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

[Highbeam]

More heartwood in the big ones?

Really big fir logs don't really have heartwood, mostly all red inside and you can't tell the difference until the very edge where there might be a bit of sapwood. These splits all had bark so were on the outside.

Does anybody that has "switched" to burning big splits noticed the need for higher stat settings? Plenty of heat, hot cat, minimal smoke, and normal burn time but maybe less surface area means you need more air for the same heat?

Or, and I would hate to think so but, maybe my cat is starting to die. I have always noticed the need to turn up the stat when the cat gets near end of life. This is year three on this cat or about 20 months of burning on this cat. I'm keeping an eye out for other symptoms of cat failure.

 

[chemie]

Probably has more to do with the fuel he is using. The cat can is stainless steel isn't it?

Nobody even noticed the melted and sagging stainless steel flame shield support thing under the cat ?

The fuel I use is overwhelmingly black locust. The wood is below %20 but not like % 15-16.
I mix it with kiln dried red oak and kiln dried pine. I set the stove low in shoulder seasons but other times I run it mostly medium-high to high trusting the stove that I cannot overfire it.
Am I running it too hot, if there is such a thing?

 

[Woody Stover]

Really big fir logs don't really have heartwood, mostly all red inside and you can't tell the difference until the very edge where there might be a bit of sapwood. These splits all had bark so were on the outside.

That one, upper left in your load pic, looks like about half heart, half sap but it could be an illusion.

Does anybody that has "switched" to burning big splits noticed the need for higher stat settings? Plenty of heat, hot cat, minimal smoke, and normal burn time but maybe less surface area means you need more air for the same heat?

Could be that the denser splits (heartwood) are slower to gas, and you have to open the air to speed 'em up a little. You hear dense wood described as "burning hot," but I'm not sure exactly how to interpret that.
A couple posters have said that dense woods gas slower. I'm going to experiment with that idea, in my SIL's stove with N-S loads where I can see what's going on. I'll put some faster-burning wood like soft Maple in the center, then flank it with some BL or White Oak splits and see if when it hits the dense wood, the burn slows down.

 

[Diabel]

The fuel I use is overwhelmingly black locust. The wood is below %20 but not like % 15-16.
I mix it with kiln dried red oak and kiln dried pine. I set the stove low in shoulder seasons but other times I run it mostly medium-high to high trusting the stove that I cannot overfire it.
Am I running it too hot, if there is such a thing?

I am not an expert, but to me it looks like you might be over firing this stove.

 

[jetsam]

The fuel I use is overwhelmingly black locust. The wood is below %20 but not like % 15-16.
I mix it with kiln dried red oak and kiln dried pine. I set the stove low in shoulder seasons but other times I run it mostly medium-high to high trusting the stove that I cannot overfire it.
Am I running it too hot, if there is such a thing?

Turn the dial down to minimum. If visible flames snuff out, your gaskets are probably in reasonable shape and the thermostat should be protecting you from overfire.

This could change in some circumstances (for example you have a tall flue, and a cold snap greatly increases your draft).

You should still do the dollar bill test every year, but you can do a quick check with just the dial.

The BK overfires we've seen here have all had excessive draft, faulty gaskets, or both. Thermostat malfunctions seem to be very rare.

I feel like even dry locust shouldn't change this math very much.

 

[Woody Stover]

The BK overfires we've seen here have all had excessive draft, faulty gaskets, or both. Thermostat malfunctions seem to be very rare.

I thought that if the stove gets hotter, the 'stat closed, slowing the burn and cooling the stove..?

I am not an expert, but to me it looks like you might be over firing this stove.

If that stainless got red hot, I think it could diminish its ability to resist rust..

 

[chemie]

Turn the dial down to minimum. If visible flames snuff out, your gaskets are probably in reasonable shape and the thermostat should be protecting you from overfire.

This could change in some circumstances (for example you have a tall flue, and a cold snap greatly increases your draft).

You should still do the dollar bill test every year, but you can do a quick check with just the dial.

The BK overfires we've seen here have all had excessive draft, faulty gaskets, or both. Thermostat malfunctions seem to be very rare.

I feel like even dry locust shouldn't change this math very much.

I can easily snuff the flame when I turn it down. I did dollar bill test prior to using the stove daily this season and adjusted the gasket at some locations. I do have a tall flue about 30’.

 

[Highbeam]

The fuel I use is overwhelmingly black locust. The wood is below %20 but not like % 15-16.
I mix it with kiln dried red oak and kiln dried pine. I set the stove low in shoulder seasons but other times I run it mostly medium-high to high trusting the stove that I cannot overfire it.
Am I running it too hot, if there is such a thing?

Minerals including salt in the fuel may contribute to the reddening. So too would super high heat. Seeing that sagging metalwork in the firebox, I'm thinking some high heat was encountered but can't say whether it was the cause of the red stuff or whether you should change your habits. Do you think the red stuff is a deposit or if it is corrosion of the actual firebox?

Myself, I would not continue running this stove at max output all the time on a 30 foot stack unless you are knowingly running it into the ground. Set her to medium and let the central furnace pick up the slack.

