2018-19 Blaze King Performance Thread Part 2 (Everything BK)

[bholler]

That makes perfect sense and was what i was thinking. With all this talk about the guys fiddling with manometers lately it just got me thinking about the other 99.9% of owners who likely pay no attention or understand any of this stuff, and just stuff wood into the box, run it as per the manual, and call it good enough. This makes me think that unless there's a mass outcry of smokey houses, most people must exceed the draft requirements for at least part of the heating season, because they do nothing to monitor or fiddle with their set ups.

Lots of people have smokey houses as well. I go into lots that smell of smoke pretty badly. This site is not at all representative of most people who heat with wood.

 

[MissMac]

Lots of people have smokey houses as well. I go into lots that smell of smoke pretty badly. This site is not at all representative of most people who heat with wood.

Hmm, that's interesting to hear.

In my particular situation I still haven't figured out why I get creo smell when I dial down my stove. It happens regardless of the weather conditions, although it is more pronounced when it's warmer out (makes sense), but i'm exceeding the draft spec (or at least did when i had it tested and was experiencing the creo smell).

And you're certainly right - this site is where the hard-core enthusiasts dwell.

 

[Ashful]

I find my BK 30’s run pretty well on any draft 0.03” to 0.10” WC. That’s a range of more than 3 to 1, so don’t get the impression they need to be dialed in to exactly some magic number to make them work. However, in a year of running with a damper and Magnehelic constantly monitoring draft, I can make the following observations:

1. Draft climbs as burn rate is reduced, which is the reverse of what a few people here have said. There are two effects working against each other, here, which may be the source of confusion. At lower burn rate, your chimney cools, and so its ability to provide draft is reduced. However, the restriction you have created at the inlet is dominant, and causes a net higher static “vacuum”, even with the cooler chimney. Net effect = draft is always higher at lower burn rates, at least on my chimneys.

All other comments below are based on measuring steady-state draft only at maximum burn rate. I ignore the climb in manometer reading when I turn down.

2. I can run even below 0.03”, down to even 0.01”, but the stove gets real sluggish below 0.03”. I can’t get a screaming high burn at draft much below 0.03”, but I guess not everyone needs to run their stove wide open for full loads at higher draft.

3. The stove is also completely controllable and useable at draft above 0.18”, but I find I can clog combustors at maximum burn rate with higher draft settings. If I were happy to never run the stove at wide-open throttle, I’d probably not need a damper... but I have a very high head load in my house.

4. You don’t need a manometer or Magnehelic constantly connected to run your stove with a damper, even on a very tall chimney. The range of draft conditions under which these stoves work very well is quite wide (as I said, greater than 3:1). Now that I’ve learned where my stove runs, I could just open the damper wide when I need to reload, and then close it to 30 - 45 degrees while running, and it’d be just fine. That said, I’m a geek, so I fixate on things like knowing my flue pressure. This forum is full of geeks, don’t mistake their constant fiddling with a requirement for you to do the same.

 

[lsucet]

1. Draft climbs as burn rate is reduced, which is the reverse of what a few people here have said. There are two effects working against each other, here, which may be the source of confusion. At lower burn rate, your chimney cools, and so its ability to provide draft is reduced. However, the restriction you have created at the inlet is dominant, and causes a net higher static “vacuum”, even with the cooler chimney. Net effect = draft is always higher at lower burn rates, at least on my chimneys.

That was my observation here. Closing the intake it just cutting the flow rate thru the system but flue still drafting creating higher vacuum and a higher reading of the manometer. Like a throttle body in a vehicle.

 

[Highbeam]

Yes and what wood stove says to use one in it's directions?

Didn’t you read bkvp tell you it was illegal for them to do so? I’m not interested in another argument with you.

 

[Highbeam]

I find my BK 30’s run pretty well on any draft 0.03” to 0.10” WC. That’s a range of more than 3 to 1, so don’t get the impression they need to be dialed in to exactly some magic number to make them work. However, in a year of running with a damper and Magnehelic constantly monitoring draft, I can make the following observations:

1. Draft climbs as burn rate is reduced, which is the reverse of what a few people here have said. There are two effects working against each other, here, which may be the source of confusion. At lower burn rate, your chimney cools, and so its ability to provide draft is reduced. However, the restriction you have created at the inlet is dominant, and causes a net higher static “vacuum”, even with the cooler chimney. Net effect = draft is always higher at lower burn rates, at least on my chimneys.

