How much creosote is normal after 1 season of heating?

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ADDvanced

Member
Dec 1, 2016
88
Milwaukee
Hey Guys, I installed my Osburn 1800 myself last year using a lot of help from this forum:


My searches here led me down many rabbit holes last season, and I learned a ton about heating your home with firewood, so I threw together this video:


Anyway, I have the wood racks half full, and I'm already thinking about winter. I decided to sweep my own chimney today, and removed the firebricks from inside the stove, and used a 6" poly brush with a 3 extensions to sweep it out.

Couple things to note about my setup:

13" Doublewalled Stainless Liner, from Stove to Chimney Cap, NO insulated liner
Chimney is NOT on outside facing wall, it's sort of central to the house
Osburn 1800 has a fairly small firebox

I would say initially, I burned very dry wood, and the stove put out a ton of heat. As the season progressed, I tried to burn only what was under 20%, but some of it was closer to 20% than 10% moisture content. I also burned anything I could find. I cut down dead standing trees, burned those, had firewood delivered, chopped up a tree earlier in the season and used that, I just burned whatever.

Anyway, I would guess over a QUART of creosote came out, most of it was light fluffy coffee grounds, but I saw a few specks of hard black shiny parts as well. Does this seem normal?

One thing I struggle with is the air adjustment plate... I've posted about it a few times in the past, but I struggle to get more than 2 hour burn times. If I REALLY get it full, I can maybe get 3 hours, but that is absolute ideal conditions and rarely attainable. Thoughts?
 

stoveliker

Minister of Fire
Nov 17, 2019
2,023
Long Island NY
Is your moisture content measured on a freshly split surface?

Post a picture of what you brushed. I presume @bholler will be able to tell you in 30 secs whether that was good or not.
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,199
central pa
Hey Guys, I installed my Osburn 1800 myself last year using a lot of help from this forum:


My searches here led me down many rabbit holes last season, and I learned a ton about heating your home with firewood, so I threw together this video:


Anyway, I have the wood racks half full, and I'm already thinking about winter. I decided to sweep my own chimney today, and removed the firebricks from inside the stove, and used a 6" poly brush with a 3 extensions to sweep it out.

Couple things to note about my setup:

13" Doublewalled Stainless Liner, from Stove to Chimney Cap, NO insulated liner
Chimney is NOT on outside facing wall, it's sort of central to the house
Osburn 1800 has a fairly small firebox

I would say initially, I burned very dry wood, and the stove put out a ton of heat. As the season progressed, I tried to burn only what was under 20%, but some of it was closer to 20% than 10% moisture content. I also burned anything I could find. I cut down dead standing trees, burned those, had firewood delivered, chopped up a tree earlier in the season and used that, I just burned whatever.

Anyway, I would guess over a QUART of creosote came out, most of it was light fluffy coffee grounds, but I saw a few specks of hard black shiny parts as well. Does this seem normal?

One thing I struggle with is the air adjustment plate... I've posted about it a few times in the past, but I struggle to get more than 2 hour burn times. If I REALLY get it full, I can maybe get 3 hours, but that is absolute ideal conditions and rarely attainable. Thoughts?
A quart is nothing to be worried about at all. The question is was that all of it? Did you go to the top and inspect to see how clean the liner got.
 

ADDvanced

Member
Dec 1, 2016
88
Milwaukee
I brushed it from the top. What was odd is that from the top, I only saw buildup near the top 2' of the liner. Looked fairly clean but blackish as it went down.

I was under the impression that creosote only deposited if the liner was cold, and the moisture from the wood caused it to condense. The upper 2' of hte liner would be the coldest, so that made sense to me. I'll post some photos in a bit, it's on my camera
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,199
central pa
I brushed it from the top. What was odd is that from the top, I only saw buildup near the top 2' of the liner. Looked fairly clean but blackish as it went down.

I was under the impression that creosote only deposited if the liner was cold, and the moisture from the wood caused it to condense. The upper 2' of hte liner would be the coldest, so that made sense to me. I'll post some photos in a bit, it's on my camera
Yes it's perfectly normal to have the worst buildup at the top
 

begreen

Mooderator
Staff member
Nov 18, 2005
90,660
South Puget Sound, WA
One thing I struggle with is the air adjustment plate... I've posted about it a few times in the past, but I struggle to get more than 2 hour burn times. If I REALLY get it full, I can maybe get 3 hours, but that is absolute ideal conditions and rarely attainable. Thoughts?
You're doing ok. The fire looks fine, and not getting too much air. In spite of what the manual says, this is a small firebox with about 1.1-1.3 cu ft of usable loading space. A 3-4 hr burn time with hot coals for say 5-6hrs is about the best it will do.

