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View Full Version : I have a UDS internal heat question


ClintHTX
11-27-2011, 05:04 PM
I have a 2" probe thermometer mounted externally on UDS. I heard that the temp in the middle will be 50 to 75 degrees warmer is this right and should I go by this? I don't have any other way of getting a reading on the middle. Not until Santa brings me a fancy maverick 732 for Christmas. Watcha guys think?

Skidder
11-27-2011, 05:09 PM
See if u can find a 12" turkey frying thermo

BigBobBQ
11-27-2011, 05:19 PM
it is possible go to lowes, walmart, or someplace and get one of those $4 oven thermometers and put it in the center of your grate and when it gets to temp open it and check to see the difference. I just use a 10" turkey thermometer poked through the hole in the side and it gives me the center grate temp really close to within 10 degrees.

smokeyw
11-27-2011, 05:25 PM
Mine does run about 50 to 75 degrees hotter in the center unless I put in some sort of heat sink between the charcoal basket and the cooking grate. I usually use a pizza stone unless I am cooking pork butts. You will be able to see this if you put in a 12" turkey fryer thermometer and compare it to your thermometer with the short probe.

colonel00
11-27-2011, 06:50 PM
Remember, it isn't always exactly in the middle either. At least for me and my lazy weed burner method of lighting my coals. Usually the fire migrates to a certain area and buries under the coals. So, areas over the coals are going to be hotter and not necessarily right in the middle. That being said, as long as you have a decent idea of the temps, you will be fine. Anymore, I just light the thing and let it go. If you worry too much about the temps you will be chasing them and never win. For instance, I could have a 15" turkey fryer thermo with the tip in the middle 1" under the grate, my Maverick probe in the center just above the grate and a couple oven thermos spread around the grate. The will all read differently and I have come to accept that that is just the way it is.

BigBobBQ
11-27-2011, 07:48 PM
colonel I agree I don't even worry to much about it any more, just use the thermo to give me a general idea if I am hot or cold I usually cook by listening to the meat and by probing, alot more than times and temps.

smokeyw
11-27-2011, 07:59 PM
Really, the only issue I had with the temp difference is when cooking ribs. The center slab would get done prior to the ones on the outside. That is when I installed a rack just above the fire basket for the pizza stone. It evened the heat out nicely. It's not a problem with butts since I put 3 on a rack and can space them so there is not one in the very center. I do worry about temps more since I cook in competitions and timing is critical. If it doesn't matter when your food gets done, temps don't matter much (within reason).

JMSetzler
11-27-2011, 08:03 PM
I have a 2.5" probe mounted on the outside of my drum. When I first tested this issue, I registered about 25 degrees warmer in the middle, but I'm, using a 16" pizza pan as a diffuser also. Every drum has its own personality and will be a little different. To compensate for the difference, I just adjusted my external thermometer to read about 25 degrees higher than actual temp (at ambient outside temp) to get it closer to mid drum temp. They don't have to be right on. Just close.

BillywannaQ
11-28-2011, 12:47 PM
Hey Carl, have you thought about using a diffuser? You can get a terra-cotta saucer at home depot for pretty cheap. If you don't like it, you can buy you wife/significant other the matching pot and give her a plant. Those temperature differences were too much for me, so I got a diffuser. Good luck to you whatever you decide.

Carbon
11-28-2011, 01:22 PM
After all the experiments I ran using multiple thermometers with different probes I ended up mounting my short stemmed Tel-Tru on the dome lid as my ONLY thermometer and plugged up all the experimental probe holes on the drum. I got to know my UDS better and learned to 'read' the dome thermometer during my cooks. My cooks are now more consistent (using K blue) and I am no longer concerned with the actual grate temp.
I am happy with the way my UDS functions now.

ClintHTX
11-28-2011, 03:11 PM
Hey Carl, have you thought about using a diffuser? You can get a terra-cotta saucer at home depot for pretty cheap. If you don't like it, you can buy you wife/significant other the matching pot and give her a plant. Those temperature differences were too much for me, so I got a diffuser. Good luck to you whatever you decide.

Explain to me what this heat diffuser is and how it works please. I'm still a noob

Carbon
11-28-2011, 03:58 PM
I don't think it makes much difference whether you use a clay saucer or a thin pizza pan. IMO, the additional thermal mass of the saucer is insignificant in the UDS. Besides, a pizza pan is cheaper and a lot easier to handle due to its light weight. I would just get a 16" diameter pizza pan.

WvSmoke
11-28-2011, 04:02 PM
I have a 2" temp probe as well. I have checked the temp on the grill with an oven thermometer several times and it is always within a few degrees of the probe. Maybe I'm just one of the lucky ones.

BillywannaQ
11-28-2011, 05:32 PM
Basically, it diffuses the more intense heat from the middle of the drum out to the sides and then up and out the drum. From what I've seen (as I use one) this give more equal temps from the middle to the drum to outer edges. It's not gonna be like one or two degree difference though. More like a ten to fifteen degree difference (in my drum anyway). I think a clay saucer would also work as a sort of heat sink also. Good luck to you.

42BBQ
11-28-2011, 06:05 PM
When I use the pizza stone (wrapped in foil for easy cleanup) I only have about a 10* difference in temp from my maverick pit probe and my side mounted 2 inch thermo. I lay my stone right on top of my coal basket. At the start of the cook it is only about 4 inches above the top of my lit coals. If you use a diverter you will have longer cooks and burn more fuel. As a result I normally cook butts up a little higher (240 to 260*) as far as pit temp goes.

42BBQ
11-28-2011, 06:08 PM
Carbon, a while back somebody did a four part biscuit test on a drum using no diffuser, a pizza pan, a pizza stone, and maybe one other item. Pizza stone worked best but not a huge difference if I recall correctly. I'll search it. Also, my wife picked up a real mice stone at a yard sale last summer for about $5

42BBQ
11-28-2011, 06:08 PM
Nice not mice ;)

Carbon
11-28-2011, 06:18 PM
Carbon, a while back somebody did a four part biscuit test on a drum using no diffuser, a pizza pan, a pizza stone, and maybe one other item. Pizza stone worked best but not a huge difference if I recall correctly. I'll search it. Also, my wife picked up a real mice stone at a yard sale last summer for about $5Yes, thanks, I remember that thread very well. :)

As far as pizza pans go I've been using an 18" perforated pan with good results.
http://i31.photobucket.com/albums/c362/jojisan/P1060228.jpg