Need Stoker help - temp spikes


 

Dave R

TVWBB Fan
Hi Everyone,
I need some help with my Stoker. I got my WSM 18.5" last November for a B-day present. In Febrary of this year, I purchased a Stoker but I am having temp spikes. I looked at the temp posts (based on title) on all 55 pages of this sub board and tried various things.

My Setup:
WSM 18.5"
Stoker
Bottom 2 vents closed
Top vent 1/4 - 1/8 open

Given my pit was leaking 'smoke' from where the middle section and lid meet, I also put self-stick nomex gasket around that area along with around the door. Those two areas don't leak anymore.

I normally use a full ring of charcoal and lit 15 briquettes and dump them on top of the unlit ring. Still get temp spikes. Have tried letting the pit come up to temp (225) before using the Stoker. This only worked once for 3.5 hours before temp spikes would start. Each spike/drop was larger than the previous one. Yesterday, I tried another test run, full ring, this time, I only used 12 briquettes and placed them at the edge of the pit ring where the Stoker blower is. Put pit together and turned on Stoker right away. Set Stoker to 225 but the first temp spiked up to 239.7. After it cooled down, it spiked again. Figure it would even out and hold steady after about 1/2 hr - hour (per Rock's BBQ) but it didn't. Kept spiking for the entire 3 hour test. Another suggestion, from Rock's BBQ was after the pit comes down from the spike, to power cycly the Stoker to 'clear' the spike from the cook history but when I tried this, it seems like it still remembered it and keep doing it (spike high, drop low, repeat).

Looking for suggests to try. Seems like I paid for a very expensive thermometer instead of an ATC.

Stoker log after 2 hours:
http://i1283.photobucket.com/albums/a543/drusscol2001/Test1-2hrs_zps8ef57107.png

Stoker log after 3 hours:
http://i1283.photobucket.com/albums/a543/drusscol2001/Test1-3hrs_zps9e23ac79.png

Below are the time and temps (Started Stoker log at 6:07 PM and stopped at 9:09 PM).
6:07 PM 145.8
6:27 PM 239.7
6:37 PM 202
6:50 PM 245
7:07 PM 193.5
7:20 PM 237.2
7:34 PM 209.8
7:44 PM 239.7
7:59 PM 210.4
8:10 PM 237.5
8:28 PM 211.4
8:40 PM 236.4
8:57 PM 213.5
9:09 PM 239.7

After I packed my Stoker up, I closed all vents on the WSM. After 30 minutes, the pit temp dropped 50 degrees so I know it is sealed pretty good, given it was about 80 degrees outside at 9:00 PM. The WSM is on my patio under my awning and out of sunlight.

Tonight I will be trying another 3 hour test, this time, setting pit temp to 200, after overshoot (if I get it), set Stoker to 225. This was recommeded by another post for someone else. The only other option would be to tinker with the top vent. I have the vent the Stoker is attached to set to full open, should I close this some?

Dave
 
The vent the Stoker is attached to should be fully open (I don't think you can even attach it otherwise). The other two bottom vents are completely closed. I run with my top vent about 1/3 open. If you're having leak issues with the door, Cajun Bandit sells stainless steel replacement doors that fit much better.

I start with a full ring of charcoal (for longer cooks) and add 15-20 lit coals. I'll let it come up a little on its own and then start the Stoker with an initial target temp about 25 degrees below my ultimate target temp. Once it comes up to the initial target, it will usually overshoot a little and then I'll bump it to up to where I want it throughout the cook.

You didn't mention anything about a water pan, but if I had to guess I'd say you're using a fairly full water pan. If so, I think that's where you're getting your temp fluctuations. My theory is that the mass of cooler water (water boils at 212 so that water mass will never reach your target temps of 225-250) requires the Stoker to work harder to get the temp up to your target, and then when the Stoker fan turns off the water mass quickly sucks the heat out of the smoker causing your temps to drop and starting the cycle all over again.

