"Dirty" Blaze King windows

Ashful

Minister of Fire
Mar 7, 2012
15,715
Philadelphia
So, I hear a ton of criticism here, often from folks who have never owned a Blaze King stove, about them having dirty black windows. I don't get it, as my two BK windows never get nearly as dirty as the critics imply they will.

Here's my cold stove after a 15 hour burn on a load that's 80% oak and 20% cedar. I use cedar for cold starts, to get the oak going.

e5a91685cf860a0ad3ccf77c17c12bd1.jpg

Here's my other stove on a fresh reload after a 24 hour slow burn. Previous load was 80/20 oak cedar, this load is all oak and ash.

c909775179882afa5a4641d358c12756.jpg

In both cases, you will note that only the lower corners of the glass are dirty, the rest is clean and clear.

Is this really dirtier than others? My Jotuls were usually dirtier than this, and they could not burn anywhere near as low and slow as these stoves.

I contend that anyone complaining about dirty glass on a BK is either always burning much, much, much lower than any other stove can, or their wood isn't quite as dry as they believe.
 
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mellow

Resident Stove Connoisseur
Jan 19, 2008
5,080
Salisbury, MD
I can't say 100% but if @BKVP notes that the glass might get dirty in a post about running on low than it happens more often than not and is not always wood dependant.

I know I burned dry wood bricks in my last stove and the glass got dirty but it had a horrible air wash, this Siracco 25 has a nice air wash and a HUGE window so we will see, with burning wood bricks I can take wet wood out of the equation.
 

BKVP

Minister of Fire
The level of glass deposits increase by model, based upon depth of firebox. Sirocco 25, all 30.1 and 20.1 models have much cleaner glass than King or Princess models.

Variables such as fuel length, MC, orientation of wood in loading, draft etc. can also have an effect.
 
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Highbeam

Minister of Fire
Dec 28, 2006
17,909
Mt. Rainier Foothills, WA
The glass on my non-cat stays spotless. The glass on my BK (not an ashford like yours) gunks up badly with the same wood. Yes, the BK is that much worse.
 
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BKVP

Minister of Fire
The low burn rate on your non cat is probably well over 1.15 kg/hr. The low burn rate on your Princess is below .8 kg/hr. Burn the Princess at 1.15 kg/hr or higher and the glass will be cleaner.

Folks need to remember that the two technologies had distinctly different attributes.

Ashful's glass stays cleaner because both the stove model (Ashford) keeps the glass cleaner and because he heats a big big house.


The glass on my non-cat stays spotless. The glass on my BK (not an ashford like yours) gunks up badly with the same wood. Yes, the BK is that much worse.[/
 
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Tocramed

Member
Sep 30, 2015
79
WI

tarzan

Minister of Fire
Jan 16, 2014
1,552
wv
As others have stated, depends on the model and how you burn.

The only time my glass gets cleaned is from a hot fire or when I physically clean it at the end of burning season. It's just time wasted (worse than processing limbs ha-ha) for me to clean the glass during burning season.
 
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Highbeam

Minister of Fire
Dec 28, 2006
17,909
Mt. Rainier Foothills, WA
The low burn rate on your non cat is probably well over 1.15 kg/hr. The low burn rate on your Princess is below .8 kg/hr. Burn the Princess at 1.15 kg/hr or higher and the glass will be cleaner.

Folks need to remember that the two technologies had distinctly different attributes.

Ashful's glass stays cleaner because both the stove model (Ashford) keeps the glass cleaner and because he heats a big big house.
I don't know, I've tried burning hot and it won't clean deposits from the princess. Even when starting with clean glass and burning loads at higher stat settings the BK glass gets dirty. So I suppose the key word is "cleaner" but never as clean as a decent non-cat which runs really hot with lots of air flow to keep smoke off of the glass.

In order:

1) Older BK, most efficient, most shmuck on glass.
2) Newer BK, less shmuck on glass but not none.
3) non-cat, if you get shmuck on glass then you screwed something up.
 
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BKVP

Minister of Fire
I don't know, I've tried burning hot and it won't clean deposits from the princess. Even when starting with clean glass and burning loads at higher stat settings the BK glass gets dirty. So I suppose the key word is "cleaner" but never as clean as a decent non-cat which runs really hot with lots of air flow to keep smoke off of the glass.

In order:

1) Older BK, most efficient, most shmuck on glass.
2) Newer BK, less shmuck on glass but not none.
3) non-cat, if you get shmuck on glass then you screwed something up.
Yes..1,2 and 3 at your home.
 

Poindexter

Minister of Fire
Jun 28, 2014
2,287
Fairbanks, Alaska
If i had to choose between clean glass or catalytic eficiency, well come get my glass.
 

