first test run. Need some help


 
J

Justin Dietz

New member
So finally got my first test run in right now.

I have a Broil King Keg.

Using newest Heatermeter with Microdamper....ALL DEFAULTS.

I used to own a Pitmaster IQ120. Figured i use my same technique.....which is if i wanted 225...i started with my set temp to 200.....and usually it would overshoot it a bit. But then I'd set to 225 and it would level right where i want it.

I set Heatermeter for 200. Well it hit 200 and way overshot it! I am now at about 270.

I assumed as the temp got closer to 200 that the fan would turn off and on a few times and slowly approach 200. It seemed to continue to blow 100% until reaching 200. I am guessing this is just maybe a setting or configuration thing I am missing.

Can someone offer any advice? I'd really appreciate it.
 
That's odd looking for sure. Can you post a screenshot of the main config page?

Any chance you were running in manual mode for a bit?
 
Steve_M said:
That's odd looking for sure. Can you post a screenshot of the main config page?

Any chance you were running in manual mode for a bit?
Click to expand...

I don't know if i was in manual mode because i honestly don't know how to get into manual mode...so i don't think so

 
Did you set your Servo Pulse Duration values, or did you just throw those numbers in there?

You fan speeds are too high for a keg too
 
SteveCK said:
Did you set your Servo Pulse Duration values, or did you just throw those numbers in there?

You fan speeds are too high for a keg too
Click to expand...

I didn't set anything honestly because I didn't know what to set. Can you suggest what to change and some numbers? I can probably give it another go tomorrow after work. Just grilled a steak so it will be hot for a while.
 
You're best off starting with the settings for a MD on Akorn PID = 4, 0.0035, 5. Fan on above 0% min 0-5% max 60% startup probably 60% as well. If you still get big overshoots you need to start your pit with a smaller fire.

The Pulse Duration values represent the full open and full closed position for the servo to operate the top disc. Tthe heatermeter doesn't magicly know where the disc is open and closed along the rotation of the servo. Without setting it your MicroDamper was likely open when the HM thought it was closed, thus the graph you have above. You have to set the duration values yourself by finding the full open and full closed by playing around the with values and running the HM in manual fan mode so you can force the HM into 0% through 100% values. The values are different for every MicroDamper, so this is a necessary process of any servo driven damper. Google "heatermeter servo mode" and you'll find some basic info on how servos function.
 
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SteveCK said:
You're best off starting with the settings for a MD on Akorn PID = 4, 0.0035, 5. Fan on above 0% min 0-5% max 60% startup probably 60% as well. If you still get big overshoots you need to start your pit with a smaller fire.

The Pulse Duration values represent the full open and full closed position for the servo to operate the top disc. Tthe heatermeter doesn't magicly know where the disc is open and closed along the rotation of the servo. Without setting it your MicroDamper was likely open when the HM thought it was closed, thus the graph you have above. You have to set the duration values yourself by finding the full open and full closed by playing around the with values and running the HM in manual fan mode so you can force the HM into 0% through 100% values. The values are different for every MicroDamper, so this is a necessary process of any servo driven damper. Google "heatermeter servo mode" and you'll find some basic info on how servos function.
Click to expand...

Good info and thank you. I will see if i can dial it in some tomorrow. I really appreciate it
 
The Keg (which I have) does not perform like a ceramic, due to the double wall insulated construction. After a few years of tweaking mine, here is what works for me:
P: 20
I: 0.01
D: 10
Fan on above 10%
Min: 0%
max: 25%
Startup max: 5%
Servo output is inverted on mine.

You need the high P and D because the keg takes so long to react.

How is your damper attached? Mine is on a bulkhead adapter on a plate in the intake, and foil duct tape to seal. Fill the charcoal well above the holes in the fire bowl, right up to the bottom of whatever diffuser you use. Light a small amount of lump, I use a MAPP torch. Put the diffuser in right away, set the top to 3, and set the heatermeter to 175. Once the temp hits 125-150, I close the top vent to 1.5 and leave it there. Once the temp hits 175, it'll overshoot and start leveling off. Wherever it levels off, set the pit temp 5 deg higher (eg if it levels off at 185, set to 190). Keep creeping up 5-10 deg at a time until you get to 225.

When adding or checking the meat, you need to be really really fast. If you open the lid for more than a few seconds, the rush of air will stoke the fire and cause it to rapidly overshoot.
 
Steve_M said:
If I'm not mistaken, if you crank up P as well as the D, they kind of cancel each other out.
Click to expand...

After reading about PID on wikipedia i still can't understand it. Would someone mind explaining in normal person terms what the P. I. D. stand for and why you adjust each one? Or point me towards a good read that isn't super technical?


I got the servo part dialed in i think Steve. Thanks for the advice. I would not have known to do that.

Mike...Walrus on Broil King Keg Forum ????? If so i was talking heatermeter with you there before
 
Since Mike say's he's been using it for years, he's likely using a blower and not a fan based system which is the newest evolution. PID values will not translate well between the two systems. Start with the PID settings I gave you for the Akorn (which is a double wall insulated steel "kamado", much like a keg). The keg is a little bigger, so I wouldn't be surprised if you ended up with a P value +1 greater, and/or your I value ending up around 0.004. And since you're using the MicroDamper it mimics a natural cook better than a blower, so instead of clamping down your top vent, put it to where it should be for a natural cook then close it just a touch.
 
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Justin Dietz said:
After reading about PID on wikipedia i still can't understand it. Would someone mind explaining in normal person terms what the P. I. D. stand for and why you adjust each one? Or point me towards a good read that isn't super technical?
Click to expand...
I have some information about what the parts of the PID are in the wiki under PID Controller Theory which explains their function with a basic example for each value. In addition I have some information about tweaking the values in the PID Tuning - Experimental Tuning. One of the two might click better than the other, as they are written in different styles.
 
Here I how I can best explain the PID values for practical use. The P factor represents the size of your pit and speed of temp recovery, the I is the driving force of the controller on the pit, the D is the amount of panic you want the controller to have over temperature changes. If you have a perfectly running pit your P and D values will be zero, and you will only have an I which represents exactly what your pit needs to achieve the set temperature.
 
SteveCK said:
Since Mike say's he's been using it for years, he's likely using a blower and not a fan based system which is the newest evolution.
Click to expand...

Yes, I'm using a rotodamper with blower.

And since you're using the MicroDamper it mimics a natural cook better than a blower, so instead of clamping down your top vent, put it to where it should be for a natural cook then close it just a touch.
Click to expand...

Not true on the keg. With the keg on a natural cook, you need to run the top vent at 1.25 to maintain 225. With the rotodamper, I can run a little more open.

When I first got the heatermeter and rotodamper, I tried (and failed) many cooks using Akorn settings for the rotodamper with blower.
 
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I think it's a little thicker steel and better insulation than an Akorn. The heat stays inside, it's always cool to the touch on the outside.
 
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