Temperature Accuracy Question

[SeanT17]

Question for those smarter than me in here regarding the temperature controller.... I put a 9.5 lb brisket on at midnight the other night at 225F. As you can see from the pics, my RT-590 shows that it maintained a rock solid temp all night long. When I got up to check it at 8am, the thickest part of the flat was temping 206 and the point was 210. I'm no competition cook, but I've done a few dozen briskets and it defies logic how it could reach those temps in just 8 hrs at 225. I was able to wrap it with tallow and salvage the majority of it, minus some charred parts at the point.

Afterwards, trying to figure out what went wrong, I troubleshot it with a different temp probe. Yes, I know what Recteq says about using 3rd party temp probes, but it was reading 90 degrees hotter than what the RT was indicating. I called RT customer service, and the gentleman was very polite and appeared very knowledgeable, but couldn't explain this to my satisfaction. Just said that I need to trust it. He said that my brisket must have been an anomaly but the probe is accurate and if it fails it will be an an extreme high or low. My question is, how can a temp probe right next to the brisket feel a temp of 315 while the brisket is feeling what the RT is sensing? It clearly cooked MUCH faster than expected and charred parts of it. His explanation left a lot to be desired and now I'm not trusting the smoker. Can anyone with a better understanding explain this in layman's terms for me? Thanks

By the way, the thermometer I was using has been calibrated and I've verified it's accuracy in both my standard and convection ovens at various temps, so I know its accurate. And I checked the temp at various parts of the barrel, including right next to the RT probe.

 

[Jim6820]

All I can say is that I rely on my ThermoWorks Signals 4-probe unit for all meat and cooking chamber temperature monitoring. I trust it a whole lot more than I trust the Recteq system. The mechanics of the RT units are generally OK, but the temperature monitoring and wifi connection part is very suspect for me.

Would I buy another Recteq? Probably not. I am reasonably satisfied with the RT-340 that I have in the context of it providing a decent heat source and cooking chamber, but the technology aspect is far-from-perfect.

 

[Waterboy]

Have you done the other cooks on this grill? Is running this hot a new phenomenon or have you had trouble with hot temps before?

The grill is clearly an older model grill (or at least an older controller) so if you picked it up used someone may have messed with the settings. You can adjust the “offset” setting to get the actual temp in line with what the controller is showing. You will get a hotter reading on the second shelf (not 91 degrees though) so you need to consider that.

You could also check the RTD to Make sure it is straight up. If it’s leaning too close to the side of the grill or too close to the third party second shelf that could be causing wonky temps.

 

[SmokeZilla]

Very interesting situation. I will start with the obvious. All proteins are not made alike. I typically use the 1.5 hours per pound for well marbled prime and Waygu or 1.0 hours per pound when the marbling is light or if it is a choice cut, or if it is over trimmed and the fat is almost non-existent, and I have not been too far off. I do notice a difference in cook time if/when I use true grass fed brisket versus grain fed, versus dry aged. For some reason, the grass fed tend to cook on the fast side. This is especially true if the meat came from Trader Joe’s or Whole Foods. I assume this is because of the low fat versus meat ratio but I never took any time to research the reason. I have a butcher friend that also told me that grocery stores will sometimes inject their product to increase the weight (lbs = $$$) or increase the shelf life. YMMV. Obviously I am speculating on your results but if we throw enough at the wall sooner or later something should stick.

With regard to your temp question, I was told many years ago by a RecTeq technician I asked that RT uses a special algorithm on their probe to compensate for latency and to “anticipate” the pellet feed rates to keep the overall temps steady and minimize the “oscillating temperature effect” that are present on other manufacturers’ cookers. That was why they purposely selected the PID controller they use and get the results they achieve. Interestingly, I “drank the “Kool-Aid” because I probed my unit with other probes from different companies and they were close to each other but not as close to the reading I saw on the RT Bull’s display. They were always slightly off. To further aggravate me, you are not supposed to use the RT built in probes for measuring ambient temperatures. They are “meat probes” not temperature probes. Whereas my Meater, Thermopro’s, inkbird, and Taylor are dual purpose. Who knew!!! I am hopeful my explanation is plausible, if not, I look forward to any corrections from the forum participants that have their own perspectives or theories.

Good luck with your future cooks.

 

[SmokeZilla]

Sorry for ranting. I just realized I have an example of your discussion point. Here are some fairly recent pictures.

 

[Tontotom]

Smoking at low temperatures without monitoring is all the hype but I suggest checking the temperatures at different locations in your smoker at different set points. I have a 340 and have a 20 degree higher temperature on the right side compared to left at 225. At 400 degrees it 50.