All other comments below are based on measuring steady-state draft only at maximum burn rate. I ignore the climb in manometer reading when I turn down.

2. I can run even below 0.03”, down to even 0.01”, but the stove gets real sluggish below 0.03”. I can’t get a screaming high burn at draft much below 0.03”, but I guess not everyone needs to run their stove wide open for full loads at higher draft.

3. The stove is also completely controllable and useable at draft above 0.18”, but I find I can clog combustors at maximum burn rate with higher draft settings. If I were happy to never run the stove at wide-open throttle, I’d probably not need a damper... but I have a very high head load in my house.

4. You don’t need a manometer or Magnehelic constantly connected to run your stove with a damper, even on a very tall chimney. The range of draft conditions under which these stoves work very well is quite wide (as I said, greater than 3:1). Now that I’ve learned where my stove runs, I could just open the damper wide when I need to reload, and then close it to 30 - 45 degrees while running, and it’d be just fine. That said, I’m a geek, so I fixate on things like knowing my flue pressure. This forum is full of geeks, don’t mistake their constant fiddling with a requirement for you to do the same.

Now that’s a valuable contribution. Best thing I’ve read in a long time. Thank you.

If @BKVP wants to hire anybody here it should be you!

#1 especially is surprising and important for folks trying to solve low burn smoke smell issues.

 

[Highbeam]

That was my observation here. Closing the intake it just cutting the flow rate thru the system but flue still drafting creating higher vacuum and a higher reading of the manometer. Like a throttle body in a vehicle.

This is a lot like a throttle body and measuring manifold vacuum except we have two throttle bodies in series. Higher flue temps mimic higher rpm.

Boost gauges, and making boost, is lots of fun too!

 

[MissMac]

I find my BK 30’s run pretty well on any draft 0.03” to 0.10” WC. That’s a range of more than 3 to 1, so don’t get the impression they need to be dialed in to exactly some magic number to make them work. However, in a year of running with a damper and Magnehelic constantly monitoring draft, I can make the following observations:

1. Draft climbs as burn rate is reduced, which is the reverse of what a few people here have said. There are two effects working against each other, here, which may be the source of confusion. At lower burn rate, your chimney cools, and so its ability to provide draft is reduced. However, the restriction you have created at the inlet is dominant, and causes a net higher static “vacuum”, even with the cooler chimney. Net effect = draft is always higher at lower burn rates, at least on my chimneys.

All other comments below are based on measuring steady-state draft only at maximum burn rate. I ignore the climb in manometer reading when I turn down.

2. I can run even below 0.03”, down to even 0.01”, but the stove gets real sluggish below 0.03”. I can’t get a screaming high burn at draft much below 0.03”, but I guess not everyone needs to run their stove wide open for full loads at higher draft.

3. The stove is also completely controllable and useable at draft above 0.18”, but I find I can clog combustors at maximum burn rate with higher draft settings. If I were happy to never run the stove at wide-open throttle, I’d probably not need a damper... but I have a very high head load in my house.

4. You don’t need a manometer or Magnehelic constantly connected to run your stove with a damper, even on a very tall chimney. The range of draft conditions under which these stoves work very well is quite wide (as I said, greater than 3:1). Now that I’ve learned where my stove runs, I could just open the damper wide when I need to reload, and then close it to 30 - 45 degrees while running, and it’d be just fine. That said, I’m a geek, so I fixate on things like knowing my flue pressure. This forum is full of geeks, don’t mistake their constant fiddling with a requirement for you to do the same.

That was a very informative post Ashful, thanks. I would not ever try to tinker like some of you fellows, because it's beyond my knowledge. However, I really enjoy following the conversations, and i have learned a lot and am interested in learning more. I did not know that draft increased when you dial the stove down. This does seem fairly opposite of the things i've heard others say. For example, why then do people get back-puffing and smells when they try to dial down the stove if the draft gets stronger on a lower setting? Also, i realize that the amount of oxygen that the fire is getting is what makes it vigorous or smoulder, however you don't see the smoke in a black box getting sucked up through the cat with the same vigour as the flames when it's on high?

Can somebody recommend an article that would help me understand this concept of draft that you're talking about in your first point. I'm intrigued!

