Obsessing over pit temps?

farris

New member
good info

I work with ovens everyday. It is part of my job and what I have been trained for. So I have a bit of knowledge on this subject.

Most of your ovens around today use on/off thermostats and rely on "average" temps. If you take the highest and lowest swing in temp then add those two numbers together and divide by two that will give you your "average" temp. If you were to sit and watch a fluke reading the temp changes in your oven you would think there is something wrong. But this is normal and how they work. I have customers who will put a oven thermometer in there and then complain it is not accurate.

The older ovens with a constant pilot used a modulating thermostat like I have in my gas smoker. These ovens can keep a constant temp. The capillary tube is filled with fluid that expands when heated. As the oven gets closer to your set temperature the modulating thermostat will continue to reduce the size of the flame until it reaches the set temp. These thermostats are also used in many commercial ovens for restaurants because they offer very even temps and consistent cooking results.

When electronic ignition came into play and there were no longer standing pilots the modulating thermostats went bye-bye.

Electric ovens also have swings because of the slow cooling and heating of the electric element. Electric ovens that have a PID controller can keep temps with 1 degree because the thermostat is "smart" and knows how fast the element can heat the cabinet and will throttle power to the element to keep a constant temp. However those are usually specialized ovens(I have a PID on my Bradley) in manufacturing where very accurate temps are critical.

And it is very important to pre-heat newer ovens...

I had a customer that complained her new oven needs to be calibrated because she has burned several trays of brownies. I asked her did she wait until the oven was pre-heated before putting the brownies into the oven and she said yes. So I placed the thermocouple from the fluke meter on the rack and started the oven. After 12 minutes the oven ramped up to 485F and then to my surprise the oven controller beeped indicating the oven was pre-heated. The digital display on the oven showed it was at 350F but that was not the true temp. It took another 15 minutes for the oven to finally level off to reach an average of 349F. So the lady was placing a tray of brownies in a 485F oven and that explained why her brownies were burned. It was not out of calibration just the way the oven operated.

So the old saying "know your pit" can also apply to your home oven.
thanks for the great information. I was thinking about using a gas over thermostat for my 6ft smoker but wasn;t sure til reading your post. I'm also wanting to make a 6ft burner out of pipe, you got any suggestions? Thanks, Farris
 

Saxguy

New member
Anyone who is overly obsessed about temperature swings should switch to sous vide cooking, exclusively. It's the only way to achieve an accurate, constant temp over time. That being said, I couldn't imagine cooking everything sous vide - you'd miss out on a great deal of textures and flavors that can only be imparted by other methods of cooking. I'm still trying to figure out a way to incorporate smoking and sous vide. Part of me wants to try to do the intial smoke on the smoker and then replace the foiling steps with the sous vide. I may give that a go once I have everything set up.

Actually, scratch that - one of the basic principles of sous vide is that you need to vacuum pack while the meat is cold. I think it may be counterproductive to do the inital smoke, cool everything down and then bring it to final temp in an immersion circulator.
 
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Tucson BBQ Fan

New member
Hi Big Poppa,

I have a few questions on this thread. I come from the wood stick burner world of smoking - been smoking on a Pitts and Spitts horizontal offset wood box smoker for years.

I fully agree and understand about temperature swings. Doing long smokes on a wood burner means you get very used to building up the fire, holding it steady for a while, then it starts to drop and you need to add more fuel. And, I agree, as long as you average out over a long smoke, and don't get too high of an upper temp excursion, you can turn out great BBQ. On my stick burner, I have one thermometer, at one end of the pit, down low near where the meat would sit. I have to know my pit and have a good idea how the temperature varies at other parts of the pit, even on the upper shelf which can be 50-70 degrees hotter!

You said: "It's so hard to explain that the readouts on most pellet cookers use an algorithm to give you an average or monitor one spot of the pit and report that."

I don't mind an average of several probes, or a single probe point - I'm used to that. What I do want is to see a reasonably accurate temperature reading. I've learned to limit my temperature adjustments to no more often than every 20-30 minutes (and actually consider that kind of obsessive - once an hour is much better)!

Some of the reasons I bought a Pellet smoker are: (1) self feeding and control - so I can sleep all night long and not wake up every few hours to add fuel and make adjustments, (2) digital controllers - improved accuracy and response in controlling temperature.

So - my question: Is it normal on the current generation of pellet smokers to have the "actual" temp display be 25-50 degrees off the steady state real temperature inside the pit? I fully understand that the actual temp is going to vary around the set temp, there will be some oscillation and variation, etc. But, I'm talking about the accuracy of the actual temp display.

My question is the accuracy of the "actual temp displays" of the various makes of pellet smokers.
 

