it a bit cool. To tell the truth, you're right I do. I can't run my flue temps any hotter. If I do, my stove top temps reach 800-900 degrees!!!!

At initial light up, my temps are at 400-500 and then I turn it down. I often cruise at 400. Creosote buildup is at 250 or less. BY the time my stack temps reach 250, there is no offgassing by the wood inside (after about 1 hr). My stove company recommends flu gas temps between 250 and 500 degrees.

I am gonna get my chimney swept in a week or so. I guess then I will be able to tell if I am either doing it right, or wrong.

Now I am paranoid. LOL.

Andrew

**Edit** I just went outside 15 mins after a reload. My temps were up to 450, turned it down, it's cruising at 400 now. Not a single puff of smoke coming out the stack. I presume that means no creosote formation?

your thermometer actually has a probe that goes inside of the pipe? If it says 250 on the face for creosote prodution either you have a magnetic surface thermometer or one that reads in Celsius perhaps?

pen
 
Yes it is a probe thermometer.

It doesn't say 250 for creosote production on the thermometer. As a matter of fact it doesn't say anything other than temperature readings.

I simply know that creosote begins to form at those temps since it's at those temperatures that the gases condense. The gases are in fact partially acidic and stick to the inside of the chimney if they cool off to their condensation points.

ANdrew
 
Swedishchef said:
Yes it is a probe thermometer.

It doesn't say 250 for creosote production on the thermometer. As a matter of fact it doesn't say anything other than temperature readings.

I simply know that creosote begins to form at those temps since it's at those temperatures that the gases condense. The gases are in fact partially acidic and stick to the inside of the chimney if they cool off to their condensation points.

ANdrew

Remember, the flue gasses will be much hotter than the stove pipe temps. As a result, flue gasses less than 400 degrees mean you have a flue pipe of roughly 200 which as you know is below the boiling point. Additionally you are measuring temps 18 inches above the stove. Temps drop a lot as it continues up the liner. I'll measure a 100 degree surface pipe drop from a few inches up the pipe to where it exits my thimble (after passing through a 90)

I suggest a surface thermometer for the stove and allow that to help you determine how things are.

pen
 
But aren't probe thermometers responsible for measuring the temperatures of the gas, hence why it's a probe and not a surface thermometer?

My thermometer is actually about 2 feet above my stove, after the first 45 degree bend. Any of this make sense?

Andrew
 
Swedishchef said:
But aren't probe thermometers responsible for measuring the temperatures of the gas, hence why it's a probe and not a surface thermometer?

My thermometer is actually about 2 feet above my stove, after the first 45 degree bend. Any of this make sense?

Andrew

What they say they do and what they actually are able to do are 2 different things .

Part of your problem is that you should have it installed below that 45, 18 inches above the stove.

pen
 
This is the amount of creosote that came out of my 12' stack, 6" diameter, from Thanksgiving to Valentines day. I usually clean the flue on a Holiday schedule, but I skipped Christmas this year because I am burning a more seasoned supply of wood. This pile does NOT include the creosote I scraped off the chimney cap, which was substantial and certainly would have added 2" more to the level of this heap inside the ash bucket. The cap is black, for sure, but it's clean now. But the top is still a shiny stainless color.

So remember, after burning for ten years with the same stove, I know what to expect. I realize that each year I have a different supply of wood, different moisture content, different variety of tree. So I know to expect the somewhat unexpected. Keep an eye on things. Listen to the draft, and inspect your cap. The cap is going to be the coldest point of your stack. Once the buildup becomes noticeable, you are on borrowed time.
 

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Not sure how high that pipe extends from the roof, but I would feel better if it had support wires if it was mine
 
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