Dome VS Grate Temperature

KenfromMI · June 2014

What type of differences are you guys getting between your dome thermometer temperature and your grate temperature. I know this can vary but an approximate would be appreciated, Ken

Skiddymarker · June 2014

The grate is the thing that holds the charcoal so it is very hot....

) The grid is the place we cook food.

For an indirect cook, you can expect the difference between grid and dome to be anywhere from 20º to 50º, the grid being the cooler. The reflected heat and convection air flow makes the dome hotter, that's why we cook pizza high in the dome.

For long low and slows, the temps will get much closer together as the cook progresses.

For direct cooks, the grid will be hotter by similar amounts as it is closer and exposed to the IR of the burning lump, that;s why we sear down low.

lousubcap · June 2014

Temperature is a reference to enable you to approximate the cook time and rate of cooking the food-as long as whatever device you use is calibrated then you can plan accordingly. There are thermal gradients within the BGE so get comfortable with how the BGE cooks at whatever temp you choose as a bench-mark and go from there. Just an opinion and we all know what those are worth...

KenfromMI · June 2014

That's kinda why I'm asking. On another forum for the WSM guys were saying their top grate is 25 to 30 degrees hotter. On my WSM I find the top grate is 15degrees lower and the lower grate 12 degrees lower than that. I haven't checked my BGE yet and was just curious. I'm amazed I'm in the minority with my WSM though. I did calibrate the dome thermometer when it was new but maybe it's time for a re check after 8 or 9 years............I agree about relative to the cook as well. I always used dome temperature and internal and never really cared too much about grate temperature.

Skiddymarker · June 2014

If I understand your post above, seems like the WSM is working just fine. Temp at the "dome" thermo would be at least 15º above the upper grid, while the lower grid might be as much as 30º cooler than the "dome" thermo. The WSM convects very much like an egg, it just doesn't hold the heat as well.

For indirect cooks, I set my temp probe on the grid, that's where the food is, that;s the temp I care about. The dome thermo is for reference only. On directs, I use the dome thermo only.

kthacher · June 2014

I monitored this through a four hour cook of chickens yesterday. This is the second or third time I have paid close attention to these temperatures. I see the opposite. Once I get to steady state, the grill is always hotter than the dome. Yesterday was was with the plate setter, so indirect.

I disagree with the idea that there is any reason for the dome to be higher temp, considering that the hottest part of the egg is at the coals. Why should we expect a temperature profile that somehow drops to the grid, and then increases to the dome? Hot air rising does not explain such a strange behaviour.

So here is what I saw yesterday. This is consistent with my measurements from other cooks.

1. Bring dome to desired temp and wait for smoke to stop billowing. Temp at about 225

2. Add two chickens to grill above plate setter. Clip probe to grill - maybe three inches from bird.

3. This stage is the only time during the entire cook that grill temp is lower than dome. I suspect due to localized effect of the probe being near the cold meat.

4. Stage three lasted maybe half an hour, where grill temp was lower than dome. But the gap gradually closed.

5. I then cooked with dome at 210 to 225 for about three hours. Grill temp was consistently around 20 degrees higher.

6. Near the end of the cook, due to time concerns, I turned the temp up to around 400. Throughout the temperature rise, the grill temp was CONSISTENTLY higher than dome. At times by as much as 50 degrees, as the temp was rapidly rising.

KenfromMI · June 2014

Kthacker, no idea why. I'm checking mine again on my next cook on the WSM. I figured that when the heat rises it is passing through a larger area. Then when the heat hits the dome it cannot escape out of the daisy wheel at the same rate it passes the top grate. The heat builds up and gives a higher dome temperature. Why are upstairs rooms on a two story home always hotter than downstairs rooms in the Summer?..........If I re calibrate my thermo and get the opposite result that would mean I have been cooking at a much higher temperature than initially thought and it has worked out well in all my cooks, Ken

Carolina Q · June 2014

I have never checked... or cared. In my oven, the temp sending sensor is at the top. Same with my egg, So I figure most recipes are to be cooked at the temp where the sensor is located.

