PID or BBQ Guru Raptor and Competitor Pkg.

bubbagump · February 08, 2006, 06:05:30 AM

Bugboat,

Sounds like you may have some setup issues. Be sure that the PID is programmed for the Type K thermocouple. What are you comparing the thermocouple output temp to? If you have the same problem after trying a new thermocouple then it's something in your setup.

When you mention 3 diferent control parameters are you talking about Proportiona band, Intregal time, and Derivative time? If so, these are the three parameters that auto tune sets up for you. These parameters can be set up manually but unless you are very familar PID control and how each of these parameters affects the controllers performance, I wouldn't advise it. Auto tune works just fine. But it is not possible to accurately tune your PID if you are getting inaccurate readings from your thermocouple or if the input parameter is set up wrong. You need to get that issue resolved before you can tune your PID

Auto tuning should not have to be done everytime you use the PID. It is just used for initial setup. As I mentioned, it sets up the Proprotional band, Intergal time, and Derivative time, (PID) along with other parameters. What you should do is get your smoker within 10 degrees of setpoint and then initiate auto tune. After it is finished your PID parameters should be set up.

Also, be sure your SSR output is not for cooling only. If I remember right the Cold Fusion PID's on ebay that had an SSR output were for cooling only.

Bubbagump

rgardjr · February 08, 2006, 07:54:17 AM

Well I'll type this out again....
Here is a link to the documentation for the TET-7100 Coldfusion PID on E-bay:

http://greenacresgypsum.com/TET7100PID.pdf

I had the same problem with the included thermocouple not being accurate. I replaced mine. I've only smoked 3 times since I built my PID controller, and I haven't had the results that I expected yet. I think part of my porblem is that I haven't run the autotune with the smoker loaded. I was still seeing around a 5-10 degree swing during my last smoke. Hopefully, tuning with meat in the smoker will dial in the tuning.
-Rick

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by bubbagump
 Bugboat,

Sounds like you may have some setup issues. Be sure that the PID is programmed for the Type K thermocouple. What are you comparing the thermocouple output temp to? If you have the same problem after trying a new thermocouple then it's something in your setup.

When you mention 3 diferent control parameters are you talking about Proportiona band, Intregal time, and Derivative time? If so, these are the three parameters that auto tune sets up for you. These parameters can be set up manually but unless you are very familar PID control and how each of these parameters affects the controllers performance, I wouldn't advise it. Auto tune works just fine. But it is not possible to accurately tune your PID if you are getting inaccurate readings from your thermocouple or if the input parameter is set up wrong. You need to get that issue resolved before you can tune your PID

Auto tuning should not have to be done everytime you use the PID. It is just used for initial setup. As I mentioned, it sets up the Proprotional band, Intergal time, and Derivative time, (PID) along with other parameters. What you should do is get your smoker within 10 degrees of setpoint and then initiate auto tune. After it is finished your PID parameters should be set up.

Also, be sure your SSR output is not for cooling only. If I remember right the Cold Fusion PID's on ebay that had an SSR output were for cooling only.

Bubbagump
<hr height="1" noshade id="quote"></blockquote id="quote">

TomG · February 08, 2006, 04:31:21 PM

I had a similar temp inaccuracy with my PID which I corrected by adjusting the "temp error correction" function until the LED indicated 212* when the probe was in boiling water. Confirmed with a 32* reading with probe in ice

bubbagump · February 08, 2006, 09:26:06 PM

rgardjr and bugboat,

When initiating auto tune, I would recommend using either parameter 1 or 2 rather than 0. The quicker your PID responds the more likely you will over or undershoot your setpoint. That may sound odd but with PID control in our application the more gradual the changes are to the output the better the PID will hold setpoint.

When I set up my PID I used the more gradual control algorithm and initiated auto tune with the smoker empty. I can hold setpoint to within 1/2 a degree.

TG,

That is how I tested my thermocouple as well and found it to be within 2 degrees or 1%. But bugboat had a 40 degree difference [:0] something's wrong.

