Smoke seeping between pipe joints

[Alex m]

Hello,
I have a hearthstone II stove, with regular stove pipe inside the house and insulated security ss insulated pipe on the exterior topped with a cap and bird screen.

Today I noticed after just feeding the stove that a couple of the joints were seeping smoke. It was a small percentage of the smoke coming out the top of the stack. The stove had been burning for over a day but the temperature just dropped ten degrees when I saw it seeping out.

This type of pipe is just twist lock with no fasteners.

Any ideas why it started it and if I should be concerned?

 

[Alex m]

Here's a photo

 

[begreen]

That is odd. No smoke should be coming from a class A pipe joint. Are you sure it was twist locked all the way? if yes, contact Security.

 

[pyro68]

check your screen at the top to make sure it's not blocked or partially blocked.

 

[Nick Mystic]

You mentioned that the temperature had just dropped ten degrees around the time you saw the smoke leaking from the joints. Is it possible that the weather change and perhaps some extra humidity in the air actually produced some steam coming off the joints rather than smoke? Like when you exhale outside in very cold air you see steam coming out of your mouth like smoke.

 

[Alex m]

Well just left the house for a bit and when I came in the house i could smell a little smoke. After close inspection I saw a little bit of smoke seeping between the single wall pipe and the thimble on the inside of the house......... Errrrr.... Must be a partial blockage right? No way that all joints could fail at once??? I just cleaned the pipe two weeks ago..... The cap and the screen are new this year (birds were getting in old cap) .... I can still see it exhausting out the cap so I don't know!!?????

 

[stoveguy2esw]

check your screen at the top to make sure it's not blocked or partially blocked.

first thing i'd look at. though the draft is at its weakest at the top of the flue so its not as likely to pull air in as below. so it would take less of a blockage at the top to cause the out-push. that said , it looks like a lot of exposed flue. could be a bit of inversion making the leaks apparant

 

[Alex m]

Another pic

 

[Alex m]

first thing i'd look at. though the draft is at its weakest at the top of the flue so its not as likely to pull air in as below. so it would take less of a blockage at the top to cause the out-push. that said , it looks like a lot of exposed flue. could be a bit of inversion making the leaks apparant

Can you break this down for me.... Speaking a bit over my head !

 

[Bagelboy]

When was the chiminey last cleaned? Perhaps there is creosote build up.

 

[begreen]

A cap screen can clog up in 2 weeks if the wood being burned is lousy. Start by eliminating the obvious and check that cap screen.

 

[Alex m]

Just cleaned 3 weeks ago. New top pipe , cap and screen this year

 

[Alex m]

Thanks be green. This wood is a mix so it is a possible cause. So if that darn screen is plugged how do I keep birds out in the spring/summer? We literally were getting a bird a day down the pipe every day!!

 

[begreen]

Burn well seasoned wood and this will not be an issue. Modern stoves want wood with <20% moisture content. If it is plugged clean it frequently until you can burn good wood.

 

[Nick Mystic]

Before I got my new stove and installed a ss flex liner I just had an open clay tile flue liner up top. I made a wooden cap that I would put on each spring after my last fire of the season and then remove it in October before my first fire of the new burn season. With your set up if you remove the screen from your cap it might be easier to just fasten a plastic bag over it each spring.

 

[stoveguy2esw]

Can you break this down for me.... Speaking a bit over my head !

k,
basically the flue is at its coolest at the top, now with a lot of exposed pipe up there the temperature drop is going to be at its most significant, so the air will be at its heaviest when you have warm air coming up at a certain speed and cool air above it at a slightly lesser speed, it can cause smoke to leak out of the seams as its easier for it to get out there than to climb up so it pushes out through the leaks

 

[Nick Mystic]

Think of that cold air outside at the top of the stack as a bit of a cork. The hot exhaust gases from your stove has to push the cold air out of the way to escape. If the draft isn't strong enough then you get some back pressure and this could force the smoke out loose seams.

 

[stoveguy2esw]

Think of that cold air outside at the top of the stack as a bit of a cork. The hot exhaust gases from your stove has to push the cold air out of the way to escape. If the draft isn't strong enough then you get some back pressure and this could force the smoke out loose seams.

nick gets an A , that's exactly right

 

[Alex m]

Not sure if anyone caught my reply that there was seeping on the inside of my house between the top pipe and thimble?

Wood has seasoned for over a year but it is a mix of hard and soft wood.

It's got to be a partially plugged screen?!?!that being said shouldn't all these joints (especially the interior) be air tight? As I said it is still mostly exhausting out the top? Seems like these other joints shouldn't seep until it is really plugged?

 

[Oregon aloha]

How cold is it there and how hot is your fire? Cold air is very heavy and if the flue isn't hot enough the stack will cool before it reaches the top and cause an inversion. Basically like closing off or plugging your stack. Try running your flue temps higher and see if that takes care of it.

 

[Alex m]

After reading I found many people complaining about plugged screens with the symptom of smoke coming out stove door when opened (noticed it had had done this a couple of times in the last few days). Went outside And lit up cap with flashlight and no light was passing through. Now I just have to figure our how to get up there to remove that screen. I had a 80 ft shooting boom lift to put the new cap and screen on (I was painting my house).....not an option to get one of those right now

 

[Sprinter]

When I had my installation done last year, my installer told me to expect the screen to clog up right away. He hated those things. Sure enough, within a few weeks, there was a big build up on it. However, with the help of the members here, I modified my burning habits and it didn't happen again at all after that and it's still absolutely clean now.

My wood was not terrible, but it was far from ideal, so I had to do a few things to compensate. IMO, you should look closely at your wood supply and make sure the moisture content is not below 25% maximum. 20% is more ideal. I'd suggest to get a moisture meter and apply the pins to the face of a fresh split and be sure your wood is adequately dry. If it isn't, this problem is likely to keep reoccurring and also risk a creosote buildup in the flue.

I think of the clogged screen as a symptom of a larger problem, rather than the screen as being a problem.

 

[Hogwildz]

Get yourself a screen with minimal of 1/2" openings, 3/4" even better. Burn better wood, and this will not longer be an issue.
1 year is not long enough for many hard woods to dry.

 

[Alex m]

Ok. Great advice. This wood had been down for over a year but was recently split.

 

[Hogwildz]

Ok. Great advice. This wood had been down for over a year but was recently split.

That says it all right there. If it was recently split, it is just no where near ready.
Don't matter how long it has been dead standing or laying around dead even.
Out west and southwest are the only areas that can get wood to dry the fastest with as dry as the air is there to start with.
And even then, I don't see many of the good hardwoods drying in even a year split and stacked.
You will see the difference when you get some seriously dry wood in there. It will be night/day. And the clogged screen issue will be a non issue at that point.
I am for screens myself, just my preference, and other than the first year I started burning semi dry wood, I have had no issue with the cap screen since using good, dry wood.
For now, just get yourself a screen with larger openings, and keep an eye on it. Check it once or twice a month. That is a pre indicator to what the rest of the stack is doing.