Interesting Temperature Observation

[Its_Raw]

I had a fire burning for some time at 250 and realized I forgot to add preheated water to the loaf-size water pan. The pan was totally empty and right against the firebox opening, perpendicular to the length of the pit. With the empty pan in this position, the temps across the cooking grate was within 10-15 degrees. After adding boiling water, the temperature swing from the digital probe near the fire box and the probe by the stack started reading 30-40 degrees apart. I let this go for a while to see if it would settle down, and it did not. I turned the water pan 90-degrees (parallel to the length of the pit) and moved it toward the opening, still next to the fire pit. The temperature swing between the two probes reacted rather quickly and I have single digit temperature differences along the length of the cooking surface - many times it hovered just 2-degrees apart.

I am baffled the empty water pan vs the filled water pan caused such a swing considering it sat in the same position. The change in the position of the filled water pan was also surprising. Just rotating it 90-degrees and bringing it forward a bit made a very positive change. I understand the water provides some heatsink function, but to pull 30-degrees out and then not just by turning the pan does not explain the improvement.

What say you?

 

[Chasdev]

Stickburner pilots have been expermenting with altering the vector of the heat/smoke as it exits the firebox and enters the cook chamber for a while.
Directing the heat up as it exits the firebox seems to creat top down cooking and directing the heat/smoke downward as it enters the cook chamber reverses that tendencey.
You are probably experencing some form of that with your water pan.
Full or empty is probably not that important heat directing wise.
I'm gearing up to tinker a bit myself, now that it's no longer Africa Hot here in Austin...

 

[Smokin Okie]

Does the Brazos still have the baffle ?

 

[Its_Raw]

Yes, it does. But I have a newer one with the removable baffle. I have replaced it with the BBQHQ baffle that moves the hot air upward. The direction of the hot air going over the top of the pan (whether full or empty) and coming down near the stack is quite plausible. Maybe with the pan out of the way, the heat enters at grate level and is pulled across the grate to the grate-level exit into the stack.

 

[Chasdev]

Perhaps in some far distant future a stickburner "wind tunnel" type device will be invented and the lucky cloned brisket pitmasters can finally conqure the ultimate question?
Why is the flat overcooked and the point needs more time?

 

[radioguy]

Water acts as a barrier 212F. Try filling it with sand. sand will heat up and act as a thermal mass. I have fire brick in the bottom of my RF. I also have few brick in the space above the firebox. Really helps even out the temps.

RG

 

[Chasdev]

I've used water pans both deep and shallow but my (perhaps incorrect) impression is that adding steam to the cook chamber slows the rate of evap from the brisket which delays getting out of the stall?

 

[radioguy]

I've used water pans both deep and shallow but my (perhaps incorrect) impression is that adding steam to the cook chamber slows the rate of evap from the brisket which delays getting out of the stall?

Yes and it serves as a thermal mass set at 212F. Not good for bark formation.

RG