help with setting servo and blower


 

JWalker

New member
I am having one heck of a time setting the servo and blower settings.

I followed the wiki, as well as the "servo settings" search thread, still not having much luck.

Not sure exactly how I control the blower, other than the startup max % box? And should I have my heatermeter to auto fan or manual during the setup?
And I tried the 1000 and 200 setting, but servo seems to adjust to a mind of its own.

1) whats the initialization process for setting up the damper closed and open, servo wise? and where should be blower setting % startup max be while doing this?
And in manual or auto mode on the HM?

2) I would think the servo would be moving in conjuction with the fan speed linearly? how do you control this?

3) where does the pit probe come into play, since the blower and damper should be adjusted as the temp changes? What temp do you start at?

Not sure how all this works, and the threads I search for and the wiki are not much help explaining everything.

thanks!
Jason
 
If you put the HM into manual mode then the % you set on the HM will be the % the servo is open. If you put XX% in the setpoint the servo will move to that position. The Servo Pulse Duration numbers in the HM config control what the 0% and 100% position are, and the HM will scale the servo between those two points.
 
Still not quite following you Ralph.

So on my HeaterMeter I need to go into the menu and set the fan to manual mode. Then set fan to 100%?

I thought the whole purpose of the HeaterMeter RD controls was to:

1) regulate the damper opening automatically, using the pit temp probe.
2) when damper reaches 100% open (fan is off at this point) and pit temp falls below the pit temp set point (ie. 225 deg) then fan turns on to the % max you setup in the confit online.
3) as pit temp rises, fan slows, then stops, and damper only takes over, reducing damper opening. Then pit temp falls, repeat step #1

I am sure this is not how it works so if you can educate me on exactly what is happening that would be great!
The wiki is good but doesn't explain in terms that I can understand...yet!

Thx
Jason
 
Ok, your post title said "help with setting servo and blower" so I assume you wanted to know more about calibration of a servo damper than the basic operation of the HM...

Here is how it works. The blower and servo are controlled by the same basic logic, which is the HM using PID parameters along with Pit Probe temperature data to assign a speed/position. The servo position always correlates with the HM 0-100% position (unless set to open/close only mode) but the fan will follow the Min/Max/Startup rules in addition to the HM %. So if Startup max is 100% and Max is 50% the fan will blow at 100% until the pit temp is achieved the first time, from then on when the HM is at 100% the fan will actually be at 50%, and when the HM is at 80% the fan will actually be at 40% etc. With the fan "on at Max Only" setting selected, in the above scenario, the fan will blow at 100% until the pit temp is achieved the first time, when the HM backs down to 99% or below the fan will go OFF and the damper alone will operate from 0-99%. However, if the HM ever reaches 100% again the blower will turn on at 50% (the MAX value) until the HM goes back down to 99% or below, at which time it will turn back off...
 
Thanks Ralph, that is very helpful!

Can you give me a step by step instructions on how to calibrate the servo? I am not sure how to control the fan while calibrating the servo.

Do I use the fan settings in the configuration PID area, and if so, which ones? And what should the HM be set to while calibrating? And what fan settings do I use for each step of the calibration?

Thanks, sorry to be a pain.

Jason
 
So the "fan on at max only" is the only setting that will allow use of the RD damper feature correct?

If "fan on at max only" is not selected, then it is blower only control, based on your info above, correct?

And where do I find this setting so I can enable it?

Ralph wrote:

With the fan "on at Max Only" setting selected, in the above scenario, the fan will blow at 100% until the pit temp is achieved the first time, when the HM backs down to 99% or below the fan will go OFF and the damper alone will operate from 0-99%. However, if the HM ever reaches 100% again the blower will turn on at 50% (the MAX value) until the HM goes back down to 99% or below, at which time it will turn back off...
 
No, the fan "ON at Max Only" is the setting where the damper ALONE will run the pit (unless the HM is at 100%), but unless you select "open/closed only" on the servo setting the servo will operate the full range of motion always. Meaning, if you do not select "Max Only" or "open/closed only" the servo AND blower will both operate the full range.
 
I am also struggling with settings. I am attaching my last cook which as at 325. After the meat came off, I lowered the grill to 225 and played with settings. Current:
12, .05, 50. fan on at max, 0-35%. smoker is a small UDS, a pit barrel cooker. I modified with a 1 inch pipe at the bottom of the basket. Rotodamper and stock fan.
view


any help is appreciated!
https://drive.google.com/file/d/0B0rVqmhTJogIMDhtLXNkbDBxZk0/view?usp=sharing
 
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I've never run a UDS smoker myself unfortunately, but I hear they need more airflow to keep them stable than say a kamado? So you might drop the fan "Max Only" setting and let it blow all the while, specially above low and slow temps. And perhaps reset back to the stock PID settings and tweak from there.

You can go through the whole PID tuning theory if you like, it looks like you have a nice stable oscillation there to calculate from if you want to do it the mathematical way. See the WIKI on that.

Or, if you do just need more flow, set the blower to run all the time and scale down the MAX speed until the HM is showing it at about 30% while maintaining your target. The blower max speed setting and the top vent should be able to dial it in without too much fancy PID calculations in my experience.
 
Ralph the pit barrel smoker is a uds type smoker, but on a scale of a 18 inch wsm. They dont have grills and instead you hang your meat on hooks. Atleast the one I saw being used. Not, sure of blower size, if it is stock or not but, I would lower the max blower speed a bit, as it looks you are getting an cooling effect when the blower turns on and it take a bit for the pit barrel to overcome the cooling before you see the temperature rise. Once the temperature rises, you see a small overshoot from the extra energy needed to overcome the strong blower.
 
I think he said he had blower set to on at Max Only??? So the blower speed wouldn't mean anything after the pit comes to temp. I think he probably needs a little more air flow than the natural convection through the original RD can provide, at least that's my guess from what I have read...
 
It is the stock blower and I had it set at 35%. I am doing another test run right now. Went back to default settings, unchecked on at max and started at 100%. Slowly scaled the fan back, ended at 10-40max.Then tweaked P from 4 up to 7, Settings: B:0 P: 7 I: .02 D: 10. Much better! Holding about 3 degrees total range on the set point. Getty happy!
Photo: https://drive.google.com/a/su.edu/file/d/0B0rVqmhTJogIZ0RGaHBSYjJTcGM/view?usp=sharing

I can't figure out how to post a photo directly on here... is that possible?
 
Hi ESchrank, I also have a PBC. May I ask what's the cfm of your blower and if you could share a screenshot of your settings please?

Thanks.
 
Hi ESchrank, I also have a PBC. May I ask what's the cfm of your blower and if you could share a screenshot of your settings please?

Thanks.

Currently out of town. I have the stock blower, which like 8 cfm? I will shoot you an email of current settings this week. This is working pretty well, still some temp fluctuation above and below set temp, about 3-4 degrees. Happy to chat with about my experience so far!
 

 

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