If you are using a water pan, my advice is to get rid of it and use a 14 or 16 inch clay saucer (planter base). The clay saucer heats up and maintains a much more consistent temp than a water pan and your Stoker doesn't have to work so hard to maintain your target temps. If you're not using a water pan, I'm not sure what's going on.

Good luck.
 
Do you have any food in the cooker or is it just an empty test? It will be difficult to maintain consistent temp of an empty cooker with or without an ATC. Put some meat in there, or a large rock and temp control should improve.

15 coals seems like a lot for 225. Also try starting with just 10 lit coals.
 
I know I forgot something in the original post. For this test, I switched from empty water pan to foiled 14" clay saucer. I didn't have any meat on it so I will try to get some from Walmart after work today...will try something small, like a sausage roll or small picnic ham. I will also try to start with 10 lit coals instead of 12 to see if that helps with the spikes. Will let it run for a little while before putting on the meat.

I will post the results tomorrow.

Dave
 
I firmly believe placing the pit probe in a location that allows for directly measuring the temperature of the heated air as it is being produced by the lit coals is paramount to a well functioning PID control system. Placing it anywhere else can introduce moderating effects which can cause the PID control system to never fully come into full control of the process. While attending Harry's class, I noted where he had his pit probe located. Instead of using the grill clip and locating the clip and probe on the grill, Harry has his pit probe's tip installed about 1" - 1 1/2" inside the WSM's inner wall. The silicone relief on the pit probe sits inside a grommet that is installed in place of one of the grill hanger machine screws. I duplicated Harry's install and I'm happy with the results.
 
Bob,
Good info. I will try that. So far for my test 2, I am using a 14" clay saucer wrapped in foil, full ring of charcoal, top vent barely open, bottom 2 vents closed. For the meat, I am using a 'fattie on a diet' (just a pork sausage roll wrapped in bacon, nothing stuffed).

Even from the get go, I get very high temp spikes. I have the probe clipped about an inch in from the side of the upper rack. I will try to put it in the silicon grommet since I have the 2014 model WSM.

Dave
 
Have always wondered if a clay saucer is beneficial or detrimental to the ATC obtaining an in-control process. Kinda of like waiting for your car's speed to change when climbing a hill before adding more throttle. Always lagging behind the actual process variable. Placing your probe before it should eliminate this.
 
I placed the temp probe in the silicon grommet but still saw spikes, could be since I did this mid smoke. Also, the grommet is above the position of the waterpan/saucer so I would only catch the air coming up the side of it. Do you remember if Harry had his Stoker fan on the same side of the pit where the probe was? I'm just wondering if I should have them on opposite sides thinking the draft from the fan would move across the coals and up the other side before dissipating the air flow to the pit side right above the fan...unless the charcoal ring helps to 'spread' out the air flow from the fan.

I did have a quick 1 second power outage which caused everything to 'reboot'. One hour after the 'reboot', the temps spikes kept getting smaller and smaller. Unfortunatley, I forgot to email myself the Stokerlog file to get the temps so I will have to do that tonight.

This may be a different issue but I also noted, with my Stoker that I am using a LAN cable with, after it starts up, I set the target temp and set the display to show the pit temp. About a minute later, it appears the Stoker does a 'warm reset'. When a Stoker starts up, you get a 'booting message' (I believe)...followed by a 'Please wait' message...for the 'warm reset' I don't see the booting message but I get the 'Please wait...' message and then the display will show the normal first startup screen and let you scroll through the options to select the temp, system info, network info, etc...Thinking, given this, that something may be wrong with the Stoker itself.

Dave
 
I went home at lunch real quick and got the temp logs but forgot to get the Stoker log graph. Will post that later. Below are the temps from last night with the changes indicated...there was a 1 second power outage for our whole neighborhood and I have it noted. Stoker seems to work better after the power outage...

