2019-20 Blaze King Performance Thread Part 1 (Everything BK)

[Highbeam]

Efficiency and Emissions are certainly an advantage of cat stoves, but couldn't a non-cat stove achieve the same temperature control? I mean, it's all about burn rate control (although that obviously would need to be a bit higher than with a cat).

I wish! Then we wouldn't need to deal with the drawbacks of a catalyst. Good noncats are very often lower emissions than a cat stove (my noncat is almost half as dirty as my cat stove) and some are only slightly less efficient. We're talking 5-10% in a lab, not a big deal. So look beyond emissions and lab efficiency to turn down ratio, aka control.

As @BKVP has proven, the huge majority of stoves spend the huge majority of their lifes being run at low output. I forget but there were 90% figures being thrown out. Sure, we all need more heat sometimes but most of the time we are cruising.

What burns you with a noncat is that they need firebox temperatures of over 1000 degrees to burn clean and often burn much hotter during that initial hour or two of the fire where gasses really spew out of the wood. The noncat runs on a surplus of air in the box, lots of air to burn any fuel. There is a definite cycle that you need to take advantage of when operating a noncat to keep your home temperatures relatively steady. With the cat stove you need 500 degree exhaust just to initiate catalyst activity and then you can drop off to just enough fire to make smoke and feed the cat fuel. That little hot cat is doing the job and allows a very long burn with steady output a lot like the old pre epa stoves could do except efficiently. Match that low output to what your home loses to the environment and you have the recipe for low fuel consumption.

 

[Tron]

Thanks for the explanation! I see that choosing a cat stove was the right decision for me (and probably a lot of others).

 

[Highbeam]

Before the noncat guys show up I'll try and guess what they're going to say. They will say, the cat stove output on low won't keep my house warm. If that was really the case for part of the year then you could increase the burn rate but more importantly some people just like noncats and that surge of feel good heat when the house is cold. Why is the house cold? It's a self fulfilling prophecy. They wouldn't need that blast of heat if they could keep the house warm.

If the noncat folks really needed double the output of a cat stove on low then they would need to burn double the fuel. Most of us full time burners are doing it on 4 cords of fuel per year, that would mean that they are pushing 8 cords through their noncats? I don't think so.

I own a noncat too. They are the right choice when you really do need high output. No cat to deal with!

 

[Ashful]

...noncats and that surge of feel good heat when the house is cold. Why is the house cold? It's a self fulfilling prophecy. They wouldn't need that blast of heat if they could keep the house warm.

Worth repeating.

Most of us full time burners are doing it on 4 cords of fuel per year

... per stove.

 

[Tron]

... per stove.

I just calculated, that would be about 14m3 or two of my round storage silos constructed with 8*20' remesh. Currently, I calculate of using about half that per winter, and with MS climate that sounds about right. Of course, it all depends on the type of wood, with pine you are likely going to use more than with oak.

 

[jetsam]

Efficiency and Emissions are certainly an advantage of cat stoves, but couldn't a non-cat stove achieve the same temperature control? I mean, it's all about burn rate control (although that obviously would need to be a bit higher than with a cat).

Nope. The cat can reburn the vocs at temps as low as 500°. A noncat with great air control would be sending all that fuel up the stack unburned. Heck, we used to do that with our old smoke dragons and a roll of tinfoil.

At a minimum, you'd have to incorporate an ignition source in a noncat, because you'd need to completely shut down air intake when heat isn't called for and light the fire again when it is. (And you can't even shut down the air intake 100% without blocking every air hole including the flue, which could kill any of your customers who have a leaky door gasket.)

Unless you go to a straight wood gasification setup, you are not getting very low burns and good efficiency without a cat, and woodgas has its own set of hurdles to clear (one of which is that you want the waste heat to stay in your house and your wife doesn't want half of the living room to be full of burn, filtration, and gas cylinders).

 

[Highbeam]

I just calculated, that would be about 14m3 or two of my round storage silos constructed with 8*20' remesh. Currently, I calculate of using about half that per winter, and with MS climate that sounds about right. Of course, it all depends on the type of wood, with pine you are likely going to use more than with oak.

Full time burner in MS will surely need less btu per year tan a full timer in Alaska. Those are two extremes. There are a lot of variables to consider such as length of burn season, and average temperatures, wood density. Using a mat of mesh is a pretty interesting idea.