Ozric

New member
I'm not BP, and can't speak to the Memphis and MAK controllers, but the Yoder controller calculates and displays a running average of the temp it reads on the pit probe. Your ET732 pit probe will likely display a different temp that the grill's controller for that reason. There's a good reason on the software side to do that. That's what little I know on the subject, and that's plenty little indeed! LOL
 

Tucson BBQ Fan

New member
I'm not BP, and can't speak to the Memphis and MAK controllers, but the Yoder controller calculates and displays a running average of the temp it reads on the pit probe. Your ET732 pit probe will likely display a different temp that the grill's controller for that reason. There's a good reason on the software side to do that. That's what little I know on the subject, and that's plenty little indeed! LOL

How different have you found them to be? I don't mind a running average, but when it is consistently way off, I get concerned. If the temp is not changing real fast, I'd expect maybe a 5 degree difference max between actual and average.
 

Vegasmailman

New member
All makes sense. But I love to BBQ for the pleasure of it. It takes away some of the pleasure I think when you noticed the temp are going up and down when you want a regulate temp, then I become obsess with watching it. Which is one of the main reason I got the pellet was for the ease of grilling,lol. But one good thing is my outdoor frig is c lose to my grill which makes getting a beer much easier then returning to the house to get one:)
 

JoeMay00

New member
Quick background on me. I am an engineer (nuclear power) and dealing with system temperatures is a very big part of the job. So you can trust me when I say it is almost impossible to avoid "hunting" around a desired temperature. Nearly every system does it, even nuclear reactors. Without very sensitive (and expensive) controllers that others have mentioned, it is unavoidable. That being said, over time, the these temp swings should level out to an acceptable level and +/- 20 for food application should be fine. Additionally, air does not transfer heat well (think of deep frying vs skillet frying vs baking/smokeing all at 350 deg). Add to the fact that this is indirect heat and the affect your food sees due to fluctuations is minimal. The Average, not instantaneous, temp is what you need to focus on.
I just became a pellet head myself, switching from a vertical electric smoker. I have a lower end model (made by smoke hollow) but am very pleased with the results so far. I took time to get to know my grill during the seasoning process using a 4 probe igrill (iphone tracker app as well) and the installed temp. It's initial overshoot was about 50-60 deg then it undershoots by about 20 deg until it settle out after about 45 minutes with a +/- of 5 deg between the igrill probes and the installed digital gage.
The lesson here is nothing new. Get to know your grill and understand the limitations of your equipment and that these fluctuations are not affecting your meat as much as you think. So set it, relax and have beer.
 

emlawpro

New member
Hi, I'm new to this site and came here for exactly this discussion since I'm a pellet griller. I have a suggestion for pellet heads who are distressed by the wild temp swings they see during a cook: Get an accurate analog thermometer that sits on the grill. They are slower to react to the temp swings and will, in this case I believe, give you a more accurate read on what your grill is really doing. My grill, a Green Mountain pellet smoker is by definition a lot like a convection oven, and when that blower is on my digital thermometer skyrockets to more than 40 degrees over desired temp, then drops to 20 or 30 under when it turns off. The analog thermometer doesn't react fast enough to these swings and gives me a better look at what temp I'm averaging. My only issue with the analog device is that I have to open the smoker to take a peek. Wondering if there is anything out there in the analog world that is attached to a wire that can be read remotely. Thx
 

mcschlotz

Member
Welcome emplawpro, glad to have ya! Since you can only smoke with what equipment you've got, understanding how our pit behaves is very important. I personally recommend avoiding opening and closing the pit as much as possible as it only serves to further expand the temp swings. It's all about constant temp over the length of the smoke to create good eats :p
 
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Kurt Reeves

New member
To me this is all part of the fun. Sure smoking is all about drinking beer, enjoying family, etc. But if that was all it was, we wouldn't even be discussing said matters on a forum like this. I agree that the small temp swings have little to no affect an the food but for most of us, we obsess over everything BBQ. From pits, thermometers, rubs, sauces etc. We will spend hundreds of $ on a thermapen to get our product exactly 1/10 of degree more accurate than before. There has been so many advancements in BBQ over obsession, so I say keep at it guys. Awesome forum by the way...who knows one day well will be BBQ'ing with Nuclear Reactor type equipment and can hold a pit to 1/100 of a degree. But someone with try for 1/1000!! LOL

Kurt
 

TentHunter

Moderator
Kurt, what a great way to think about it! Necessity is the mother of invention and someone felt it was necessary to "get more accurate temps," or "create a electronically controlled smoker that utilizes pellets," and such.

And welcome to the forum!
 
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