Help with PID.....again

[Smoking Duck]

Hey guys,
Smoking a pork tenderloin this evening.  Did an autotune on the PID and it went through its course.  However, now I have the temp set at 215 but I'm only reading 210.  Shouldn't it be reading the same?  It's staying steady at 210 but I'd like it to be at the temp I set.  Do I need to adjust the Pb on this or should I do another autotune or what?

Thanks!

SD

[KyNola]

You should open the next beer. 

KyNola

[Wildcat]

If you are comparing with the Maverick and both probes are next to each other and have tested the Maverick for accuracy, then I would adjust the Pb setting.  You may want to wait until the meat temp hits its stall stage first.  If you adjust the Pb, just go about 2.5 degrees and see what happens.

[Arcs_n_Sparks]

Put a sticky note next to the display that says: "+5" and reach for an adult beverage.

Arcs_n_Sparks

[Smoking Duck]

No, I wasn't comparing it to the Maverick.  It was my PID that was set at 215 but read 210 after I'd done an autotune.  However, about 30 minutes later, I checked it again and it was reading exactly as I set it.

Electrical things are a lot like women to me.......just when I thought I had 'em figured out, someone goes and changes the schematics 

Now I don't want to get in trouble for that last statement, so I'm carrying a 6 pack and a bottle of Jack a long distance to drink with Sparky.

I guess it's close enough for government work for me, so I ain't gonna fool around anymore.  However, it seems that after every time I turn the darn PID off and then use it again, I have to autotune it to get it to read what I set the temp at.  Is that unusual?

[pensrock]

Smoking Duck, when you ran the autotune did you have a good load in the tower? Once a set of PID numbers are in the controller it should remain the same unless the controller can be set to autotune everytime the power is cycled or something like that. I have used temperature controllers the had what they called 'adaptive tuning'. What it did was to constantly adjust the PID numbers as the loading would increase and decrease. I do not know if the Auber instruments have any kind of function similar to that, since I have never used one. One note about adaptive tuning.... it does cause some variences because it is always tuning itself. I have never kept it active, I used it to fine tune the furnace over a day or so of constant running then shut it off and made the final adjustments myself to get the control to work like I wanted. I guess what I am getting at is.... can your instrument be in some mode where it is running an autotune everytime it is turned on? It should be set so it will only autotune when you tell it to.
Have fun..... 
pensrock

[Smoking Duck]

Hey Pens,

It didn't have a real big load in it.  The first time I smoked yesterday, I had about 12 chicken thighs in it.  I did an autotune on it but unfortunately, the thighs got done quicker than it took to do an autotune (my autotunes have been going about 90 minutes each time) and I had to pull the load before the autotune got done.  So, I just kept the Bradley on and proceeded to do some pork tenderloin which had soaked in apple juice for 2 hours and then some dry rub.  As soon as the temp came near where I wanted it to be for the pork to be smoked, I then did another autotune.  The auto tune was done when I noticed the 5 degree difference between the temp I set and what the PID was reading.  I don't worry about the difference between the PID and Maverick.  I just assume the PID to be more accurate.  I really only use the Maverick now for the meat temp (in fact, I'm contemplating using two meat thermometers in the Maverick for when I'm doing more than 1 piece of meat.  Anyways, after about 30 minutes I rechecked the PID and it was reading exactly as I set it.  However, it seems everytime I do a new smoke, I have to do an autotune as the temp I set and temp achieved in the box are never the same unless I do an autotune on it.  It is not set up to do that automatically as far as I can tell (it doesn't do the autotune unless I program it to do one).  I guess I'm not overly concerned about it as I never really worry about a 5 degree swing that much (haven't really smoked anything that requires that amount of precision).  However,, sometimes my quasi-OCD tendencies get the better of me and I wonder why.

[Wildcat]

I never had that problem with mine except once in the beginning.  It just went away on its own.  Mine does an autotune in 30 to 45 minutes when I tell it to do the autotune.  I have read on here that it takes about an hour.  In the beginning mine took about 10 to 15 minutes.  Sometimes I think a PID is like a vehicle - requiring a break-in period  .  I have noticed that sometimes it takes an hour or so to stabilize itself.

[Smoking Duck]

I think you're spot on with your assessment Wildcat.  I think they're like kids with personalities all their own.  However, even with its little idiosyncracies, mine has made me feel much more confident about leaving the smoker for a while and trusting no big temp changes.