Reduced Draft, creosote?

bbeals · Dec 6, 2008

We had our Jotul 550 installed in late August and have been running it non-stop since mid October. Burning 2 year seasoned, mixed hardwood with the occasional chunk of 6 month old split maple (fairly dry, doesn't sizzle, although I do not have a meter). The unit is installed in an exterior masonry chimney (24'), fully lined SS. So as of late last week we now get a little smoke (more than I have ever seen and not something you would tolerate long) rolling out of the insert when you open the door to reload. This has not happened in the past and I believe that I am getting some creosote buildup in the cap. Still have a good stream of smoke coming from the stack when you reload it and it still drafts well with the door shut (burn between 500-600 degrees is easy to maintain). No smoke with the door shut and it runs as it always has. We have a sweep coming out on Monday, as the chimney cap is 40' off the ground and we have a 12 / 12 pitch roof (not as young as I used to be).

I pulled the secondary burner bars and baffles to take a peek up the stack. All I can see with a flashlight an mirror is a very light / dry dusty looking ash on the pipe. I did get up to the roof (within about 12 feet of the cap) and noticed that the cap is pretty black). Have you seen this before and do you see an issue running the unit over the weekend with this issue? We have it running now @ 563 degrees and it is performing well, only get the smoke every 3-4 hours when we go to refill.

All I can figure is; last week I had been traveling for work and the wife and kids got into a pile of wet birch that I had cut and split less than 1 month ago, I got home and it was on the porch and they had been burning it for a couple of days. Just want to keep it safe...

Thanks in advance. Brian

LLigetfa · Dec 6, 2008

It's not unusual to have black on the chimney cap. It is quite exposed to cold and will condense some creosote. Does the cap have a spark guard screen that could be partially clogged? Wet Birch will creosote a lot especially with bark on it but while one week could be enough to clog a spark guard, it should not be a threat to a chimey fire.

I would be more inclined to consider stack effect inside the house as your culprit. Crack open a downstairs window to see how much in-rush you get.

gibson · Dec 6, 2008

BI,
Same stove, same exact chimney setup. Burning for two weeks and the vents on my chimney cap are black, nothing else. I have been burning fires at 600-700* as measured with a magnetic thermometer in the blower vent. No smoke from the chimney when I'm burning hot. I'm not worried because everything is working great and it is too early to have any creosote. I will get up on the roof, weather permitting, in a month or so, to take a look down. Sounds like you are burning hot enough...

I couldn't be more pleased with this stove. It is easy to run and the family loves the heat (we are not used to 75* inside in the winter!).

cheers

bbeals · Dec 6, 2008

It's a new liner and cap and there does not seem to be a visible screen spark arrestor. Actually the cap is designed in such a way, it is hard to tell where it actually vents from. Nothing has changed within the house and I ensured that the dryer, bathroom vents, etc were not creating a negative draft source. I do believe that my cap is becoming plugged (early stages), as we could open the door up until a week ago and would not even get a whiff of smoke, now you can get a visible snout full. They probably ran 10-20 splits of that birch through it when I was gone and these things were wringing wet when I split them. Good news is that the sweep will be here Monday. Were having a neighborhood party at our house tomorrow and wish to continue to run the stove, so looking for opinions on whether this is reasonable under the circumstances.

bbeals · Dec 6, 2008

carl spackler said:
BI,
Same stove, same exact chimney setup. Burning for two weeks and the vents on my chimney cap are black, nothing else. I have been burning fires at 600-700* as measured with a magnetic thermometer in the blower vent. No smoke from the chimney when I'm burning hot. I'm not worried because everything is working great and it is too early to have any creosote. I will get up on the roof, weather permitting, in a month or so, to take a look down. Sounds like you are burning hot enough...

