"I" parameter

I'm trying to figure what triggers the output produced by "I" to change.

For example, I forgot to close my top vent soon enough on my Akorn while starting my fire and overshot my 225F set point significantly. "I" remained stuck at 11.8% for probably the entire time I was over my set temp. I would have expected the "I" output to start dropping or go to 0 because it was obvious some positive amount of output wasn't required. My total output remained at 0%. So, I get that P and D were preventing "I" from winning the output battle. But, it still seemed like it could have (or should have) cleared itself after some period of time.

After thinking about "I" some more, could the output of "I" based on the area under the previous curve, rather than the current half period (the Integral)? I don't know. I'm still figuring out PID tuning.

EDIT: The original question was phrased poorly. Hopefully, this is clearer.

your PID settings don't change once you set them, unless you set them to something else. i don't understand your I setting being 11.8%?? my I setting is 0.02

my PID=B=0; P=4; I=0.02; D=5
Fan pulse; min 10%; max 30%; max at startup

Dave Smith said:

your PID settings don't change once you set them, unless you set them to something else. i don't understand your I setting being 11.8%?? my I setting is 0.02

my PID=B=0; P=4; I=0.02; D=5
Fan pulse; min 10%; max 30%; max at startup

Click to expand...

Thanks. I worded that poorly. I'm going to go back and clarify the original post. I was referring to the output produced by "I", not the parameter value itself.

I was watching the I output yesterday and couldn't quite figure out what causes the output to change. Is it based on the area under the curve in a cycle (or half a period)?

Darren C. said:

For example, I forgot to close my top vent soon enough on my Akorn while starting my fire and overshot my 225F set point significantly. "I" remained stuck at 11.8% for probably the entire time I was over my set temp. I would have expected the "I" output to start dropping or go to 0 because it was obvious some positive amount of output wasn't required. My total output remained at 0%. So, I get that P and D were preventing "I" from winning the output battle. But, it still seemed like it could have (or should have) cleared itself after some period of time.

Click to expand...

The I% output is the running sum of I * temperature difference. For example, if I=0.05, Setpoint=225F, Current Temp=220F, each second it adds (225-220)*0.05=0.25% to the output. The reason that the I% doesn't decay after your overshoot is because the PID output was 0% and I% can only change when the output is in control, i.e. not at 0% or 100%. It is the same reason that when you turn your HeaterMeter on it doesn't jump up the I% to 100% in the first second.