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**Pellet cookers** - YS480, YS640
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May 5th, 2019, 2:43 pm
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  • Joined: April 18th, 2014, 3:12 pm
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The Yoder Smokers pellet cookers were designed to mimic the functionality of the Yoder Smokers offset wood pits, with the exception that the fire is managed by the digital controller, rather than the cook periodically putting wood on the fire.

The Yoder Smokers pellet cookers utilize a large offset firebox and grate, which allows for a large and efficient fire, and the flow of smoke and heat through the full length of the cooker. Because the fire is larger, and is burning wood (pellets), the changes to the fire (heat) are not instantaneous, nor will the temperature in the cooker be a flat line constant, which is caused by the fuel (pellets) added to the fire being of differing sizes and amounts for every iterative turn of the auger. So just like cooking on any offset wood pit, you manage the fire based on the average temperature over a time period.

Calibration of the ACS controller is a new function that allows you to "dial in" your cookers performance, based on your requirements. This calibration is NOT something that you do constantly, but rather something that you may do to periodically to baseline your cooker's performance. Calibration is NOT required for you cooker to function, but allows those that desire a tighter control over the performance of their cooker, to make the necessary changes to match their desired level of performance. NEVER change the calibration of the controller with food in the cooker, as calibration is a function that requires a specific set of parameters to be followed when the cooker is empty.

The new ACS controller comes with the calibration set to 0 (zero), which means that the controller will manage, and adapt, in maintaining your desired set temperature. If you desire to achieve a tighter control on the temperature management in the cooker, or want to change from the controller using physical lower grate temperature to some level of suspended air temperature, the new ACS controller allows you to calibrate this directly into the controller using the menu on the controller.

I updated my early 2012 YS640 competition cart with the ACS controller. After I installed the controller, I ran the cooker through the 2 hour factory temperature test (using the 2 built in probes and Fireboard session for data and graphs), and was well pleased with the performance of the cooker without doing any calibration at all. The cooker heats up much faster, and settles in to your set temperature much quicker that the original controller. The pellet consumption seems to be less than before (I only use BBQR's Delight pellets, so this may be different for you if you use a different brand - results may also be different using a different brand of pellets because of lower BTU consistency). There seems to be less ash left in the burn grate after running, and the residual ash seems to be finer than previously seen with the old controller, with more residual ash dropping into the firebox through the burn grate.

I decided to calibrate the controller to see how the process works and what the process does, and how it would affect the performance of the cooker. The process to calibrate is outlined below.

To calibrate the cooker, the cooking chamber needs to be cleaned to remove all residual cooking debris, grease and ash. I keep the inside of my cooking chamber pretty clean, so all I needed to do was to completely vacuum all the ash from the inside of the cooker, the firebox and the burn grate, paying attention to also vacuum the ash from the igniter tube. Once I had the cooker cleaned, I made sure that the burn grate fitment in the firebox was up to factory specs, installed the 1 piece diffuser and the lower cooking grates, and pulled the sliding damper all the way open (handle pulled out fully to the right). I then attached the 2 temperature probes to the new ACS controller, put them through the factory probe port (I had previously installed the new factory probe port in the factory location on the left side of the cooking chamber - https://www.atbbq.com/yoder-smokers-pro ... style.html) and laid the directly on the lower cooking grate with one of the probe tips at 11" and the other at 22" from the hopper wall.

probe placement.jpg

After getting the probes placed, I closed the probe port door and closed the cooking chamber lid. I plugged in the cooker, pushed the power button, and pushed the START button, then set the controller to 250 degrees by turning the dial counter clockwise. To verify, I went to the calibration screen and made sure that the calibration was set to 0 (zero).

start button pushed.jpg

Here is the Fireboard session chart for the entire calibration test

fireboard session.jpg

At about the one hour mark, the grate probes had been reading lower than the cooker thermocouple, so I set the calibration to a -5 (minus five) to tell the controller that the physical grate temperatures had been reading an average of 5 degrees lower that the display. I set the -5 by pushing in on the dial to select the change, and then turning the dial counter clockwise.

setting first calibration.jpg

This is what the -5 calibration looks like after verifying the setting by pushing in on the dial.

calibration set to -5.jpg

I then let the cooker run for approximately 30 minutes to settle in with the new calibration change. I noticed from the session chart that it seems that the -5 change was making things a little worse that what I had expected, so from looking at the average differences between the grate probes and the cooker's thermocouple, I changed the calibration to +5 (plus 5), which accounts for a 10 degree upward change in temperature, i.e., -5 to +5, which is effectively is setting the calibration to +5 from the default 0 (zero) calibration. So the end result is that I told the controller that the display temperature of the cooker's thermocouple was an average of 5 degrees cooker than the actual temperatures of the grate probes.

calibration to +5.jpg

I let the cooker run for a total of approximately 3 hours, from pushing the START button until I pushed the power button to shut the cooker down. By the end of the session, the temperature of the display and the two grate probes were within 2 degrees of each other, and the overall temperature averages were within 1 degree of each other. I would say that the cooker and ACS controller are calibrated, and performing as they were designed.

3 hours into calibration before shutdown edited.jpg

After going through this 3 hour process, personally, I am not sure that I would suggest that the time spent doing the calibration wouldn't have been better spent cooking some lunch, as the ACS controller actually does a stellar job of managing temperatures all on it's own.

As a side note, here is a photo of the residual ash from the 3 hour calibration test, using a 50/50 mix of BBQR's Delight pecan and cherry. You can use this to compare with your residual ash if you decide to do this calibration test. Notice the lack of any fluffy whitish fly ash. Unlike most other pellets, BBQR's Delight has no bark in the pellets, and are super consistent from bag to bag and pallet to pallet.

residual ash.jpg

May 5th, 2019, 5:26 pm
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  • Joined: April 18th, 2014, 3:12 pm
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Here is a follow up and some vital information.

I decided to run another the 2 hour factory temperature test, just to verify the calibration test I did was correct. I cleaned all of the residual ash from the cooker, firebox and burn grate (as I always do), and placed the temp probes back exactly as I had done for the calibration test, and started the cooker.

Here is the vital information: I neglected to change the default temperature of 350 on the controller, to my desired temperature of 250 for the 2 hour factory temperature test. After pushing the START button, I walked in the house and was getting a drink of water, when I remembered that I had neglected to change the set temp to 250 on the controller. It was between 2 and 3 minutes before I got the temperature changed from 350 to 250. WOW! The new ACS controller is very quick to heat up to the set temp, and quick to recover when the temperature is changed.

If you compare the graph from the post above, where I set the temperature on the controller to 250 as soon as I hit the START button, and the graph below, where I didn't get the temperature changed for 2 to 3 minutes, you can clearly see the difference. So, if you allow your cooker to always start up at the default 350, you have nothing to worry about. If you want to set your temperature to something other than the default of 350, make sure that you do it as quickly as possible after hitting the START button.

As you can see, the calibration that I did, pulled the controller displayed temperature, and the 2 probes on the grate, right in line with each other, for a very consistent temperature across the grate.

verify calibration.jpg

May 9th, 2019, 10:16 pm
* Abilene ** Abilene *
  • Joined: May 2nd, 2019, 10:59 pm
  • Posts: 1

Thank you for posting your experiment, it's nice to know we can run a calibration if needed. I can't wait for my YS64s to ship!

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