Clogged cap

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begreen

Mooderator
Staff member
Nov 18, 2005
104,423
South Puget Sound, WA
There have been lots of threads on this, though I have never experienced it, until now. Normally I have our wood stacked and drying in the shed by late spring. Our chimney stays clean year after year. Well this last summer it was different. We started on a new garage project. Unfortunately, with tearing down the old garage we needed a place to store the stuff that resided in the garage. Even after a massive purge there was still stuff to store. It got put in the house, on the porch and in the wood shed. The garage was "supposed" to be done by September and that would have been fine. I had a large 2 cord pile of split fir that was drying out nicely. Unfortunately, Murphy's law kicked in. Between the contractor and the county, the project got delays adding up to over a month. And then the rains came.

Long story short, for the first time in years we have been burning less than ideal wood. The tarps on the locust and maple leaked and the faces of the cords got soaked in what turned out to be a non-stop wet Nov. record setter. So we burned the best we could. The fir got into the shed in late Oct. and started to dry out. Not perfect, but with its high oil content, totally burnable. But here we are mid-season and the symptoms of a clogging flue are not ignorable.

I post this to help others that may be in a similar situation. Over the past two weeks, draft has weakened. At first it was just slower secondary performance and a little longer delay before being able to close off the air. Then a hint of smoke spillage started creeping in. It didn't take long to get worse. I went on the roof yesterday and checked the cap screen. It's not fully clogged, but there is clear evidence of it starting to fill up the gaps. I'll take some pictures tomorrow. Today it is impossible to start a fire without smoke spillage whenever the door is opened. The fire starts as if I have the air closed off. Tonight is our last fire until things are cleaned. This is after only a cord of wood burned. Tomorrow will definitely be cleaning day. I'll take some pictures.

This has been quite an education. Air control wide open, stove burning like it's half-closed. Stove top temp struggling to reach 500F. And a nasty smell of smoke lingering in the house. Tomorrow is cleaning day for sure.
 
BeGreen, definitely post the pictures. I think we would all like to see what it looks like after burning just one cord.
 
Funny thing is when this started a couple weeks ago I took out the binoculars and could see daylight through the cap screen. It's not plugged solid by any means, but evidently it's enough to slow down draft.
 
Over the past two weeks, draft has weakened. At first it was just slower secondary performance and a little longer delay before being able to close off the air. Then a hint of smoke spillage started creeping in. It didn't take long to get worse... it is impossible to start a fire without smoke spillage whenever the door is opened. The fire starts as if I have the air closed off... Air control wide open, stove burning like it's half-closed. Stove top temp struggling to reach 500F. And a nasty smell of smoke lingering in the house...

These same exact symptoms resulted from my clogged cat. converter. It seems to me that anyone who has the symptoms described above has restricted airflow somewhere between the firebox and the great outdoors... Could be the cat, the cap, the flue itself, or ???
 
For sure, you know immediately when you have an air flow restriction. It is very evident on start up. Could be screen, cat, flue or cap that is partly obstructed. I start by checking the screen. If it needs cleaning, the cat likely does also.Both are realtively easy to chek and clean. Have not had to clean flue or cap mid season. That would be a pain.
 
I can tell when the cap starts to get a little clogged too.
Same type of clues start showing up. Some air leakage, slow draft, flue temps down a bit......
Clean the cap and check the flue...maybe run the brush down, ad all is well.
Very easy to have happen in shoulder season with the older stove (harder to get a low burn w/o gunking up the flue/cap).
I commend you for putting this out there for all to see, begreen. :cool:
 
OK, here's the fugly truth.

This is what a clean cap looks like: IMG_1482web.jpg And this is what I found. IMG_1484web.jpg IMG_1485web.jpg


The accumulation in the pipe wasn't too bad. Just about 3/8" of fluffy stuff, but the cap was gross.

IMG_1483web.jpg

My wife reminded me that we had some burn time from last year so this is more like 1.5 cords worth. But I'm fairly certain that most of the accumulation has been since fall. I checked the cap last summer and it looked pretty good. Highbeam will be happy to note that I pulled the screen and am going to finish out the season without it. If birds get to be a problem I'll put it back in or I'll bag the pipe for the summer.
 
OK, here's the fugly truth.

This is what a clean cap looks like: View attachment 89838 And this is what I found. View attachment 89840 View attachment 89841


The accumulation in the pipe wasn't too bad. Just about 3/8" of fluffy stuff, but the cap was gross.

