2020-21 Blaze King Performance Thread (Everything BK)

[Dustin]

Low of 42 last night, high of 52 today. Supposed to get down to 35 tonight.

loaded up at 1800 last night, stuffed full. As of noon today I still had a nice bed of coals and my cat was mid active zone. Heat still coming off the stove.

I freaked out and added three splits to limp along for a full load tonight. Did I mess up? I feel like I messed up. Probably could have just left it on low and still had coals and heat for a few more hours.

Not adding wood is a hard habit to break

 

[Highbeam]

Low of 42 last night, high of 52 today. Supposed to get down to 35 tonight.

loaded up at 1800 last night, stuffed full. As of noon today I still had a nice bed of coals and my cat was mid active zone. Heat still coming off the stove.

I freaked out and added three splits to limp along for a full load tonight. Did I mess up? I feel like I messed up. Probably could have just left it on low and still had coals and heat for a few more hours.

Not adding wood is a hard habit to break

This is a good problem to have. Remember that your firebox is really just a huge fuel tank. Some people refill at half and some barely make it to the fuel station on fumes. You’ll get the best efficiency and lowest emissions by reloading full loads when the previous load is just down to coals but the cat is still active.

When it’s really cold out and I need more heat than a 24 hour cycle will give, I drop to 12 hour reloads and “top off” a half full firebox.

Make it work around your schedule with the least number of fuel additions.

Looking forward to some heavy frost this weekend.

 

[BKVP]

Oh sure, rub it in lol it's way too warm here. Beautiful setup!!

thank you

 

[Dustin]

This is a good problem to have. Remember that your firebox is really just a huge fuel tank. Some people refill at half and some barely make it to the fuel station on fumes. You’ll get the best efficiency and lowest emissions by reloading full loads when the previous load is just down to coals but the cat is still active.

When it’s really cold out and I need more heat than a 24 hour cycle will give, I drop to 12 hour reloads and “top off” a half full firebox.

Make it work around your schedule with the least number of fuel additions.

Looking forward to some heavy frost this weekend.

How do you address the cat temp when reloading? My KE40 manual says “don’t reload unless your cat gauge is below” basically the last lower line on active.

Problem is, either my cat probe is a liar or, this thing really really good. Mine stays well into the active until the fire is out. I mean like barely any coals to relight out. It can be done with some help of a fire starter but I’m not sure I want to wait that long.

 

[Dieselhead]

Regardless of cat temp my hot reload procedure goes as follows: I throw it into bypass, and open the thermostat to about 3/4 for 5 min. Then I’ll open the thermo all the way just before opening the door. I do my reload and close the door. Once the firebox becomes fully involved for about 5 min, I close the thermo to 3/4 and close the bypass. Let it sit at 3/4 for about 15min then put it to my usual setting for the outdoor temperature at the current time. Never any problems for me doing reloads this way.

 

[Highbeam]

How do you address the cat temp when reloading? My KE40 manual says “don’t reload unless your cat gauge is below” basically the last lower line on active.

Problem is, either my cat probe is a liar or, this thing really really good. Mine stays well into the active until the fire is out. I mean like barely any coals to relight out. It can be done with some help of a fire starter but I’m not sure I want to wait that long.

I think that is a mistake in the manual. Like an Easter egg! Thought for sure they would have fixed it by now. You obviously can’t wait for the stove to go ice cold for every reload.

Maybe bkvp can verify?

 

[BKVP]

How do you address the cat temp when reloading? My KE40 manual says “don’t reload unless your cat gauge is below” basically the last lower line on active.

Problem is, either my cat probe is a liar or, this thing really really good. Mine stays well into the active until the fire is out. I mean like barely any coals to relight out. It can be done with some help of a fire starter but I’m not sure I want to wait that long.

Cat activity is not based upon amount of fuel in the stove. It is based upon unburnt/released gases. I've been able to get a large charred piece to spike cat activity by reaching in with a poker and breaking open that same piece. Cat went from 375F to 1200F in 10 minutes....scale read 0.5lbs.

With that said, pull the cat therm out,wear gloves if hot, allow it to come to room temperature. Then see if the needle is pointing around 7, referring to click face. If not, give me or my team a call and we can help calibrate.

 

[Poindexter]

Similar to @Dieselhead , my combustor stays in the active zone from November into February.