 

[begreen]

Before the noncat guys show up I'll try and guess what they're going to say. They will say, the cat stove output on low won't keep my house warm. If that was really the case for part of the year then you could increase the burn rate but more importantly some people just like noncats and that surge of feel good heat when the house is cold. Why is the house cold? It's a self fulfilling prophecy. They wouldn't need that blast of heat if they could keep the house warm.

Not really. This is somewhat of a myth. We see little temp swing and what there is, is intentional because we like it cooler at night for sleeping. 68º at night and 72-73º day temps heating 24/7.

 

[Highbeam]

With the cat stove you need 500 degree exhaust just to initiate catalyst activity and then you can drop off to just enough fire to make smoke and feed the cat fuel.

Sorry to quote myself but I am questioning my theory and there are some geniuses on this forum. Once we get an active cat temp and engage it the cat temps rise up to well over 1000 and the dang thing glows. Then we can lower the thermostat setting. This is normal operation for me and most.

So long as the fire is making enough smoke to sustain the hot cat (not stalling it by starvation), does the firebox and smoke need to be 500 degrees anymore or is the heat within the catalyst enough to ignite and burn the cold smoke?

I think the smoke can be cold so long as the catalyst is staying hot due to burning the smoke.

 

[Tron]

Next time I'm in the yard I'll snap a picture of the silos. Best way to cheaply store and dry firewood.
To retrieve the wood you just cut a door in and close it with a few zip ties.

On another matter: first fire, yay!

 

[Tron]

BTW, is that normal that I can turn the thermostat almost 360 degrees? The arrow on the dial covers only about 90 degrees or so, and I can turn it way past "low".

 

[BKVP]

Yes, the effective range is about 2-6, referencing a clock face. Draft will determine how low you can run.

 

[Tron]

Ok, so the positions 7-2 don't really do anything? Besides turning the intake air so low it will just go out?

 

[Highbeam]

Ok, so the positions 7-2 don't really do anything? Besides turning the intake air so low it will just go out?

If your pointer swings clockwise past 6 o'clock position then you've got a problem. It should hard stop pointing at the ground.

 

[Diabel]

Next time I'm in the yard I'll snap a picture of the silos. Best way to cheaply store and dry firewood.
To retrieve the wood you just cut a door in and close it with a few zip ties.

On another matter: first fire, yay!

Very clean set up! I like it. As said ^^^^ your thermostat dial should stop at 18:00h

 

[Tron]

At full throttle it stops at 6 o'clock. But turning it counterclockwise it dials down all the way to about 7 o'clock.

 

[Tron]

I took a picture of the storage silos. I'll make a new thread for it for later reference, so it will be easier to find.

 

[Woody Stover]

We hear this over and over when people make the switch from noncat to a good and properly sized cat stove. It happened to me too when moving from a modern hearthstone noncat. More comfort and at least 20% less wood. Not so much due to the efficiency improvement but due to the constant temperature control. On top of this, being able to only reload once per day has allowed me to enjoy wood burning more and have more time for other hobbies.

Efficiency and Emissions are certainly an advantage of cat stoves, but couldn't a non-cat stove achieve the same temperature control? I mean, it's all about burn rate control (although that obviously would need to be a bit higher than with a cat).

Yep. I think that quite a bit of the perceived "less wood used" is due to people burning non-cats wide open to get the stove up to temp..that wastes a lot of wood and heat up the flue, and doesn't get the stove up to temp all that much faster. As in most things, moderation is the key.

Dangerously off topic here

Good one! This thread goes way off topic, countless times; It's one of the things that keeps it interesting.
Also, taking the BK thread off topic hasn't been dangerous to me so far..
And what are your "other hobbies.." loafing on redundant internet forums? You need to switch to a part-time job, like I have. At my advanced age, I don't have time to waste, working a full-time job.

Not really. This is somewhat of a myth. We see little temp swing and what there is, is intentional because we like it cooler at night for sleeping. 68º at night and 72-73º day temps heating 24/7.

