Bull Bull Temperature Probes Testing and Unit Calibration

[Brickhouse]

Ok, so after my first 4 cooks I noticed some issues in my end product, mainly.....under cooked. My first 4 smokes were the following with results:

- 9lb Pork Shoulder: Smoked at 225 for 9hrs. Had to raise temp continually last 1.5hrs in order to get it to 195. It was 10hrs before it was close....I pulled it and when I attempted shredding it was not ready, very tough. I blamed the shoulder and my haste in getting it done by jacking the temp up. Still decent....but not great.

- 6 standard chicken thighs: Had to get dinner done, so did them at 350 for 40 mins. Pulled them and they were pink/red in center. Not good, ruined dinner.

- 3-2-1 Pork Baby Back Ribs: Standard 3-2-1 and they were fantastic, hard to mess these up though.

- 7lb Whole Chicken: Smoked at 225 for 3hrs.....wasn't getting to temp, had to raise temp and go another 45 mins. Pulled at what I thought was 155. Cut into chicken and red liquid poured out.

After this 4th cook I knew I had an issue. Where the issue was, I wasn't sure. I either had Temperature Probe inaccuracy or smoker temperature inaccuracy...but something was not right. So I dug into this forum and some other areas and found some methods to test/calibrate. The following is what I did in order to identify the issue and correct it.

First: I decided to run the test on the temperature probes. I did this by first find 2 other temperature probes that I know and trust. A quick stab kitchen probe and my previous go to, an iGrill Weber probe.

I filled an RTIC full of ice, added water, stirred and let it sit 3 minutes. I then stirred again and dropped in my 2 trusted thermometers and waited for them to reach the desired 32 degrees assuming they were good. Here is a picture of that result:

As I had figured, my two non RecTec probes were dead on....32 degrees. Now I knew I had two accurate probes I could use in the rest of testing, and I knew the ice/water test was accurate.

Second: So I moved on to testing the RecTec probes in the same manner. I went out to the Bull, plugged both probes in, turned on the Bull just to get it powered up and functioning, and dropped the two RecTec probes in the same ice/water. Below is a pic of that:

I waited a few minutes and then took the read off of the unit, see below:

As you can see, the probes were dead on as well. This was great news. It's my understanding the calibration of the probes is either not possible or difficult without replacing the unit, so I was happy to see this. So at this point I had eliminated the possibility of the probes being inaccurate.

Third: I moved on to testing the actual temperature accuracy of the unit itself. Was the unit heating/maintaining the temperature that the read out was saying.

I conducted this test by setting the Bull to 350 and placing the probes on a brick (see below) so that they were suspended above the grates and only testing ambient temperature rather than the touch of the metal. This picture only shows the RecTec probes, but I later added the iGrill just to put a 3rd in there I trusted.

I let the Bull run for 1 full hour before making any measurements. However, I did look at the app from time to time to see how things were progressing. I could tell early on what the issue was going to be. I let the Bull hold 350 for one hour and took the following reads from my thermometers. See both pics below:

As you can see......both thermometers measured the ambient temperature of the smoker to be 330 when the unit itself was set at and telling me it was 350. My Bull was reporting a full 20 degree difference in temperature. I had discovered my issue. So....how to fix it?

Fourth: Thankfully, the RT-700 works with the app that can actually calibrate the temperature read out of the smoker itself.

I opened the app --> Selected the Control option at bottom --> Selected my grill name --> Selected the "cog/widget" in the upper right corner --> Selected "Temperature Calibration" --> Set it to "-3".

I then let the smoker do its thing another 30 minutes.......after 30 minutes my new readout was, see pic below:

Much much better.

I have yet to do another cook with the new calibration, and I will follow up with how it goes, but at least wanted to post this for anyone having similar issues, so show how I got to what appears to be a solution.

*Edited to fix pictures and title more accurately.

 

[Mike]

Wow, great set of troubleshooting steps and glad you ending up finding the issue.

It's my understanding the calibration of the probes is either not possible or difficult without replacing the unit

This is only true on the older Rec Tec Bull controllers. The newer controllers are very easy to calibrate the meat probes. I can do mine directly from the mobile app.

 

[Brickhouse]

This is only true on the older Rec Tec Bull controllers. The newer controllers are very easy to calibrate the meat probes. I can do mine directly from the mobile app.

