Trailblazer Chamber temp vs set / measured temp.

[jeff7117]

New Trailblazer RT-340 owner here. I've had this smoker for about 2 months and cooked a few meals at hotter temperatures with great results. Some of the cook times were a little long but I chalked it up to just learning the quirks of this pellet grill. Over the holiday, I tried to cook my first brisket, and the grill was struggling with keeping the temp set at 220 in this summertime heat. I was getting crazy temperature swings, and it took almost 2.5 hours per pound to cook an 8 pound brisket.

After chatting with RecTec on the phone, I got the feed rate set low enough to get the smoker to maintain the set temp with no crazy temperature swings. However, while I was testing the grill the next day, I setup my fireboard to monitor the internal temps just to see if the internal probe might be off or out of adjustment. If the grill is set at 220, and the internal probe says 220, my fireboard will range from 185-200 in various parts of the chamber, but never close to 220. RecTec says this is normal and they plot the temperature in 5 degree increments based on 20-30 thermometers throughout the grill to reach the "actual temperature." This is my first pellet smoker, so I dunno if this is normal or not. But if I'm supposed to cook at 220 or 225, am I really cooking at 190-200 inside the chamber? I know the fireboard is accurate and I've tested the ambient probes in ice water to verify.

Has anyone else measured the temp of the chamber and if so, does it match what the actual temp says on the display? Should I offset the rectec probe to make it read the actual chamber temp, or is this temperature range normal for these pellet smokers? I'm not opposed to running it like it's set, I just want to know if the temperature range inside the chamber is supposed to be that far off from RecTec measured temperature.

 

[ifican]

Yes, if the controller is the same as the bull you can calibrate it to the fireboard and call it a day. I experienced the same basic thing, a cook that took far longer than it should have at set temp. Well after calibrating to my liking my cooks are now within the range i expect at lower temps. They tell you to calibrate at 350 but i do most cooks at 225-250 so thats where i calibrated. Granted it is off a bit now at 350 but its stop on where i need it.

 

[NU2SMOKE]

Yes, if the controller is the same as the bull you can calibrate it to the fireboard and call it a day. I experienced the same basic thing, a cook that took far longer than it should have at set temp. Well after calibrating to my liking my cooks are now within the range i expect at lower temps. They tell you to calibrate at 350 but i do most cooks at 225-250 so thats where i calibrated. Granted it is off a bit now at 350 but its stop on where i need it.

When you say its a bit off at 350 because you calibrated at 225....how much off is it? Just curious.

 

[jeff7117]

I'd like to know this as well. I'm going to calibrate for 250 and see how far off it is at higher temps.

 

[NU2SMOKE]

I'd like to know this as well. I'm going to calibrate for 250 and see how far off it is at higher temps.

Looking forward to your results @jeff7117 Thank you!

 

[NU2SMOKE]

Question....would it be safe to say that if you are using the large rack in the grill that the temp at that level would be hotter than at the grate level since heat rises?

 

[ifican]

Question....would it be safe to say that if you are using the large rack in the grill that the temp at that level would be hotter than at the grate level since heat rises?

Now this one i am curious about . So i dont recall how far off i just remember it was a bit low. I tweaked the calibration a little bit after that to bring it closer and just called it good. Ill run it through its paces again soon and report back what i get.

 

[NU2SMOKE]

Now this one i am curious about . So i dont recall how far off i just remember it was a bit low. I tweaked the calibration a little bit after that to bring it closer and just called it good. Ill run it through its paces again soon and report back what i get.

Im looking at getting a fireboard system. Once I have that and all the probes are calibrated I planed on bringing the pit up to 250 and having all 8 probes all over the grill grate and on the shelf to see what it looks like and then slowly raise the temp to 350...400...450..500 and see how the pit performs and make a chart. that would be the very best way to see where are the hot spots and the overall performance of the pit. OK OK Im a bit OCD

 

[ifican]

So when i was calibrating and playing with temps i used the two it came with and another one spread equally across the middle. The RTD is quick to tell you its at a certain temp but it may take several more minutes for the heat to distribute through the cook chamber. All 3 always matched at some point just never as fast as the RTD.

 

[ndfan6464]

What menu calibrates the cooking chamber prob and does it also go by degrees like the meat probes?

 

[NU2SMOKE]

So when i was calibrating and playing with temps i used the two it came with and another one spread equally across the middle. The RTD is quick to tell you its at a certain temp but it may take several more minutes for the heat to distribute through the cook chamber. All 3 always matched at some point just never as fast as the RTD.

I would agree with that. I was amazed at how fast the pit said it was at temp but from my time with ovens I have always learned to wait some time for heat soaking.

One thing I did do during my burn in was I set the unit to 400 deg and put the 2 probes side by side in the center of the grill to see if they both read the same thing. They did within 5 deg of each other but never during the 90 min burn in did they get to 400 deg. 387 was the highest probe reading at grate level.

I attached pics of the grill temp chart of the burn in process. Along with a pic of the prob placement.

Would love to hear what you all think.

