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Thread: HeaterMeter First test Fire

  1. #1
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    HeaterMeter First test Fire

    So after a long Hiatus and my heater meter and Rotodamper sat fully assembled in a box for nearly a year its time....

    Due to house moves and family illness and to be fair the appalling weather we have here in the UK i have finally got around to Doing my initial PID tuning

    i've got the Pit Boss 24 kamado oven i purchased the BBQ Guru adaptor to attach to the intake.

    i've gotten the PID settings from the Wiki.

    P - 2.5
    I - 0.0035
    D - 6

    Fan on above 50%
    min 10%
    max 40%

    Startup 75%

    i'm a complete novice should i keep these settings? or try a brand new profile so to say?
    any advice would be greatly appreciated and i'll keep updates flowing through the course of the day.

    Cheers

    Andy

  2. #2
    TVWBB Guru Steve_M's Avatar
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    Those look like pretty safe numbers.

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    so it overshot slightly its only been running about half an hour near the temperature range still trying to rise back to 100

    changed the fan to startup 100% other than that everything the same

    I will keep updating through the day

    system log just posted a new Peak

    Sun May 5 12:12:29 2019 user.info : New -1 peak @1557058251=100.7 half=135 per=876 amp=-0.5 gain=4.4
    Sun May 5 12:12:29 2019 user.info : Ziegler P=1.5 I=0.003 D=5.5

    i think the time on the heatermeter isnt set to British Summer Time so should be 13:12:29

    should i input these into the PID or leave that alone for another hour and see how it runs?

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    Initial tuning end



    So i got it to stabilise at 100 Celsius ish with the settings it varied about between 99 - 101 (blue arrow)

    P - 3
    I - 0.0035
    D - 9.5

    FAN above 30% - 10%min - 50%max

    it sat quite well at 100 so i decided to ramp up to 110 (red arrow) whilst i popped for a meal

    it wobbled about a bit and ive just switched it off with the same settings
    i dont know why i changed the settings especially the D setting

    any advice how to fine tune it more would be grateful

    its cold here in the uk about 14 celcius high today

    Cheers

    Andy

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    Quote Originally Posted by ARowe View Post


    So i got it to stabilise at 100 Celsius ish with the settings it varied about between 99 - 101 (blue arrow)

    P - 3
    I - 0.0035
    D - 9.5

    FAN above 30% - 10%min - 50%max

    it sat quite well at 100 so i decided to ramp up to 110 (red arrow) whilst i popped for a meal

    it wobbled about a bit and ive just switched it off with the same settings
    i dont know why i changed the settings especially the D setting

    any advice how to fine tune it more would be grateful

    its cold here in the uk about 14 celcius high today

    Cheers

    Andy
    It will behave differently at different temperatures, amounts of charcoal left, and with big hunks of meat.

    So adjustments are needed during. Cooks sometines.

    My base is

    p=3.5
    I=.03
    D= 6

    Usually adjust p/d and leave i alone. Sometimes more d will stop cycling, sometimes it will cause it.

    My blower today ran 40% max setting for cooking chicken at 325.
    Last week it was 20% max to control at 130 -180 f while smoking bacon.


    Just cook with it. And adjust. During cooks, and you will have hang of it.
    Last edited by MartinB; 05-05-2019 at 08:09 PM.

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    Yeah the more I use it the better I will get at working it out.
    Is there a code that could be written to "autotune" . So the system could work out the best settings to use and adjust itself to them? I owned a PID before and that had a learn feature that must of worked out the best settings and saved them. Then once ramped up would re learn then.

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    Quote Originally Posted by MartinB View Post
    It will behave differently at different temperatures, amounts of charcoal left, and with big hunks of meat.

    So adjustments are needed during. Cooks sometines.

    My base is

    p=3.5
    I=.03
    D= 6

    Usually adjust p/d and leave i alone. Sometimes more d will stop cycling, sometimes it will cause it.

    My blower today ran 40% max setting for cooking chicken at 325.
    Last week it was 20% max to control at 130 -180 f while smoking bacon.


    Just cook with it. And adjust. During cooks, and you will have hang of it.
    Is it major changes in the P & D settings or just minor per temperature setting I think if I swapped from Celsius to Fahrenheit it would work better?

    Also my thermocouple was an open ended one with tinfoil wrapped around it. I've since ordered a stainless thermocouple probe that should also help the system run more stable I think so the temperature wouldn't fluctuate as much

  8. #8
    TVWBB Honor Circle Bryan Mayland's Avatar
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    Note that PID parameters are specific to the units of the temperature, so the values need to be multiplied by 9/5 to convert them to Celcius. So that would be P=6.3, I=0.54, D=10.8 for the coefficients Martin posted.

    For what it is worth, I never change my PID settings on my Big Green Egg, but I also only go as low as 225F and as high as 400F (with the bottom vent cracked as well). My values are PID=4, 0.02, 7. I'd also not use a "min fan speed" (set to 0%) unless your blower can't run all the way down to 1% speed (5V I think?). The standard blower has no problem. It turning on and off when below that min speed blows a burst of air through the system which can cause oscillations.
    Last edited by Bryan Mayland; 05-08-2019 at 06:44 AM.
    I'm that HeaterMeter guy what ruins everybody's free time.

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    Quote Originally Posted by Bryan Mayland View Post
    Note that PID parameters are specific to the units of the temperature, so the values need to be multiplied by 9/5 to convert them to Celcius. So that would be P=6.3, I=0.54, D=10.8 for the coefficients Martin posted.

    For what it is worth, I never change my PID settings on my Big Green Egg, but I also only go as low as 225F and as high as 400F (with the bottom vent cracked as well). My values are PID=4, 0.02, 7. I'd also not use a "min fan speed" (set to 0%) unless your blower can't run all the way down to 1% speed (5V I think?). The standard blower has no problem. It turning on and off when below that min speed blows a burst of air through the system which can cause oscillations.
    Ahh cheers Bryan!!
    I was going to do another run today but in typical British style it's been raining all day!
    Yes I got the 12v fan from yourself,
    I know that I would only be using it between those temps aswell I cook low and slow cook sausages and pizza so hopefully once it's tuned and I can get the hang of watching the graph it should be cool,
    I know some of my cycles were like 1000+ seconds so that would be a weird one to work out

    Thanks for all your help as usual!
    Andy

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