KenfromMI · June 2014

Carolina, I agree and my BBQ is always enjoyable. I was just puzzled how people with the same units can have direct opposite results. I go by dome and internal. I guess when I get my Party Que I'll start knowing my grate temperature better.

kthacher · June 2014

Ken, Your house is different. You don't have a fire burning in the basement.

Carolina Q · June 2014

KenfromMI said:

I guess when I get my Party Que I'll start knowing my grate temperature better.

I have a DigiQ and I still don't know. I clip the probe to my dome thermo.

And if I'm also using my Maverick, I clip that up there too. Don't recall ever checking grid temp.

KenfromMI · June 2014

Well I'm a Cop not a Scientist but I do have a Huge Boiler from 1925 in my basement that gets just as hot LOL We will see on the next cook, I have three Polders so I'll lay all three on the grate and do an average.

mlamb01 · June 2014

Was the temp probe on the grid placed in the shadow of the platesetter? If it is exposed to direct heat, it can cause it to read higher than the dome. I did a 10 hour pork butt this weekend, and while my dome temp read 275 to 300, my grid temp was reading 230 to 250. I made sure when I put the probe on the grid, it was shielded from the direct heat of the coals.

jfm0830 · June 2014

I have become a convert to measuring everything on the Egg at the level I am cooking at. I went through a three month stretch from November to January where I was making the same rolls and desserts that I had made a year ago for the holidays and I was having TOTALLY different results. My various baked goods were starting to burn on the bottom, even though the tops hadn't completely cooked. I was doing everything the same, but having different results. <BR><BR>

But there was actually a difference as it turned out. What I finally figured out was this winter was about 30 to 40° colder than the winter before. For short cooks like baking, there was a wide variation between the dome temperature and the grill grate temperature. It was taking the dome and the grill grate a much longer time to get in equilibrium with one another. So going by the dome temp I was actually using a grate temperature that was way too high. I went back to the way I have used every other grill I've owned, which is measure the temps at the grate level where the food is cooked. I have had ZERO problems since then. The food is cooking in the right ballpark time and is evenly cooked. For me the dome thermometer no longer exists. Your mileage may vary. <BR><BR>

Jim

SidZer0 · June 2014

So when cooking a pork butt on the grate, temp shoul be monitored by the grate temp and not the dome temp correct. What if your cooking on an elevated grate say 5" above the main grate with a Woo and plate setter below?

smbishop · June 2014

Most of the recipes and comments on this site refer to dome temp, unless specifically stated as grill temp. So on an indirect with a dome temp of 250, the grate at the felt line is around 235 at the start of the cook. I have found they stabilize several hours into the cook. So if you are 5" above the felt, the grate would be closer to the dome temp.

That being said, with a butt, 25 - 50 difference in your target dome temp is not going to make a difference with the end result.

jfm0830 · June 2014

SidZer0 said:

So when cooking a pork butt on the grate, temp shoul be monitored by the grate temp and not the dome temp correct. What if your cooking on an elevated grate say 5" above the main grate with a Woo and plate setter below?

I'd put my temperature probe at the grate level 5 inches up. While many recipes for the Egg are written for the dome thermo, the problem comes with the extremes of weather. I'm sure the recipes for the Eggs are written with 70° Atlanta weather in mind and the assumption that the grate temperature is about 50° off from the dome. The problem I was having is a lot of baked goods are only a 20 minute cook. Even letting the Egg stabilize for a while wasn't really helping in the super cold weather. The dome temperature was simply all over the place depending on whether was 30° or 3° out. I was seeing variations of over 100 degrees between the dome thermometer in the readings I was getting my on my Maverick at my cooking level. This meant I was cooking nearly 100° higher than what I should've been. I use the AR myself and one of the things I like about it is if I can't fit a probe right of the grate level, I will add a shelf just below the level I'm using and put the grate probe there. By the time the clip for the grate probe is taken into account, the grate probe is right underneath the level of my food anyway.

Dome VS Grate Temperature

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