Time Temp Notes
5:08 PM 125.3
5:38 PM 236
5:47 PM 214.8
5:54 PM 239.9
6:09 PM 207.8
6:21 PM 245.8
6:38 PM 202.4
6:53 PM 254 Moved pit probe
7:06 PM 161.1
7:12 PM 262.6
7:34 PM 207
7:41 PM 239.5 set pit to 250 from 225
7:42 PM 239.5
7:49 PM 263.3 Power outage
7:54 PM 256.4
8:02 PM 239.9
8:09 PM 264.7
8:21 PM 234.9
8:29 PM 262.2
8:43 PM 239.5
8:51 PM 258.3
9:01 PM 242.4
9:07 PM 256.7
9:14 PM 243.2
9:21 PM 254.1
9:28 PM 243.6
9:30 PM 248.4


Started with only 8 briquettes lit, full ring of charcoal (KBB), clay saucer wrapped in foil, bottom vents closed, top vent barely open. At the start, the pit temp sensor was on the rack about an inch or two from the side. I moved it down to hang out of the silicone grommet since it is the 2014 model. Used Stoker to bring the entire pit up to temp. I had my meat on since the start so as not to introduce a temp drop (which I did anyway moving the pit sensor). Pit temp set to 225 at the start and changed to 250 just over an hour and a half into the smoke since I needed the test meat to get done.

I tried to get a video of the Stoker acting up at power on but, as Murphy's would have it, it behaved but my link lights on the NIC don't work...looks like I will be calling Rock to see about the link lights. I do have the wireless turned off and using a wired connection.

Dave
 
Dave,

Something is most certainly amiss. Looks like the fan comes on at 220 (or is that 225... ) then cycles and finally stays on full time until you reach setpoint. Wondering if your top vent setting is helping to throw things off. I normally keep it wide open unless I get a wood chunk that fully ignites, which no amount of automation (at least the types that are available) could control.

On Harry's 18", if the fan is at 12, the probe is at 4.... If I remember correctly... has only been 29 months since taking note of it. Will be seeing him this Saturday and will ask.

Think you are on the right track, ie Calling Rocks.

Have, in the past run the wireless as well as copper to the router. It's been so steady that I just run it by itself. Normally see, at the most, a single degree or two swing.
 
Bob,
I did call Rocks and let him know what I did. He suggested to try the Weber quick starter cubes and/or try lump. Claims the ash from the briquettes may be causing the issue. I did email Harry only because I read an article (I think it was on his website) where he was talking about fire management on the WSM and to control the temp using the top vent. In the article he stated he would make a guide for using the ATC but I wasn't certain if he did.

While I was next to the Stoker, I did notice the fan comes sometimes will do little 'puffs' once it drops under 225 but then since it keeps dropping it will come on full blast, causing slight temp drop. Once temp gets back to 225, the fan stops but the temps keep rising to the spikes you see. I don't think I have even seen/heard the fan on while the temp was over what I set. It seems to stop when the temp is at 225 but something is causing the temp spike...may be a slowness in the pit sensor reading the temp??? I do wipe clean what I can from the pit temp sensor after each smoke. I don't soak it or anything, just take a wet paper towel with some soap on it, hold it by the silicone boot and wipe forward then rinse that section off with water being careful not to let the water get 'behind' the boot I am holding on to.

One thing I did notice, my link lights don't come on. I could have sworn when I first used it with a wired cable they came on. I will start a different link about the link lights.

If you do see Harry this weekend, I would definitely appreciate if you could briefly ask for any suggestions.

My goal is to try and get this nailed down before July 4th weekend so I can try a brisket. Will definitely need the ATC to keep steady temps on that long cook.

Dave
 
Gotta love Harry! He replied to my email within 30 minutes. He believes I may have a bad temp probe. He cc'd Kevin from Rocks on my reply so I will be calling Rocks back to see if I can get a new temp probe sent out.

