Blaze King King 40 New Cat Stove 2020 Smoke Smell

[RogueChili]

I mentioned the testing of the new door and the BK rep verifying the location of the leak. During our conversation he mentioned he owned a older model King and has no issues with smoke smells. I asked if he would use my draft gauge and make measurements at different temperature settings so we can compare. Long story short, overall his draft measurements are not a good as what I measure in my installation. I use the phrase "as good" because of the negative values in draft measurements make it confusing.

From the start I have not found draft specifications however decided to find the manual for the older King; to my surprise these measurements are in print in the old manual (attached) and for some reason removed from the new manual .

This is the requirement in the manual for the older king:
"Flue Collar 8” I.D.
Recommended Flue Draft .05” water column (on high burn)
.02 -.03 in. water column (on medium fi re)"

I can tell you in my setup there is .02" water column when the chimney is stone cold, kindling brings it up to .05 never mind low burn; at high burn I see .07 - .09 depending on outside temperatures.

What the hell is going on here!

 

[Highbeam]

Too much draft can cause problems too. On average, the firebox pressure is negative but the air wash “blasts” the glass with air. There is turbulence that leads to different pressures throughout the firebox.

Also, “medium” or “high” burns are not really what they seem on the BK. The thermostat closes the intake even with the thermostat knob set to “medium” once the stove heats up, it also opens up the flapper really far until it heats up so it’s kind of confusing to measure at the right time.

Either way though, your draft sounds strong!

 

[RogueChili]

Yep, glad someone finally said it, and that is exactly the defect in the design! I know that, proved it experimentally, difficult to convince others.

Where the turbulences exist are a function of the tolerances of the stove components and their positions. Each stove is slightly different, welding positions, shield angles and so on, explaining why the leak is prevalent in some stoves and not others.

I bet there are others out there, easy to prove, bring it up to high temperature for half hour, turn it down to middle, wait about ten minutes then test around the top of the door with the cone, if your sense something harsh it is leaking. It may be slight but the cone will concentrate it and let you find it.

 

[webby3650]

test around the top of the door with the cone, if your sense something harsh it is leaking. It may be slight but the cone will concentrate it and let you find it

Ahh, the old smell the dogs ass after a poop trick! 😂

 

[Highbeam]

With regard to the studs under the door gasket, I don’t like it either but a skilled gasket installer can make a good seal despite this obvious challenge. It is particularly easy to underapply the rtv bed or to push the gasket into the rtv too hard with your fingers vs. by bedding it with the door.

 

[RogueChili]

Regardless how skilled one may be unless the High Temp rtv bed is at the height of the stud the compression force will be greater at the studs. Additionally, depending on the centerline of the hinge pin vs the top of the stud there is a good chance the stud will create a fulcrum point and as the door closes causing poor engagement between the stud and hinge. Then when you attempt to compensate by adjusting the latch the door will bend.

A skilled gasket installer will replace the nuts with thin jam nuts and grind the studs flush to them before going any further.

 

[Highbeam]

This is not a head gasket on an engine. The gasket has a lot of squish ability to fill in between these “imperfections”. It’s been working pretty well for decades. Though I would prefer a better design this is not a show stopper.

 

[rdust]

Too much draft can cause problems too. On average, the firebox pressure is negative but the air wash “blasts” the glass with air. There is turbulence that leads to different pressures throughout the firebox.

Also, “medium” or “high” burns are not really what they seem on the BK. The thermostat closes the intake even with the thermostat knob set to “medium” once the stove heats up, it also opens up the flapper really far until it heats up so it’s kind of confusing to measure at the right time.

Either way though, your draft sounds strong!

Thank you for typing it so I didn’t have too!

 

[RogueChili]

I agree, the system is not a show stopper, and doesn't matter if it does leak as long as the fire is controllable. It just aggravates me whenever I think about it.

Good description of the "flapper" operation. Lets expand the conversation, what happens to the air velocity in the firebox as the working temperature approaches the set temperature?

 

[stoveliker]

I beg to differ on the turbulence argument with respect to the door. Turbulence only results in incredibly small pressure differences across a space. Yes, it can go from below to above the nominal pressure in the box, but only to such a small degree that I don't think it would measurably affect the leak rate out through a decently functioning gasket. If such small differences would matter, the gasket would be leaking like crazy and you'd be seeing burn rate changes.

Moreover, turbulence would result in variable places with "overpressure", i.e it would not consistently leak in one place on the gasket.

