Help! Can't figure out why I am getting smoke blow-back suddenly

[ylekyote]

I live in Western Colorado. We've been having some warm weather lately...in the 40s at day and mild upper 20's/30's at night...for the last 3 days. This is my first season burning a woodstove. The stove was already in place when I bought the house and the previous owner said the system worked great.

My woodstove platform (pic attached) has been burned everyday since late October. It's only had two spells of doing this, but they are unexpected when they occur and cause a smokey mess at the worst times it seems (like right before bed, or in the middle of the night, or when we are about to leave).

I bought the stove new. This is the stove I have:
http://www.homedepot.com/p/Pleasant...u=203883464&ci_kw=&ci_gpa=pla&ci_src=17588969

The first time it happened about 3 weeks ago I tore the entire thing apart to inspect and clean. There was hardly any creasote buildup. Wasn't worth cleaning but I did it anyway. I put it back together and it seemed to work fine afterwards. I thought maybe a bird or something had gotten in my chimney. We were having higher winds that day than normal, and it was warmer and also snowing quite a bit.

The 2nd time this inside smoke happened was yesterday, and it continues to present..about 36 hours so far.

After the first time I thought it must have been strange wind or a depression that was forcing air back into the house so this time I tried opening windows, doors, fans...all sorts of things. It does make the smoke slow down from blowing back into the house through the stove and pipe seams, but it doesn't help enough and doesn't stop it completely.

So as I was airing out the house tonight and suffocating the starter fuel I had in the firebox I went outside and shined my flashlight on the top of the chimney and followed it down to its base. I was standing on the ground. Smoke is coming out of the chimney top (a lot), and also a little out of the seams??? How could smoke be coming out of the seams of the exterior pipe??? It's a double-walled stainless steel pipe!! Is that normally possible with a system that is tight? That means smoke is getting past the inside pipe wall and coming out of the exterior pipe wall.

This is how it behaves inside:
When I open my stove door (cracked or wide open) smoke comes billowing out of the door. If the close the door with the house closed, smoke comes billowing out of the interior stack and back of the stove. If I open windows/doors and then open the stove to any degree, smoke still comes out, just not as much. If I open windows/doors and close the stove, the smoke seems to stop on the inside, and comes out of the exterior chimney top (and seams). Regardless of what position the air intake door is set to, it doesn't seem to really affect a thing. However, I noticed closing this all the way doesn't seem to really do much even when the stove is working well.

Is this a weird air pressure issue I'm having due to the warm weather and no (or very light winds)? I live in somewhat of a little bowl, with hills almost completely surrounding me.

I hope someone know what my problem is because I'm about ready to scrap the whole thing! lol It will be cold again soon and I need a working firebox. Thanks much! chris

 

[KindredSpiritzz]

kind of hard to tell from one picture but it looks like your 6 inch pipe off the stove increases to 8 inch going thru the ceiling so im wondering about the connection coming thru the roof if its 6 inch or 8 inch chimney. If its 8 inch and it should be 6 inch that would explain getting smoke thru the seams. Be nice if you could add pictures of the outside chimney as well.

 

[Bigg_Redd]

Smoke is coming out of the chimney top (a lot), and also a little out of the seams??

Your chimney is clogged

 

[ylekyote]

Your chimney is clogged

It can't be clogged...unless a critter flew or crawled into it, which is unlikely. It has a screen. It was just cleaned 3 weeks ago.

The top portion of the chimney (above the exterior roof) is 8" ID. The interior chimney pipe is 6" ID. Never had a issue for nearly 4 months. I would think the smoke would seep out of the seams and screw holes of the inside 6" pipe, before it the outside 8" pipe, since the 8" pipe section has more room for the smoke to travel up.

 

[Bigg_Redd]

If smoke is coming out the seems, it's clogged.

 

[Kosmik]

Have you inspected the chimney? From the inside of it?
Pic of chimney?

Also the hard winds we've had really accentuate the problems of chimney not meeting minimum clearances or the slowed draft from 6" going into 8".
Air pressure, winds are easily overcome by the draft caused when your air control is running open more and keeping the flue hot. Still not ideal because then you have problems keeping a slow burn going, or have runaway problems from too many coals getting flared up by the crosswinds (have to add less wood).

But my setup is pretty crap and I'm not having problems your having, so something is probably blocking airflow up the chimney.

And do you have a stovetop and flue thermometer? They really help, worth the $.

