Stampede Temp swings

[randomguy]

Hey all,

I wanted to get some input before I called support. I've had my 590 for about 2 weeks now and it has been working well up until today. Temps normally hold +/- 5 deg as long as I'm not opening it up. Today, it has been all over the place, and I haven't opened the lid at all since putting my brisket in. I've attached a screenshot of my temp logging from the app. Nothing has changed - I'm using the same pellets (Rec Tec branded) from the same bag. My last cook was yesterday and the weather today is essentially the same as yesterday.

Probably unrelated, but my notifications seem to be very delayed on the last 2 cooks - I'd get "food within 5 degrees" notifications when it was at temp to take off.

Thoughts? Thanks.

https://imgur.com/a/lHFpVOU

 

[Buckeye1]

Is it windy out today?
Are you vents dirty?

 

[Greg Jones]

Support will, if honest, tell you that the recorded temps are based on an algorithm, not the actual temp recorded in the grill at a particular point in time. The idea is that over time, a grill set for say 225° will average 225°’. The actual temp at any particular time will ebb and flow based on how the controller is compensating. I’m surprised that the app developer has not built the same algorithm into what the app displays.

 

[randomguy]

Thanks to both of you for replying.

Vents are unobstructed and it was recently cleaned. No winds today, or yesterday. I read through some other similar posts here and made sure nothing similar was happening here - the probe isn't contacting the side of the grill and my grill was recently cleaned per the rectec maintenance page.

Greg, I could understand that story if my temps weren't so well controlled prior to this cook. I'm having fluctuations over 100 degrees every few minutes now. I did some further testing and found that they aren't even remotely accurate. I put a 3rd party probe right beside the factory probe and saw no temp swings whatsoever. In fact, when the grill was reporting "stable" temps, it was 20+ degrees higher than the 3rd party probe (which I confirmed accuracy with ice water and boiling water before testing this). When the grill was reporting temps in excess of 300 degrees, the other probe showed no significant change in temperature until the grill "corrected" itself. At that point, the temps just dropped even less than 20 degrees below the target temp.

For comparison, I attached another log from a few weeks ago where I was having trouble with one of the meat probes (since replaced and working well). Nice and stable temps except when I opened the lid and even then, not even close to what I'm seeing now. This screenshot is very typical of how my prior runs have done.

Update: my meat probes are now showing my brisket has suddenly dropped from 160 to 29 degrees. I think my unit is dying.

https://imgur.com/a/dXfVHhG

 

[Jim6820]

I think my unit is dying.

I think you’re right. It is probably a failed control board. If it was just the compartment temperature varying, I’d say you need a new probe, but with both cooking chamber and meat temps going wild, it sounds like a control board issue.

Glad you have a reliable secondary temperature monitoring system. I have so little confidence in the RT temp monitoring that I just use my ThermoWorks Signals for everything. I turn the RT-340 on with the push-button and set the temp with the knob; after that, it is all Signals.

Good luck on getting your problem solved.

 

[Greg Jones]

I’m just saying that recteq is famous for showing pictures of a controller display that shows a set temp and an actual temp that are identical. When using a third party unit like the ThermoWorks Signals, it records a variance in the pit temp that is greatly different than what the controller displays. Recorded pit temp is in red.

 

[Threadcutter]

I’m just saying that recteq is famous for showing pictures of a controller display that shows a set temp and an actual temp that are identical. When using a third party unit like the ThermoWorks Signals, it records a variance in the pit temp that is greatly different than what the controller displays. Recorded pit temp is in red.
View attachment 17387

Yep, I've noticed this as well with my 700. I retired out of the electric motor drive industry after 35 years. We applied a lot of PID in various applications.

A. It seems like my 700 has the most rock solid temperature control of any PID controller I've ever seen.....

-Or-

B. There's one hell of a lot of filtering/smoothing/averaging/manipulating of the temperature feedback/display signal going on.......