Finally, the airwash happens, i.e. the flow happens, because the box is seeing underpressure, lower than the outside. It is, on average, not higher than the outside pressure. Moreover, the fact that the air is flowing (rather than static) means that the actual pressure there is even lower than the static pressure would be. (Bernoulli).

Given all this, I think that the cause is not gas pressure or gas flow thru the gasket. I think the cause is permeation of the gasket by liquid (creosote) that then evaporates on the outside side of the gasket. (Yes, liquid can wick thru a fiber based material even if the gas tightness is good.) Surface tension forced (causing wicking) are much, much larger than any of the minute gas pressure differences present in the system would cause.

 

[RogueChili]

Everything you say is sound however the liquid creosote theory is not the cause, at least in my application. The liquid will take some time to penetrate the gasket and the leak occurs with a brand new gasket installed and on the first burn cycle.

From the time you set the stove from high to "black out" mode (I read that term somewhere and love it!) there is a long delay before the leak is detectable opening the possibility that small positive pressures focused in one area of the gasket over long period of time may very well be the cause. The fact that the leak is in only one specific location supports this possibility.

By the way, pics of the glass stains would be very helpful and appreciated.

 

[stoveliker]

Everything you say is sound however the liquid creosote theory is not the cause, at least in my application. The liquid will take some time to penetrate the gasket and the leak occurs with a brand new gasket installed and on the first burn cycle.

From the time you set the stove from high to "black out" mode (I read that term somewhere and love it!) there is a long delay before the leak is detectable opening the possibility that small positive pressures focused in one area of the gasket over long period of time may very well be the cause. The fact that the leak is in only one specific location supports this possibility.

By the way, pics of the glass stains would be very helpful and appreciated.

That makes sense (new gasket).
Pic of my window here. Not sure if that's what you meant.

 

[jdonna]

Wondering what your length of pieces you are running? I’ve noticed more smell from longer pieces in my princess on occasion.

Keep the updates and theories coming.

 

[moresnow]

Everything you say is sound however the liquid creosote theory is not the cause, at least in my application. The liquid will take some time to penetrate the gasket and the leak occurs with a brand new gasket installed and on the first burn cycle.

From the time you set the stove from high to "black out" mode (I read that term somewhere and love it!) there is a long delay before the leak is detectable opening the possibility that small positive pressures focused in one area of the gasket over long period of time may very well be the cause. The fact that the leak is in only one specific location supports this possibility.

By the way, pics of the glass stains would be very helpful and appreciated.

Have you ever tried going from char mode to black out mode in a few steps instead of one fell swoop? I have and I think it may be worth a try. Let it run 10-15 minutes at each reduced setting. Worth a shot!

 

[RogueChili]

Sure, I did the incremental steps, only delays the leak.

Topic for discussion, theory on the cause of fumes exiting the door attached.

 

[stoveliker]

Hm, I find your stain pattern, widening at th bottom, suspect. Mine, and all I've seen, are V or U shaped, not X shaped like yours. This to me suggests the bottom of the door leaks (in).

I have a hard time believing combustible gases can enter the air wash system ("manifold"). After all there is always a flow there, regardless of whether the flapper is closed (courtesy of the hole).

I do also see asymmetry, and I think your thoughts on that are correct.

These are just my observations and thoughts.

 

[RogueChili]

Two observations lead me to believe that combustibles are entering the manifold during low air velocity conditions, when you change temperature settings from hi to low and enter blackout mode you can see the smoke flow pattern, which is from top to bottom on the sides of the door, when looking carefully there is a slight swirling pattern and upward flow around the left manifold area, additionally there is a slight brown streak projecting into the manifold in that same corner which lead me to believe some type of combustion is takin place. The theory is the pressure of the circulating gases is slightly higher than the pressure in the manifold at the corner. When you think about it the natural flow out the channel is straight across not down especially at the corners however when both left and right air streams collide in the center pressure is created across the manifold due to the gap at the glass. If the air flow is low pressure can not build enough to pressurize all the way to the corners.

 

[stoveliker]

if you have brown stuff deposited into the tube, that's undeniable.
However, getting in there a few inches is not by far reaching a place where it could go out again (crossing the stove to the back and then down).

Do you smell it at the air inlet?

And did BK comment on the (odd to me) pattern on your window?

 

[RogueChili]

No, there is nothing exiting the air inlet, only the top left corner of the door.

 

[Vgk]

Did anything come of this?