Ok, where are you accessing that option....not that I need it now, just curious. I just received my RT-700 BULL less than a month ago. So I assume I have the newest controller.

I see in the app where I can adjust the calibration of the smoker itself....but not the meat probes. Where is that at?

 

[Mike]

@Brickhouse I believe I stand corrected, you don't do it through the app but on the grill itself.

Press and hold the Gear (Settings) button then scroll until you see PrA (Probe A) and PrB (Probe B). During the dial allows you to calibrate the temp up or down.

 

[Whitey]

Oh, great info. I noticed something similar last weekend smoking a 8lb pork butt. I smoked it for about 7 hours at 225. Then wrapped for another three hours and it still was about 180. I raised the temp a few times to 275 or so and that got it moving a bit, but it was getting late so I pulled it. The meat probe temp seemed to be right as my hand held probe showed the same temps. It was good, but not as cooked through as it should have been. I'll try this for next time.

I've also read that the rear-right side of the grill tends to be hotter and the front-left tends to be cooler. Cooking burgers seems to prove that out. So I've considered moving meat around with that in mind.

 

[navydroid]

It depends on the firmware installed on your controller. To know, you'll have to get into your settings and look for this:

Probe Calibration: 3 PrA - The screen will display PrA, the current probe temperature offset degree value will be displayed under. Turning the knob will increase and decrease the value by degree within -15 to 15 degrees.
Probe Calibration: 4 PrB - The screen will display PrB, the current probe temperature offset degree value will be displayed under. Turning the knob will increase and decrease the value by degree within -15 to 15 degrees. Values are degree based not percentage based.

Online Manual:
https://www.google.com/url?sa=t&sou...FjAAegQIARAB&usg=AOvVaw2YHOh5Vs4d_YcrTgoiF0Sv

You will have to access this option from the actual controller in the grill, no app. Hold the setting button in, when the screen comes up, cycle to the PrA and PrB if you have the option. There is another thread on here we've been talking about the same thing.

https://www.rectecforum.com/threads/how-to-calibrate-meat-probes-or-thermometer.88/#post-1022

 

[Cowboykirch]

I opened the app --> Selected the Control option at bottom --> Selected my grill name --> Selected the "cog/widget" in the upper right corner --> Selected "Temperature Calibration" --> Set it to "-3".

@Brickhouse nice write up, thanks. I’ve already calibrated my meat probes and I intend to calibrate the internal barrel probe tonight.

I’m curious though, wouldn’t you need to adjust the calibration to “-6”? It gets a bit confusing because it seems like the meat probes are calibrated in degrees, whereas the internal probe is calibrated in percentage points?

The math looks like this:
350 degrees * .06 = 21
350 - 21 = 329 (very close to your 330 temp you stated was being read).

If you watch the Rectec video online, they did 250 set point and got 225 actual. To adjust they lowered 10 percentage points.
250 degrees * .1 = 25 degrees
250 - 25 = 225 degrees

However, your pics showing the revised temp would suggest you did it properly? Any insights?

 

[msarro]

@Brickhouse nice write up, thanks. I’ve already calibrated my meat probes and I intend to calibrate the internal barrel probe tonight.

I’m curious though, wouldn’t you need to adjust the calibration to “-6”? It gets a bit confusing because it seems like the meat probes are calibrated in degrees, whereas the internal probe is calibrated in percentage points?

The math looks like this:
350 degrees * .06 = 21
350 - 21 = 329 (very close to your 330 temp you stated was being read).

If you watch the Rectec video online, they did 250 set point and got 225 actual. To adjust they lowered 10 percentage points.
250 degrees * .1 = 25 degrees
250 - 25 = 225 degrees

However, your pics showing the revised temp would suggest you did it properly? Any insights?

I'd definitely like to see this better explained as well.

IMO, the current implementation is kind of confusing from a user perspective. I build systems like this for a living (writing APIs and such, developing firmware, etc). If I was the one designing this particular system, my preferred solution would have just been to allow end users to punch in a degree offset rather than a percentage. So, if it's under by 20 degrees, go into set mode, rotate the knob to -20 and commit. Then let the controller do the percentage calculation on the back end away from the user's eyes, and save the resulting percentage the same way the current percentage offset gets saved. It would make it a bit more user friendly, and this approach would work whether you're using fahrenheit or celsius since it's still just calculating a percentage offset.