I couldn't be more pleased with this stove. It is easy to run and the family loves the heat (we are not used to 75* inside in the winter!).

cheers

I would not have believed that this could have occurred so soon myself. It has been running so incredibly well, that I must say, it has made us proud. Given it has been about 3 months of running, it probably is not a bad idea to have the sweep risk life and limb on my roof just to put my mind at ease. Really curious to see if others have seen this happen so quickly. Again, with the door shut it drafts well, with the door cracked open slightly it drafts well and just roars.

bbeals · Dec 6, 2008

LLigetfa said:
It's not unusual to have black on the chimney cap. It is quite exposed to cold and will condense some creosote. Does the cap have a spark guard screen that could be partially clogged? Wet Birch will creosote a lot especially with bark on it but while one week could be enough to clog a spark guard, it should not be a threat to a chimey fire.

I would be more inclined to consider stack effect inside the house as your culprit. Crack open a downstairs window to see how much in-rush you get.

LLigetfa,

Are some caps better than others at helping prevent some of this? It just seems that a more "open" designed cap might provide better flow with less areas to build up. Then again, that could lower the overall stack temp and affect the overall stack.

LLigetfa · Dec 6, 2008

Is it a multi-storey house? How can you be sure nothing has changed? Could there be window ajar or an attic hatch that did not seal well? Try cracking a window near the stove. I've seen my HRV become unbalanced from dirty filters and fuzz clogging my outside air vent. My wife has a habit of opening a widow upstairs.

As your brick chimney gets cooler with the cooler weather, there is going to be a progressive reduction of draft. You will have to adjust how you run the stove to allow more heat to service the chimney.

bbeals · Dec 6, 2008

LLigetfa said:
Is it a multi-storey house? How can you be sure nothing has changed? Could there be window ajar or an attic hatch that did not seal well? Try cracking a window near the stove. I've seen my HRV become unbalanced from dirty filters and fuzz clogging my outside air vent. My wife has a habit of opening a widow upstairs.

As your brick chimney gets cooler with the cooler weather, there is going to be a progressive reduction of draft. You will have to adjust how you run the stove to allow more heat to service the chimney.

New 2 story colonial, 2X6 exterior construction. Just verified all windows are closed and also tossed on two more splits with the slider open a couple of inches (it is near the stove). Got the same puff of smoke that we have never dealt with before.

bbeals · Dec 6, 2008

LLigetfa said:
Is it a multi-storey house? How can you be sure nothing has changed? Could there be window ajar or an attic hatch that did not seal well? Try cracking a window near the stove. I've seen my HRV become unbalanced from dirty filters and fuzz clogging my outside air vent. My wife has a habit of opening a widow upstairs.

As your brick chimney gets cooler with the cooler weather, there is going to be a progressive reduction of draft. You will have to adjust how you run the stove to allow more heat to service the chimney.

This has only been happening for a few days and while I think we caught it in time as to not pose a danger to the chimney / house, just real curious as to what you think about this running for a couple of days until the sweep calms my nerves?

snowtime · Dec 6, 2008

My bet is plugged screen on chimney cap. In the old days up here that would happen often. There is no regulation here but people just removed their screens. Some who had bad cap problems would even cut out some of the cross supports that were there to keep the wind out. Basically they made their caps as free flowing as possible. Those heaters never had another problem as the creosote only built up on the cap quickly the chimney just needs a yearly clean.

bbeals · Dec 6, 2008

snowtime said:
My bet is plugged screen on chimney cap. In the old days up here that would happen often. There is no regulation here but people just removed their screens. Some who had bad cap problems would even cut out some of the cross supports that were there to keep the wind out. Basically they made their caps as free flowing as possible. Those heaters never had another problem as the creosote only built up on the cap quickly the chimney just needs a yearly clean.

Snowtime,

I will inspect the cap when the sweep is here, it might be well served with a couple of 3/4" holes in it, for that matter, I suppose I could do that from the ground with a 12 gauge and buck shot. :lol:

gibson · Dec 6, 2008

LLigetfa said:
Is it a multi-storey house? How can you be sure nothing has changed? Could there be window ajar or an attic hatch that did not seal well? Try cracking a window near the stove. I've seen my HRV become unbalanced from dirty filters and fuzz clogging my outside air vent. My wife has a habit of opening a widow upstairs.

