Smoke coming out of stove pipe (during wind gusts)

[Timnus]

Hey everyone,

For the first time I had smoke coming out of the joints in my stove pipe and have been trying to figure out the variables. The biggest one is that it is very windy today. Let me know what the issues might be or how this would happen. I'll try to give as many details about my setup first.

• I have a Woodstock Progress Hybrid with 5 feet of double wall stove pipe, then 9 feet of triple wall - all going straight up from the stove in the middle of my house. The stove has been working well for 2 years now.

• I cleaned the chimney just yesterday (with a soot eater) but did not clean the cap (just checked the screen with binoculars on the ground and could see through the screening pretty well).

• I have an outside air kit connected to the stove.

• I had a fire last night with no problems after cleaning the stove pipe.

So, I started the fire with the stove cold, during strong wind gusts. For about 30 minutes as the temp of the stove top climbed to 300 degrees, on each wind gust, I could see visible smoke leaking in 3 places -- out of my telescopic double wall pipe, the bottom of the stove flange, and one spot directly on the front of the stove top griddle (near the handle).

It is still windy right now, but I don't see anymore smoke. I assume it is due to the better draft due to the higher temps in the stove pipe. But I believe I can still smell some smoke coming out in those areas during the wind gusts (just not visible anymore).

Let me know your thoughts or what to look for or change.

Thanks!

 

[Timnus]

I just searched some other threads that mentioned a clogged cap and decided to go up and double check things. The cap was 50% + clogged. I cleaned it off and hope that was the main culprit.

Could that have happened from cleaning it yesterday and then loose pieces rising? Or the strong wind clogging it somehow?

 

[Swedishchef]

Hrm. The only thing that can clog is a chimney cap is the formation of creosote. So at some point you were burning either at too low of a temperature or your wood was too wet.

You may have loosened up some chunks of creosote while sweeping and they may have got caught up in the cap.

The wind likely created a downdraft. With the already semi clogged cap, the smoke had to exit somewhere and it escaped through the joints.

Andrew

 

[Grisu]

Was the wind coming from the opposite side than the OAK inlet is installed? Having the OAK on the leeway side of the house can create a low pressure which will create a downdraft.

Another point: Your chimney is certainly on the short side.

 

[Timnus]

Was the wind coming from the opposite side than the OAK inlet is installed? Having the OAK on the leeway side of the house can create a low pressure which will create a downdraft.

The wind comes from the same side most of the time (today also) - the same side as the OAK inlet.

 

[Timnus]

The wind comes from the same side most of the time (today also) - the same side as the OAK inlet.

I also think my chimney may be on the short side as you said.

 

[Nick Mystic]

I think the clogged chimney cap was your culprit. I can always tell when my cap is starting to get some creosote build up because I'll start getting a little smoke coming out my door when I reload the stove. Normally, my draft is so strong I never get smoke out my door during reloads, so it's a good signal to go up on the roof and check my cap. I've looked at it from the ground with binoculars and think it looks okay, but once I get on the roof I'm shocked to see how much creosote is on the screen. While wetter wood is often the cause of creosote build up it is also a natural occurring event even with dry wood when we have extremely cold temperatures. No stove burns 100% clean and most stoves put off a fair amount of smoke during cold start ups. That smoke can condense on the cold cap and eventually your screen will get clogged.

 

[English BoB]

I think the clogged chimney cap was your culprit. I can always tell when my cap is starting to get some creosote build up because I'll start getting a little smoke coming out my door when I reload the stove. Normally, my draft is so strong I never get smoke out my door during reloads, so it's a good signal to go up on the roof and check my cap. I've looked at it from the ground with binoculars and think it looks okay, but once I get on the roof I'm shocked to see how much creosote is on the screen. While wetter wood is often the cause of creosote build up it is also a natural occurring event even with dry wood when we have extremely cold temperatures. No stove burns 100% clean and most stoves put off a fair amount of smoke during cold start ups. That smoke can condense on the cold cap and eventually your screen will get clogged.

One more thing on the spring clean list - if it ever arrives here in the North East.
PS it was mid 40s today.

bob

 

[Timnus]

Thanks for all the replies. I do believe the cap was the cause, and likely it was more clogged than I thought from seeing it with the binoculars.

Nick (or anyone else) -- can you explain how the extreme cold temps could cause buildup even with 20% moisture wood? I have had very dry wood this year, but there was also a few ice ages this winter...

 

[begreen]

20% moisture will still condense when the flue gases cool down enough. By the top of the chimney in very cold weather it could be well below the 250F condensation point in some chimneys, especially at the cap.

 

[Nick Mystic]

Even very dry wood will give off some smoke during start ups. That is also when the smoke going up the flue is at its coolest temperature. As begreen said, in cold temperatures condensation is going to occur and most heavily on the cap where it is coldest. Over time even "clean" burns will produce enough condensation to clog a cap with screen in it.

 

[Swedishchef]

Personally, I am not a fan of screens on chimney caps. But that's just me.

Andrew