I would think that a batch of dry skinny splits might overwhelm the cat with smoke from all outgassing rapidly at once.
2021-2022 BK everything thread
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kennyp2339
Minister of Fire
Tonight we are forecasted to have our first freeze - low 29, the princess has been lit and rolling along since early Monday, I now have a decent layer of ash as the base and rolling with 24hr reloads, the house has been stable at 72 deg f, I might burn a little higher tonight but basically my cat probe needle hasnt really drifted below noon, so I'm running solid with no flames in the fire box, and absolutely no smoke out of the stack either.
you are right. I'll try. Thanks. (bumps head against the wall)
in the beginning maybe. But I'm talking about burn times. As long as the cat is active when I walk away (the pre-requisite in any experiment, because otherwise things just go south), the Tstat should cut the air to regulate the heat output. Of course doing anything that suffocates the cat won't work, but that's not what I'm asking about.
3-4" splits or 6-8" splits...
You'll need to control for weight too. So 40# of 6-8 vs. 40# of 3-4. And then of course a similar outdoor air temp for draft strength, similar heating needs since the thermostat to some extent responds to a house cooling the stove.
I expect the little wood to burn up faster but I do appreciate the experiment.
On edit, maybe control for volume since we all tend to pack the box full for long burn times.
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Living in MS must be nice. We have a 9 month burning season so I get two seasons per cat (well over the 10,000 hour expected life) so I'm always within a year or so of the next one. It's really no big deal to change these out and it's worth every bit of the price in wood savings for me.
So I have a question about Blaze King stoves (or perhaps about all the other stoves on the market) and this seemed like a good place to post it. I did search on this figuring it had beed discussed somewhere but didnt find an answer.
So I was looking at the 24 to 30 hour specified potential burn time for BK stoves when all the other brands on the market of similar size, weight, material, and technology specify 8 to 12. Most use catalysts. They all have a low air setting (yes BK adds a t-stat).
So I did some math. A firebox of a certain volume can hold a % of that in wood that has an energy density and corresponds to a number of BTUs of heat for a full load. Of that # of BTUs the EPA gives efficiency numbers (HHV) on how much of that energy gets released, and they give low burn rate numbers on how low a stove can burn before it ceases to function well. From the load BTUs, the efficiency, and the low burn rate a potential burn time can be computed.
So I did that for a few stoves in the 3 cuft firebox size - BK and another brand. I got times close to 40 hours. Not exact, but in the ballpark. So at this point my question changed a little. It went from "how does BK claim a 30 hour burn when no-one else claims even half that?" to incude "and how come nobody else gets a 30 hour burn time when they have stats at just as low a burn rate and just as big a firebox?
So I was looking at the 24 to 30 hour specified potential burn time for BK stoves when all the other brands on the market of similar size, weight, material, and technology specify 8 to 12. Most use catalysts. They all have a low air setting (yes BK adds a t-stat).
So I did some math. A firebox of a certain volume can hold a % of that in wood that has an energy density and corresponds to a number of BTUs of heat for a full load. Of that # of BTUs the EPA gives efficiency numbers (HHV) on how much of that energy gets released, and they give low burn rate numbers on how low a stove can burn before it ceases to function well. From the load BTUs, the efficiency, and the low burn rate a potential burn time can be computed.
So I did that for a few stoves in the 3 cuft firebox size - BK and another brand. I got times close to 40 hours. Not exact, but in the ballpark. So at this point my question changed a little. It went from "how does BK claim a 30 hour burn when no-one else claims even half that?" to incude "and how come nobody else gets a 30 hour burn time when they have stats at just as low a burn rate and just as big a firebox?
BKVP
Minister of Fire
If you place a thermocouple in the firebox, connected to a digital display and manually lower the air input (not always possible depending upon minimum air setting used in testing for certification) to compensate for the unmetered nature of burning cord wood, you can impact burn times. I've experimented with this in cooperation with another manufacturer and adjustment intervals were nearly every 2 minutes. At times you'll need to increase air to sustain combustion....Great question by the way.
BKVP
Minister of Fire
I should add, emissions reductions of PM 2.5 takes place in chemical conversion at 550F or thermally at 1176 F. So, "low" can be very different between combustion designs...not always FBV that fixes need for low, longer burn times. It's like having a Camry with a 50 gallon fuel tank. It won't get you further than the 30 gallon Camry if you drive 100 mph!
kennyp2339
Minister of Fire
Great question.. short and simple - alien technology.
Now the real answer - cat placement in relation to the firebox, stove top and flue collar.
Princess owner here, I judge my burn times by useable heat coming off the stove top or really a minimum of 280deg f, and my max is 24hrs burn time in that dept, now I've had small coals and a hot ash bed after 36hrs but nothing of useful heat coming off the unit.
Think of a firebox as a fuel tank, load it up with 40 lbs of oak or large splits of doug fir, once the fire is established and the cat probe is showing the cat is warmed up and operating in the normal range start the timer of the burn, if is go low and slow, that means no flames in the fire box, very dirty solid black glass, maybe occasional embers flaring or glowing I will get 20-24 hrs a load, this serves me well when temps are in the lower 30's at night and the day recovers to mid 40's or warmer.
