Lump Burn Rate in XL

Ozzie_Isaac

Condition:  Egg = XL, Lump = Rockwood, Load = 13 lbs, Egg Temp = ~240 deg F, Weather = 15deg low/40 deg high drizzle, Burn Time = 20hrs, Consumed Lump = 7.8 lbs, Lump Left = 5.2 lbs

Burn rate was 0.4lbs/hr

Process:  I completely emptied my XL out.  I cleaned all the ash and removed all the old lump.  I put some big pieces of rockwood carefully on the bottom, worked to place the lump, got tired of doing that and dumped the rest in.  I filled the egg up to the top of the fire ring.  I moved the lump around until my Woo2 and stone would fit on top of the fire ring and not the lump.  I lit a small fire in the center of the lump.

Next I attached my Flame Boss 100 and hit go to 190.  Temp climbed to 300, fought with that for 2 hours, finally realized the copious amount of foil I used around my wires was keeping the lid slightly propped open and I could actually see into it from around the dome/base intersection.  Well no duh I couldn't cool it off.  I fixed that and the temp began to drop.  When it hit 280 I put on a 9.5 lb brisket.  Temp ramped down to 240 and stayed there for the duration of the cook, except for a minor ramp of 30 minutes at the end.

The weather over night was cold, it began to rain around 9am the next day and drizzled on and off till i pulled at 5:45PM.  At that point I capped the Egg and shut it down.  Total burn time was 20hours.

I removed all the lump left and weighed it.  I had 5.2 lbs left.  So I could have gone for another 10 hours or so.

Side notes, I weighed all the bags of Rockwood I had and @stlcharcoal might want to retrain his guys.  They loaded exactly 21 lbs in all 6 bags I have, even though I only bought 20lb bags  ! I guess I can forgive the occasional pebble I have come across

Also, when your wife asks why you are bringing the scale to the garage it is best not to answer.  When your neighbors ask why you loaded all the used lump into grocery bags, again it is best not to answer.  People might get the wrong idea and begin to think you are crazy.

Here is a pic today after everything cooled down:



Here is another pic after I stirred and reset all the lump:

stevesails

Mmmmmm.  Way too complicated stir dump and light.  Clean out when full of ash. 

Ozzie_Isaac

stevesails said:

Mmmmmm.  Way too complicated stir dump and light.  Clean out when full of ash. 

Thats normally what I do.  I was curious though.  I have now satisfied that curiosity.

Foghorn

stevesails said:

Mmmmmm.  Way too complicated stir dump and light.  Clean out when full of ash. 

That's my practice, too.  But I love that @Ozzie_Isaac took the time to do a little science that benefits us all by letting us know just a little more about our eggs.  THANK YOU.

Grillmagic

Is that the top of the fire box or the fire ring? I maybe doing something wrong. Here is what's left after a 12 hour cook at 275 with lump filled to the top of the fire box. This is the relit lump for tonight's cook.

Ozzie_Isaac

@Grillmagic if you did your 12hr cook with no issue then you are doing nothing wrong.

I filled to the top of the fire ring this time.




 Normally I fill to the middle of the fire ring.

thegooddocta

Nice research! :]

DoubleEgger

Bravo sir. You definitely redeemed yourself from the earlier miscalculation. You get a 10 here. 

Ozzie_Isaac

Thanks @thegooddocta, @DoubleEgger and @Foghorn .  Sometimes I over think things, but its part of the fun to me.

DMW

I was resisting clicking on this thread because I had a feeling differential calculus was going to be involved, and it was way too late for that kind of craziness...

But thankfully my brain has not been strained back to calculus. Your XL lump consumption is similar to my results. I've never weighed mine to get empirical results like you did, but looks about the same. I'm fairly certain @stlcharcoal has mentioned before they overfill their bags intentionally to compensate for the occasional piece of kiln shelf that end up in the bag, etc. 

Ozzie_Isaac

@DMW I've seen that mentioned before.  I was very surprised at how consistent all my bags were.  Jonathans process must be very good, which isn't surprising considering the quality of his lump (yeah no real good way to word that last sentence)

Jeepster47

@Ozzie_Isaac ... don't forget the tare weight of the bag ... not much, but still.  When some were talking about rocks in the bag, Jonathan mentioned that all bags were overfilled to guarantee full value.  He mentioned a figure more like a half a pound.  Now he'll probably go check the scales and reduce the overage ... geez, way to spoil a good thing.

Ozzie_Isaac

@Jeepster47 I did account for the bag.  I used the same bag for all the measurements.  Even the used lump measurement.

The main issue I have is the lack of cal cert for my scale

stlcharcoal

Jeepster47 said:

@Ozzie_Isaac ... don't forget the tare weight of the bag ... not much, but still.  When some were talking about rocks in the bag, Jonathan mentioned that all bags were overfilled to guarantee full value.  He mentioned a figure more like a half a pound.  Now he'll probably go check the scales and reduce the overage ... geez, way to spoil a good thing.

First and foremost so we don't get nailed by the State's Weights and Measures inspectors.  But yes, it also covers for any rocks or a scale issue. 

And yes, the bags do weigh something.  The old bags were heavier than the new ones (3 ply 50# paper), the new ones are stronger but lighter (2 ply 70# paper).