On a 12 hour reload cycle I don't even look at the combustor probe temp, it is time to reload. Move the lever to bypass, turn the throttle to wide open and go pee or make some coffee or something. Come back in 5-10 minutes, crack the loading door open, wait a two count, open the loading door wide, maybe wrangle the remaining coals to a relatively level layer, load it up to the gills with fresh fuel.

Swing the loading door to just a crack open, hold it there until the whooshy-whooshy stops and the draw is sounding more like a hurricane or an engine just pulling steady nears its peak torque, one steady noise. Close and latch the loading door. Give it, oh 1-5 minutes there with the loading door closed, throttle wide open, combustor bypassed.

At this step you need the fuel to char. A fresh split of wood has essentially infinite surface area from all those little hair sized fibers sticking up. As it catches fire and chars it is going to release LOT of VOCs really fast. Once every surface is charred the amount of wood on fire is pretty simple to calculate, this side is 3x16 inches for 48sqin on fire, the next side is 4.5x16 for 72sqin on fire etc, instead of infinity plus infinity plus infinity... The drier your wood is, the faster this step goes.

Engage the combustor, leave the throttle on full tilt and bake the lastof the free water out of your fresh fuel. I think the book says 30 minutes for this step. If my fuel was up around 18-20-22%MC I would stick to 30 minutes for the free water bake. I am running 14-15%MC again this year and 20 minutes is working good for the bake.

Once the free water is baked out, adjust the throttle knob to your desired setting, come back in 12 hours.

 

[Dustin]

Similar to @Dieselhead , my combustor stays in the active zone from November into February.

On a 12 hour reload cycle I don't even look at the combustor probe temp, it is time to reload. Move the lever to bypass, turn the throttle to wide open and go pee or make some coffee or something. Come back in 5-10 minutes, crack the loading door open, wait a two count, open the loading door wide, maybe wrangle the remaining coals to a relatively level layer, load it up to the gills with fresh fuel.

Swing the loading door to just a crack open, hold it there until the whooshy-whooshy stops and the draw is sounding more like a hurricane or an engine just pulling steady nears its peak torque, one steady noise. Close and latch the loading door. Give it, oh 1-5 minutes there with the loading door closed, throttle wide open, combustor bypassed.

At this step you need the fuel to char. A fresh split of wood has essentially infinite surface area from all those little hair sized fibers sticking up. As it catches fire and chars it is going to release LOT of VOCs really fast. Once every surface is charred the amount of wood on fire is pretty simple to calculate, this side is 3x16 inches for 48sqin on fire, the next side is 4.5x16 for 72sqin on fire etc, instead of infinity plus infinity plus infinity... The drier your wood is, the faster this step goes.

Engage the combustor, leave the throttle on full tilt and bake the lastof the free water out of your fresh fuel. I think the book says 30 minutes for this step. If my fuel was up around 18-20-22%MC I would stick to 30 minutes for the free water bake. I am running 14-15%MC again this year and 20 minutes is working good for the bake.

Once the free water is baked out, adjust the throttle knob to your desired setting, come back in 12 hours.

That was really, really informative. Thank you!

I did, most of that this time but went a little light on the char. Right now I have the the thermo set all the way low. Stove top cruising according to a thermo on the top right hand side at about 250-300. Cat probe temp it at about 1 o clock and flue temp is around 250.

the window has become so black I can’t see anything. Went out and looked at the chimney, and I’m getting some whisps of white steam that dissipates quickly. When I shine a flashlight into the stove I can actually see some smoke in there through the black glass, but none from chimney. Does any of this sound like I might be running too low? It’s been on this setting for 5 hours and the combustor hasn’t stalled

I’ve never ran this low. I half expected the stove to go out.

 

[BKVP]

That was really, really informative. Thank you!

I did, most of that this time but went a little light on the char. Right now I have the the thermo set all the way low. Stove top cruising according to a thermo on the top right hand side at about 250-300. Cat probe temp it at about 1 o clock and flue temp is around 250.

the window has become so black I can’t see anything. Went out and looked at the chimney, and I’m getting some whisps of white steam that dissipates quickly. When I shine a flashlight into the stove I can actually see some smoke in there through the black glass, but none from chimney. Does any of this sound like I might be running too low? It’s been on this setting for 5 hours and the combustor hasn’t stalled

I’ve never ran this low. I half expected the stove to go out.

