Second element mod in BS611 and dual probe Auber PID

[Meatatarian]

I was reading up on how to set the P value in my controller to compensate for the dual 500 watt element mod I did in my 4 rack.  What I found out was you are supposed to change the P value from 70 to 140.  When I check the P value in my controller, it reads 7, not 70.  Is this the number I change to 14 vs 140?

I sent off an email to Auber to confirm but I figured I would check here as well as I would like to get it up and running tonight.

[dave01]

it should read 140, the 7 was meant to be 70

[Meatatarian]

Thanks Dave.  I wondered if that maybe there was an error from the factory.  Is it worth running an auto tune as some suggest with the dual element mod or does changing the P value make things right?

[tskeeter]

Not to steal Meatatarian's thread, but does anyone know how the p-value works?  I've run autotune more than twice since I did my dual element mod, with a couple of bricks in the smoker to simulate a load.  I'm getting about 2F +/- my set point.  Not a significant problem.  But I'm wondering if manually changing the p-value would tighten up the range a bit.  And, if so, which direction do I go from the current p-value setting? 

[dave01]

I tried running the auto tune a couple of times and wasn't really satisfied with the results so I changed everything back to the factory settings and just changed the P value. now it works great

[TedEbear]

For an explanation of what the 'P' value and other parameters in the controller are for, the instruction manual explains it pretty well.

Dual Probe PID Controller Instruction Manual

Single Probe PID Controller Instruction Manual

Also, the factory default 'P' value is 7 according to the manual.

[Meatatarian]

I noticed the P value in the manual is 7 as well when I was going through it again. Now I'm confused. Where does the 70 and 140 settings come into play?  Hopefully I get an answer  from Auber tomorrow.

[Meatatarian]

Here is the response I got from Auber this morning regarding P values:

The definition of P unit is 0.1 for WSD-1204 CPH and 1 degree for WSD-1200GPH. So 70*0.1=7

For your questions running one element at 500 watts vs. running two at 500 watts, the P value should be 7 for one and 14 for two elements.

Best,

Azalea
Auber Instruments

[ghosttown]

I know this is an old thread but do you have to change the p value if I change the smoker to a 900 element instead of two 500?

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[TedEbear]

I know this is an old thread but do you have to change the p value if I change the smoker to a 900 element instead of two 500?

Since a p value of 7 is for 500W and a p value of 14 is for 1000W, I'd say changing it to 13 for 900W would give you a better result.

[ghosttown]

Okay I had many smokes already with the p value set to 7, it's not until yesterday I notice this thread. What does the p value do anyways?

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[TedEbear]

What does the p value do anyways?

This link explains it all:  Auber PID Controllers