Highbeam

Minister of Fire
Dec 28, 2006
17,909
Mt. Rainier Foothills, WA
If i had to choose between clean glass or catalytic eficiency, well come get my glass.
@BKVP I've noticed some pretty serious discrepancies on the BK website with regards to efficiencies of the 30 and 20 box stoves. I know that they were a little less efficient but one page shows them down to 75% for the real HHV efficiency.

http://www.blazeking.com/EN/efficiency.html

Then the actual ashford page claims 80% HHV.

http://www.blazeking.com/EN/wood-ashford30.html
 
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BKVP

Minister of Fire

OhioBurner©

Minister of Fire
Aug 20, 2010
1,535
Center of Ohio
I don't mind dirty glass as a cost of higher effeciency of a low and slow cat only burn. I don't have a BK but I figure dirty glass is pretty much normal for a really low cat burn. It will self clean with a higher burn, so if I were to have company and wanted a 'pretty' looking stove I'd keep the burn up while company was over. Just myself I really could care less.
 

St. Coemgen

Feeling the Heat
Feb 4, 2016
272
Hungary
www.stcoemgen.com
I don't mind dirty glass as a cost of higher effeciency of a low and slow cat only burn.
A slow and low burn is often LESS efficient in getting the most potential heat out of wood, especially if you experience significant soot on your glass.

In other words, if you have any stove type (Cat or non-Cat) and still have significant deposits on your glass, then that is from volatile compounds that did not undergo a complete or secondary burn.

When volatiles do undergo a complete or secondary burn they in fact do release more energy and heat, thus the burn is more efficient.

If theses volatiles do not undergo a secondary burn, their potential energy release is not realized, and these compounds instead are just being deposited on your glass, and in your chimney, or released outside to annoy your neighbors and their lungs. Which is less efficient with the burning of wood. One my consider not having to load up wood in a hot fire every four hours as "personally" efficient, but I for one would rather call that simply improved convenience (which is fine as long as you are aware of the trade off and not claiming you are burning more efficiently).

So if one sees a lot of dirty glass that typically means one is not squeezing all the heat out of the wood one could, and is thus being less efficient. The "old slow burn is best" idea is just old thinking.


See:

http://woodheat.org/wood-smoke.html

and

"What day-to-day practices produce less smoke and higher efficiency?"

Never let a fire smolder. In advanced, EPA certified stoves, the wood should be flaming brightly when you go to bed at night and you should still have plenty of coals in the morning with which to rekindle the next fire. Gone are the days of "banking" fires with huge unsplit "blocks" and choking off the air supply before bed, a procedure that wasted much of the wood's potential energy and coated the chimney with flammable creosote. The new stoves call for new operating procedures.
 
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edyit

Minister of Fire
Nov 30, 2014
835
Wilmington NY
for the most part i fully agree with what you say, unless you are using a catalyst stove, there the catalyst actually does the work not the combustion of the wood as in a tube stove, thus it is able to burn clean at a much lower rate.
 
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BKVP

Minister of Fire
A slow and low burn is often LESS efficient in getting the most potential heat out of wood, especially if you experience significant soot on your glass.

In other words, if you have any stove type (Cat or non-Cat) and still have significant deposits on your glass, then that is from volatile compounds that did not undergo a complete or secondary burn.

When volatiles do undergo a complete or secondary burn they in fact do release more energy and heat, thus the burn is more efficient.

If theses volatiles do not undergo a secondary burn, their potential energy release is not realized, and these compounds instead are just being deposited on your glass, and in your chimney, or released outside to annoy your neighbors and their lungs. Which is less efficient with the burning of wood. One my consider not having to load up wood in a hot fire every four hours as "personally" efficient, but I for one would rather call that simply improved convenience (which is fine as long as you are aware of the trade off and not claiming you are burning more efficiently).

So if one sees a lot of dirty glass that typically means one is not squeezing all the heat out of the wood one could, and is thus being less efficient. The "old slow burn is best" idea is just old thinking.


See:

http://woodheat.org/wood-smoke.html

and

"What day-to-day practices produce less smoke and higher efficiency?"

Never let a fire smolder. In advanced, EPA certified stoves, the wood should be flaming brightly when you go to bed at night and you should still have plenty of coals in the morning with which to rekindle the next fire. Gone are the days of "banking" fires with huge unsplit "blocks" and choking off the air supply before bed, a procedure that wasted much of the wood's potential energy and coated the chimney with flammable creosote. The new stoves call for new operating procedures.
With catalytic stoves being a small percentage of the market, most references, such as those above are directed at secondary combustion stoves. Lab data for all stoves, regardless of technology, are to be posted on all manufacturer web sites as of May 15, 2015. There you will read, for each certified model, burn data for all burn rates. In the data you will find the inverse relationship of the various technologies with regard to emissions and other data. Enjoy the reading....
 
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Highbeam

Minister of Fire
Dec 28, 2006
17,909
Mt. Rainier Foothills, WA
A slow and low burn is often LESS efficient in getting the most potential heat out of wood, especially if you experience significant soot on your glass.

In other words, if you have any stove type (Cat or non-Cat) and still have significant deposits on your glass, then that is from volatile compounds that did not undergo a complete or secondary burn.

When volatiles do undergo a complete or secondary burn they in fact do release more energy and heat, thus the burn is more efficient.