Yep, even though you have windows pulling the heat out, temp only varies a few degrees. Some of that's due to your mild climate of course. Nevertheless...
I have a leaky, poorly insulated envelope (moderated by a somewhat mild climate,) and I'm pretty sure room temp wouldn't vary more than a few degrees if I burned a properly sized non-cat here. Sure, it takes a little more messing with the stove to do that with a non-cat, but it's still easily done.
And if you factor in all the time the BKers waste removing and cleaning fly ash from the cat, checking their door and window gaskets, having to replace the door gasket if you change the window gasket (no biggie, really,) re-calibrating their loose thermostat knobs, brushing their chimneys three times a year and all the rest, they have wasted way more time than any non-cat burner ever did.

 

[BKVP]

Ok, so the positions 7-2 don't really do anything? Besides turning the intake air so low it will just go out?

Correct...below 2 the plate is already closed.

 

[Ashful]

.
And if you factor in all the time the BKers waste removing and cleaning fly ash from the cat, checking their door and window gaskets, having to replace the door gasket if you change the window gasket (no biggie, really,) re-calibrating their loose thermostat knobs, brushing their chimneys three times a year and all the rest, they have wasted way more time than any non-cat burner ever did.

Of that list, I haven’t done any of those things in the last two seasons. In fact, the only thing on that list I’ve ever done in the five years I’ve owned two BKs is vacuum the cat face, when I was running 3x the recommended draft. Since correcting that blatant installation problem, my cat cleanings have been reduced to when I remove it to sweep my chimney once each summer.

I still haven’t adjusted the door or gasket on either stove after five years, and nearly 35 cords thru one of them. I’m still getting the same 12 hour burn times out of one as when it was new, but the one I burn on 24 hour cycles may be due for an adjustment. Not a surprise if the one being operated closer to its limits is the first to show a need for a little fine-tuning, which I would guess is a summary statement you could apply to all things BK: when you operate closer to the limits of any technology, you’d best have your system more finely-tuned to achieve it.

 

[Tron]

@Highbeam: I would agree, the combustion of the gases within the cat is an exothermic reaction and sustains itself. So the smoke temperature is not relevant, but the release rate from the wood is. And you probably are only going to achieve that with a certain minimum temperature in the firebox, whichever that is.

 

[jetsam]

But lower airflow through the cat drives down the required firebox temperature. If there is fuel to burn in the exhaust, and if the cat is managing to hold 500°, you will get secondary combustion. You can raise the cat temperature only by raising the firebox temperature above 500 at first, but after you hit that mark, you can lower firebox temperature again as long as there is enough fuel to keep the cat burning. It would not amaze me to learn that at certain points in a low burn the firebox was cooler than the stovetop.

In theory, this all is actually an argument in favor of ceramic cats during shoulder season, as they have a heavier, less thermally conductive substrate. In practice, I don't see a ton of difference.

 

[Kwehme09]

My wife and I have decided it's time for a new CAT for our Sirroco 20. This is our 4th winter with it, it's our primary heat and we burn mid-Ocober through April usually. I've clicked around online CAT shopping, and was initially thinking a steel CAT from condor, but can't seem to find one for our stove.

I'm not against ceramic either and was hoping to have you all weigh in both on material, and a good source to buy from. Thanks!

 

[BKVP]

Have you tied cleaning the combustor?
1) Compressed air can to blow out combustor?
2) Deep cleaning involving removal, distilled water and vinegar?

The place to purchase an OEM combustor is either through a dealer of our products of www.firecatcombustors.com
However, you can purchase from any source you prefer.

 

[moresnow]

My wife and I have decided it's time for a new CAT for our Sirroco 20. This is our 4th winter with it, it's our primary heat and we burn mid-Ocober through April usually. I've clicked around online CAT shopping, and was initially thinking a steel CAT from condor, but can't seem to find one for our stove.

I'm not against ceramic either and was hoping to have you all weigh in both on material, and a good source to buy from. Thanks!

I have the same stove model. Roughly the same amount of years on it. This may be the fifth. Very similar months of 24/7 burning each year. I bought a replacement cat through my dealer this fall after feeling that the original was off in performance. While I waited for it to arrive I let the stove go completely out. Cleaned her out nicely including my pipe. While I was at it I vac'd the face and the rear of the original cat carefully (normal procedure while cleaning my pipe/stove). On a whim I went to town and grabbed a can of compressed air for cleaning electronics etc. Blew out the cat from the front as I had re installed my pipe by then. Figured I had a new cat en route. Why not. Huge cat performance difference. . My new cat is sitting in it's package on a shelf. True story.

If you have not adjusted your door tension I would. Mine had gotten very loose.