secondaries burning FAST and glass turning black....?

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TTigano

Member
Jan 19, 2012
129
Southeastern, Ma
My wood is less than ideal and I finally got my door gasket fixed so figured i would load up for the overnight burn with some biobricks.... Got the stove loaded up on a hot coal bed and left the draft open full for twenty minutes or so... Continuously checking stove temp I look and see the top glowing again..... Thermometer reads right in normal burn range... WTF?.... Turned the blower on high and closed the draft fully and after 45 seconds or so lost the glowing....but the secondaries are glowing and are burning HOT...is this normal for them to burn this way?.... I've also noticed since I have completely shut off the air the glass is blackening instantly.... Will it clean itself next good burn? Stove is a Hampton HI300 insert.... Thanks.
 
Black glass most likely from wood loaded too close to glass along with not being dry enough.
Secondaries glowing- perfectly normal.
Top glowing, not normal.
Your going to damage stove if you keep getting the top glowing.
Cut the air down at a lower temp, somewhere before the top glows.
 
Hogwildz said:
Black glass most likely from wood loaded too close to glass along with not being dry enough.
Secondaries glowing- perfectly normal.
Top glowing, not normal.
Your going to damage stove if you keep getting the top glowing.
Cut the air down at a lower temp, somewhere before the top glows.

I wonder if my thermometer isn't working correctly.... I have it on top of the stove and it read WELL within normal burn even with top starting to glow.
 
Time for a new thermo.
IN time, you will learn to rely less on the thermo using it more for reference, and go more by the wood burning stage, flames air setting etc.
Is it directly on top of the stove firebox plate or is there a baffle or shroud on top that you are resting the thrmo on?
This is an insert isn't it?
 
Hogwildz said:
Time for a new thermo.
IN time, you will learn to rely less on the thermo using it more for reference, and go more by the wood burning stage, flames air setting etc.
Is it directly on top of the stove firebox plate or is there a baffle or shroud on top that you are resting the thrmo on?
This is an insert isn't it?

I have the thermometer ( purchased rutland two weeks ago ) mounted directly on top of stove in between the top of stove and bottom of the pot ledge. This is where the blower blows air through. Yes, it is an insert
 
Did I read correctly that the biobricks were place on a hot coal bed? Was this with a full charge of wood? How many biobricks?
 
BeGreen said:
Did I read correctly that the biobricks were place on a hot coal bed? Was this with a full charge of wood? How many biobricks?

Ah I missed that part somehow, a full load of biobricks would surely make that sucker cherry
 
BeGreen said:
Did I read correctly that the biobricks were place on a hot coal bed? Was this with a full charge of wood? How many biobricks?

It was about 8 biobricks ( the small ones ) or 1 pack from TSC.... I figured before I did it I now have a way to kill the air ( door gasket fixed ) and haven't seen warnings on it so if things got hot I would be able to cool it off....man was I wrong...... Probably stupid but won't do that again.....I don't think it was so much the heat in the firebox making the top red as it was more than likely the flames from the secondaries rolling over the baffle and towards the flue colar. I see now how important the right wood at the correct MC can make life easier...
 
Yeah, you need to be careful with those compressed wood products, they have pretty low moisture content. We use Ecobricks and they can really ramp up the heat in the stove quickly. If you're loading that many in, I'd suggest raking all the coals forward into one place, packing the bricks in relatively tightly so they are touching, and killing the air pretty quick. If the fire can surround the bricks on all sides, they get things HOT, FAST. I think the only times we've gotten the tubes glowing was using ecobricks. I'm pretty sure 5 is the most we've put in at a time, and that was a cool (a few coals left but not a hot coal bed) restart. Two splits n/s on the sides, 3-4 ecos e/w between and the remainder on top of those, either e/w or n/s. Makes for a good overnight/daylong burn.
 
Yes, I will not be doing that again... The only flames that were even visable in my stove were the secondaries... None on sides or anything... I guess we all make mistakes sometimes when learning this art...
 
With the air shut right down your glass will turn black since you are closing off the air to the airwash which goes over the glass.

pen
 
TTigano said:
BeGreen said:
Did I read correctly that the biobricks were place on a hot coal bed? Was this with a full charge of wood? How many biobricks?