As your brick chimney gets cooler with the cooler weather, there is going to be a progressive reduction of draft. You will have to adjust how you run the stove to allow more heat to service the chimney.

Shouldn't the stove draft better as it gets colder? It's harder to start the stove when it's 50* than when it's 20*...

RedRanger · Dec 6, 2008

Unless I missed something? I suspect wood not dry enough?

Just saying that last year with my old smoke dragon, it would eat any kind of wood. Always thought I was burning hot and clean, but my wood was suspect, and end of season about a 5 gallon bucket full of creosote. Not the bad stuff, mostly gray ash junk. And about mid dec, open door and smoke exiting in my face.

Not this year, long rows of wood drying in the sunshine and wind.

And my ss liner is only 5.5. so any buildup I know right away.

So, have you re-split your wood and checked the inners with a moisture meter?/ If it ain`t reading 25% or preferrably less than that is the culprit.

LLigetfa · Dec 6, 2008

carl spackler said:
Shouldn't the stove draft better as it gets colder? It's harder to start the stove when it's 50* than when it's 20*...

I have never seen or heard of that.

Draft works on the principle that warm air rises. An outside chimney is influenced by outside temperature. As the smoke slowly rises it cools and gets heavier. The SS liner helps by reducing the volume (increasing velocity) but the cold of the masonry will still reduce draft a bit. For that reason, some installers will use an insulated liner. A solution is to adjust the stove to allow enough heat up the chimney to service its need.

LLigetfa · Dec 6, 2008

Now, I'm not familiar with the Jotul 550, but I have to wonder why there is smoke present when the door is being opened. Unless you are opening the door early to fiddle with a problem burn, when the door is opened to reload, there should only be a hot bed of coals and hot coals don't smoke.

If it smokes after you start to stoke it, you need to review how you are stoking. Stage what you need on the hearth before you open the door. Pull coals to the front. Put bigger pieces behind the coals and smaller pieces on top of the coals. Don't doddle.

gibson · Dec 6, 2008

LLigetfa said:
carl spackler said:

Shouldn't the stove draft better as it gets colder? It's harder to start the stove when it's 50* than when it's 20*...

Click to expand...

I have never seen or heard of that.

Draft works on the principle that warm air rises. An outside chimney is influenced by outside temperature. As the smoke slowly rises it cools and gets heavier. The SS liner helps by reducing the volume (increasing velocity) but the cold of the masonry will still reduce draft a bit. For that reason, some installers will use an insulated liner. A solution is to adjust the stove to allow enough heat up the chimney to service its need.

Hey, I'm no fire scientist. All I know is that my stove is much easier to start when it's cold out. It may be different in the rest of the world.

bbeals · Dec 6, 2008

LLigetfa said:
Now, I'm not familiar with the Jotul 550, but I have to wonder why there is smoke present when the door is being opened. Unless you are opening the door early to fiddle with a problem burn, when the door is opened to reload, there should only be a hot bed of coals and hot coals don't smoke.

If it smokes after you start to stoke it, you need to review how you are stoking. Stage what you need on the hearth before you open the door. Pull coals to the front. Put bigger pieces behind the coals and smaller pieces on top of the coals. Don't doddle.

No sir, I do not doddle. All wood is staged on the hearth according to size, density, etc... In the evenings when I am tending the fire, I do not let it go to nothing more than a coal bed, I will have a couple of splits that are pretty much coal, but still generating some decent flame / secondary burn. I have been burning in a stove since I was a child, took a break for 20 years (Navy and other stuff) and recently picked up the sport (should be an Olympic event) again with a new EPA burner this year. Given the feedback that the site has given, I believe I have gunked up my cap with some of the wet wood that went through the unit when I was not home. Does anyone think that this situation calls for NOT running the stove until the sweep shows on Monday?

gibson · Dec 6, 2008

Run it. You haven't been burning long enough for any significant creosote buildup. It seems that you burn hot fires as well. Enjoy your insert!

oconnor · Dec 6, 2008

The BI Guy said:
.... Does anyone think that this situation calls for NOT running the stove until the sweep shows on Monday?

