Chimney Cap Caught Fire Tonight.

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76ER

New Member
Nov 30, 2007
80
Southern Ontario
As the burning season comes to an end I have been only lighting the stove up at night. Tonight I didn't change the ritual except for the really dry kindling the neighbour gave me. Strike of the match, light the paper and off outside with my beer. I looked up and saw an ember come out of the cap..then another...then a sizzling sound..a very loud sizzling sound...I rushed inside and closed the bypass damper and the air control..the stove responded and went black...I went back outside to witness the stainless steel screen that keeps out the little birdies, glowing orange...it did so for about 10 minutes...I opened the air input after this and the stove came to life...the cap and screen remained quiet...I might just have the chimney sweep remove the screen (he put it on)c Cheers all!

Ian
 
I think the Spark Screen is by far a greater detriment than it is a help.
It is more likely to clog-up, wreck your draft, and then cause a chimney fire than
it is to allow an ember to fall & cause problems.

I have yet to experience anything positive with them......
 
Rob From Wisconsin said:
I think the Spark Screen is by far a greater detriment than it is a help.
It is more likely to clog-up, wreck your draft, and then cause a chimney fire than
it is to allow an ember to fall & cause problems.

I have yet to experience anything positive with them......


A controversial topic, to be sure.

I'd imagine that, for someone who spends time on Hearth.com, as an enthusiast of wood heat, as well as (hopefully) knowing and following best burning practices, doing frequent inspections/cleanings, and simply understanding wood heat safety in all its respects, a spark arrestor/screened flue may be more of a detriment. The flip side of this is that if you do know and follow all the best burning practices including making sure to ONLY burn 2 yr seasoned, dry wood and do regular inspections, it doesn't seem all that likely that the spark arrestor will cause a problem.

However, for a casual burner that doesn't know all the best safety practices or how to recognize a dangerous chimney situation, it is likely better. Someone like this is less likely to inspect the flue at the beginning of burning season, and could easily light up a bird/rodent/bat nest in the flue. They are also less likely to realize when a smaller chimney fire is occurring, and might think a few embers coming out of the chimney is "perfectly normal", and a series of events resulting from this could light up the whole roof.

I've heard of several people using larger mesh to prevent the spark arrestor from clogging, and I think something like this is likely a better solution than just taking the thing clean off. It's also best to know and comply with the local codes for your area. If you take your spark arrestor off, and then need to make an insurance claim or get a chimney fire inspection done, and your install is no longer to code, you've got more problems that you now have to deal with as opposed to needing to take a wire brush or a rubber mallet to your spark arrestor/chimney cap a few times per season.
 
I hear ya on the cap being more of a problem. I hadn't had my stove going for about 2 weeks. The other night i wanted to light it and take the chill of in the house. As i got the fire going, i herd stuff falling in my chimney. I was just up on the roof days before to take Christmas lights down. The cap was pretty clean. So i herd the crap fall down don't know what it was or if it could be bad so i just the stove down and cleaned it the next day. Come to find out with all the warm weather and rain we had made all the junk that was on the cap loose and all fell down to the bottom of my tee. it wasn't a while lot, prolly would have been fine, but for as long as it takes to clean i just cleaned it. the chimney wasn't even that dirty 3 cups full. i would like to cut the screen out or get a different cap or just take it off for winter. If i took it off for winter i don't want rain coming in and laying the bottom of my SS tee. I was wonder if anyone has every had a fire at the cap.
 
Two years with a cap and mesh screen (albeit large mesh screen) and no problems . . . of course burning seasoned wood and burning at proper temps and cleaning the chimney regularly may have something to do with the zero issue deal.
 
It doesn't matter how well seasoned your wood is. Doesn't matter how good you are at burning it. Those screens will plug up long before any accumulation is deposited in your flue. The only exception to this that I've seen is the occasional cat stove burner.

There is nothing good about a cap screen. I also wonder what value a large screen has since sparks are pretty small. Even with my spark screen removed, the largest hole in the simpson cap is way way smaller than an open flue.
 