Dave
 
Haven't called Rocks yet but here is a link to another test I did tonight. Before the test, I calibrate the probes...pit probe was about 4 degrees off along with my 2 meat probes.
For the first 2 hours, I had spikes, then things seemed to look good for another hour then major spike/drop. Checked the pit and most of the briquettes near the fan were ash covered so I stirred them. Waiting to see if the Stoker will settle back down since it spiked again...the fan shut off when the pit hits 225 but it appears the residual air or something keeps stoking the briquettes for a while and it spiked up to 238.

http://i1283.photobucket.com/albums/a543/drusscol2001/Test3-4hours_zpsef756364.png

I also noticed that after 1 minutes of running, my Stoker soft resets (as I call it). I got this on video and will be sending it to Rocks as well.

Dave
 
Got home last night and thought I would try to check the calibration on the probes. The pit and both meat probes were 4 degrees off. I set Stoker to compensate. Used my Maverick ET-733 and Thermapen to verify boiling water was about 210-211 degrees for the calibration.

Using old and new KBB, full ring, bottom vents closed, top vent 1/4 - 1/8 open (hard to tell exactly). Pit probe hanging out in the silicone grommet in the middle section. Lit about 15 briquettes. Foil wrapped clay saucer. Let Stoker bring pit up to temp after pouring lit briquettes on briquettes near Stoker fan.

Results after 12 hours:
http://i1283.photobucket.com/albums/a543/drusscol2001/Test3-Finalhours_zps3632d497.png

First 2 hours, temp spikes and drops. Third hour, it is rock steady at 225. Just after 9:30 PM, temp spike followed by a big temp drop. Once temp hit 191, I stirred the coals, looked like ash caked up on them. More temp spikes/drops until around 1:09 AM, that was the last temp drop before Stoker held @ 225 until 3:40 AM when more temp spikes occurred. At 4:21 AM, the temps held steady @ 225 until 6:35 AM when the next spikes started...

Since I had the smoker going for 12 hours and had to go to work, I shut everything down.

Just not certian what is causing the temp spikes once the Stoker 'gets dialed in'.

Will be doing more testing this weekend.

Since Harry thought that my pit probe may be the issue, I was thinking of setting a food probe as the pit probe just to verify if the probe is the issue.

Dave
 
For those that are following, I emailed Weber, since my lid isn't round more like slightly oval. Asked them for suggestions on how to get it round again. I got a reply asking for my shipping address and they would ship a new lid out. Cool...I love Weber support.

Maybe this may help with the temps besides having the nomex gasket.

Dave
 
Heading out to the Pechanga competition in a couple of hours for a comp trimming class this evening. Tomorrow, will be there most of the day. It's on my todo list, ie ask Harry.

You might want to try opening the top vent more, even to full open.
 
Spoke briefly with Harry regarding your issue. Harry's sure it's the probe.
Harry was placing the whole hog in the smoker when I arrived at his site.
 
Hi Bob,
Thanks for checking. Harry did reply back to my email confirming he thought it was the pit temp probe as well. I also noted that after about 1 minute of turning the Stoker on, it does a 'warm reset'. I got it on video and sent the link to Rocks BBQ and Harry. Harry replied back that he had the same issue in the past and the power supply was bad. I'm not certain how the probes work but giving I may have had a bad power supply, it could adversely affect the probes. I have since gotten in contact with Rocks BBQ and sent the unit with power supply, blower and probes back to have them look at it. Hopefully it will be a quick turn around as I would like to try my hand at a packer July 4th weekend.

I even tried with the top vent fully opened and still not stable. Another smoke, I bought some lump charcoal and that couldn't hold steady temps either.

Dave
 
Dave,

I used mine on Sunday and noticed the same spiking issue. When it first started I powered the Stoker down and then it ran fairly well for a bit then it started the "roller coaster" ride again. I'm not too sure what to think about it after reading everything in this post. I usually don't worry too much about the spikes since I mainly do ribs and butts, but with a brisket I would like to have a more consistent temp. I'm anxious to hear with Rock's has to say about your Stoker. Keep us posted please! Thanks for all your time with this.

Tim
 

 

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