PID Settings

Looking into information regarding PID tuning. I've read the wiki as well as searched the forum.
I'm specifically looking for settings that are successfully working for a Weber Smokey Mountain 22.5, but I was not able to find much.

I'm wondering if it would be beneficial for everyone to post there PID settings and max fan setting for the type of smoker they are using? This would give a noob like myself a starting point, maybe even include a graph if you have one available to show how its working.

If you do post, can you post your type of smoker/grill in the post title area so others can quickly scan the post title to make it easier to locate.

Maybe at some point if we get good starting points for a variety of different smokers we can add the information to the WIKI.

Thanks,

John

Wsm 22.5

Settings were:
B: 4
P: 3
I: .005
D: 5
Fan 100%
Bottom vents closed except where fan was mounted.
Top vent 1/4 open

Comments: Not happy with the fluctuations I was getting

I don't think PID settings are your issue, looks more like airflow with or without the fan. You need to have control of the system before the PID can do it's thing. You may be choking the fire, as it looks like temp is dropping at 100% fan before opening the lid. If I keep the top vent closed to tightly, condensation plugs the holes & my fire dies. Opening the lid hurts you more than it helps. The rush of oxygen & temp drop both work against you at that point - the HM can only read the air temp, not the condition of the fire. You need a longer 'lid open' delay & to leave the lid closed more (once you figure out why it's choking).

I would suggest AL foil tape over the 'closed' intake/bottom holes, then opening the top a bit more. I also tape over the fan intake until there's ~1/4 open as my pit needs very little airflow at 225-250 (the servo + fan would probably work better for me).

I actually agree with Andy. Looking at the graph the fan is ramping up properly as the temperature nears your setpoint. It passes the setpoint very high and never recovers until you open the lid, providing O2 to stoke the fire.

I run with my top vent all the way open and the bottom vent closed enough that the smoker would run about 25 degrees less than my desired temp. This lets the fan stoke the fire the last 25 degrees and maintain a nice temperature.

dave

Thanks for the info.
I plan to do a test smoke after the weather clears. If I get a chance I may wire in a servo.

John

John Case said:

Thanks for the info.
I plan to do a test smoke after the weather clears. If I get a chance I may wire in a servo.

John

Click to expand...

Keep it simple. Don't add another variable until you get it working with the fan. Temp dropping with 100% fan output isn't because of the HM (I'm looking specifically at the 4:42 section of your graph). The HM works WITH a well-regulated grill/smoker, it doesn't fix one that isn't running right.

Took me 3 or 4 tries to get a stable long-term cook, but it was all the grill/operator, not the heatermeter. I mentioned the servo because it will HELP me as I'm choking the fan off, don't need the airflow. But I have learned that over time & can run stable with the fan. My first test was at 350*, worked like a charm for 4hrs, so I decided to try a butt at 225* overnight. I slept about 30minutes that night, chasing overshoot & snuffed fire (I think I re-lit 2x). Ended up finishing it at 275* as that was as low as I could run stable. After sealing up the intake, I can run all night at 225* and have 1/3 of a load of charcoal left. I want the servo as more of a damper - my grill will run >225* at the size of the fan opening....

Andy,

I'm getting ready to do my first cook with the HM this weekend. I've been reading the forums looking for ideas about how to connect it to my WSM. I spent no telling how much time last weekend walking around HD and brain storming. What I came up with was a sink drain. I haven't been too satisfied with it, mainly for cosmetic reasons. It looks pretty ghetto.

Another reason that I didn't really like it was because I couldn't envision how I would be able to include a damper that I would operate with a servo. I was going to start with the fan only because that's all I had completed and just see how it goes.

After reading your post, I'm starting to like my idea a little better, because you never lose control over the WSM vent. And, although the vent is still manual, it sounds like from your comments that once I get the hang of where to set the vent, I probably won't have to worry about the servo.

It fits over the vent snuggly against the 2 tabs on the vent without any irreversible mods to my smoker. It fits fairly tightly against the weber, too. I ordered some gasket material to fit between the grill and my contraption to help seal the air leaks around it. Also, if I need to I can drill 2 holes through the drain and into each tab and secure it with sheet metal screws. That's not as bad to me as drilling through the sides of the weber.

I bought the sink side. So, it has a metal "x" to prevent large pieces of food from making into the house plumbing which will limit airflow. But, I could get the garbage disposal side if I need the extra air flow, which I probably will.

Here's what it looks like. (had problems getting the image to display, so gave up and inserted a link -- hope it works)
https://www.dropbox.com/s/p8yau02queyhbrr/heatermeter_connection.jpg

Darren, what is the OD of that pipe?

I believe that it's inch and a quarter but I'm not sure if that's ID or OD. I haven't actually measured it. It's standard drainpipe. I can get a measurement later if you'd like.

Actually, it is 1-1/2. The part # is H800-1.

That's really similar to what other people are doing - bowl & toggle bolt through a hole. I have a big steel keg, basically the same design as a big green egg. I have a sliding door for my intake. I made a plate with a square hole in it the same size as the fan outlet, then cut/bent up a sheet of AL to match the fan & create a runner. I then JB welded it to the plate. TO install, I put the plate in, shut the door, then use AL foil tape to seal everything up. I even put tape over ~2/3 of the fan intake to keep the draft down (why I need the servo or a damper).