 

[lsucet]

That was a very informative post Ashful, thanks. I would not ever try to tinker like some of you fellows, because it's beyond my knowledge. However, I really enjoy following the conversations, and i have learned a lot and am interested in learning more. I did not know that draft increased when you dial the stove down. This does seem fairly opposite of the things i've heard others say. For example, why then do people get back-puffing and smells when they try to dial down the stove if the draft gets stronger on a lower setting? Also, i realize that the amount of oxygen that the fire is getting is what makes it vigorous or smoulder, however you don't see the smoke in a black box getting sucked up through the cat with the same vigour as the flames when it's on high?

Can somebody recommend an article that would help me understand this concept of draft that you're talking about in your first point. I'm intrigued!

I think @aaronk25 figured it out good. When you close the intake the flue creates a higher vacuum/higher draft causing sucking the air from the air wash right up the flue. Till this point i think that is what make more sense. The load is not getting to much oxygen= not sucking smoke as you are saying..

 

[jetsam]

This forum is full of geeks, don’t mistake their constant fiddling with a requirement for you to do the same.

BUT WE WANT TO

 

[showrguy]

I find my BK 30’s run pretty well on any draft 0.03” to 0.10” WC. That’s a range of more than 3 to 1, so don’t get the impression they need to be dialed in to exactly some magic number to make them work. However, in a year of running with a damper and Magnehelic constantly monitoring draft, I can make the following observations:

1. Draft climbs as burn rate is reduced, which is the reverse of what a few people here have said. There are two effects working against each other, here, which may be the source of confusion. At lower burn rate, your chimney cools, and so its ability to provide draft is reduced. However, the restriction you have created at the inlet is dominant, and causes a net higher static “vacuum”, even with the cooler chimney. Net effect = draft is always higher at lower burn rates, at least on my chimneys.

All other comments below are based on measuring steady-state draft only at maximum burn rate. I ignore the climb in manometer reading when I turn down.

2. I can run even below 0.03”, down to even 0.01”, but the stove gets real sluggish below 0.03”. I can’t get a screaming high burn at draft much below 0.03”, but I guess not everyone needs to run their stove wide open for full loads at higher draft.

3. The stove is also completely controllable and useable at draft above 0.18”, but I find I can clog combustors at maximum burn rate with higher draft settings. If I were happy to never run the stove at wide-open throttle, I’d probably not need a damper... but I have a very high head load in my house.

4. You don’t need a manometer or Magnehelic constantly connected to run your stove with a damper, even on a very tall chimney. The range of draft conditions under which these stoves work very well is quite wide (as I said, greater than 3:1). Now that I’ve learned where my stove runs, I could just open the damper wide when I need to reload, and then close it to 30 - 45 degrees while running, and it’d be just fine. That said, I’m a geek, so I fixate on things like knowing my flue pressure. This forum is full of geeks, don’t mistake their constant fiddling with a requirement for you to do the same.

Exactly my findings as well Ashful, nice write up...

 

[Ashful]

That was a very informative post Ashful, thanks. I would not ever try to tinker like some of you fellows, because it's beyond my knowledge. However, I really enjoy following the conversations, and i have learned a lot and am interested in learning more. I did not know that draft increased when you dial the stove down. This does seem fairly opposite of the things i've heard others say. For example, why then do people get back-puffing and smells when they try to dial down the stove if the draft gets stronger on a lower setting? Also, i realize that the amount of oxygen that the fire is getting is what makes it vigorous or smoulder, however you don't see the smoke in a black box getting sucked up through the cat with the same vigour as the flames when it's on high?

Can somebody recommend an article that would help me understand this concept of draft that you're talking about in your first point. I'm intrigued!

This forum is likely the best resource, for figuring this stuff out.

The back-puffing issue is an interesting one. My first stove was a Jotul Firelight 12, a large catalytic stove, on a 15 foot x 8” clay tile chimney. I had frequent back-puffing troubles on that rig, so I had to learn a little bit about it, from more experienced forum members that pre-dated me.

The basic issue, as I understand it, is similar to that old axiom about gasoline. We hear that gasoline doesn’t burn, it is the vapors above the liquid fuel that burns. Similarly, your wood is constantly producing “wood gas”, and that is the fuel feeding the catalytic combustor at low burn rates. However, at very low burn rates, insufficient draft can cause this wood gas to accumulate in the firebox, to a critical mixture point. When this critical mixture is achieved, it can combust in the firebox or in the combustor chamber, causing the momentary expansion we recognize as a back-puff.