The 340’s internal probe is on the left side out of the airflow and goes through the control before it displays. By putting the meat and probe up on a rack it’s in the airflow allowing more convection cooking. It looks like the flat is to the right on the grill. On mine I always position the thicker part to the right as it’s the hottest part of the smoker.

I’ve used the offset control to get my smoker to run at 180-190 degrees on the smoke setting. I still use my Smoke X4 to determine what temperature I’m actually getting.

 

[SmokeZilla]

Smoking at low temperatures without monitoring is all the hype but I suggest checking the temperatures at different locations in your smoker at different set points. I have a 340 and have a 20 degree higher temperature on the right side compared to left at 225. At 400 degrees it 50.

The 340’s internal probe is on the left side out of the airflow and goes through the control before it displays. By putting the meat and probe up on a rack it’s in the airflow allowing more convection cooking. It looks like the flat is to the right on the grill. On mine I always position the thicker part to the right as it’s the hottest part of the smoker.

I’ve used the offset control to get my smoker to run at 180-190 degrees on the smoke setting. I still use my Smoke X4 to determine what temperature I’m actually getting.

Tonto…,

I agree. I sometimes forgo this check on smaller cookers but on larger, it is very important to understand the hot versus not, spots. I had/have several stick burners and even with my Bull, used calibrated gages and thermocouples to verify temps. Fortunately, this only occurs when major changes or alterations happen with the equipment but it does give you clues about your capabilities and limitations.

 

[SmokeOCD]

I’ve used the offset control to get my smoker to run at 180-190 degrees on the smoke setting. I still use my Smoke X4 to determine what temperature I’m actually getting.

Have you had an incredibly bad experience that you're that precise, or perhaps your career field has you super scientifically precise? Not knocking your methods at all; smoking and precise temp control is a little foreign to me coming from offset, barrels, wsm, etc - with not a lot of control at all, just hoping for moderate swings when you can't quite lock it in depending on the weather and the wind.

 

[SeanT17]

Have you done the other cooks on this grill? Is running this hot a new phenomenon or have you had trouble with hot temps before?

The grill is clearly an older model grill (or at least an older controller) so if you picked it up used someone may have messed with the settings. You can adjust the “offset” setting to get the actual temp in line with what the controller is showing. You will get a hotter reading on the second shelf (not 91 degrees though) so you need to consider that.

You could also check the RTD to Make sure it is straight up. If it’s leaning too close to the side of the grill or too close to the third party second shelf that could be causing wonky temps.

I've had this grill for about 2 1/2 years, bought brand new. Have only started noticing issues for the last 5 or 6 cooks but this was the most obvious one, hence why I am reaching out for help. I agree that on the 2nd shelf it'll be hotter due to the convection properties of these styles of grills but yes, 91 degrees is excessive.

 

[Waterboy]

I’d give the offset adjustment a try and see if it fixes the problem, and holds, or if it moves hotter from there. At least if you call customer service again and they can see you ”fixed” it then it moved again.

 

[SeanT17]

Very interesting situation. I will start with the obvious. All proteins are not made alike. I typically use the 1.5 hours per pound for well marbled prime and Waygu or 1.0 hours per pound when the marbling is light or if it is a choice cut, or if it is over trimmed and the fat is almost non-existent, and I have not been too far off. I do notice a difference in cook time if/when I use true grass fed brisket versus grain fed, versus dry aged. For some reason, the grass fed tend to cook on the fast side. This is especially true if the meat came from Trader Joe’s or Whole Foods. I assume this is because of the low fat versus meat ratio but I never took any time to research the reason. I have a butcher friend that also told me that grocery stores will sometimes inject their product to increase the weight (lbs = $$$) or increase the shelf life. YMMV. Obviously I am speculating on your results but if we throw enough at the wall sooner or later something should stick.

With regard to your temp question, I was told many years ago by a RecTeq technician I asked that RT uses a special algorithm on their probe to compensate for latency and to “anticipate” the pellet feed rates to keep the overall temps steady and minimize the “oscillating temperature effect” that are present on other manufacturers’ cookers. That was why they purposely selected the PID controller they use and get the results they achieve. Interestingly, I “drank the “Kool-Aid” because I probed my unit with other probes from different companies and they were close to each other but not as close to the reading I saw on the RT Bull’s display. They were always slightly off. To further aggravate me, you are not supposed to use the RT built in probes for measuring ambient temperatures. They are “meat probes” not temperature probes. Whereas my Meater, Thermopro’s, inkbird, and Taylor are dual purpose. Who knew!!! I am hopeful my explanation is plausible, if not, I look forward to any corrections from the forum participants that have their own perspectives or theories.

Good luck with your future cooks.