Each fire is unique. If the difference of outside temp versus inside temp is great enough, in most instances with good mc fuel you can run pretty low. Poindexter chars for 30, so do I but my fuel is very low mc. Expect some variability due to mc differences in each piece and outside temps. In a few weeks, it will all become second nature....like how hard to throw a baseball to reach the intended target.

 

[Diabel]

I follow most of the steps mentioned here. I do have a bit of an issue with the 30min char. After about 10-15min with bypass closed my cat probe will read around 4pm. My flue probe will read around 600 and i have a raging inferno in the box. I also start smelling those new baking paint smells. Plus, i am burning 3yr old basswood and hemlock. I have a feeling if i let it go for another 15min i might have a super clean firebox (free of creo) and only 1/2 load of fuel left.

 

[Tron]

I admit that I oftentimes also go light on the char, especially during "shoulder season", which is what it is around here mostly. I usually light smaller fires and top up with a few splits every couple of hours. And then I do let them catch for a few minutes on "high" with the cat bypassed, but close the bypass and turn it down about 5 minutes in or so. If I would let it run at high for 30 minutes, the living room would be a sauna.

 

[Dustin]

I’m happy to report that as of 0600, the cat is still active and the house is still warm! It was 75 in here when we went to bed.

34 outside at the moment. Maybe I can really get away with running this thing as low as she goes...

Glass, so black I can’t even see through it except for the faint hue of a glowing combustor.

 

[Highbeam]

I’m happy to report that as of 0600, the cat is still active and the house is still warm! It was 75 in here when we went to bed.

34 outside at the moment. Maybe I can really get away with running this thing as low as she goes...

Glass, so black I can’t even see through it except for the faint hue of a glowing combustor.

You say 250 flue temp which we must assume is internal flue probe measured temperatures? It helps if you specify this because many folks are referring to surface temps of their single wall flues which run about half as hot as internal.

So the bk will run very very efficiently at this ultra low setting. 250 internal means your flue pipe skin is only 125. The steam in the smoke condenses in your chimney at such low temperatures. Things can get ugly fast when you’re running your stove so low. You’ll also notice a wet, shiny, tar coating inside the firebox and your glass will get bark.

Myself, I avoid going that low. Keeping internal flue temperatures up around 400 to maintain a dry and brown chimney and firebox. If you choose to run that low all the time then you’re supposed to burn it out once a week by running at max thermostat setting for one hour after engaging the cat on a full load. This is what bkvp has prescribed and it does clean out the goo but it’s a little spooky.

Running the fans on the princess this morning. We had our first heavy frost overnight and the house got cold due to no fire. I’m supposed to BBQ a pork butt starting soon, you can bet that pellet bbq will make some condensation as it warms up.

 

[Diabel]

If you choose to run that low all the time then you’re supposed to burn it out once a week by running at max thermostat setting for one hour after engaging the cat on a full load. This is what bkvp has prescribed and it does clean out the goo but it’s a little spooky.

I have that shiny black stuff in the firebox (not everywhere) mainly upper sides and upper back and glass. On a cold stove when i shine a light through the bypass door i mainly see brown dry pipe walls. But i think i will start doing the once per week furnace blast burn on full throttle. It will be spooky

 

[Highbeam]

I have that shiny black stuff in the firebox (not everywhere) mainly upper sides and upper back and glass. On a cold stove when i shine a light through the bypass door i mainly see brown dry pipe walls. But i think i will start doing the once per week furnace blast burn on full throttle. It will be spooky

I’ve seen at least one BK with a hole corroded right through it up above the bricks and then folks on this site had behind the brick corrosion. That wet looking tar is supposed to be pretty corrosive.

I don’t know, maybe a topic for discussion, but I prefer to run it just warm enough to keep things dry. That’s still very cool compared to other stoves which is why these crazy bk stoves can deliver such long burn times.

 

[MTASH]

I’ve seen at least one BK with a hole corroded right through it up above the bricks and then folks on this site had behind the brick corrosion. That wet looking tar is supposed to be pretty corrosive.

I don’t know, maybe a topic for discussion, but I prefer to run it just warm enough to keep things dry. That’s still very cool compared to other stoves which is why these crazy bk stoves can deliver such long burn times.

X2. I try to maintain flue @350-400 (double wall probe). I could run lower than that without stalling, but my senses tell me not to.

