Differential temps

Jeepster47 · September 2016

When you first start cooking on an egg, it's hard to understand why the air temp inside the egg is not consistent.

It's somewhat easy to wrap your arms around the idea that there is a temperature differential based on elevation. After all, we do cook direct, felt line direct and raised direct for a reason. Pizzas are generally raised indirect to take advantage of the radiated heat coming off the dome. Plus, there is a noticeable difference between the grid and dome temp during the beginning of most cooks ... on low-n-slows they tend to normalize.

Last night I saw a fantastic example of temps being different from front to back. Did a monster chop cook with the protein elevated four inches above the felt line. Since the stem of the dome thermometer, on my large, is only six inches above the felt line, the grid and dome temps should have been very close ... yes?

I used the SmoBot to fire up the egg and had the pit probe at about 10 o'clock. The SmoBot doesn't use a fan, so no worries about the fire moving out of the middle of the egg ... that's where I start the fire ... one spot in the middle. Turns out that the natural airflow yesterday pushed the fire towards the rear of the egg and almost directly under the pit probe. The egg stabilized at 550 degrees, or so the pit probe for the SmoBot said. But, the dome temp read 460 degrees. A whopping 90 degrees difference from front to back ...

So, do pay attention to where the fire is located and adjust accordingly ... it wasn't the controller's fault that the temp gradient was different from front to back. Had I run the egg without a controller and the fire moved to the rear, I would have ended up with 550 degrees under the dome thermometer and somewhere around 640 degrees at the rear.

I probably should have stirred up the hot coals and let the egg re-stabilize. But, I was up against time and simply rotated the protein from front to back during the cook ... still took about 60% more time than usually.

Jeremiah · September 2016

I read the title and thought you meant the differential in your truck. Which would be just a little off topic I guess. Lol

itsmce · September 2016

Great explanation, thanks.

Darby_Crenshaw · September 2016

air temp is irrelevant when cooking direct, in my world anyway.

i don't pay too much attention to dome temp when searing close to the lump for example.

fwiw, there are temp differentials in all grills and cookers, except maybe convection ovens.

the heat element in an electric oven is well above 350, even though the temp says '350'. the closer you are to that, the more radiant heat there is.

and as the element cycles on and off, the temp actually goes up and down in an electric oven. the average may be 350, but it isn't rock-steady 350

in fact, the egg is probably more stable.

i don't worry too much about temps in the BGE. it's all relative

mikeinccfl · September 2016

Darby_Crenshaw said:

i don't worry too much about temps in the BGE. it's all relative

Wait! What? Newbie here... I can see where temps don't matter much to a direct cook but indirect, slow cooks?

Sincerely,
Confused in Eggland

Carolina Q · September 2016

mikeinccfl said:

Darby_Crenshaw said:

i don't worry too much about temps in the BGE. it's all relative

Wait! What? Newbie here... I can see where temps don't matter much to a direct cook but indirect, slow cooks?

People do "lo n slo" indirect cooks anywhere from 225-350°, even as high as 400°. The higher the temp, the faster it cooks, that's all. I don't know (or care) about brisket, but for pork butts, it doesn't matter much.

As for the OP topic, it's always hotter in the back. I cooked 4 leg quarters last night, 2 by the hinge and 2 by the handle. Direct, felt level. Had to switch places halfway thru because the hinge pieces were cooking so much faster. Yet the dome was a steady 400°. I never check grid temps so I have no idea what they were, just that they were hotter in the back.

When I cook on the weber, I don't know what the temp is, dome or otherwise. Haven't for the 25+ years I've owned it. I just use more charcoal or less and place the coals in different places depending on what I'm cooking. But I don't know the temp.

HeavyG · September 2016

Darby_Crenshaw said:

air temp is irrelevant when cooking direct, in my world anyway.

i don't pay too much attention to dome temp when searing close to the lump for example.

fwiw, there are temp differentials in all grills and cookers, except maybe convection ovens.

the heat element in an electric oven is well above 350, even though the temp says '350'. the closer you are to that, the more radiant heat there is.

and as the element cycles on and off, the temp actually goes up and down in an electric oven. the average may be 350, but it isn't rock-steady 350

in fact, the egg is probably more stable.

i don't worry too much about temps in the BGE. it's all relative

When cooking direct in my kamados I just use the dome thermometer as a guide to let me know if my fire has gone out.