I DO. When something changes in your stoves performance, make sure you undertand why before you continue. I'd bet dollars to doughnuts that with a new stove and an uninsulated outside flue, you have a partial blockage up there. That means that eventually, it will either block completely and the smoke will fill your house, or you will have a chimney fire.

As for waiting for a sweep, you might consider buying a ladder, rods and brushes. Its easier than changing your oil, so long as you can handle the heights. And cheaper, given that most manufacturers recommend checking the flue a few times a season. If you get into some wet wood by accident (tarp blows off in a storm), you can plig a flue in a matter of days.

But to answer your question, I think the level of concern YOU have indicates that YOU are not comfortable running the stove with this occuring, so don't. Advice from Rhode Island or Nova Scotia is nice, but we can't call 911 for you.

Wrigley · Dec 6, 2008

The problem is very similar to what I routinely experienced when first learning to burn my old Morso 1125 "smoke dragon". Whenever the chimney cap started to clog up with creosote a progressively worsening reduced draft and smoky smell occurred. My best guess is that this resulted: 1) because I didn't really know my stove or how to burn, and 2) my wood was likely too wet. I now always keep a close eye on my spark arrestor screen and get up there and clean the cap when any build up begins and this keeps everything running right. As has been repeatedly noted already, good hot fires with well seasoned wood will minimize, if not eliminate, the problem. A more open design of cap might not hurt either. But I'd get up and clean that cap of yours before burning any more ....

begreen · Dec 6, 2008

carl spackler said:
Run it. You haven't been burning long enough for any significant creosote buildup. It seems that you burn hot fires as well. Enjoy your insert!

Creosote build up is not just a factor of time. We've seen people plug up here in a few weeks of burning. Factors that can increase creosote accumulation are: temperature of fire, temperature of chimney (exterior flues will condense creosote much quicker), and dampness of wood.

For any new wood burner it's a very good idea to have an inspection after a month or two of burning. It's good to get a perspective on how the system is doing from a professional. This is part of the learning process. Once you've got a couple seasons of burning under your belt, you will have a good sense of how to burn cleanly, but this is not always apparent at first.

If the cap is clogging, clean it, but don't cut out the screen. It's a helpful indicator of how the system is burning. FWIW, we are going on our 3d season with the new flue and our cap screen has not been cleaned yet.

LLigetfa · Dec 6, 2008

BeGreen said:
If the cap is clogging, clean it, but don't cut out the screen...

If my cap had a screen I would take it off. I've seen where burning some paper would leave large black flakes on the snow and a fine screen certainly would have clogged. I stopped burning paper except for fire starter.

Also, I have a self cleaning chimney. Small amounts of creosote will curl and flake off during a hot burn getting carried up by the draft and settle on the snow. A spark screen would be a real PITA.

begreen · Dec 6, 2008

Taking out the screen in this situation is like removing the batteries from the smoke detector because it keeps going off. We use newspaper for starting the fires and have not had any issues with screen clogging.

If the screen is clogging, address the issue, not the symptom.

Wrigley · Dec 6, 2008

BeGreen said:
If the screen is clogging, address the issue, not the symptom.

+1 ;-)

LLigetfa · Dec 6, 2008

BeGreen said:
We use newspaper for starting the fires and have not had any issues with screen clogging.

Newspaper for starter is not as bad as burning certain glossy flyers.

BeGreen said:
If the screen is clogging, address the issue, not the symptom.

Do you really want to re-open the debate of burning Birch bark?

My smoke detectors are all hard wired so no batteries to remove but I do often have to flip off the breaker. Don't mean to dis' the wife's cooking but we call the smoke detector the "dinner bell". Her oven is self cleaning, much like my chimney.

Reduced Draft, creosote?

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