Bubbagump

bugboat · February 08, 2006, 11:07:06 PM

Thanks bubbagump. My PID is the same one as rgardjr
has. I thought that outotuning was a 4th paramator, seperate from
0,1,2, and that it defaulted back to your set paramator after unplugging. I quess it makes sense now. Until about a month ago I
didnt even know what a PID was. I originally had a bulb thermostat
from an old coffee pot rigged up to the Bradley. It worked OK but
way under and over shot my set point. Thats why I sprung for the PID. I'm currently testing another thermocouple I borrowed from work. The PID was set up correctly for a type "K" thermocouple that the unit came with. I suspect that it is defective. It was fairly accurate at 32 degrees, but way off at boiling.

common sense isnt common

bugboat · February 09, 2006, 03:11:46 AM

Problem solved. The thermocouple that came with the coldfusion PID
works just fine. The problem was how I had mounted it in the smoker.
I didnt want to have to snake a bunch of wires through the top of the vent, so I drilled a hole in the back of the smoker and mounted it just under the second shelf. Directly opposite of the stock thermometer that comes with the Bradley. This thermocouple has a very
short probe. It seems that the metal wall of the smoker was acting as
a heat sink and was sucking heat away from the thermocouple. The hotter the smoker got the farther off the thermocouple was because of the cold outside temperatures. So the solution would be to buy a
thermocouple with a longer probe that puts it away from the wall of the smoker. Or I think I will Make some sort of metal "stand off" that I will mount to the back wall and then mount the thermocouple to it.

After autoprogramming and then letting the smoker temp stabilize, I was able to hold a consistant 199 degrees with the set point at 200.
It wouldnt even very a single degree.

My next project is to put in a fan to mix the air, so I can have stable temps from top to bottom. I think this would be great for jerky. You wouldn't have to rotate the racks. I know a few people here have tried this, but I havnt heard much about the results yet.
Anyone care to share their experiences with fans?

common sense isnt common

rgardjr · February 09, 2006, 07:11:33 AM

Bugboat-
I did an autotune on my tonight, but I was still seeing around a 5 degree temp swing. Did you change to the 1 or 2 parameter? I know my problem isn't with my thermocouple because it does register the temp changes and I tested it in boiling water and it was within 1 degree of my Maverick. Any chance you could post or send me your autotune values (P,I,D, ect.)? I just don't understand why it's not holding the temp better and I'm beginning to think it that I may have a defective PID. Mine just doesn't cycle the element on long enough to maintain the set point. It will cycle on quickly and continue to do this until the temp falls about 5 degrees and then it will bump back up. My set point was 210 and I'm guessing that it averaged 207. I was seeing anything from 205 to 209. I will try then autotune again with the parameter 1 set to see if it does a better job.

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by bugboat
 Problem solved. The thermocouple that came with the coldfusion PID
works just fine. The problem was how I had mounted it in the smoker.
I didnt want to have to snake a bunch of wires through the top of the vent, so I drilled a hole in the back of the smoker and mounted it just under the second shelf. Directly opposite of the stock thermometer that comes with the Bradley. This thermocouple has a very
short probe. It seems that the metal wall of the smoker was acting as
a heat sink and was sucking heat away from the thermocouple. The hotter the smoker got the farther off the thermocouple was because of the cold outside temperatures. So the solution would be to buy a
thermocouple with a longer probe that puts it away from the wall of the smoker. Or I think I will Make some sort of metal "stand off" that I will mount to the back wall and then mount the thermocouple to it.

After autoprogramming and then letting the smoker temp stabilize, I was able to hold a consistant 199 degrees with the set point at 200.
It wouldnt even very a single degree.

My next project is to put in a fan to mix the air, so I can have stable temps from top to bottom. I think this would be great for jerky. You wouldn't have to rotate the racks. I know a few people here have tried this, but I havnt heard much about the results yet.
Anyone care to share their experiences with fans?

common sense isnt common
<hr height="1" noshade id="quote"></blockquote id="quote">

bubbagump · February 09, 2006, 12:38:09 PM

rjardjr,

This is the procedure I would use to setup autotune. First, start your smoker and put in a setpoint of 200 degrees. Select autotune paremeter 2 but wait until your smoker is within 10 degrees of setpoint (190) before you start autotune. When autotune is finished let your smoker run for an hour or so to see how well it holds setpoint.

If you find your smoker temp. lagging below setpoint then start over and try autotune parameter 1. When I say start over I mean to shut off your smoker and open the door to let it cool down. Repeat the above procedure using parameter 1 and see if you get better results.

If your are still not happy with the results you can try parameter 0, but from my experience this can cause the PID to "hunt" for setpoint, which can result in over or undershooting setpoint.

On my PID (Red Lion) I ended up using atuotune parameter 1, I did try them all though.

Bubbagump

bugboat · February 10, 2006, 12:06:23 AM

rgardjr, I used parameter 1. This seemed to work well.

