2020-21 Blaze King Performance Thread (Everything BK)

[BKVP]

I’m having a back puffing issue on my 2 year old freestanding princess. My picture shows an insert but that was a previous house. Last night I loaded the stove up with elm that had been split and stacked for a year and a half. I’m in the Boise area, very dry hot summers. After the load caught fire, I ran it on high for 20 min or so then turned the stat to about 3 o’clock. It was in black box mode for about an hour, then the smoke ignited in the fire box and filled the room with smoke. Tonight I loaded it up with 3 year stacked cherry and had the same problem. I turned the stat down in increments with the cherry.

I first noticed this at the end of last winter. It would back puff, fill the room with smoke, I’d turn up the stat and that would solve the issue. This fall, I added 18” to my outside stove pipe, cleaned the entire chimney, removed the cat and cleaned every cell with a pipe cleaner.

I can normally run the stat at 2 o’clock or even 1 o’clock, with the new chimney height, all night and not stall the cat. And no back puff.

Last night after the back puff, I turned the stat down instead of up and all was normal. I did not get the heat output I wanted but no smoke in the house. Same result tonight. Maybe tomorrow I’ll try 4 o’clock and see what happens. Seems like a waste though.

I have 3 feet of double wall inside above the stove, 2 45s to the outside tee then exposed class A on the outside of the house that almost needs aircraft warning lights on it.

When you used the pipe cleaner....you probably removed precious metals. Never, ever use anything like pipe cleaner, gun brush etc. Only compressed air.

 

[Highbeam]

@Ctd92 - the back puffing your describing seems like its because the fuel to air ratio is to rich, I have witnessed the same thing (but no smoke entering the house) What I've done was after running the stove on high to achieve a full char, I turn my stove low enough to just get candle like flames coming off the wood, I let that go like that for 45 min to an hour then I turn it down to black box mode, during times of high draft for me (when the temps fall below 20 deg f and I have a NW wind above 8 mph) I don't char the wood as long on high, I tend to get some flames on it then turn the T stat approx 2:30 and let it go, this lets the stove function, the cat to burn the smoke and no heavy off gassing of the log splits.
A few things to check, the T stat function, sometimes the knob turns without turning the t-stat (this happens sometimes when turning to low) check this by turn the t-stat way up, max should have the knob stop at the 6 o'clock position
Obviously check the cap for any plugging, also check to front face of the cat for any fly ash plugging, check the rear chamber behind the cat for any debris build up.

That burst of flames is often called whoofing and happens when you chop the throttle on a pile of logs that is ripping hot. The logs don’t stop making smoke very quickly so for a while you will have tons of raw gas in the combustion chamber until enough air comes in and then woof it blows up and eats up all the air. Then it goes out, starved of air again, and this repeats until the logs cool off. You’re flooding it.

Two ways to resolve this: don’t get the load so hot before chopping the throttle and then not chopping throttle so fast.

These mini explosions in your stove cause pulses of pressure in your chimney system. Sometimes significant enough to rattle the whole stove. The chimney system is designed to work with constant vacuum so pressurizing it will allow smoke to be pushed out of the joints. It doesn’t take much smoke to stink up the house.

Stop flooding it, the woofs go away, the smoke stays in the pipe.

 

[BKVP]

I'll be glad next winter when I no longer have to deal with the coaling properties of hardwoods. Just raked them forward, burning them down NOW!

 

[Highbeam]

So, I procrastinated to long on purchasing a new cat for my BK princess and Midwest Hearth is out of stock of the ceramics. They do however have metal ones in stock, they are $40 more. I am in north east Pennsylvania and mainly burn when the low is 30* and under which equals about 1.5 cords per year since I got the BK.

Should I eat the $40 extra on the metal cat or wait an unknown amount of time until the ceramics are in stock?

I recently got a sensitive digital thermocouple good to 2000* from my dad who works with very large gas fired kilns and the cat seems to be lazy compared to the analog thermometers. I am seeing 450-550* cruising temps behind the cat where the analogs used to show 600+, and charring in a fresh load I am only getting 1050-1150 degrees on the thermocouple where the analogs show 1350-1500. I have the tip of the thermocouple about 2" below the stove top surface like the analog would be and snug in the hole with furnace tape wrapped around the lead. So with this added data, I am thinking my cat isn't full of piss and vinegar like it was 2 years ago.

You're in a pinch. 40$ isn’t too much of a penalty. Steel works fine in a princess, no better but no worse. Smaller holes more prone to clogging with ash but that doesn’t seem to be a common problem with the princess model. Personally I experienced a noticeably shorter cat life from the steel cat but I only used one.