 

[Highbeam]

Could be that the denser splits (heartwood) are slower to gas, and you have to open the air to speed 'em up a little. You hear dense wood described as "burning hot," but I'm not sure exactly how to interpret that.

Again, this is softwood doug fir. There is no significant difference between heartwood and sapwood with douglas fir. It's all just wood or bark. The difference must be related to the larger splits and reduced surface area releasing gas slower.

 

[SpaceBus]

Again, this is softwood doug fir. There is no significant difference between heartwood and sapwood with douglas fir. It's all just wood or bark. The difference must be related to the larger splits and reduced surface area releasing gas slower.

I think only cedar has a noticeable difference in heartwood among conifers. My local spruce and fir have very little diffences across the grain surface unless the tree had some kind of health problem. The only difference I can tell in my splits are the centers being less dense, but that's probably more of a new growth timber thing than a conifer thing.

 

[Woody Stover]

There is no significant difference between heartwood and sapwood with douglas fir.

I've seen various Pines here, so I know what you're saying.
As an aside, I see BTU charts all over the place on DougFir. Have you burned any hardwoods that us more eastern folk might be familiar with, that you could compare it to?

 

[Alpine1]

In my BK European larch gave the same heat and burning times of beech. Larch is significantly heavier than pine or spruce that are, in turn, denser than silver fir (Abies alba). No idea about their American counterparts though.

 

[SpaceBus]

In my BK European larch gave the same heat and burning times of beech. Larch is significantly heavier than pine or spruce that are, in turn, denser than silver fir (Abies alba). No idea about their American counterparts though.

I find Tamarack, the same thing as Larch, to be fantastic firewood. I wish there were more on my property. I can only distinguish it from my spruce and fir by weight after I cut and split it.

 

[webby3650]

All this talk of pine, spruce and larch has me feeling guilty about burning all this hickory and oak in campfires!

 

[Diabel]

All this talk of pine, spruce and larch has me feeling guilty about burning all this hickory and oak in campfires!

No, I would not share that info here. I only burn punk stuff and branches in my fire pit. And I have endless supply.

 

[webby3650]

No, I would not share that info here. I only burn punk stuff and branches in my fire pit. And I have endless supply.

I happen to have more than I could ever burn. So I burn it.

 

[Woody Stover]

All this talk of pine, spruce and larch has me feeling guilty about burning all this hickory and oak in campfires!

I go for Pine every time..makes for a lively little fire. But maybe you build 'em a bit bigger.

 

[Highbeam]

I've seen various Pines here, so I know what you're saying.
As an aside, I see BTU charts all over the place on DougFir. Have you burned any hardwoods that us more eastern folk might be familiar with, that you could compare it to?

Not really. We have red alder, maple but I’m not certain if it’s called big leaf or sugar maple. Almost all of our available hardwoods are of low density. A few oddballs around like madrona but rare. All burn well though when dry!

Some Doug fir is definitely more btu rich than the rest. Variable pitch content and variable density are the big reasons. Sometimes it hisses and bubbles when first lighting it but it’s not water it’s pitch melting and boiling.

Here’s some boiling pitch from a super dry split of fir.

 

[webby3650]

I go for Pine every time..makes for a lively little fire. But maybe you build 'em a bit bigger.

Always big!

 

[SpaceBus]

Not really. We have red alder, maple but I’m not certain if it’s called big leaf or sugar maple. Almost all of our available hardwoods are of low density. A few oddballs around like madrona but rare. All burn well though when dry!

Some Doug fir is definitely more btu rich than the rest. Variable pitch content and variable density are the big reasons. Sometimes it hisses and bubbles when first lighting it but it’s not water it’s pitch melting and boiling.

Here’s some boiling pitch from a super dry split of fir.View attachment 252859

My Balsam fir does this, especially if they have more bark.

 

[Woody Stover]

We have red alder, maple but I’m not certain if it’s called big leaf or sugar maple. Almost all of our available hardwoods are of low density.

Yeah, I think that's Bigleaf Maple out there. I'm seeing 22.7 mBTU..not too bad but I'm sure Doug Fir is better than that.

 

[Poindexter]

I have been burning off some very pleasing scraps of Doug Fir. I have been piddling about with entry level timber framing joinery, mostly making expensive saw dust and chips. I have been buying the stuff labeled DFir and S-GRN, it is pretty uniform at 19.99% MC as near as I can tell.

It is much denser than my local spruces and burns pretty nice, especially down around 15-16% MC.

I also have another flue temp data point. I don't have an approved waiver yet to burn during air quality episodes, so had to shut down (not add fuel ) for about 36 hours or so. The house cooled down to about 68, -11 dF outdoors. I have it running like a train, top of the swoosh throttle, convection deck fans on high and the box fan down the hall supplying cool air from the bedroom floors. I am about halfway through burning the whole load in about 2.5 hours. Flue gas temp is right around 450dF if my Condar is credible.