I did notice some problems when I smoked steelhead this past weekend using Kummock's recipe. The recipe calls for smoking the salmon first at 100 degrees then 140 and finally 175. When smoking at 100 degrees the heat from the smoke generator rose the temp above the 100 degree set point. The PID was trying to controll the temp at 100 degrees by having the heat off. But the heat was still rising. This seemed to get the PID lost. And it didnt work well after that. Even after raising the set point. At least that is what I think happened.
From experience I have found that once a computer looses its way and gets lost you need to start all over.

I also had the thermocouple mounted to the back wall during this smoke. This could have been the problem also.

Let me know if you get your PID woking properly, and I could give you my PID settings. Really a 10 degree swing doesnt sound that bad.

common sense isnt common

bubbagump · February 10, 2006, 04:14:42 AM

bugboat,

I would agree that the placement of your thermocouple is most likely the cause of your problems and not that the PID lost its way. Are you comparing the temp readout from the thermocouple against any other thermometer? If your probe is short it is most likely picking up heat from the cabinet wall.

I personally think the best place for the probe is centered in between the racks and not permanently attached. This way it will not be affected by the cabinet walls. I use the clip that came with my ET-73 to hold my probe. I like the flexiblity of being able to place it in different positions depending on what, or how much I'm cooking.

No offense, bugboat but if you're happy with a 10 degree swing then you don't need a PID. It should control much better than that.

Bubbagump

rgardjr · February 11, 2006, 06:01:11 PM

So the #1 algorithm helped out quite a bit. I still see a few degree swing over the corse of an hour, but much better than what I was getting with 0. I'm going to do some baby backs today and a shoulder tonight so I'll see how it perfroms with meat in the smoker.
Thanks for the help!
Rick

IKnowWood · February 11, 2006, 09:54:20 PM

Took me a while, but I finally wired and built my LOVE TS. In the project box I got a 6 ft appliance cord, wired to a set of switch and the TS. The switch enabled me to enable a single outlet plug. The LOVE TS is direct wired to the feed to turn on. The out feed is then sent to another switch which then leads to a 2nd outlet plug.

what this does is allows me to turn on or off the TS operation. Why, I don't know yet. Maybe for those times that I want the probe to give me a reading and not operate the cabinet.

the extra selectable plug is for allowing me to easily turn off the puck feed and extra heat. I did buy a simple single pole switch that I will eventually set for a puck advance switch.

I love the switch. I don't need to keep an eye on it. And the temp swing is just fine.

The interesting find I did find, if the TS probe (more accurate) is a 10 to 12 degree difference to the simple Maverick / Polder probe and meter. Could explain my long cook issues in the past. We will see.

Thanks for all the help, this is great...

owrstrich · February 11, 2006, 11:23:47 PM

wood...

my 73 box probe and 73 meat probe ar 2 deg apart...

my 73 box probe and love ts probe are 4 deg apart when temp is steady...

when temp is going up fast or going down fast they are as much as 12 deg apart...

i guess its because they react differently to rise and fall...

the love ts aint as cool as the pids talked about here however it has done its job in the 6 smokes i have done in the last 3 weeks...

you gotta eat...

owrstrich

bubbagump · February 12, 2006, 01:04:25 AM

<blockquote id="quote">quote:<hr height="1" noshade id="quote">Originally posted by IKnowWood
 The interesting find I did find, if the TS probe (more accurate) is a 10 to 12 degree difference to the simple Maverick / Polder probe and meter.
<hr height="1" noshade id="quote"></blockquote id="quote">
IKW - The TS probe and Maverick ET-73 are both thermistor type probes. I believe Owrstrich is on the right track when he says it's the reaction time. But the difference in reaction time is not necessarily in the probes. It's more likely the devices using them (TS & ET-73). Don't be concerned if there is a big temp difference during rapid temp changes. It's more important that the probes read a more stable temp accurately.

The best way to check their accuracy is to get a small pot of water boiling and place the tip of each probe in the water making sure the probes are not touching the bottom or the sides of the pot. DO NOT fully immerse the probes in the water. Watch how fast the temp rises on both units and at what temp both of them top out at. Since the boiling point of water is dependent on altitude and pressure you can use this link to check what the boiling point should be for your area.

http://www.biggreenegg.com/boilingPoint.htm

When I tested my probe. The ET-73 was within a degree of my thermocouple. But the ET-73 did take longer to reach its max. temp. When testing your probes, if you find the ET-73 is still way off then switch the probe to the other port (food). If you get the same reading then you probably have a bad probe. But after switching ports the temp changes and reads more like it should then you most likely have a bad port on the transmitter.

Hope this helps. [:)]

Bubbagump