I just use my third party probes and don't really look at the Recteq display or app very much. Problem solved.

 

[mofarmer]

Hey all,

I wanted to get some input before I called support. I've had my 590 for about 2 weeks now and it has been working well up until today. Temps normally hold +/- 5 deg as long as I'm not opening it up. Today, it has been all over the place, and I haven't opened the lid at all since putting my brisket in. I've attached a screenshot of my temp logging from the app. Nothing has changed - I'm using the same pellets (Rec Tec branded) from the same bag. My last cook was yesterday and the weather today is essentially the same as yesterday.

Probably unrelated, but my notifications seem to be very delayed on the last 2 cooks - I'd get "food within 5 degrees" notifications when it was at temp to take off.

Thoughts? Thanks.

https://imgur.com/a/lHFpVOU

Good luck with CS, my 590 has had swings like yours since day one! I've called CS numerous times and talked to several different reps, they've looked at my temp graphs and agree the temp swings are not normal but they refuse to admit theres a problem with my unit. I'm tired of arguing with them and ruining expensive cuts of meat, when my new y***r arrives this "pos" is for sale!

 

[C. Keeper]

Yep, I've noticed this as well with my 700. I retired out of the electric motor drive industry after 35 years. We applied a lot of PID in various applications.

A. It seems like my 700 has the most rock solid temperature control of any PID controller I've ever seen.....

-Or-

B. There's one hell of a lot of filtering/smoothing/averaging/manipulating of the temperature feedback/display signal going on.......

I just use my third party probes and don't really look at the Recteq display or app very much. Problem solved.

I would have bet you were retired plumber cutting threads.

 

[Thor8594]

Good luck with CS, my 590 has had swings like yours since day one! I've called CS numerous times and talked to several different reps, they've looked at my temp graphs and agree the temp swings are not normal but they refuse to admit theres a problem with my unit. I'm tired of arguing with them and ruining expensive cuts of meat, when my new y***r arrives this "pos" is for sale!

Good luck with that Y***r (temp swings, rust, broken parts), I sold mine and went to the 700. All smokers have issues, we just need to learn them better.

 

[Motodad1776]

Good luck with that Y***r (temp swings, rust, broken parts), I sold mine and went to the 700. All smokers have issues, we just need to learn them better.

Yup they are all basically Chinese made contraptions now......luck of the draw.

 

[Threadcutter]

I would have bet you were retired plumber cutting threads.

Well, I may (or may not) have a plumber's crack, so there's that.........

 

[Threadcutter]

Good luck with that Y***r (temp swings, rust, broken parts), I sold mine and went to the 700. All smokers have issues, we just need to learn them better.

Actually, all things considered, I'm not unhappy with my 700. I know, not exactly a ringing endorsement. But, there are some things on it that could/should be improved by the factory. The first thing ? The stock casters/wheels are atrocious. I've done a few Mods on mine and it's now dialed in pretty well.

I keep mine in the garage/out of the lousy PNW winter weather, so I think it will last a good long life.

 

[Inscrutable]

Interesting … I am experiencing similar things with mine. Excursions every 10-20 minutes. Usually high, not low.
The pit and meat probes were both really close to my Inkbird on first cook, so haven’t checked again. Will the next time.

 

[Eatmoremeat]

My 590 is about 2.5 years old now (my stimulus gift to RT). I’ve been having temp swings since the beginning, but I guess I’ve learned to compensate. Lately though I started having crazy probe readings with the RT probes. I’ve tightened the nuts down as others suggested with no real difference noted. I calibrated them per RT in ice water, still crazy swings ( like from 25 degrees to 600). So I emailed customer service asking for suggestions. The next day I get an invoice in my email, zero dollars since under warranty, for two new probes and a new controller board. When they arrived, one of the controller board attach screws sheared off. So I called and described my problem and new hardware in the mail.