AFAIK they're just using an arduino microcontroller to do all of their lifting, and I don't think it would have any limitations on either storage or doing the math. And arduino language is just C and C++, so the languages themselves wouldn't have any limitations.

But somewhere, that design decision was made, and most likely it was made for a reason. So, I don't wanna rag on what other devs have done because I know necessity can sometimes make for some seemingly wonky solutions, lol. But at least outwardly, it looks like there could have been a better way. In general, you don't want end users to do math - it's too easy to make mistakes and for end users to have a bad experience as a result.

 

[CopperDoc]

If I was the one designing this particular system, my preferred solution would have just been to allow end users to punch in a degree offset rather than a percentage.

The reason it's done as a percentage is because the error usually isn't constant. If it's off by 20 degrees at 250, it'll be off by more at 350 or 450.

 

[msarro]

The reason it's done as a percentage is because the error usually isn't constant. If it's off by 20 degrees at 250, it'll be off by more at 350 or 450.

Yup, you are 100 percent right about it not being constant.

The way I mentioned though, you'd still be storing it as a percentage offset inside the controller, right? You just ask the user to input an offset in degrees. Basically, prompt the user for the offset in degrees, and then accept their input. Then on the backend (hidden from the user), the controller would do the math to calculate the percentage offset so the user doesn't have to. So, it's still being stored as a percentage, it's just arriving there a little differently.

Like I said though, I'm an outsider looking in. There could be other very good reasons that approach would be taken vs some other approach. But since the result would still be a percentage offset being stored somewhere, I can't immediately think of it causing any major issues.

Edit: Rethinking what I wrote a bit, I can see what you mean. If a user calibrates at 350, and then heats to 500, there could be a use case where they go back into the menu and check their calibration. Since you wouldn't be storing their original offset, you'd have to calculate it based on the percentage offset. You'd also need to modify that function to show the new degree offset, which could be equally confusing to an end user when their -20 degrees is now -40 degrees or whatever.

 

[Cowboykirch]

I intend to calibrate the internal barrel probe tonight.

Mine was off by 8% points, OOTB. Set point 300, grill internal probe read 300, already properly calibrated probes read 275 after 1 hour. I adjusted “-8” and let it warm up 20 more minutes and then I had everything read the desired 300. I found my meat probes to only be a couple degrees off but the barrel probe appeared off quite a bit OOTB. Hope others take this worthwhile step!

 

[CopperDoc]

Yeah, this ain’t your grand dads old stick burner. The temp control is more accurate than my electric oven.

These are computer controlled ovens!

 

[NU2SMOKE]

@Mike @Brickhouse @Uncle Bob I can tell you guys now that when I finally get my new grill...you guys are going to be my new best friends getting it setup from the get go...LOL Since I cant cook for you guys youll have to settle for constant pics of my endevours.?

 

[Uncle Bob]

Congratulations! However, if you're only going to taunt us with pictures instead of actually sharing the food then you're on your own bud...…………………...

 

[NU2SMOKE]

Congratulations! However, if you're only going to taunt us with pictures instead of actually sharing the food then you're on your own bud...…………………...

Ok how do I get fresh smoked BBQ to you in Texas.

Unless your coming for a visit?

 

[FrontierAJL]

Mine was close to 8% off OOTB also. Calibrated and everything has been ok so far. Annoyed when I had to do it because it’s new but glad I was able to do it.

 

[bfletcher]

I appreciate reading this thorough detail but I'm confused. My understanding is that your findings concluded an inaccurate pit temp reading and accurate meat thermometer probe readings. If I have the correct understanding of your issue, how did that result in under-cooked food? Didn't you gauge doneness by the food probe(s)?

I ask because I'm in the middle of my first smoke on the RT-700 and early indications suggest that the controller is reporting a higher-than-actual pit temp, though its unlikely I'll make a calibration adjustment from my first attempt.

Thanks

 

[Seattlepaul1975]

So something I was wondering......I did my calibration yesterday, one was high by 2 and other low by 2. Easy fix. Are the calibrations tied to the probe or the probe port? So if I mix prob a/b on the next cook, is it off?

 

[Wslayer]

Not sure it would really matter, but in their video he marked the probe that was off with where it was plugged into so would be the same each time. ? ? ?

 

[Seattlepaul1975]

I didn't pick up on that in the vid. I did label them so I was clear on it for future......was wondering.....it's the techie in me curious on the probe or the unit tracking it.