Note that moisture meter reading should be done with room temp wood and always on the freshly exposed face of a re-split piece of wood.
 

Poindexter

Minister of Fire
Jun 28, 2014
2,434
Fairbanks, Alaska
What bholler said.

I would not be comfortable, on 13 feet of stack, only brushing once a year and getting a quart out, but grey fluffy with a few black specks is as good as it gets.

Can you maybe brush bottom up around the New Year to get the first pint out, and then top down over the summer when the roof is safe to be walking on?
 

bholler

Chimney sweep
Staff member
Jan 14, 2014
26,199
central pa
What bholler said.

I would not be comfortable, on 13 feet of stack, only brushing once a year and getting a quart out, but grey fluffy with a few black specks is as good as it gets.

Can you maybe brush bottom up around the New Year to get the first pint out, and then top down over the summer when the roof is safe to be walking on?
Why would you not be comfortable with that? A quart is nothing to worry about at all.
 

Poindexter

Minister of Fire
Jun 28, 2014
2,434
Fairbanks, Alaska
Why would you not be comfortable with that? A quart is nothing to worry about at all.
I appreciate the reality check/ data point. On I think 18 feet of pipe I am accustomed to seeing less than one measuring cup, less than half a pint, of fluffy grey with some hard shiny black flecks after four cords. I guess I am doing pretty OK.
 
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begreen

Mooderator
Staff member
Nov 18, 2005
90,660
South Puget Sound, WA
I appreciate the reality check/ data point. On I think 18 feet of pipe I am accustomed to seeing less than one measuring cup, less than half a pint, of fluffy grey with some hard shiny black flecks after four cords. I guess I am doing pretty OK.
That's pretty remarkable considering how cold the exposed part of the chimney must get. It's about the same as what I see after 3 cords with 20' straight up, but in a much milder climate.
 

EbS-P

Minister of Fire
Jan 19, 2019
1,503
SE North Carolina
This was probably close to 1.5 cord insulated liner. Lots of pine. Nothing shiny and very fluffy.

754B6669-3BAB-4077-882A-FE63F8857266.jpeg
 

ADDvanced

Member
Dec 1, 2016
88
Milwaukee
Alright, following up. Just edited my video on my first sweeping! This shows how much creosote buildup was in my liner after 1 season of burning about 1.5 cords of wood.

It seemed like most of the creosote happened way down low, near the stove itself. Up top, there was not a lot of buildup other than maybe the first foot or two. Would this be due to burning some wet wood?

 
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begreen

Mooderator
Staff member
Nov 18, 2005
90,660
South Puget Sound, WA
Yes, that is a lot of buildup for a cord and a half burning, but at least it's powdery. Most likely this is due to the wood.

For comparison, we average a half of an 8oz. yoghurt cup a year burning ~3 cords. Most likely this is due to the wood differences. We have been burning doug fir almost exclusively. I am on an every other year sweep cycle right now, but the winter will be different. We will be burning mostly hardwood until probably around Jan or Feb 2022, so our luck may change and soot accumulation may go up. We'll see.
 

Riteway

Member
Jul 27, 2020
125
Kitsap County, WA
One of my co-workers is a long-time wood burner, and is an absolute zealot about wood seasoning. He said that he only needs to get his chimney swept about once every 5 years because his flue stays so clean. I think he only burns about 1 to 2 cords a year, though. Obviously sweeping once a year would be a safer bet, but it goes to show the benefit of burning dry wood and knowing how to properly operate a modern stove.
 

stoveliker

Minister of Fire
Nov 17, 2019
2,023
Long Island NY
One of my co-workers is a long-time wood burner, and is an absolute zealot about wood seasoning. He said that he only needs to get his chimney swept about once every 5 years because his flue stays so clean. I think he only burns about 1 to 2 cords a year, though. Obviously sweeping once a year would be a safer bet, but it goes to show the benefit of burning dry wood and knowing how to properly operate a modern stove.
the other benefit being not having to evaporate all that water in the wood. See how much power an (electric) stove uses to do the same - all that energy from your wood now comes into your home rather than going out as latent heat in water vapor thru the chimney...
 
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ADDvanced

Member
Dec 1, 2016
88
Milwaukee
All good points. It seems like that might have been my issue, as at the end of the season I was burning some dead standing stuff that I did not season at all.
 

Woody Stover

Minister of Fire
Dec 25, 2010
12,277
Southern IN
A quart is nothing to be worried about at all.
Agreed. That is not much fuel at all for a chimney fire, and if most of that was up top it would probably take accidentally leaving the air wide open on startup to even ignite it.