I’m not really sure I buy into the whole theory of the cause, but in all cases the solution has been to do one of the following:

1. Increase your burn rate. I could avoid back-puffing on that stove by just opening the air inlet a hair. A few Woodstock Fireview customers having the same troubles reported the same.

2. Increase your draft. I installed a second Jotul Firelight 12 on a tally chimney, and never had any back-puffing issues on that stove.

 

[showrguy]

Hey, Ashful, have ya given anymore thought about the OAK'S we were yackin about 6 mos or so ago ??

 

[bholler]

Draft will not always increase at lower burn rates. Both ashful and shower guy both have very tall chimneys which are going to pull hard no matter what you do. So in their cases yes restricting the intake will increase the vacume. On a shorter chimney initially the measurement will jump up but it will end up lower

 

[lsucet]

Draft will not always increase at lower burn rates. Both ashful and shower guy both have very tall chimneys which are going to pull hard no matter what you do. So in their cases yes restricting the intake will increase the vacume. On a shorter chimney initially the measurement will jump up but it will end up lower

I have one of 19' and the other around 24'. I do have the same effect when closing the intake on both. Can those highs are qualified as tall chimneys?

 

[bholler]

I have one of 19' and the other around 24'. I do have the same effect when closing the intake on both. Can those highs are qualified as tall chimneys?

I have never experienced that on chimneys under 25'. Does it stay up or does it drop off after a min or 2?

 

[lsucet]

I have never experienced that on chimneys under 25'. Does it stay up or does it drop off after a min or 2?

It stays up around the same. I have 0.12 WC on one wide open. it goes to 0.18 or so, on my low setting. hours later is lower but always higher than with intake wide open.

 

[MissMac]

This forum is likely the best resource, for figuring this stuff out.

The back-puffing issue is an interesting one. My first stove was a Jotul Firelight 12, a large catalytic stove, on a 15 foot x 8” clay tile chimney. I had frequent back-puffing troubles on that rig, so I had to learn a little bit about it, from more experienced forum members that pre-dated me.

The basic issue, as I understand it, is similar to that old axiom about gasoline. We hear that gasoline doesn’t burn, it is the vapors above the liquid fuel that burns. Similarly, your wood is constantly producing “wood gas”, and that is the fuel feeding the catalytic combustor at low burn rates. However, at very low burn rates, insufficient draft can cause this wood gas to accumulate in the firebox, to a critical mixture point. When this critical mixture is achieved, it can combust in the firebox or in the combustor chamber, causing the momentary expansion we recognize as a back-puff.

I’m not really sure I buy into the whole theory of the cause, but in all cases the solution has been to do one of the following:

1. Increase your burn rate. I could avoid back-puffing on that stove by just opening the air inlet a hair. A few Woodstock Fireview customers having the same troubles reported the same.

2. Increase your draft. I installed a second Jotul Firelight 12 on a tally chimney, and never had any back-puffing issues on that stove.

Huh, I always thought that backpuffing was due to a combination of not enough draft and negative pressure in the house pulling smoke into the room.

 

[bholler]

It stays up around the same. I have 0.12 WC on one wide open. it goes to 0.18 or so, on my low setting. hours later is lower but always higher than with intake wide open.

That is not at all typical of what I have measured on chimneys roughly your height. I wonder why

 

[bholler]

Huh, I always thought that backpuffing was due to a combination of not enough draft and negative pressure in the house pulling smoke into the room.

It can be caused by quite a few things.

 

[lsucet]

That is not at all typical of what I have measured on chimneys roughly your height. I wonder why

Regardless what is the draft at any point of the burn, always when i close the tstat it climbs. When it goes down, the draft at wide open throttle is also lower. i will do more testing next week after i install the damper but that is the present behavior of both of my systems. I have some time now to play with the stoves. After two storm in one week, more than a foot of snow is melting now and everything is mud outside, not much to do outside for awhile. plenty of time to play with fire. lol

 

[bholler]

Regardless what is the draft at any point of the burn, always when i close the tstat it climbs. When it goes down, the draft at wide open throttle is also lower. i will do more testing next week after i install the damper but that is the present behavior of both of my systems. I have some time now to play with the stoves. After two storm in one week, more than a foot of snow is melting now and everything is mud outside, not much to do outside for awhile. plenty of time to play with fire. lol

I beleive you it just doesn't coinside with what I see typically

 

[A.K.304]

Hi, I have questions about running a BK with or without the fan. What I have observed is:

If I run it without the fan: I get longer burn times, but less heat, and the cat gets VERY hot and stays active even when I am down to embers. Is it bad for the cat to be super hot when the stove is on high?