I’m more concerned that Midwest is out of stock in November! I would hate to have to buy a spare just in case but this does remind us of a weakness in operating a cat stove. You need new cats.

 

[moresnow]

I'll be glad next winter when I no longer have to deal with the coaling properties of hardwoods. Just raked them forward, burning them down NOW!

Haaaa! Gotta agree to a extent. I've been pulling large coals to the front and plopping a small split on top EW most mornings to combat the same situation. Today I skipped the additional split and simply piled the chunks. 4.5 hrs of active operation later I am getting ready to reload. Finally. Waaaaay off schedule! Guess its called full heat extraction mode

Watching a granddaughter for a few weeks due to a Covid laced daycare provider has been a hoot! I have a built in stove monitor now. "Grandpa... it isnt ready yet, its still red in there" "Grandpa... we need to put moooo wooood in.. NOW!" To funny. Have a great day everybody.

 

[Nealm66]

Quick question before I forget, I bought some northern Idaho logs and some home fire logs to get see what burns best and will buy more to get me through this first year. I do have about 1/2 cord of bone dry fir , should I use the regular wood to do the break in fire? I was also noticing , some of my fir has a lot of pitch , it’s all dried up and I can sort it out but just curious if I need to. Also, should I stick with the recommendation of just two logs at a time of the press logs that was recommended for the previous stove?

 

[Highbeam]

Quick question before I forget, I bought some northern Idaho logs and some home fire logs to get see what burns best and will buy more to get me through this first year. I do have about 1/2 cord of bone dry fir , should I use the regular wood to do the break in fire? I was also noticing , some of my fir has a lot of pitch , it’s all dried up and I can sort it out but just curious if I need to. Also, should I stick with the recommendation of just two logs at a time of the press logs that was recommended for the previous stove?

I just burn the fir that has pitch. It can be a little sooty but I don’t think it is reasonable to not burn softwoods because of the inevitable pitch. If it’s just a super heavy, lardy, shiny, pure fat wood chunk I would try to avoid it or at least mix those lard logs with cleaner logs and bury them under the fuel load to slow down their burn.

Start small with the compressed wood logs. Do the 2-3 recommended and see how that goes for you. I’ve burned them too in an effort to go smoke free and found complete control so no need to limit how many you burn at once. Noncat stoves don’t have that control so they can really spiral out of control.

 

[Nealm66]

Thank you, and so when I do my break in, I’ll check my moisture content and just use fir for break and follow the manual instructions? Sorry if I’m asking a lot of questions. Really appreciate the help. If you ever need help whacking down a bad tree let me know. Not licensed or insured any more but still do a few jobs here and there to help people I know out.

 

[JKanor]

You're in a pinch. 40$ isn’t too much of a penalty. Steel works fine in a princess, no better but no worse. Smaller holes more prone to clogging with ash but that doesn’t seem to be a common problem with the princess model. Personally I experienced a noticeably shorter cat life from the steel cat but I only used one.

I’m more concerned that Midwest is out of stock in November! I would hate to have to buy a spare just in case but this does remind us of a weakness in operating a cat stove. You need new cats.

Highbeam, I contacted Midwest about when they might get ceramics back in stock and this was their reply...

"Hi Jay,
Demand for the Princess combustor was unusually high this year!
It will be a few weeks before I have more of the ceramic version.
I do have the metal version in stock if you would like to try it."

Not sure if I am going to try the steel cat or not at this point, although we will finally be in the 20*s next week so I will def have a fire going and need to decide. It doesn't seem like the current one is totally dead, but seems to be leaving some on the table.

 

[Ctd92]

Thanks for the reply’s. At 8:45 this morning I loaded it up with cherry. Once the load caught, I turned the stat down to 3 o’clock. 3 hours later there are still flames in the box. Not roaring flames and they seem to be slowing down. No whoofing.
Copy on the no pipe cleaners.

 

[stoveliker]

I'll be glad next winter when I no longer have to deal with the coaling properties of hardwoods. Just raked them forward, burning them down NOW!

I don't understand; do you not like the coals? As you know I'm new, but I was pretty happy with the heat being put out by the stove when there were only coals left (and you have quite a bit in that pic).
Why do you open the stove at this stage, rather than letting it burn down more on its own before you load more wood? To ignite a new load you only need 6 or so coals, so you could leave it closed for longer?

-maybe these are stupid questions, but that's what you get with people still learning ... -

Nice pic though - that orange heat is just so appealing.