 

[ylekyote]

Have you inspected the chimney? From the inside of it?
Pic of chimney?

Also the hard winds we've had really accentuate the problems of chimney not meeting minimum clearances or the slowed draft from 6" going into 8".
Air pressure, winds are easily overcome by the draft caused when your air control is running open more and keeping the flue hot. Still not ideal because then you have problems keeping a slow burn going, or have runaway problems from too many coals getting flared up by the crosswinds (have to add less wood).

But my setup is pretty crap and I'm not having problems your having, so something is probably blocking airflow up the chimney.

Guess I don't have much choice but to open up the stove again Tues afternoon and see if anything might be up there. If its anything, it has to be a dumb bird, because I've been burning dry aspen and that's pretty clean from what I gather. I ordered a draftmaster chimney cap tonight to put on the top. I am surrounded by hills higher than me, so I think that may be playing into the problem, like it was the first time a few weeks ago. I think the warm weather and winds is messing with my draft/flow. thanks!

 

[Kosmik]

It can't be clogged...unless a critter flew or crawled into it, which is unlikely. It has a screen. It was just cleaned 3 weeks ago.

So now you've learned that your screen needs cleaning at least every 3 weeks?

I'm on top of a mesa with 60+ mph winds, a chimney that is 2ft below the roof ridgeline 8' away (45deg pitch), some chitty wood scaffolding holding it up adding a horizontal surface right up to the cap almost...
Yeah it has a wind guard (double banded!), but that don't mean nuffin!

If you check it and determine it isn't clogged?
Get a bigger flashlight and check again.
Screens like to clog in anything.

But if it really isn't clogged, and it's clean, then try running the flue hotter.

 

[Kosmik]

This is my first season burning a woodstove. The stove was already in place when I bought the house and the previous owner said the system worked great.

If you're buying it, ofcourse it works great...
Even if it don't.

You say your wood is dry.
But if it is your first season burning wood, how do you know it's dry?

I bought mine from the guy 'seasoned', but that is not a defined term for the purposes of 'quality' of fuel.

 

[KindredSpiritzz]

even with a clogged chimney cap how is the smoke escaping the inner wall and getting into the outer wall to leak out the seams?? and he said he had smoke (alot) coming out of the cap. And he said he cleaned it after the first incident and it wasnt dirty. Something isnt adding up.
Whats the overall height of your chimney? is it 3 ft above any peak within 10 ft? or is it 2 ft? i always forget

 

[Kosmik]

even with a clogged chimney cap how is the smoke escaping the inner wall and getting into the outer wall to leak out the seams??
Whats the overall height of your chimney? is it 3 ft above any peak within 10 ft? or is it 2 ft? i always forget

Yeah, that's why I said get a bigger flashlight, maybe not clogged, maybe a break/tear.
Fact is, it probably didn't 'run like a dream' for the previous owner.
That is the only thing that adds up.

Have you gone through all the threads in the newbie section:
https://www.hearth.com/talk/threads...lem-stoves-air-is-restricted-faq-about.59225/

See you have thermos.
What is your flue temp when it was running and backdrafting.

You might have to get in the attic (or wherever) to inspect the chimney where it runs through the house to see if they didn't try to bury a defective section where you wouldn't see it...They did in my house...Probably broken when it was installed.

Easiest way to tell if your chimney is clogged (or the screen) is to run a brush through it, then daylight should reflect down the stainless interior.

 

[KindredSpiritzz]

The top portion of the chimney (above the exterior roof) is 8" ID. The interior chimney pipe is 6" ID. Never had a issue for nearly 4 months. I would think the smoke would seep out of the seams and screw holes of the inside 6" pipe, before it the outside 8" pipe, since the 8" pipe section has more room for the smoke to travel up.

and you said the 8 inch is double walled right? so where it connects to the double wall its connected on the inner wall and not the outer wall right?

 

[begreen]

A screen can clog up in 3 weeks if the stove is burning semi-seasoned wood like pine and the flue is being kept too cool. The run of single wall will cool down the flue gases rapidly, especially with a fan blowing at it. What temperature are you typically seeing on the flue thermometer after the stove has been running a couple hours?

 

[AK13]

OP, you said you cleaned the chimney. But did you go up on the roof and clean the screen and cap? I had some coming out the seams this year. The double wall flue itself wasn't that bad, but the cap was gooped up enough that it was restricting the draft and causing leaks. It sounds like that is what is happening to you.