So, overall pretty happy with my unit overall. I understand most everything made in China to some extent now, and every brand will have its issues. I’d say that the customer service is still off the hook excellent overall, even if a frustrating issue pops up here and there. The app is pretty useless to me since alerts sometimes work and usually don’t. Finally got off my wallet and got a Thermapen. Shoulda bought one two years ago.

Thanks to everyone for all the great advice. I love this forum.

Oh yeah, almost forgot. When I was changing control board and removing wires, I noticed that both wires going into the probe connectors basically fell out before I even pulled connectors from board. I reinserted wires and crimped them again. Although I haven’t tested this repair with old probes, I did relay this to customer service to add to their “toolbox“ when helping others with probe issues.

 

[Maule Guy]

There is a Pellet grill mfg that promotes the temp swings as a feature, says it increases the smoke.

Even you gas or electric oven has temp swings. That being said, I would have expected a more even distribution around the mean temp on your 590.

On my 590 I am more concerned with the constant temp differential between the left and right side. I compensate by putting larger thicker pieces on the right side or swapping things like pork butts L to R mid cook.

I have been toying withe the idea op putting 4 to 6 fire bricks in the bottom of the barrel to even ou swings and maybe L/R temp difference.

Bottom line these grills are glorified oil drums with a “controlled “ fire in the bottom.

 

[Inscrutable]

There is a Pellet grill mfg that promotes the temp swings as a feature, says it increases the smoke.

Even you gas or electric oven has temp swings. That being said, I would have expected a more even distribution around the mean temp on your 590.

Which is a simple Non-PID controller. Emphasize ‘Non’.
In your oven or non-PID smoker, it attempts to match the Process Variable PV (actual oven/pit temperature), to the Setpoint SP by activating the Control Element (the coil or auger) in an on-off cycle. It inherently will oscillate about the setpoint.

A Proportional-Integral-Derivative controller is much more sophisticated. The Proportional Gain setting determines how fast the PV will race toward the SP, and without getting too technical both the Integral Time and Derivative Time settings help manage/reduce any overshoot/oscillation.

All these problems point to a poorly tuned PID control loop. A well-tuned loop, with reliably accurate and consistent sensors, will hold the PV very very close to the SP with minimal oscillation.

 

[Inscrutable]

Now, to be fair, the programmer had to select settings under some set of empirical or predicted conditions, and I would make allowances for what could be external events and actual conditions at significant variance with impacts (ash in firepot impeding combustion, maybe intermittent cold rain or strong winds … not sure how much those would impact), but mine have been under favorable and consistent steady state conditions.

I‘ve not yet asked, but wonder if the RecTeq guys tune these loops themselves (and uniquely for each model), or if it is outsourced or however these controllers are pre-programmed when arrive at their doorstep, and if these parameters are user-accessible?

 

[Inscrutable]

Hey all,

I wanted to get some input before I called support. I've had my 590 for about 2 weeks now and it has been working well up until today. Temps normally hold +/- 5 deg as long as I'm not opening it up. Today, it has been all over the place, and I haven't opened the lid at all since putting my brisket in. I've attached a screenshot of my temp logging from the app. Nothing has changed - I'm using the same pellets (Rec Tec branded) from the same bag. My last cook was yesterday and the weather today is essentially the same as yesterday.

Probably unrelated, but my notifications seem to be very delayed on the last 2 cooks - I'd get "food within 5 degrees" notifications when it was at temp to take off.

Thoughts? Thanks.

https://imgur.com/a/lHFpVOU

Hey, how did you get that vertical resolution on the temp graphing? All I can get is 0-1000*F so the magnitude of the excursions is hard to really gauge.

 

[mikeporter616]

Hey, how did you get that vertical resolution on the temp graphing? All I can get is 0-1000*F so the magnitude of the excursions is hard to really gauge.

That seemed come in the next to the last app update ~2 weeks ago. The latest added a note capability. Android.