I've found that the biggest "hidded" problem with all spark arrestors,
(mesh or band - I've had both) is the issue of heavy snowfall.
As it falls, sloppy snow seems to "beard" around the screen,
draft begins to slow, soot deposits on the slush, and so on.
Once the snow lets-up, and the slop is overcome & melted-away
by the prevailent heat of the chimney, & custy deposits are left
behind on the screen. These deposits build-up with numerous
heavy snowfalls. Needless to say, we have had lots of snowfall
for several winters now. I've had less of this problem on light
winters. For me, a good draft on my chimney is prime......
 
Just took this photo. The cap has not been touched since it was installed in 2006. Over 9 cords of wood smoke have gone through it. I'll be pulling it this summer for inspection and will take some close up shots then. Dry wood is good.

PS: stove has a nice fire going in it now, started an hour ago. Love how there is no smoke.
 

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I've got Simpson screened caps on both of my chimneys. ~½" mesh stainless screen. Look just like BG's. I'll leave the screens in place for two reasons:

1. They've caused me no problems whatever.

2. They're required to be in place where I live, because of the ever-present danger of wildfire.
 
BeGreen,
Looking at your picture..that is the same cap I have...for the last 4 seasons I'd have to say my cap looked like that with respect to the blackness. I had the screen installed to keep out the feathered friends..opening the stove door and having a bird fly out into the kitchen was a weekly occurance. The screen itself has 1" square openings...not much of an arrestor. I had the sweep clean everything and he installed the screen. I did notice that snow seemed to stick on the screen which never happened before. Any ways..it is something I am going to have to ponder for next season.

Ian
 
Did the stove burn a lot of paper or cardboard recently? That could plug things up.

My screen is still the stock 1/2" screen that came installed by Simpson.
 
"spark arrestors" will stop large chunks of burning soot to be "ejected" during instense chimney fires. small sparks are not the issue...

remove screens at your own risk. while a maint. issue, they are required in some areas for a reason. fire danger in dry climates is very real especially at the start of the burn season.

keeping your roof and gutters clean, all combustibles clear to a minimun of 10' from the cap, and regular chimney inspections are the recomended steps if you want to remove screens

about 80% of all "my stove is smoking, help!!" calls i get are related to dirty caps... frankly, clogged screens let the customer know cleaning is needed long before the chimney develops dangerous deposits.

in California you'd get a ticket from cdf for not having a screen (if they had money in budget for inspectors(haven't heard of any locals getting cdf drive bys for a year or two))
 
Unless you have a smaller holed screen on your cap, your doing something wrong.
My first year I had bad buildup on the cap. Was also burning less than dry wood. And that sucker was almost completely clogged.
Been burning drier wood and better practice all around, never had a problem since.
Screen it or don't. To each their own.
But to say that screens are no good, and everyone will clog is just plain BS.
If that thing was glowing, you more than likely had a chimney fire and didn't even know it.
The debate can go on & on. But the plain simple truth is, that burn dry wood, and go light on the paper products used in there, and you will not have cap screen problems.
If the screen is smaller than say 1/2" openings, you may want to replace with a screen with 1/2" openings or better.
To generalize that ALL cap screens clog and cause problems is merely a one sided view, and nothing more, nothing less.
Do what you feel is right for your situation. I doubt there is a screen Nazi running round town to check this out. But somehow I am sure it would void the warranty on the chimney due to altering the product.
Any excuse for any company to weasel out of something, they will surely take. And you can bet this includes Ins. Co's.

I don't know bout other stacks. But when burning 24/7, there ain't no snow settling anywhere near the stack & cap here.
 
I had an unscreened Metalbestos cap. I had no problems except for the endless number of birds entering that I had to catch and release and all of the soot stains on my ceilings from the ones that got out of the stove (cold stove of course) and flew around the house. I finally decided to replace it with a screened cap and never looked back. I heard how screens clogged which caused me to wait until I couldn't stand having any more bird problems, but, since I replaced my cap with a 3/4 mesh stainless steel cap, I have more time to do other things (like monitor the creosote buildup on the screen). Just kidding.... my screen appears to be reasonably clean (no visible ash/creosote buildup).
 
I am just finishing up my first season with screens in the caps in thirty+ years of burning. Always hated the thought of them. I just walked out in the yard and looked up and there isn't a sign of anything in the screens with three cords burned so far. 3/4" inch mesh in the things.

