PID settings for Chargriller Akorn with fan only

I'm gonna try my first cook with the HM this weekend and was hoping for some guidance on a starting point for the PID and fan settings for my Chargriller Akorn. I already had a 6.5 CFM Auber blower with the built-in gravity damper, so that's what I'm using for now. I've been using the Auber controller for a while and it has done a great job holding steady low and slow temps, but I wanted the extra features of the HM. I would like to eventually get a RD3 or MicroDamper, but the Auber fan will have to do for this weekend.

So what would you guys suggest for the BPID and fan min/max with only the fan?

It depends on the cook, if you're doing low and slow I would say set the fan max really low, like 30% or so... I've used all sorts of PID settings but the default settings generally do a pretty good job TBHWY. The Akorn is a bit leaky, so good thing you have at least the gravity flap damper. Lately I've been running my akorn with the RD3 setting the servo fully open at 33% and fan on above 33%, so my low and slows are pretty much damper only but when I do mid to high heat cooks the fan kicks in and takes it to the next level, works great without much tinkering with the HM settings...

Where do you set your top vent when you use the RD3 for low and slow?

I leave the Startup Max to 100% so it starts up the fire quick using 1/2 a weber starter cube, during that initial lightup period I leave the top vent just cracked a little bit past the dimples... The blower will have no problem pushing a good amount of air through the crack and stoking the fire, when the target temp is achieved the damper closes off and with the tight setting on the top vent it tamps down the overshoot you would normally get from stoking the fire that fast. (a general rule of thumb is when you have a fan blowing you need to keep the top vent pretty tight, when you have a damper on the input you can run the top vent wider open) From there on (during a low and slow) the HM stays in damper only mode, when I put the food on I open the top vent up a decent crack to let that convection flow get going. During the cook I set the top vent in a position where the damper is running about half open which gives the HM plenty of room to control the pit without the blower.
It was a long time coming, but the "servo fully open" and "fan on above" settings are really working out great for me. I used to run one set of fan settings for low and slow and another for high heat, with these options now I can pretty much do any temp cook with the same settings...

That's awesome. I have the top vent just barely cracked past the dimples through the entire cook with Auber controller and fan. The temp is steady, but I never felt like I was getting the smoke like I did just using natural ventilation and manually operating the vents. I may have to move forward on the damper sooner rather than later. How does the RD3 do on a UDS? I'd like to be able to cover the Akorn and UDS with the same fan/damper. What is the best way to go about procuring an RD3 if you don't have a 3D printer?

I've got a set of output caps that that makes a press fit that goes on/off easily so you can move it from grill to grill. Shoot me an email at rotodamper AT hotmail dot com and I will help you out...

I asked a similar question not long ago....I did a test run yesterday with my new HM/LM setup even though I haven't yet been able to connect it to my home WIFI. I used the stock PID settings on my UDS with 4-3/4" holes in the lid and a 3/4 ball valve intake wide open with a 20CFM fan set at max 30% (approx 6CFM max) connected to it and I was super impressed with the performance. My set point was 225 and the temps stayed between 223 and 228 for 4 hours then I shut it down. It's early to tell, and it was a "dry" run (no meat), but it seems this may be even more fuel efficient. But the conditions in DE yesterday were about 100 degrees and very little wind so that helped the fuel efficiency factor.

I did a dry run on the Akorn with the Auber blower tonight. It was very unstable. I tried the default PID settings and some other suggestions I found in other threads. I had the max fan at 30%. I tried letting it bring the grill up to temp and it overshot and snuffed the fire before the fan ever came back on. I lit it back up and tried walking it up to the setpoint slowly, but it still overshot. I tried 225 and 250 deg setpoints with no difference. The Auber was always very steady, so I know it's not the grill leaking or anything like that. I do have to walk the Auber up slowly to the setpoint, but once I got to it, it would hold +/-5 degrees with no issues and usually within 2 or 3 degrees.

I went ahead and ordered a RotoDamper, but I thought I'd love to get it to work with the Auber blower too.

What is the method by which you start your smoker? Did you perhaps start with too few coals with your minion method? I have a UDS and have the luxury of "pre-heating" by opening up my air intakes at the bottom first while I get the racks, etc, sorted out so I haven't ever run into that problem. I find starting with 12-15 whole coals or about 20-25 near spent coals (from my Kettle for grilling) works well for me. Lately I have been just putting charcoal chimney inside the UDS to give it a kickstart before dumping it into my charcoal basket and hustling my racks, heat diffuser, thermometers, and food in.
I also run an Auber 20CFM fan at 30% and knock on wood I am very pleased with the fan results. Now, if I could just get the thing to connect to my WIFI consistently...

I started it with a alcohol-soaked cotton ball in the volcano method like I've always done on the Akorn. Usually works great with the Auber controller. I'm sure it just needs some tuning, but I don't even know where to start. I had to change the PID settings on the Auber when I first got it as well. I'll have an RD3 soon enough, which should help since there seems to be a lot more information on the forum from folks using the rotodampers than folks just using a fan.