As is gets colder out I adjust my t-stat air control, this makes the fire burn hotter, the hotter the fire more flames ect.. my max burn in the depths of winter (temps low teens / upper single digits at night and teens during the day) running the blower will average 10-12hrs per full load, more or less the same (maybe slightly better burns then other 3cu ft stoves on the market, but pretty close to others) this results in constant flames in the firebox, a hot cat to the burn clean, stove top temp of 600 ball park and a warm house.
What makes the BK's stand out is the flexibility and consistency on desired outputs by leaning and adjusting your t-stat.
Now this isnt a fix all brand either, there are many other great stoves out on the market, if you live in a house that is poorly sealed, or bad insulation and you need to be ripping 24/7 (+65btu hr) then I would say you would be a little disappointed with the stove, but for someone with average 2x4 construction, average winter temps from the lower teens through 50's then this is the brand. You can also buy the biggest king stove and fool the house, but that stove requires some space and an 8" venting system which can be costly for some.
Thanks KennyP; I get it now. The extreme slow is a smouldering, dirty burn. How well does the cat deal with that?
tech is a good answer too.
It’s a smoldering dirty burn in the firebox but very high efficiency and very low emissions after the cat eats that dirty smoke for fuel. This low and slow is when the catalyst does the best job.
Still dont see why stove brand X with a cat doesnt claim a similar burn time. Or do they just not consider that slow a burn?
No, it's the combi.of cat and Tstat. Wood fires always fluctuate. Set it at your lowest speed (longest burn), things settle, move, and suddenly your speed goes up. That needs to be damped.down to reach the longest burn. Without a Tstat cutting the air, you can't do that, and your total burn time decreases.
When things get hotter, draft increases, and it gets even hotter. Tstats control that. Also preventing runaways, overfiring.
So the best comparison would be to compare to another stove with a Tstat (not that common) AND a cat. I don't know of one, but I vaguely remember having read that at least one other exists. Someone more knowledgeable will confirm or tell me I'm full of it .
When things get hotter, draft increases, and it gets even hotter. Tstats control that. Also preventing runaways, overfiring.
So the best comparison would be to compare to another stove with a Tstat (not that common) AND a cat. I don't know of one, but I vaguely remember having read that at least one other exists. Someone more knowledgeable will confirm or tell me I'm full of it .
Hello everyone, just getting caught up on this year's thread. On page 6 of 20 lol. Anyway, it's finally in the mid 30s here in NE PA and the sound of the heat pump running is getting me itchy to light up the Princess. Its been match ready since early April. Supposed to have a few nights in the 20s this week. Anyway I'll start with 2 questions.
1 - on my indoor pipe, I've been using single wall since I put in the princess 3 years ago. I have 2 straight sections and 2 - 45ish adjustable elbows with 18 feet of blanket insulated double wall above the T. I was going to replace the inside pipe put of precaution this year, although it's in good shape with no rust. Is it worth it performance wise to try and get a double wall stainless to fit? Draft wise the stove runs good wit a low burn around 145-2 o'clock on the Stat on hardwood.
2 - maybe this was covered, but is Ashford still on the forum? I used to enjoy is scientific approach to stuff and his writings. If he isnt around anymore, I hope all is well.
1 - on my indoor pipe, I've been using single wall since I put in the princess 3 years ago. I have 2 straight sections and 2 - 45ish adjustable elbows with 18 feet of blanket insulated double wall above the T. I was going to replace the inside pipe put of precaution this year, although it's in good shape with no rust. Is it worth it performance wise to try and get a double wall stainless to fit? Draft wise the stove runs good wit a low burn around 145-2 o'clock on the Stat on hardwood.
2 - maybe this was covered, but is Ashford still on the forum? I used to enjoy is scientific approach to stuff and his writings. If he isnt around anymore, I hope all is well.
There are other cat stoves that have been more efficient, cleaner, better looking, but the only one that comes close to the BK for long burn times is the Woodstock IS.
It seems that the other brands don’t think that users would appreciate the ability to burn wood slowly, quickly, or anything in between.
I don’t think anybody offers a thermostat for actual output level control other than BK on stoves. The wood furnace and boiler guys do it electronically.
Lots of new cat stoves coming out recently with some smart manufacturers. Some even promise similar long burn times at low output but so far haven’t delivered. I think it would be great if there were some other similar performers.
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BKs coil spring is unique.
Realistically, having a stove that makes 8-10 hours or so is important so i can sleep 8 hours. if it was hot enough cook coffee ☕ 1st thing in the am, that would be deluxe. id also like it to run low enough to be useful when its 40F outside. replace the function of the furnace as thats when i notice it. 24 hours, im divided between convenience and deciding if or what kind of fire is warranted.
Realistically, having a stove that makes 8-10 hours or so is important so i can sleep 8 hours. if it was hot enough cook coffee ☕ 1st thing in the am, that would be deluxe. id also like it to run low enough to be useful when its 40F outside. replace the function of the furnace as thats when i notice it. 24 hours, im divided between convenience and deciding if or what kind of fire is warranted.
Alpine1
Feeling the Heat
Yep, you must put in a new gasket every time you pull out the cat. Mine crumbled to dust when I pulled the cat out in order to clean it… I’ll never do that again: pull the cat out only if you want to replace it with a new one.
VC stoves have the cat and tstat combo but I bet the down draft design probably requires a little more air to burn properly thus reducing burn times. Also the new Jotul F500 has a tstat for it’s secondary air only. You would think more non cat stove manufactures would do this for the secondary air systems to keep them a bit more controllable. I believe PE is the only one?
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