It was about 8 biobricks ( the small ones ) or 1 pack from TSC.... I figured before I did it I now have a way to kill the air ( door gasket fixed ) and haven't seen warnings on it so if things got hot I would be able to cool it off....man was I wrong...... Probably stupid but won't do that again.....I don't think it was so much the heat in the firebox making the top red as it was more than likely the flames from the secondaries rolling over the baffle and towards the flue colar. I see now how important the right wood at the correct MC can make life easier...

Never put that many BioBricks on a large hot coal bed. Let the coal bed die down further by opening up the air, raking the coals to the front of the stove and putting one small split on top of the coals.
 
….."I don’t think it was so much the heat in the firebox making the top red as it was more than likely the flames from the secondaries rolling over the baffle and towards the flue"
Mine does that all the time with no problem.
 
I am trying to understand why the OP's glass was turning black. The bricks are bone dry, the fire is raging almost to the point of being out of control. So why can't he turn reduce the air without the glass turning black?
I have recently experinced this in my Homestead, not with bricks, but with small splits of <= 18% maple.
Thanks.
 
mtbon said:
I am trying to understand why the OP's glass was turning black. The bricks are bone dry, the fire is raging almost to the point of being out of control. So why can't he turn reduce the air without the glass turning black?
I have recently experinced this in my Homestead, not with bricks, but with small splits of <= 18% maple.
Thanks.

Like I said above:
pen said:
With the air shut right down your glass will turn black since you are closing off the air to the airwash which goes over the glass.

pen

W/out airwash air, volatiles from the wood still "fly" around inside the stove until they are consumed by the secondaries. W/out airwash having air, some of the unburnt fuel w/ stick to the glass and not be burned off.

pen
 
Same thing happened to me last night. Loaded up the liberty with 5 splits N/S and within 15 minutes the secondaries where firing like the bowls of he** and the front air tube was cherry red which is an all the time thing with this stove, stove top was 760 with the blower on low, watched to stove for an hour and when it came down to 700 I decided it was settled in and went to bed. Didn't reload until 9:30 this morning with a living room temp around 86.
 
I think he has a low draft issue. Good draft and a hot fire should keep any glass clean regardless of air wash or not. Puzzling though that ecobricks should burn clean enough that even under the worst conditions I couldn't see black glass.
 
If the wood or biobrick is too close to the glass it will soot up, even with a hot fire. If not, perhaps a gasket leak?
 
This all seems to be expected for a full load of biobricks on a hot coal bed with a faulty thermometer. You loaded up bricks on hot coals, then left the air fully open. This will heat the coals up really hot and probably start the bricks burning vigorously. The result will be lots of gas coming out of the bricks and burning very hot, so you had a glowing stovetop. The thermometer must be faulty. When you turned on the blower and shut down the primary air, the gas didn't stop coming out of the bricks because gassing from the wood is mostly controlled by temperature, not air supply. This led to tons of secondary flames plus blackening of the glass, both caused by a lot of wood gases in the stove. This all seems normal for the situation, which is not to say that the situation you have should be the norm, just that it all makes sense to me.

i would avoid loading up bricks on such a hot coal bed and/or be more cautious about leaving the air open after you load the bricks. I have not burned biobricks so I don't know how they react to hot coals, but it seems from your experience that they give off gases more rapidly than cordwood.
 
Wood Duck said:
When you turned on the blower and shut down the primary air, the gas didn't stop coming out of the bricks because gassing from the wood is mostly controlled by temperature, not air supply. This led to tons of secondary flames plus blackening of the glass, both caused by a lot of wood gases in the stove.

I think you are spot on, Wood Duck. Excessive off gassing from the biobricks - to the point that it could not all be consumed. I'll bet the stack was smoking too.
 
BioBricks loosely placed on a hot coal bed are going to outgas intensely. They are meant to be either packed tightly, or just a couple, mixed with firewood to help promote a brisk fire with less than ideal wood. The proper restart method is to pack BioBricks in tightly around a brick-sized pocket of hot coals in the rear of the stove. That should provide for a controlled burn.

http://www.biopellet.net/instructions.html
 
I don't know about other stoves, but even with cord wood I'm not leaving my air wide open for twenty minutes; Something would be glowing for sure! It's possible that with full air, the thermometer area wasn't heating up as fast as the area that ended up glowing. I like to bring my stove up to temp in a more controlled manner, letting different areas of the stove heat up at similar rates. Maybe this is what you normally do, but with the bricks it just took off on you...
 
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