You may just be getting too big a fire going to start, I recall you saying you used to step the temp up bit by bit at first with the Auber, so your technique may need to be refined with your HM. You could either try the step up method you used before, or just make sure you are starting a very little fire.
How long do you let the cotton ball burn before you close the lid? If you let it burn off that may be too much lid open time, the fire may be too large at that point. I used to use the cotton ball method but tired of the smell of burning cotton. I settled in on Weber starter cubes, which are just about as economical really, I can start a low and slow using just half of a weber starting cube. If your are getting overshoot and then the HM chokes out your fire you probably are stoking up too large a fire to start with.
For PID settings I have always had good enough performance with the stock settings, I find the fan speed settings to be more important really. The fan can really stoke the fire so you need to run that slower if you are getting overshoot, particularly if you don't have a damper sealing off the input reliably. Lately I have been checking the HM log after running the pit in steady state for a while and using the suggested "Auto Tune" PID values that are reported there. TBHWY whatever PID settings I use my rig seems to work reasonably well. You may want to take a moment to read the WIKI about PID tuning to get a grasp on what each setting does, this may help you tune things to work better with your grilling techniques.

After it snuffed out, I lit it back up and walked it up slowly like I do with the Auber, but it still overshot. Maybe I didn't bring it up slow enough. I only let the cotton ball burn with the lid open for a minute or two. At that point I can usually close the lid and use the vents to bring it up to about 175, then I start the blower with the setpoint only a few degrees above the pit temp, then I slowly walk it up. That didn't work so well with the HM. Maybe I'll try again this evening. I had the max fan at 30%, but I think I'm going to lower it some more. The Auber only ever did really short puffs of a second or two. I'm not going to put a lot of effort into it since I'm going with the RD3.

Nothing changed about my hardware or methods other than the logic that drives the fan.

Just verify that the flap on the auber fan isn't hung on a piece of coal or whatever...
If you do another test cook that goes bad, after the initial low and slow set a higher setpoint and let the HM hit it and oscillate, with a higher setpoint it will be easier to get that oscillation without snuffing out the fire. After several cycles of oscillation look at the HM system log (Config\Status\System Log) and note the most recent suggestion for "auto tune" PID settings and give them a try. You can also use the manual PID tuning method suggested in the WIKI using the data you gather here.
The Auber (and most other controllers) does only on/off at a constant speed with the blower, the HM will actually ramp the blower speed up and down. The HM method is far superior IMHO, however, it is different and may require tweaks to your hardware and technique.

the flap on the blower was moving freely

If you actually like the puff puff puff control you can set the blower min and max to the same value and the HM will pulse the blower at that speed rather than ramping the speed. That's the beauty of the HM, it has a ton of flexibility in the Config so you can make it operate pretty much however you want....

Thinking back on my pre-servo damper days made me recall setting up my ping-pong ball valve to work with the HM and a suggestion for you. IDK how much air flow it takes to open the flap on your auber fan? You might want to take a look into that, set the auber fan in the position it will be on your grill then manually inch the HM output up to see at what percentage the flap opens reliably. Toggle Lid Mode a few times at that percentage to make sure the flap opens every time, then set that value as the MIN blower speed. This may result in a puff puff puff sometimes when the pit barely needs air. Since the Auber controller runs the fan using pulses of on/off at a constant speed opening the flap wouldn't be an issue, but with the HM scaling the blower speed it may require you to set a MIN value in the config.

Yeah, checked that. I put it in manual mode and 5% was enough to open it.

I finished putting together my RD3 tonight. I got the limits set on the servo. I've got the servo set to be fully open at 33%. I was going to set the min fan at 33% like Ralph suggested. What should I set as a max?

Also, when configuring the HM like this, does it just re-scale the fan speed to be 0% speed at 33% demand and max % at 100% demand?

No, you've got my suggestion wrong or I mis-stated my advice.
I suggest you set the servo "fully open at 33%", and the "FAN ON ABOVE 33%" (not the fan Min=33%). These settings will make the servo alone work when the HM output is between 0-33%, and the fan will start to blow (at MIN speed) when the HM output is 33% and ramp up to Max speed when the HM output is at 100%. So first third of the way it is damper only, the final two thirds it will be fan assist. You can play with the cut-off point if you like, but I like this arrangement. If you cut off too low the damper gets closer to open/closed behavior, if you cut it off too high the fan ramps up in speed really quick, 33% is a cutoff that works well for me...
As for Min/Max fan speed, that depends on the grill. I suggest you start with the Startup Max at 100%, to stoke your fire to temp fast, if you get unreasonable overshoot after you first achieve your setpoint then lower the Startup Max value. I suggest you set the Fan Min to 0%, unless you have a fan that will not spin at 1%, in that case set the Min to whatever speed will get your fan spinning. The Fan Max is the setting that needs to be most tailored to your grill. If you do low and slow and high heat cooking you want the Max to be fairly high, if you do just low and slow you're better off setting it low. For most grills you can achieve mid to high temp cooking the with the blower set to about 50%, if you need to achieve higher temps or need faster recovery you can run the blower Max as high as 100%. So set your Max to whatever speed will achieve your high end cooking temp in the time you need it to. The negative to having the fan Max set too high is if you are cooking in low or mid temp, running mostly with the HM output below 33% (where it will be controlled by the damper only) when the fan kicks in it will ramp up air flow quickly and cause the temp to first dip due to the in-rush of cool air, and then bloom high because the fire is being stoked rapidly. So its a balance, I would start with my Max at 50% and if the temps are touchy if/when the fan kicks in then lower it, if you are not achieving high temps when you need it raise it...

Oh, I see. I had the fan min mixed up with "on above". Thanks again.