 

[Buckeye smoker]

Yep interesting...sooooo did you adjust the probes by ice water calibration? And then adjust the main probe to the meat probes?... I'm asking cause I wonder how far the main probe was off from the meat probes after calibration... I'm waiting for my new probes so that I can see why my readings change after calibration just by hitting the "on switch"

 

[NU2SMOKE]

I did calibrate the meat probes after the burn in the next day using ice water. First I wanted to see if it was a probe problem or a controller reading problem. I did this by putting both probes in the ice water and let them settle into their temps. Probe (A) read 32...Probe (B) read 36
Once I had that done...before I adjusted anything I unplugged the probes and switched inputs. If the bad reading followed the probe then Probe (A) would have read 36 and so forth...If it did then you would not be able to just re calibrate and go unless you designated that probe to be port A only and used it as such. Well it did not! Probe A still read 32 deg with the other probe. So that confirmed that the controller was reading a different resistance and calibration would work.
So I calibrated the 2 probes to read 32 deg. Checked by switching the probes back and fourth and they still read the same so as far as the probes go .... im good.

My next course of action I am thinking is to have both probes installed one on each side of the grill at 2" above grate level. Bring the pit up to 250 (according to the controller) let it sit for 30 min ...see what both probes read (hopefully the same) and then adjust the pit temp probe to match.
How does that sound to you?

 

[dsandersus]

@NU2SMOKE

Question - will meat probes provide you with the temp. readings in a similar way an ambient temp probe does? My thought is no, but I'm not knowledgeable enough on the subject to make that determination.

I typically have two types of probes running during my cooks - the meat probes (in what i'm cooking) and a ambient probe on my iGrill thermometer (placed opposite end of the grill chamber).

 

[NU2SMOKE]

To my knowledge if the ambient and meat probes are of the same type (thermistor...ect) they should read the same. I ordered another thermometer setup that includes both ambient and meat so I will be testing again and seeing how it all works out. I am intent on getting the Bull set up to work at its very best and knowing the temps across the grates....yes Im anal that way!

 

[ifican]

For the probe temps on the grates you want to have them elevated as the metal will read different then the air just above it. Can simply use a ball a foil with the probe pushed through it. Yes the meat probes should read the same in our case. I did a quick few hour test as i have things to get to now but my notes follow. Just know the RTD temp setting was in 25 degree intervals and yes i could have done them all like i did the 350 but since the 350 stayed aprx the same as the rest ill call it good. Plus i didnt feel like taking 10 hours to do the test that i am otherwise happy with. What i did learn for my grill at least is the right side is consistently cooler then the left where i have read by many others that is the hotter side (not sure if they actually tested or simply took the words of others). Anyways here are my notes if any clarification needed please ask and i will answer later when i get back:


right quarter centerline

RTD / Thermoworks ambient temp probe
200 / 190~
225 / 217~
250 / 238~
278 / 272~
300 / 285~
330 / 321~
351 / 338~

middle and spot i used to calibrate previously (with same ambient probe)
(lid open about 5 seconds on move and temp did not move)
350 / 351

left quarter centerline
(probe slipped from clip and lid was open about 30 seconds, rtd dropped to 318 and recovered to 355, only moved to 354 after about 15 minutes)
354 / 372~

back to middle
(lid open about 5 seconds, rtd temp dropped to 352 within 1 minute of closing continued down to 350 over next several minutes)
350 / 355

Overall no complaints. With the RTD being far left i would not expect it to be the same temp across the grill surface. I have learned with years of smoking things that 15-20 degrees (even 25) is nothing to be concerned with, its just at least for me nice to know the difference across the grill surface so i can make mental notes when doing bigger cooks. In some cases if wanting as an example racks of ribs to finish at the same time the far left and the far right will need to be rotated but that is nothing new and needed most often with stick burners but generally on any indirect setup that isnt a kamado.

 

[NU2SMOKE]

@ifican Now that is some incredibly useful data!! Thank you.

Looking at your data...

RTD / Thermoworks ambient temp probe
200 / 190~ 10 deg split
225 / 217~ 8 deg split
250 / 238~ 12 deg split
278 / 272~ 6 deg split
300 / 285~ 15 deg split
330 / 321~ 9 deg split
351 / 338~ 13 deg split

It averaged to 10.42 deg over the whole spread. Did you adjust the pit temp calibration to compensate to get you as close as possible?
Looking at it ...an 8 deg adjustment would put you within 4 deg across the whole spectrum of our usual cooking temps. Just a thought. Yes I know I have ocd...lol I just like to limit the variables as much as possible...lol

 

[ifican]

So the above is all the right side of the grill. The middle is very close and the left is a bit hot (about the same as the far right is low). I was hoping for a little closer spread across the surface but am also not surprised or concerned how it worked out. Though i am curious if sealing will change that and have considered sealing and rerunning test again.

 

[NU2SMOKE]

So the above is all the right side of the grill. The middle is very close and the left is a bit hot (about the same as the far right is low). I was hoping for a little closer spread across the surface but am also not surprised or concerned how it worked out. Though i am curious if sealing will change that and have considered sealing and rerunning test again.

Well I ordered a 6 probe thermometer and the door seal material. Once I get it all I plan on doing exactly just that. The 6 probes should be able to allow me to test the left center & right side of the grill both at grate level and on the large rack all at the same time.

 

[ifican]

Im hoping the large rack will go on sale at some point, i dont need it but figure why not. I have plenty of room now between this and other one i have but like having options. I just sealed the lid to test, not sure when i will test but the seal is done. Thing to note my lid even with felt still has a gap on bottom left and side. Everything else looks good, i suspect over time and use it should seat better we will see.