PID & ET-73 not same temp

Started by JF7FSU, August 14, 2009, 03:44:18 PM

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JF7FSU

I just got my Auber PID and am in the process of doing a Kummok Salmon.  I started out at 120 and the PID was dead on for the first stage.  My ET-73 was reading about 6-7 degrees higher than the PID.  I am now on stage 2 and it is reading 6 degrees higher as well.

I have the wall mounted sensor from Auber in their recommended position of just under the top rack.  The ET-73 probe is clipped on my non-stick rack in the back one rack below the ET 73 probe, so they are pretty close but the ET 73 is closer to the element.

Shall I assume the Auber is spot on being a much more precise and expensive piece of equipment?  I dont want to remove the sensor to test the Auber as it says it is calibrated from the factory and seems very well made?
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mikeradio

I also notice some difference between the PID and ET-73, I figure that you just have to pick one of them to be your main reading.  I use the PID for controlling the smoker temp and the ET-73 to watch the internal temp of the food.

Mike

squirtthecat

Quote from: mikeradio on August 14, 2009, 03:59:06 PM

Mike


Unrelated to this post, but I just clicked through your website and found this...  A 'blast from the past', so to speak:

http://www.interiorhobbies.com/Itemdesc.asp?ic=EST1948&eq=&Tp=

That was my 4H Project many many years ago.  Model Rocketry.  Big Bertha was my first.

Ahh..  It's all coming back now.  So many rockets lost in the corn/bean fields around our farmhouse, my mother scared to death of the 'explosive' engines, so they had to come home locked in the trunk of the car, etc.


mikeradio

I think we all remember playing with rockets as kids. They are still a big seller for us.

Mike

JF7FSU

I had many rockets when I was a kid, I used to build Centauri (.sp?).  I notice all they have now is Estes.  My crowning jewel was the Saturn V, I have a picture of it somewhere.

Back on point, so is the ET 73 that inaccurate?  I mean it was 39 bucks..but I thought it would be better.   I have to figure the Auber is more accurate.  So I have to think about how this will effect internal temp readings as well.  6-8 degrees can be a lot.
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pensrock

they would have to be placed right next to each other to judge them, I mean the probes need to be next to each other. If I read correctly you have the one probe a shelf below the other? of course they are going to read different, your pid is controlling the temp where it is placed, the further down in the tower you go I would expect it to read hotter. unless you circulate the heat with a fan you will have a slight temp difference from one location to another. that is why you should rotate your racks top to bottom and front to back every couple hours or so. if doing salmon I rotate at least every hour. I have my pid probe in the center of my four rack tower. even if both probes are right next to each other you may get a slight difference in readings, most thermocouples are only accurate to +- 3 to 5 degrees F, same for each instrument. also one may have something like a piece of food right above or below it that can affect the reading slightly. I only use my maverick to measure internal temps and trust my pid to control the tower temp.

manxman

Quotethey would have to be placed right next to each other to judge them

I agree with pensrock, if the maverick et73 probe is nearer the back wall and lower towards the heating element then it will read a few degrees higher.

My BS running at the moment, I have the back wall Auber PID probe the same as yours JF7FSU and have run the maverick cabinet temp probe through the vent and it is hanging at the same level and position as the Auber probe, around an inch or so apart. The temps are running within +/- 2 F of each other.

I have found similar differences in temp if the maverick probe is in a different position, also if it inadvertantly touches the rack or sides for example.

Pens also gives good advice re rotating etc.  :)
Manxman

JF7FSU

Thanks guys, I will try to clip the ET 73 higher and see if it comes closer.  My paranoia was just kicking in  ::)
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outdoorsfellar

Though this topic has been on the shelf so to speak, I have been having issues with my temp readings. I can place both probes of my Maverick IN the heating element & get different readings. I place my probes alongside my PID sensor & can get a different reading from each of the three probes as well ! Last night after my brisket failure, I did place both probes in a bowl of hot water ... & got two different readings, though just 1 degree off or so & even that kinda fluctuated to being the same .... just the same. It's like a tale of three sensors & I don't know which to believe anymore.

Quarlow

If you are getting less than a 5 degree difference that is not bad. Just learn which is which and remember to take that into account.
I like to walk threw life on the path of least resistance. But sometimes the path needs a good kick in the ass.

OBS
BBQ
One Big Easy, plus one in a box.

outdoorsfellar

No, I can get a 8-11 or more degree difference. That's why I don't know what to rely on.

Quarlow

Yeah I have 2 digitals and 3 dial probes and can't get the same temp out of any of them.
I like to walk threw life on the path of least resistance. But sometimes the path needs a good kick in the ass.

OBS
BBQ
One Big Easy, plus one in a box.

pensrock

As I explained earlier, type k thermocouples can be off by as much as 2-5 degrees F. As well as the instruments reading them.  So 1-10 degrees really is not necessarily anything bad. I suggest doing what I do. Use the PID to run the temp and stick the Maverick probes in the meat. Unless each probe is calibrated to the instrument and the probes are placed right next to each other it very unlikely they will read the same. Say you have 3 probes, one is 1 degree off when checked the next 2 degrees and the last 3 degrees. Now you have the same thing with the instruments that are reading the probes. It can be +- degrees off so if inst 1 and probe 1 are both off 1 degree than the reading can be off by two degrees. Same for the other two instruments.Now if probe 1 and inst 1 are both reading 1 degree low but probe 3 and inst 3 are both reading 3 degrees high, then you have a four degree difference. And all probes and instruments are within calibration tolerances. Trust one reading and use the other probes to read the internal temp of the meat. You will drive yourself crazy trying to get each probe to read the same exact temp. BTW even using a PID you still should rotate your racks top to bottom and front to back every hour or so. You will get a constant temp with the PID but it will not even out the temp variance within the smoker itself. I put my PID probe right in the middle of the tower and I expect it to be warmer closer to the heating element, and cooler near the top. IMHO

Quarlow

Thanks Pens, I basically don't rely on them anyway. I just use them as an indicator as to what is happening. Then I use my eyes as to what is really happening. A little cut here or there, juices run red or clear. You know.
I like to walk threw life on the path of least resistance. But sometimes the path needs a good kick in the ass.

OBS
BBQ
One Big Easy, plus one in a box.

outdoorsfellar