I appreciate your detailed response! Up unto recently I have accepted the "trust us, our controller is programmed for this" answer from them. But unfortunately it has really messed up a lot of recent cooks for me. Hate to say it, but I'm not trusting my grill right now at all and that's a lousy feeling. I'd be willing to accept a +/- 20* difference, but 90* is ridiculous and nothing they can say will convince me otherwise. If the probe feels those temps, so does the meat, and my overcooked & charred brisket tells the story.

It sucks because this thing has been rock solid for years and now its all over the place. If I want to babysit a cook, I'll just go back to my offset or cylindrical and enjoy the better results

 

[SmokeZilla]

I appreciate your detailed response! Up unto recently I have accepted the "trust us, our controller is programmed for this" answer from them. But unfortunately it has really messed up a lot of recent cooks for me. Hate to say it, but I'm not trusting my grill right now at all and that's a lousy feeling. I'd be willing to accept a +/- 20* difference, but 90* is ridiculous and nothing they can say will convince me otherwise. If the probe feels those temps, so does the meat, and my overcooked & charred brisket tells the story.

It sucks because this thing has been rock solid for years and now its all over the place. If I want to babysit a cook, I'll just go back to my offset or cylindrical and enjoy the better results

No problem. We’re all trying to be helpful on this site.

Since it sounds like your problems are recent, have you cleaned your temp probe lately? I have heard it can get dirty and throw off the readings. Also make sure it is nit bent or didn’t get wet. You can also use a VOM (volt-ohm-meter) and check the resistance in the probe. Once done, ask RT what it should be. That would at least remove one potential issue from the list and it’s worth a try. Use a green pad or very light emory cloth and see if it makes a difference. Other than that if your warranty is still in effect call RT and have them send you another one. Good luck.

 

[Jim6820]

Building on what @SmokeZilla said about the probe(s), check the tightness of the nuts on the probe connector sockets. If loose, that can result in wonky readings. It won’t affect your cook chamber temp readings, but can certainly affect the readings from the meat probes.

 

[Maule Guy]

Question for those smarter than me in here regarding the temperature controller.... I put a 9.5 lb brisket on at midnight the other night at 225F. As you can see from the pics, my RT-590 shows that it maintained a rock solid temp all night long. When I got up to check it at 8am, the thickest part of the flat was temping 206 and the point was 210. I'm no competition cook, but I've done a few dozen briskets and it defies logic how it could reach those temps in just 8 hrs at 225. I was able to wrap it with tallow and salvage the majority of it, minus some charred parts at the point.

Afterwards, trying to figure out what went wrong, I troubleshot it with a different temp probe. Yes, I know what Recteq says about using 3rd party temp probes, but it was reading 90 degrees hotter than what the RT was indicating. I called RT customer service, and the gentleman was very polite and appeared very knowledgeable, but couldn't explain this to my satisfaction. Just said that I need to trust it. He said that my brisket must have been an anomaly but the probe is accurate and if it fails it will be an an extreme high or low. My question is, how can a temp probe right next to the brisket feel a temp of 315 while the brisket is feeling what the RT is sensing? It clearly cooked MUCH faster than expected and charred parts of it. His explanation left a lot to be desired and now I'm not trusting the smoker. Can anyone with a better understanding explain this in layman's terms for me? Thanks

By the way, the thermometer I was using has been calibrated and I've verified it's accuracy in both my standard and convection ovens at various temps, so I know its accurate. And I checked the temp at various parts of the barrel, including right next to the RT probe.

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Couple shade tree mechanic thoughts.

Is your grill the same temp at the main grate as the second shelf grate?

Have you cleaned the 590 built-in probe? When I can remember to do this the probe seems to give more reliable results. Could be placebo effect.

As said above, 590 is hotter on the right but, I would have expected something in the 240-250 range on the right at a 225 setting.

Trust your “at grate” readings and fudge the 590 setting accordingly.

 

[okie]

After trying to trust RT CS I have concluded that they do a great job to help us out but are bound to supporting their own tech data. After testing both my old 590 and later my 1070, with multiple probes in multiple positions, I had to adjust the offset on the 590 to +6 and on the 1070 to +7 to get smoking temps into reasonably accurate settings. Two of my children each have 590's and have not done so, but have had to either adjust their cooking times or "set" temps to compensate. (and are perfectly happy doing so). I think that the crucial issue is smoking temps accuracy and not so much on high temp accuracy. I would trust your certified probe, but remember it is the "average" temp that you are after. That is why I purchased the new Square Dot from Thermoworks. It can be switched to "average" temp settings which gives you 15 minute averages and adjusts every minute thereafter. You can check current temp any time in this process.
Other than this one area of concern, I find the RT control to be very stable and reliable, and IMO it is the only unit that is consumer adjustable in several parameters. (meat probes, minimal drop rate, Offset, ).