Of course they may completely clog up in the next three weeks.
 
Highbeam said:
It doesn't matter how well seasoned your wood is. Doesn't matter how good you are at burning it. Those screens will plug up long before any accumulation is deposited in your flue. The only exception to this that I've seen is the occasional cat stove burner.

There is nothing good about a cap screen. I also wonder what value a large screen has since sparks are pretty small. Even with my spark screen removed, the largest hole in the simpson cap is way way smaller than an open flue.
Large screen keeps out birds, squirrels, and other critters. Keeps large chunks from being ejected during a chimney fire, too. I've had an expanded metal (diamond) screen on my stainless cap for decades. Never had it clog up, but have had deposits on it when our old stove was not burning cleanly. I'm used to giving it a cursory brushing with a wire brush every off-season when I clean the chimney. 3.5 cords this past season with the new stove, and it is still shiny silver color from the ground. Haven't climbed up to clean the chimney yet, so I don't know if it looks as clean on the inside as the outside.
 
IMHO, paper and cardboard used to start fires is not the safest method to start a fire... in any chimney, especially where itermittant burning is used. It floats up the stack and can ignite buildup.

Been there, and done it, twice, in an open fireplace many yrs ago.

I now just use super cedars to start fires.
 
When it clogged, it happened very fast. My fault - first year in this house so wood is not perfect. The flue was pretty clean. Just need to get up there and clean it more often.
 

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I've never had a problem with my chimney cap and I burn all sorts of wood, some not so perfectly dry, 2x4's, plywood & osb scraps, white paper, newspaper, small cardboard boxes, brush - basically anything that will burn that is not too toxic I use to light the stove. I sweep 1X per year and I have never had a problem. I think the key is to run your stove hot. I burn as high as 600-700 pretty much everytime I run the stove.
 

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I have been told to remove the screen, but I figure it is there for a reason, so I kept it. I was amazed how much gunk was around it when I did go to clean it. This was after 1 year. Stove was installed 1/09. Cleaned it 12/09. The wood was not ideally seasoned, but it was the best I had. Same cap as BG, simpson.
 

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BucksCounty said:
I have been told to remove the screen, but I figure it is there for a reason, so I kept it. I was amazed how much gunk was around it when I did go to clean it. This was after 1 year. Stove was installed 1/09. Cleaned it 12/09. The wood was not ideally seasoned, but it was the best I had. Same cap as BG, simpson.

Heck that looks downright clean. You should have seen it before the spring and summer rains cleaned it up for ya.

Chimney caps collect crud. Ya ain't gonna stop it. Mine without screens used to have a pile of sote laying around the base when I would go up for the mid-year and the end of season cleanings. It would collect under the top of the cap and then fall off on the top plate. When there was nothing but fine soot in the pipe. Just be happy you don't have a single wall outside chimney. The whole inside of the pipe would be coated with the stuff.
 
I had not seen this thread before posting my question about caps and draft, but in looking at the pictures, and watching my own cap in action, it seems to me at some point in every burn cycle smoke is lifting and being almost contained at the cap. If there is no wind at all, smoke just kind of rolls around and out up there. I can see the need of mesh for critters, and there has to be a height restriction lest angled, driving rain get down the flue.

I think I'm going to try and configure some kind of cone with a hole at the top, like a tee pee. Keep out rain, but also allow smoke to ascend and escape more easily, rather than trapped in a confined space.
 
Unless you have a screen that is clogged, a cap is not affecting the draft as much as you think it is. What you have is a draft problem.
Even with the cap off, I bet the smoke still will just roll out. You can try and build a better mouse trap. But in the end, until you address the draft problem, your tippi is going to do the same thing.
 
Based on the web page I looked at (from ye ol' web master), there is definite difference in some caps and how they work with various winds. No cap at all leaves the charts. But you have rain and critters to deal with, so caps are invented. They are not all the same. So, yes, I think there's always room for a new mouse trap.

I have no draft problem. Whatever draft problem may have existed has been corrected with a liner and another foot and half of flue length. Though I have not noticed any great differences in stove performance as a result. But I have noticed a difference between the cap I had on the chimney and the cap that came with the liner kit, and how the smoke escapes.
 
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