 

[BKVP]

Quick question before I forget, I bought some northern Idaho logs and some home fire logs to get see what burns best and will buy more to get me through this first year. I do have about 1/2 cord of bone dry fir , should I use the regular wood to do the break in fire? I was also noticing , some of my fir has a lot of pitch , it’s all dried up and I can sort it out but just curious if I need to. Also, should I stick with the recommendation of just two logs at a time of the press logs that was recommended for the previous stove?

Stick with two. I used them for years. Load in your cordwood and play 2 NIELS on top. When they drop down, you get a cool nuclear blast of high heat!

 

[BKVP]

I don't understand; do you not like the coals? As you know I'm new, but I was pretty happy with the heat being put out by the stove when there were only coals left (and you have quite a bit in that pic).
Why do you open the stove at this stage, rather than letting it burn down more on its own before you load more wood? To ignite a new load you only need 6 or so coals, so you could leave it closed for longer?

-maybe these are stupid questions, but that's what you get with people still learning ... -

Nice pic though - that orange heat is just so appealing.

I hate coals! Yes they are great for heat...but when I burn Larch, Fir or NIELS, it burns down to the finest ash. Most certainly I get more energy (pounds) into my King using walnut, cherry, locust and maple, but as you know, the King has a 9" belly and I want wood in there not coals. If I had a smaller house, I could run at a lower burn rate and allow everything to cook down to ash. But I burn hotter (keeps wife happy...just ask @Poindexter why we do this)...and burning hardwood with high specific gravity attributes means 9" of coals.

Almost cooked down now....happy happy.

 

[stoveliker]

I hate coals! Yes they are great for heat...but when I burn Larch, Fir or NIELS, it burns down to the finest ash. Most certainly I get more energy (pounds) into my King using walnut, cherry, locust and maple, but as you know, the King has a 9" belly and I want wood in there not coals. If I had a smaller house, I could run at a lower burn rate and allow everything to cook down to ash. But I burn hotter (keeps wife happy...just ask @Poindexter why we do this)...and burning hardwood with high specific gravity attributes means 9" of coals.

Almost cooked down now....happy happy.

ah, so it's the lower heat output of the coaling stage that you wish to avoid. And for good reason (yes, I did read a lot, including those discussions).
In my case (cases, a number which can be counted on one hand so far...), I've been running at the lowest setting possible (at least, it's 1/5th of the swoosh, but I have not the cat it drop out of active yet, so "lowest" is a guesstimate), so the difference between coaling and the stage before that is not that large making it appear that burning the coals is just a "same level" extension of the burn stage before that.

A little of maple left, and then 3.5 cords of oak here (and the odd 50 splits of cherry and red cedar). Coals it is, then, for me.
Thanks (all of you) for your generous education. I hope to pay it forward at some point.

 

[Highbeam]

Thank you, and so when I do my break in, I’ll check my moisture content and just use fir for break and follow the manual instructions? Sorry if I’m asking a lot of questions. Really appreciate the help. If you ever need help whacking down a bad tree let me know. Not licensed or insured any more but still do a few jobs here and there to help people I know out.

Moisture is not as important as we make it sound. Fir dries fast. Under 15% is as good as you can get in our climate, under 20% is all good, but it’s not bad up to about 25%. We tend to optimize performance here on a wood burning forum and best results come from driest wood but pretty dang good performance can happen with sub 25% fuel if it’s split a little smaller. You’ll see, wetter wood won’t break the stove but super dry wood is great.

I think I would prefer natural firewood for break in. Just a few splits. Or even some 2x4 scraps.

You’re going to love it. Our climate is a pretty ideal match to exploit the low end performance of these Bk stoves.

 

[Nealm66]

Perfect, thank you again

 

[Poindexter]

The thing about coals is there is no cat food in them. Carbon combines with oxygen right about 600dF, just barely up in the active zone on my BK cat probe indicator, but since there are essentially no VOCs coming off the charcoal, the cat is hot enough to be active - but there is nothing in the exhaust plume for it to eat. A hungry cat so to speak.

You can try this with hardwood lump charcoal right in your stove. I did. Wood coals are wood coals are wood coals. Do not try this with briquettes. Briquettes have all kinds of binders (glue) in them, and glue is verboten.

I did ask @BKVP I think two seasons ago if, when burning charcoal with an indicated active cat if there was measurable heat being produced combining carbon monoxide with oxygen at the substrate to exhaust carbon dioxide. I didn't hear back from him, but I suspect it would take some very precise intrumentation to find a BTU or two here and there in this situation.