When you say its leaking out the seams, I assume you mean the horizontal seams between sections and not the vertical seams of the flue pipe.

 

[oconnor]

Makes sure the flue is totally unrestricted.

In the mean time, give this a read. http://woodheat.org/all-about-chimneys.html

Having smoke come out the stove and connector pipe isn't uncommon with poor draft. Problem is that the poor draft eventually results in cooler flue temps, then the flue clogs. That is usually when we see smoke exiting the flue seams.

 

[ylekyote]

I will try to answer all the questions here.

I have two temp gauges on my flue. One on top of stove center, and one about 36 inches up from the stove top. I have a double walled interior pipe, but it is connected about halfway up to my ceiling with a single wall barrel connector where I put my pipe temp gauge. So there is about 3" inches of single wall on the interior pipe where I put the temp gauge for a more accurate readings.

I try to always burn so the stove gauge reaches 500 to 800 degrees F. I'm lucky if the pipe gauges reaches 300 to 400 degrees F, 36 inches up from the stove top. I would put the pipe gauge closer to the stove (18 inches) but the pipe is double walled there and does not give me good readings.

I bought seasoned Aspen from a local firewood guy. And some crap scrap pine from a lumber yard that I'm letting dry out more...even though I thought most of it was supposed to be kiln dried before trimmed off. I could tell some was lacking age, but most of it was light and had dry cracks in it. I am seasoning next years 2 cords of oak and assorted hardwoods presently, and using that next year with a little mixed Aspen/Pine for starter. The Aspen burns and starts good and hot, but burns fast. I like it better than pine thought, because it doesn't seem as smokey and seems to burn better in general.

I cleaned my pipe from the stovetop up and it is clean looking. There was a little debris in it but not much. I can't see my flue screen good enough from the ground to tell if it is partly clogged. My brush knocked some small stuff off the top-center of the flue cap, but not much at all. I will inspect the screen up close when my new $200 cap comes in, and get up there only once. However, after I brushed the pipe all the way to the flue cap I was able to start a fire the next day with no blowback....but the weather had cleared and cooled and the wind was back to normal also. So not sure if I knocked a little screen debris away, or if it was the wind and atmospheric pressure issues I expect it may be.

The pipe was leaking smoke both inside and outside from the horizontal seams (where the pipes connect) and the small holes (inside pipe only) where I reinforce the pieces together. I have double wall interior pipe, and double wall exterior chimney pipe. But like I said, the cap was also putting out smoke.

I am thinking about removing the cap screen on the new one, and putting a round screen around the entire cap to prevent any future clogging. My guess is the farther away the screen is from the pipe outlet, the less likely crap will clog it up.

I don't have a fan blowing at the interior pipe, it blows across the front area of it, so the heated air is dispersed towards my home living area.

My chimney top is above 2 and 3' of the highest roof peak, which is more than 10' away (more like 20 to 25' away). Also, my chimney is on the side of the house where the winds usually hit first.

I bought the house from an investor. I discovered the previous owners name and contacted him with questions about various stuff. He had no reason to lie about what worked well or not.

thx,
chris

 

[ylekyote]

And if the cap is surrounded with a screen about 3" around it (rather than inside of it), it is easier to inspect from afar (the ground, etc).

Does anyone have tips as to the best way to connect the interior chimney pipe (from stovetop to the interior ceiling)? most of my pipe sections twists together, but two parts of it don't (such as the adjustable section that slides up and down on itself, and my mid-way barrel connector, where my temp gauge is). I've been using small screws, but in doing so that makes additional holes that are VERY hard to match up when I remove and reinstall after cleanings.

 

[Kosmik]

So it's not coming out of the seams anymore? Perhaps you have small enough screening that it clogs easy.

I use stovepipe cement for all connections that don't need to be separated, then use a fireplace silicate cement that comes in a caulking tube for the seams that need removal (like the telescoping piece), just place around like caulking. The silicate cement can need at flathead screw driver or chisel to remove, but seals up nice.

For matching up holes get a magic marker and make a straight line perpendicular through the seam. Just like marking car parts. You can even label screw locations with the marker.

I bought 'seasoned' firewood too. But if you read the threads you'll see there is a difference usually from what the seller calls seasoned and what they call here seasoned. That could be making extra soot that just clogs the little screen.