As far as charring, I jumped the gun yesterday with my turn-down. After a while I noticed a lot of smoke in the fire box, so I turned it back up to finish charring whatever got missed the first time. This morning I waited a bit longer before turn-down and have a nice load of splits cruising @350 flue with absolutely no smoke whatsoever. The point is it takes a bit of practice and experience with different loads to figure out what works best for your own particular fuel and load size.

 

[Poindexter]

I see a bit of inconsisteny of word usage. In all fairness I did make these up, they aren't , that I know of, in the BK manual.

Charring step, to me is with the combustor bypassed, loading door may be open or closed. This simply burning the roughness off the fresh splits and letting that initial infinity surge of thick smoke from all those fine hairs burning off bypass the combustor. In deep winter with cold outdoor temperatures and a relatively thick bed of coals on the floor of the stove, my wood is done charring before I can get the loading door closed. In more moderate temperatures, not so much. This is going to vary with just about all the available variables, wood species, MC, coal bed thickness, wind speed and direction at the chimney mouth, blah blah blah. If you are getting 15-20 cords through a combustor before the performance tails off, something like 10-12k active hours, you are charring enough.

Baking is with the loading door closed, and the bypass door closed, engaged combustor, running on high throttle. What we are doing here is baking the last of the free water out of each split. The smoke coming off the burning wood is going to be relatively moist, as each split in the firebox dries down from 20% to 0% MC, or 14% down to 0% MC, or whatever.
You want to be running on high throttle for this so you have plenty of heat energy in the stack to carry all that water out and away.
If you got sandy grey/brown deposits in your flue, you are baking long enough and have no other problems. If you have shiny black deposits you might not be baking long enough, or have some other problem that needs addressed.

 

[MacinJosh]

That's been my experience too. 209$ every other year. These days, you can't even buy a cord of wood for 209$.

You replace your cat every other year?

 

[MacinJosh]

Yes. However, I like to see all those pets staying warm. I have been pheasant hunting the last two weeks and miss having a dog. But since this is a BK Thread.....I thought I'd challenge the loading capacity of my new KE40.....will all these half rounds fit?
View attachment 265238

Your back clearance is fairly close like mine. How warm do you find that back wall gets right on the corner? My thermal gun has shown close to 150 F before IIRC.

 

[Highbeam]

You replace your cat every other year?

Yes, for several cats now whether steel or ceramic. Honestly didn’t even get 2 years out of the steel cat I tried. See, I’m not a part time pleasure burner, I burn for 100% of my heat and while my climate isn’t as cold as some it is cold for a long time so I easily pass 10,000 hours in a couple of years. That’s not many hours for a full time burner.

Catalysts are only rated for 10-12 thousand hours of active life and that’s been my experience over and over again. You really know when they’ve worn out. They die a nasty, Smokey, tar creosote dripping, lack of heat, death.

But it’s totally worth it. A new cat is cheap and brings back that new stove performance plus wood savings that easily cover the cost of a new cat.

 

[Poindexter]

I agree with @Highbeam . With the combustor I am burning less wood. The replacement combustor is less expensive than all that extra wood to keep my house the same temperature would have cost in $, plus I didn't have to split it or stack or carry it in to the house. I am saving about two cords per year that I don't have to burn, still burning about 8 cords annually.

I replace mine when the performance has tailed off noticeably, having to load the stove more often or running higher than usual throttle settings, house seems cold for how much I am using, that sort of thing. First step is to shut it down, let it cool, remove the flame shield, brush off ash accumulation if there is any, put it back together, fire it back up and then if performance isn't restored order a replacement cat. And a gasket.

I don't know that I have ever had a cat fail, they just start failing to meet my expectations up around 15-20 cords and get replaced.

 

[Dustin]

Great discussion guys!

250 is an internal flue temp on a condor probe. And you’re right, that’s really cold.

My cat never dropped out. As a matter of fact it’s still active right now and the stove is still producing heat 26 Ish. hours later. But boy is my firebox shiney and gross...

 

[Dustin]

Just now, at about 26 hours in on softwood (alder / maple).

 

[lsucet]

Just now, at about 26 hours in on softwood (alder / maple).

View attachment 265353

The flue temp is okay nothing wrong with it at that stage of the burn. Rake the coals to the front and turn the air up, you will get some heat for awhile and the flue temp we will go up a little or you can load it, char the load and dial it down for the night.