Help with my new PID

Smoking Duck · April 17, 2008, 12:44:07 PM

Hey all,

As usual, Iceman went above and beyond the call during my "super-smoke" fest and made me a PID. I have a couple of questions. Should the temp as read by the probe be the same as what I set the temp to be on the PID? In other words, is it normal for me to have to set the temp at 215 to achieve a box temp of 200 or should I be able to set the temp at 200 to achieve the 200 temp in the box? Is this just a process of auto-tuning? It was auto tuned when I received it, but it is quite possible that I've done something to throw it off. Also, is it normal to have a variation of 10-13 degree reading in the box between what the PID is reading and what the Maverick is reading? I would assume the PID would be more accurate, but I try not to assume. Sorry for the dumb questions......the wife tells me that if she put my brain on a piece of bread, it would look like a BB rolling down the highway. ;D I guess the only reason she married me was cause I'm Italian (yes, the rumors are true.....just ask Consig)

Thanks as always!

SD

Tiny Tim · April 17, 2008, 02:08:24 PM

It is possible to have a variation between the PID and your maverick (test with boiling water to see which one is off and by how far). Also, I'm assuming you would figure this part anyway, but it's easy to overlook, the probes should be in the same area if you are comparing the readings, not on different levels and one in the front, one in back.

If the probes are in the same place and reading the same temp, you can play with how much of an offset temp to set the PID to in order for you to reach your desired cooking temp by moving the Maverick to the area where you are placing the meat while leaving the PID probe in a set location. (did that make any sense?)

Best I can do for ya right now...if it helps, great, if not I'll try again later. :D

Mr Walleye · April 17, 2008, 02:51:55 PM

Marc

Here is a link to some trouble shooting that went on with WildCat's PID. Lots of good info there.
http://forum.bradleysmoker.com/index.php?topic=6763.0

In addition to what Tiny said I would probably re-run the autotune when you have a decent load in it. I think you will find the temps in various parts of the tower will very depending on how long the meat has been in and where you measure the temp in the cabinet.

Mike

Smoking Duck · April 17, 2008, 03:52:44 PM

Thanks Tim and Mike. I've got yard work (yuck!) to do right now but this weekend will be when I put the work to the PID. Either of you guys fancy a trip to Indiana to help a smoking brother out? :D Pretty please ??????????

SD

Wildcat · April 17, 2008, 04:27:02 PM

It does not take too long to get the hang of it. Check out the link that Mike has. I have not smoked since I got my newest probe and went on the trip to TN, but will real soon. I am not sure, but I think my Maverick (or its probe) might be going bad on me. I will post more once I have it figured out.

Tiny Tim · April 18, 2008, 07:15:20 AM

Quote from: Smoking Duck on April 17, 2008, 03:52:44 PM
Thanks Tim and Mike. I've got yard work (yuck!) to do right now but this weekend will be when I put the work to the PID. Either of you guys fancy a trip to Indiana to help a smoking brother out? :D Pretty please ??????????

SD

Buy the gas for round trip for my truck and I'll leave tonight. :)

Smoking Duck · April 20, 2008, 02:44:28 PM

Thanks TT,

However, what with the price of gas being what it is, I figure I could buy another Bradley for what I'd have to pay you in gas ;D

I did the auto-tune today with a load of 4 bricks in the box. It took about 90 minutes for it to complete and when it did, my thermocouple was reading 215 and I had set the temp at 215. That's close enough for government work if you ask me. I did fail to put the Maverick in when I set the auto-tune, so the Maverick is in now and I'll wait till I get back to my set temp and see how much they are off. If I read Wildcat's thread correctly (and I think I did), I can adjust the PID under the Pb heading so that they both read the same temp. I would guess that if the Maverick reads 205 and the PID reads 215, then I would simply set the Pb at -10. Is that correct?

My PID numbers, if Arcs is still collecting them and is reading this thread are:

P= 2400
I= 110
D= 144

Thanks again,

SD

Wildcat · April 20, 2008, 03:03:58 PM

My advice would be to make sure the PID is adjusted to the true temperature, regardless of what the Maverick says. You can do this with the Pb. Do the cold and hot water test on it if you can. You will also want to run a test on the Maverick. Be sure when you compare in the smoker that the PID probe and Maverick probe are right next to each other. When you go to smoke the first time, monitor the difference between the two as the meat temp rises. My Maverick tested good with the hot and cold water but either the Maverick or the PID started registering different (several degrees) as the meat temp approached 160. I have another measuring instrument now, but have not had the opportunity yet to figure out if it is the Maverick or PID that is getting weird on me. I suspect it is the Maverick (or its probe) since it is getting up in age.

Smoking Duck · April 20, 2008, 03:15:35 PM

So should I assume that the PID is spot on in temp? The Maverick and PID are side by side. Neither are touching metal. There is a 7 degree difference (PID reads 215 and the Maverick is reading 208). I'm not one to want to get too technical (I prefer the drinking at a distance mode), but shouldn't I assume the PID is correct and just adjust what I read on the Maverick (in other words, if I check my Maverick and it says 208, shouldn't I be able to just add 7 degrees and know that I'm at 215?)? I would assume the PID thermocoupler is a much more precise measuring instrument than what the Maverick is, but I've been wrong with assumptions before.

Wildcat · April 20, 2008, 03:19:42 PM

Unsure. The PID is probably the most accurate. I suggest the cold and hot water tests on both. If not possible, then I suggest a third thermometer and do an average. This should be fine for most smokes.

Mr Walleye · April 20, 2008, 03:35:06 PM

Marc

I find that there is a larger difference between the ET73 and the PID when I first put a load in. Then once the load starts to reach alittle higher temp the difference seems to become less. What I have done is adjust the offset once the load has been in for a few hours (3 or 4 hours with a butt). By setting it up this way I just ignore the difference and once the meat starts to get up to temp it balances out. I'll just mention though that my probes are not in the same location in the cabinet. In my situation it seems the meat effects the ET73 a little more than the PID temp probe. This makes sense because my PID TC is in the back of the cabinet and I usually clip my ET73 close to the meat to see what the meat is experiencing.

Mike

Arcs_n_Sparks · April 20, 2008, 04:15:10 PM

Latest PID value update. Smoking Duck is lookin' to be a high gain guy... :D

P I D
Mr. Walleye 400 225 225
Tiny Tim 400 1583 28
Patience 718 196 349
MRH 500 1000 120
carnie1 624 472 384
Wildcat 498 191 172
Smoking Duck 2400 110 144

Smoking Duck · April 20, 2008, 04:26:05 PM

I'm not sure what that means....unless you're talking about weight :D

Why is it that my P is so much bigger than the rest? I've lived with it most of my life. ;)

Seriously, though, can anyone explain (in simple, kid-like terms) why the big difference in my P number versus the others?

Mr Walleye · April 20, 2008, 04:30:23 PM

Nope.... :D :D :D ;D

Mike

Smoking Duck · April 20, 2008, 04:37:12 PM

Hey Mike,

I put the Maverick in after I had done the auto-tune. The box was already heated up pretty good (I did lose some temp when I opened the door), but I waited until the PID reached its set temp and then read the Maverick. I then gave it an extra half hour and still had the same that the Maverick was reading 208 while the PID read 215. It's been going for some time and both temps are rock steady. I figure this is close enough for government work. Even if I assume that the real temp is somewhere in between (say 211 or so) I'm as close as I need to be for most smokes. I tend to smoke no higher than 225 and usually do most smokes at the 200 or so level that the extra degrees either way won't hurt the food. I have a tendancy to screw things up the more I fiddle with them, so I guess I'll be pretty happy but still wonder about the high P reading.