In shoulder seasons a heap of coals might be plenty to keep the house at a comfortable temp. In colder weather an accumulation of coals is in the way of loading more catfood into the firebox,

 

[stoveliker]

The thing about coals is there is no cat food in them. Carbon combines with oxygen right about 600dF, just barely up in the active zone on my BK cat probe indicator, but since there are essentially no VOCs coming off the charcoal, the cat is hot enough to be active - but there is nothing in the exhaust plume for it to eat. A hungry cat so to speak.

You can try this with hardwood lump charcoal right in your stove. I did. Wood coals are wood coals are wood coals. Do not try this with briquettes. Briquettes have all kinds of binders (glue) in them, and glue is verboten.

I did ask @BKVP I think two seasons ago if, when burning charcoal with an indicated active cat if there was measurable heat being produced combining carbon monoxide with oxygen at the substrate to exhaust carbon dioxide. I didn't hear back from him, but I suspect it would take some very precise intrumentation to find a BTU or two here and there in this situation.

In shoulder seasons a heap of coals might be plenty to keep the house at a comfortable temp. In colder weather an accumulation of coals is in the way of loading more catfood into the firebox,

Okay. I understand. It's just the heat output per hour (the power of the stove) that's less b/c it's only "box-heat" and not "box+cat heat". That is what I meant; when I run really low, as I've done, the difference may not be that much - and that's consistent with your shoulder season remark, I think.

I learnt something - on a Friday afternoon. Thank you, again.

 

[Tron]

I did ask @BKVP I think two seasons ago if, when burning charcoal with an indicated active cat if there was measurable heat being produced combining carbon monoxide with oxygen at the substrate to exhaust carbon dioxide. I didn't hear back from him, but I suspect it would take some very precise intrumentation to find a BTU or two here and there in this situation.

Chemist here. Actually, that is quite a thing. Coal combustion mostly leaves carbon monoxide as the primary combustion product, not carbon dioxide. That's why it's so easy to kill yourself by barbecueing indoors. And carbon monoxide has a lot of BTU's that are released when the cat combusts it to carbon dioxide.
Back in the day, "city gas" was not methane as it is today, but carbon monoxide. They powered street lamps with it, and people cooked with it. Quite dangerous, but without alternative at the time.

So, TLDR, the coals indeed give a lot of food to your cat.

 

[Nz3000owner]

So I’ve had my Ashford 30 for a year. I’m burning from November to April as primary heat source. I’m just cleaning it for the first time now. These 2 pics are of the cat front and back as I pulled it out. After I pulled it out I brushed it with a paint brush gently then used a soft brush with a vacuum. There was still gunk on the back side. So I used my compressor set at 40 psi max and blew it out. It looks like it’s about 98% clean but not 100. Is that good enough? My ocd is killing me right now. Should I spray with down with water and vinegar or leave well enough alone. As I said my ocd is killing me but I don’t want to ruin a 1 year old cat.

 

[Nz3000owner]

It’s hard to see but you can see the small deposits still in there. I don’t want to poke anything inside of it.

 

[Tron]

Other experts may give their 2 cents, but I'd say leave it at that. Those 2% left over (if that) are not going to be noticeable.

 

[Nealm66]

Isn’t it better to leave the cat in place and use a soft brush and vacuum? Then pull the pipe off and vacuum behind? Or is it better/easier to pull and replace gasket ?

 

[Nz3000owner]

Isn’t it better to leave the cat in place and use a soft brush and vacuum? Then pull the pipe off and vacuum behind? Or is it better/easier to pull and replace gasket ?

This is my first time doing it so idk. The pipe on top of my stove is a adjustable and when I put it on last year it scratched the paint. So I figured if I did it by removing the pipe then I’d be touching up paint and don’t want to get into that if I didn’t have to. Also I think doing that would make a bigger mess cleaning the chimney. This way everything just falls into the firebox. OCD sucks!

 

[Highbeam]

Isn’t it better to leave the cat in place and use a soft brush and vacuum? Then pull the pipe off and vacuum behind? Or is it better/easier to pull and replace gasket ?

Behind the cat is a steel curtain that hangs down and prevents thorough cat access from the rear. A plugged up cat is very unlikely in a king or princess with a ceramic cat. The gasket is 6$ but I never buy it, my cats never clog like that, just some fuzz on the face that I sweep off with a soft paint brush. For fun, and maybe to be thorough, I’ve also vacuumed the face of the cat and blown them out over the years but they were clean already so no improvement.

To verify your cat cells are clear you can shove a phone up there and take pictures right through the installed cat.

Good chance that NZ3000’s cat could have been blown out from the front with compressed air but he seems to be happy to verify with close inspection.