 

[Highbeam]

I have been burning off some very pleasing scraps of Doug Fir. I have been piddling about with entry level timber framing joinery, mostly making expensive saw dust and chips. I have been buying the stuff labeled DFir and S-GRN, it is pretty uniform at 19.99% MC as near as I can tell.

It is much denser than my local spruces and burns pretty nice, especially down around 15-16% MC.

I also have another flue temp data point. I don't have an approved waiver yet to burn during air quality episodes, so had to shut down (not add fuel ) for about 36 hours or so. The house cooled down to about 68, -11 dF outdoors. I have it running like a train, top of the swoosh throttle, convection deck fans on high and the box fan down the hall supplying cool air from the bedroom floors. I am about halfway through burning the whole load in about 2.5 hours. Flue gas temp is right around 450dF if my Condar is credible.

When you say flue gas temperature are you speaking of internal temperature as read with a probe meter? If so, your numbers are very low. The cat needs above 550 to be active. My internal flue gas temperatures easily approach 900 on max stat setting.

 

[Poindexter]

When you say flue gas temperature are you speaking of internal temperature as read with a probe meter? If so, your numbers are very low. The cat needs above 550 to be active. My internal flue gas temperatures easily approach 900 on max stat setting.

I had the combustor probe indicator way above the word "active" on that dial a while ago.

I drilled my double wall telescope about 19" above the firebox, the Condar probe sits in about the middle of the inside of the pipe and is supposedly reading gas temp, not wall temp. First I drilled a through hole to fit the probe and then a larger hole in the outer layer of pipe to seat the magnetic bushing that is part of the unit.

Running out of stuff to burn that isn't carbon I am about 3:15 after a cold start, I am keeping everything on full throttle, top of the swoosh all the fans running to finish this load off down to just charcoal so I can reload and go to bed, I have another 14 hour day tomorrow.

When the last of the flame dies out in the box my combustor probe should be right at that white tick mark just a quarter inch up in the active zone, the same place the combustor probe sits when I run a half bag of hardwood lump charcoal out of my BBQ supplies, and the same tick mark where my stack plume goes from some opacity to no opacity, just steam.

Just in the ten minutes or so since I took the picture my flue gas probe is down to about 350 dF, and the combustor probe has closed half the distance from where it was to the tick mark I was banging on about in the previous paragraph.

I'll reload soon, get it ripping and see how high I can get the Condar flue gas probe to go, outdoor ambient is -12dF forecast to -30 tonight.

 

[Poindexter]

So hot reload. Clearly in the tail end of the burn, check, see previous post. Shut down convection loop bringing cold air to stove room check. Shut down convection deck fans, check. Combustor probe within a couple or three needle widths of the magic tick mark, check. Wait two minutes for air flow convection loop down the hall to wallow like soft jello and then disintegrate, check.

All of this to avoid giving the combustor a facefull of cold air. The total stove is raging hot, I just burnt down a full load of good dry spruce in about four hours. I can't stand within about six inches of the stove without the hair on my legs getting extra curly.

Have a quick snack, check. Stand between the stove and the hallway to the bedrooms, confirm convection loop is stopped, check.

Flip big lever to bypass, check. Stuff it like a holiday turkey



Run it with the door cracked until the chimney starts huffing whoo-fuh whoo-fuh, about ten seconds. Close the loading door. Get the load charred good by waiting for a slow count to 60 before flipping the big lever. After slow count to sixty, channel Jean Luc Picard, engage, full swoosh.

Run that 25 minutes with fuel at 13-14% MC and get to here:


Now the load is baked and ready to be controlled in a predictable manner. I could turn all the fans back on and start pulling BTUs off that thing like cases of beer off a UHaul truck, or I can turn it down and coast it for hours and hours and hours. Either way the flue gas probe will drop pretty quick. I turned this load down to 5/8 swoosh and my flue gas probe is showing a touch under 600dF in just a couple minutes. Another 3-5 minutes I will pop it down to somewhere between 3/8 and 1/2 swoosh and it should settle in right around 400dF flue gas temp. The combustor probe will start coasting down over the burn. I should be able to do another active cat hot reload 8-10 hours from now no problem.

I make an effort to not be dogmatic about disputable stuff. I am personally a firm believer in running the stove on high for thirty minutes ( at least 25 minutes with dry fuel at 12-16%MC ) before trying to turn it down for a long slow burn. I know folks do it all the time and don't have any problem. I also like running on high for 30 (25 with dry fuel) minutes before restarting the convection deck fans and the box fan down the hall on the floor. At the end of the 30 (25 dry) burn on high I need long pants to stand within 12" of the stove, but my burns are approximately as predictable as gravity.

If you are new to this stuff and your burns aren't consistently predictable and your fuel is at 17% MC or higher try tuning out the folks getting away with RTFM errors for one week and see if suddenly your BK stove is about as dependable as an anvil.

I turned the thermostatic control valve (the throttle dang it) from 5/8 to 7/16 after 3-5 minutes at 5/8. I have no visible flame, black box, flue gas probe is showing 450dF and dropping. If tomorrow was Saturday and I could sleep in I could probably do a hot reload (on an active combustor) 16 hours from now.


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