Anyone have recommend pid settings for weber smokey mountain 18?

[Daniel Nolan]

I have version HM 4.2 and I am using a fan only setup on a weber smokey mountain 18 with the stock fan. It holds temp pretty close to the set point, but I see a lot of others graphs where the fan doesn't come close to 100%. Settings here were b=0, p=10, i=0.05, d=10
Here is the graph from last night, there was a weird spike in the meat probe, jumped up to like 700. The meat was a 6 pound chicken.

With stock pid settings this was my first cook. The temp wasn't as steady as the second cook. The meat was a rack of St louis ribs.

 

[NickMV]

Most people cut the fan's max output to about 50% or less. I ran an Auber 6.5CFM fan on my 18" WSM (when I still had it) and used max output 40% and it worked well.

I think if you search these forums there's a post or 2 with some decent settings for WSM users in terms of the other settings. I'd play with fan output independently of the other settings.

 

[Dave from Denver]

Can the heatermeter autotune? Your ribs cook looks very stable except for when you opened the lid...

Also you may want to look into air burners for more stability http://tvwbb.com/showthread.php?41158-so-how-are-you-attaching-your-blower-to-the-smoker

 

[NickMV]

Nope, there's no autotune, though the controller software itself is pretty smart. Once you've dialed in settings that you'd like, it runs pretty darn well.

It already has some logic built-in that senses the rate of approach toward setpoint, whether approaching from too high or too low, and adjust the fan output. So for example, if your setpoint is 225 and you're at 220 but approaching at a rate of 1 degree every 5 secs, as it gets closer and closer to 225, it's going to cut the fan speed down to practically nothing, then establish setpoint, then resume, to assure no overshoot.

It's pretty nifty.

tldr -- the software itself controls things just fine, and needs no tweaking. The parameters for the output to the fan, however, DO need to be tweaked to your specific application.

 

[Dave Smith]

this is what I use on my WSM 22.5
B=0; P=4; I=0.02; D=5
Fan pulse; min 10%; max 30%; max at startup

 

[Daniel Nolan]

Thanks for the suggestions guys, I think I got it more dialed in now.

Also you may want to look into air burners for more stability
http://tvwbb.com/showthread.php?41158-so-how-are-you-attaching-your-blower-to-the-smoker

The rib cook was just fan in one of the side vents.

Then I made a copper "air ring" that I used during the chicken cook.

I made another more "air burner" style one today with the remaining copper tubing I bought.

I did a test cook with it tonight. It seems to work really well. B=0, P=3, I=0.02, D=4

 

[RalphTrimble]

Sweet, another "air-burner" born!

 

[NickMV]

Ralph, once I get time to sit down and plan it all out, that's what I'm doing --- RotoDamper + airburner setup (though in a rectangular grid).

 

[Nathan J]

Could you tell much of a difference between the air burner setups? What size holes are you starting with?

 

[Daniel Nolan]

Could you tell much of a difference between the air burner setups? What size holes are you starting with?

The one under the grate seems to work better in my tests so far. I did 1/8 inch holes.