If theses volatiles do not undergo a secondary burn, their potential energy release is not realized, and these compounds instead are just being deposited on your glass, and in your chimney, or released outside to annoy your neighbors and their lungs. Which is less efficient with the burning of wood. One my consider not having to load up wood in a hot fire every four hours as "personally" efficient, but I for one would rather call that simply improved convenience (which is fine as long as you are aware of the trade off and not claiming you are burning more efficiently).

So if one sees a lot of dirty glass that typically means one is not squeezing all the heat out of the wood one could, and is thus being less efficient. The "old slow burn is best" idea is just old thinking.


See:

http://woodheat.org/wood-smoke.html

and

"What day-to-day practices produce less smoke and higher efficiency?"

Never let a fire smolder. In advanced, EPA certified stoves, the wood should be flaming brightly when you go to bed at night and you should still have plenty of coals in the morning with which to rekindle the next fire. Gone are the days of "banking" fires with huge unsplit "blocks" and choking off the air supply before bed, a procedure that wasted much of the wood's potential energy and coated the chimney with flammable creosote. The new stoves call for new operating procedures.

I'm sorry you wrote all that out in a thread specific to cat stoves. It is all false for a cat stove but true for a non-cat. The cat stoves are actually most efficient with their lowest emissions at the lowest burn rates. The smoldering fire is what creates the smoke that feeds the cat. The cat needs only a relatively cool smoke to be fully active and eating the pollutants.
 

Ashful

Minister of Fire
Mar 7, 2012
15,715
Philadelphia
I'm sorry you wrote all that out in a thread specific to cat stoves. It is all false for a cat stove but true for a non-cat. The cat stoves are actually most efficient with their lowest emissions at the lowest burn rates. The smoldering fire is what creates the smoke that feeds the cat. The cat needs only a relatively cool smoke to be fully active and eating the pollutants.
... and if Coemgen is going to imply that small amount of soot left in the inside of the glass is unburned fuel, let's not forget it is just fuel in the tank, to be burned in the next reload, never wasted. [emoji14]
 

OhioBurner©

Minister of Fire
Aug 20, 2010
1,535
Center of Ohio
A slow and low burn is often LESS efficient in getting the most potential heat out of wood, especially if you experience significant soot on your glass.

In other words, if you have any stove type (Cat or non-Cat) and still have significant deposits on your glass, then that is from volatile compounds that did not undergo a complete or secondary burn.

When volatiles do undergo a complete or secondary burn they in fact do release more energy and heat, thus the burn is more efficient.

If theses volatiles do not undergo a secondary burn, their potential energy release is not realized, and these compounds instead are just being deposited on your glass, and in your chimney, or released outside to annoy your neighbors and their lungs. Which is less efficient with the burning of wood. One my consider not having to load up wood in a hot fire every four hours as "personally" efficient, but I for one would rather call that simply improved convenience (which is fine as long as you are aware of the trade off and not claiming you are burning more efficiently).

So if one sees a lot of dirty glass that typically means one is not squeezing all the heat out of the wood one could, and is thus being less efficient. The "old slow burn is best" idea is just old thinking.
This is not correct for a CAT stove which is what we are talking about. If the cat is bunring properly there is no wasted fuel going out the pipe. The small amount left on the glass is miniscule and will burn the next time you have a high burn, it's not wasted either. What makes the low and slow burn even more effecient is not just utilizing the fuel but in a slower rate of the gasses moving through the stove and pipe, the hot exhaust gasses are in contact with the stove body (heat exchanger) longer and is radiated into the room and less is lost out the chimney. I higher rate of burn while it may consume more fuel in a primary or secondary combustion will also waste more heat right out the flue.
 

ohlongarm

Minister of Fire
Mar 18, 2011
1,427
Northeastern Ohio
This is not correct for a CAT stove which is what we are talking about. If the cat is bunring properly there is no wasted fuel going out the pipe. The small amount left on the glass is miniscule and will burn the next time you have a high burn, it's not wasted either. What makes the low and slow burn even more effecient is not just utilizing the fuel but in a slower rate of the gasses moving through the stove and pipe, the hot exhaust gasses are in contact with the stove body (heat exchanger) longer and is radiated into the room and less is lost out the chimney. I higher rate of burn while it may consume more fuel in a primary or secondary combustion will also waste more heat right out the flue.
Amen,want clean glass burn hotter,I do it all the time when we want to watch the fire. Black glass on a 20 24 hour productive burn doesn't bother me at all. You get what you pay for.
 

OhioBurner©

Minister of Fire
Aug 20, 2010
1,535
Center of Ohio
25hrs20min-720.JPG
I've coated it fully black on occasion but there is typical sooting up of the ISH's door on a low catalytic burn, that pic was a 25 hrs burning a mix of ash and ecobricks, cat was in active range over 500F right up to ~24 hours.

I don't mind the soot as long as it means nice long burn!
 
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begreen

Mooderator
Staff member
Nov 18, 2005
84,892
South Puget Sound, WA
Impressive. Super burntime there. That's right up with the best.
 
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