View attachment 89839

My wife reminded me that we had some burn time from last year so this is more like 1.5 cords worth. But I'm fairly certain that most of the accumulation has been since fall. I checked the cap last summer and it looked pretty good. Highbeam will be happy to note that I pulled the screen and am going to finish out the season without it. If birds get to be a problem I'll put it back in or I'll bag the pipe for the summer.
I dont use a screen i put a trash bag over the top of the pipe at the end of the burning season.
 
OK, here's the fugly truth.

This is what a clean cap looks like: View attachment 89838 And this is what I found. View attachment 89840 View attachment 89841


The accumulation in the pipe wasn't too bad. Just about 3/8" of fluffy stuff, but the cap was gross.

View attachment 89839

My wife reminded me that we had some burn time from last year so this is more like 1.5 cords worth. But I'm fairly certain that most of the accumulation has been since fall. I checked the cap last summer and it looked pretty good. Highbeam will be happy to note that I pulled the screen and am going to finish out the season without it. If birds get to be a problem I'll put it back in or I'll bag the pipe for the summer.
Wow that looks seriously clogged! Your screen is way too fine I believe my screen has slots 3/4"x 1" (not 100% sure) ..Have you considered getting a coarser screen? My screen looks like this BG, http://www.woodstovepro.com/store/M-G-DuraVent-9-Ventinox-Bird-Screen-RCB-9-p16437.html

Ray
 
Cha Cha Cha Chia... %%%
 
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Since you brought my name up, yes, I have seen something similar though in my case it was brown and light where yours looks black and wetter. We have the same simpson caps but I don't get any of that now that the screen is gone. No birds, rats, or chimpanzees have ever tried to climb down my flue.

It is amazing that you could even burn a fire with such a restriction at the cap.
 
Thanks for posting this Begreen. It has to be a real challenge sometimes living in the wet area like yours. We've had screen plug in the past, especially when we had the Ashley stove. We actually got into the habit of just tapping on it with the cleaning poles and this would get us to the next cleaning without doing any harm. Just tap on that screen and we could hear all the junk falling. No, I really do not miss those days.
 
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Excellent post BG..especially for newbies. I had the same thing happen to me the first year I burned wood. I started burning from a different stack and had the same thing happen to me. I sent the pics to one of the other members here because I did not know what to do.
Thanks for posting...it is a good learning experience not only for newbies but for newbie-graduates..like myself....(3rd season burning wood.)
 
Highbeam will be happy to note that I pulled the screen and am going to finish out the season without it. If birds get to be a problem I'll put it back in or I'll bag the pipe for the summer.​
I ditched my screen a few yrs before an EPA stove came in the house. I do bag the thimble each spring and I do catch lots of birdies in the bag. I release them all when they reach the bag. By late summer my chimney is literally polished. So I have turned a negative into a positive.
 
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@ Gamma...
You got a 30.
You're an old pro now.:cool:

I forgot to mention it was not with the "30"...it was with the englander 12....;sick
 
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Our screen went away, too, back while we were using the pre-EPA stove. I wasn't about to pay the sweep to clean it (and am too chicken to go up the slate roof and then up the chimney), and the brush from the inside wasn't getting it all off. That last foot or two of liner can slow things down, too, when burning bad wood. Once we went to a regimented monthly cleaning schedule all was well. Can't say I've ever missed that screen.
 
Wowza, BG !!

The Dixette is heading up on the roof over the weekend before the cold snap hits us Sunday night, just to check things out & clean if need be.

Thanks for posting those pics, good heads up.
 
Since you brought my name up, yes, I have seen something similar though in my case it was brown and light where yours looks black and wetter. We have the same simpson caps but I don't get any of that now that the screen is gone. No birds, rats, or chimpanzees have ever tried to climb down my flue.

It is amazing that you could even burn a fire with such a restriction at the cap.

You've got that right. I couldn't burn without a lot of smoke coming back as soon as the door was open, even just a couple inches. It's amazing how now the stove just takes off. Top went right to 675 with 5 splits in 30 minutes. I had forgotten how eager the stove is to burn. Funny thing is I have burned with a screen for the last 15 yrs or so. This is the first clogging.

No chimpanzees eh? I was wondering about that now that we have a banana plant. Good to know. ;)
 
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I had the screen removed when the liner and cap were installed. I was not going to climb on my roof, and I did not want to handle any clogging issue. Been two years and I have yet to see a bird come through. If one were to come into the flue, I am pretty certain that I would be able to smoke it out come fall.
 
Thanks for posting BeGreen. I had this happen once as well, you've given us good reminders.
 
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