When grilling a steak or burger or chicken I'll still just use the old "how long can I hold my hand over the grid" method to let me know if my fire needs more or less oxygen.

Foghorn · September 2016

@mikeinccfl, see Carolina Q's comment above and know that most of us do our low and slow cooks at whatever temp the egg seems to like that day. We don't sweat the difference between 225 and 275. We use meat temp and feel to determine doneness.

NorthPilot06 · September 2016

Foghorn said:

@mikeinccfl, see Carolina Q's comment above and know that most of us do our low and slow cooks at whatever temp the egg seems to like that day. We don't sweat the difference between 225 and 275. We use meat temp and feel to determine doneness.

True story. Many folks won't sweat the difference between 250 and 375 either (at least for pork butts).

As far as the differential in temperature goes, I would suggest that it's a byproduct of where the coals were lit (and caused more by radiant heat versus convective)...that's why, for quick cooks like burgers, I try to either light in multiple spots or give the fire time to spread organically.

nolaegghead · September 2016

The hot flue gas rises up along the inside of the egg around the heat shield (plate setter or whatever). That's usually hotter than the area over the shield where you cook. You probably already noticed ribs and brisket that hang over will overcook where they are in that flue.

Jeepster47 · September 2016

In the beginning, I used to tell my wife that the protein would finish tonight around x o'clock ... maybe. I didn't understand all of the variables that occurred in the egg, and thus, finish times were a little arbitrary ... one pork butt finished around midnight when it was supposed to be for dinner ... damn.

You guys who have cooked for years and years already intuitively understand the variables, but we have a lot of new cooks on the forum who don't understand!!! At least now they might look down at where the fire is located before they throw the protein on and plan accordingly. 90 degrees of difference front-to-back surprised me!

lousubcap · September 2016

I always put a platesetter leg to the back to help mitigate the delta T and light forward of center line but did not realize it could be such a difference. Given I now know, I'm good with my current process but thanks for the info.

THEBuckeye · September 2016

Go manual.

Learn temp control

It's not perfect.

But, it's not that hard, no matter the configuration.

Jeepster47 · September 2016

@lousubcap said:

I always put a platesetter leg to the back to help mitigate the delta T and light forward of center line but did not realize it could be such a difference. Given I now know, I'm good with my current process but thanks for the info.

Funny, you and I have the same data ... but, I place the plate setter leg directly under the dome thermometer to shield it from the radiated heat and the hot gases coming up the side. My temps seem to stay more consistent that way.

However, I will be moving the single starting point a little more towards the front of the egg.

Jeepster47 · September 2016

@THEBuckeye said:

Go manual.

Learn temp control

It's not perfect.

But, it's not that hard, no matter the configuration.

The differential temperature has NOTHING to do with the controller operation. Running the egg on manual could cause the same differential temperature.

mikeinccfl · September 2016

Thanks for the explanations! So much to learn, so many tons of meat to cook while learning. Maybe there's a market for a BGE simulator app...

theyolksonyou · September 2016

mikeinccfl said:

Thanks for the explanations! So much to learn, so many tons of meat to cook while learning. Maybe there's a market for a BGE simulator app...

My advice to you: relax, enjoy, cook to temp don't worry about temp gradients front to back top to bottom, unless you too are a retired engineer whose grandkids just moved many states away.

Carolina Q · September 2016

theyolksonyou said:

unless you too are a retired engineer whose grandkids just moved many states away.

he did that stuff before they moved. once an engineer...

DMW · September 2016

https://youtu.be/g8vHhgh6oM0

mikeinccfl · September 2016

theyolksonyou said:

My advice to you: relax, enjoy, cook to temp don't worry about temp gradients front to back top to bottom, unless you too are a retired engineer whose grandkids just moved many states away.

Cool! I'll double my standing order for Woodford Double Oaked and learn a sip at a time

JMCXL · September 2016

Great conversation
i am doing ok with my LS cooks ( don't worry about a temp range +/- 50 degrees) I watch it and all has been good. My problem with direct cooks (maybe both cooks) I don't let the temp stabilize enough before starting the proteins

Differential temps

Comments

Categories