If I run the fans, I definitely get more heat, shorter burn times and the cat never gets into the last quarter of the gage, even on high, so it stays cooler overall and it goes inactive much, much faster ... even though I still have a good couple of hours or more of burn left. But isn't this creating more creosote?

I am burning birch, which has about 11% moisture content.

Should I worry about the cat going inactive so soon when the fans are on or it getting super hot (near the end range of the cat thermometer) without the fans on?

How much smoke is normal to be seen going out the chimney with the cat in the active zone? When my cat is at 12 o'clock position, I am able to see smoke, not just vapours. Is this normal?

 

[lsucet]

If everything is ok with door and bypass gaskets, i will not worry about the temp. With no fan is hotter, the point is that the fans distribute the heat over the house better. the cat going inactive with fan on, is cause the fan are blowing over the probe and what you are getting at this point is a false reading. If you shut down the fans you will see that the probe goes back into the active zone again.

About the smoke, many variables to tell what is causing it. Maybe the wood is out gassing too much at that point etc.

 

[Woody Stover]

the thermostat has to be open farther, which is more efficient at putting heat into the room vs high draft and a more closed thermostat.

Follow me for a second....air pressure though the stove is similar to snaking a rope though it. Imagine running a rope though the OAK, ducting, thermostat, though the air tubes in the top of the box, over the air wash and then lay 5’ of rope coiled up in the bottom of the fire box on the middle of the wood, then run the rope thought the. Cat up the collar and out the chimney.
Now under .03 flue conditions there is very little pull on the rope and it lays where it was left.
Now run up to .15 or some high number and pull 10lbs of force on one end, oh and the other end is tied to a tree or car or somthing solid outside. Once the rope goes tight the biggest noticeable difference is it goes from the air wash straight to the cat and out. The 5’ of rope laid in the fire box is gone. Secondly when the rope goes out the flue collar it is tight to the front edge, no where near the thermostat so the thermostat becomes less effective which could lead to over firing.

Back in my school days, I wasn't inclined to pursue a career as a scientist...I'm still perplexed. Might have been before your time, but I remember a Star Trek episode where Harry Mudd says to Kirk, something to the effect that "You sing and dance as well as anyone, but what in the hell are you talking about??" No offense, I just thought it was a funny line that vaguely applied..
I'm not sure how well the "rope"analogy applies; An enclosed container of water with a supply pipe and an exit pipe might be closer. If you apply suction to the exit pipe, it will draw in whatever will move with the least resistance. Yes, the air wash air is getting a little "push" and might move more readily toward the cat, but I think there are other forces and flows at play at the same time, not exactly like a direct pull on one end of a rope.
The BK is the only stove I've seen that has the air wash air coming through tubes that are totally suspended within the top of the fire box. Other stoves have the air ducts running along the edges of the box, so the air wash air is hotter in the BK. That probably helps the cat keep burning longer before falling out of active, allowing for lower burn rates, but the air doesn't fall straight down the glass like cooler, dense air does in other stoves. That may be a reason that BK glass doesn't stay as clean.
Another factor is that if you have high draft (suction) applied to the box and you close the thermostat flapper way down, more suction is applied to any other place where air can enter, like past the door gasket. That would account for the more pronounced "V" pattern you see on the glass with high draft; The "V" gets wider at the bottom as the air wash weakens further down the glass and cool air leaking around the door gasket becomes more dominant, cooling the glass and condensing creo. It's also possible that your better-burning coal bed is a result of more air coming all the way down the glass and into the coals in the low-draft fire box, and air being pulled past the door gasket is proportionally less than air wash air than in the high-draft box with the primary air closed down.
Those are a couple things I like about my stove; 1.) It's a side-loader so the door gasket is away from the glass (which also has double glass and two gaskets.) 2.) It has the 1/4" hole in the ash pan housing, so the lower you cut the air, the less air comes in the air wash to burn the coals but more air comes in through the ash grate to keep 'em burning. Sorry for the Ws ad but you expected that, right?