RT590 Stampede vs Backyard Beast

[DesertRat]

I'm old. Real old. I just smoke with my aging but dependable Stampede and while away the time swearing at its app.

 

[BChristo]

I think that happened because, by then, the controller is sensing the chamber is too hot and trying to do its cool-down process. Your graph on the far right showed the ambient temperature increasing high…and the white line (set temp) hadn’t moved. At that point, the controller is trying to cool it down.

Here I am trying to think of why the grill shot up in temperature but yet was trying to execute its cool-down process. And the thought occurred to me…Keep It Simple Stupid (me). I may be wwwaaayyy overthinking this. I still think your green probe is bad or maybe not placed well…maybe just pushed too far into and through the meat. It’s still suspect in my mind. But, here’s where I’m going to take the proverbial fork in the road…grease fire. The controller isn’t going to overfeed the fire pot and yet still try to execute the cool-down process…not both at the same time. That makes no sense to me. So what else would/could jack up the heat in the cooking chamber? A grease fire! Could have been small…short-lived. .

Could have been some grease dripped over the side of the drip tray. Could have been grease not dripping to the grease trough or bucket properly. Could have dripped from the meat (wrapped or not) into the bottom of the chamber…maybe not centered directly over the drip tray. But it occurred so late in the cook when we’d expect the fat to be melting the most. In light of the controller trying to cool down while showing an over temp condition leads me to think that’s the culprit. It’s the only logic I can come up with.

And I’ll admit to another bias I have…rear air vents and no smokestack. Superstition? No! I originally owned a Traeger BBQ075 (smokestack). The grill performed well for somewhere around 10-years or so. But its poor construction showed its age. So I bought a new Traeger from Costco somewhere late 2018/early 2019. I forgot its model name but it was made specifically for sale through Costco. “Stapleton” or something like that. No smokestack…multiple rear air vents. Forward about six months and I have a grease fire in the back right corner. Somewhat bad. I cleaned it up and had some successful cooks afterwards…until the next fire. It burned up paint off the outside, inside, and just generally messed up the entire right third of the cooking chamber. I used my (always nearby, properly rated for grease fires) small fire extinguisher to put the fire out. At this point, I had lost all confidence in it. I procrastinated a bit but I reached out to Costco to ask them if there was any relief. I received a prompt “yes”. I borrowed my son’s truck and we took this damaged grill to my local Costco…a little over a year after I had purchased it. They gave me a full refund! I was flabbergasted. So my “jury” is still out on whether that was maybe some flaw in how grease drained, if something inside the grill wasn’t level (I checked from the outside), or if it was a design flaw. As a result, I have a general bias against a vented pellet grill…right or wrong.

No…my experience with that particular grill and the fact that it had air vents and not a smokestack isn’t really why I suspect you had a grease fire. But having experienced two grease fires, it reminded me why a pellet grill with a pretty smart, yet simple controller would graph an over temp situation when the set temp wasn’t changed.

All that said, it led me to do some research and a visit to Evans GA. The rest is history. I have what I now believe to be a generational pellet grill. The RT-700. The Bull.

Yes, I agree these grills are a generational leap -- applying the PID technology to a pellet grill is sublime. I also have the Bull. It was my first RecTeq. That was good enough to convince me I needed another one at my Denver house. These current runs are on my RT-590.

I really appreciate all the thought and analysis you put into this. You clearly have a lot of experience to rely on. I'm glad you are willing to share that and put your time into this forum. I don't think you are wrong in anything you say; however, what I have been seeing is probably not anything you have ever experienced. I do think you could recreate what happened to me.

Before I go on, I'd like to say that the support from ReqTec has been good. They helped me resolve this issue. I followed their suggestion after showing them my results. They also said a simple change in weather shouldn't cause problems -- that the PID should be able to handle it, but they said to try lowering the MFR. That in fact fixed the problem.

You're not the first person to suggest a grease fire; however, I can assure you that didn't happen. A long time ago in a small college town (Davis -- maybe where the father of our Basque friend received his enology training?), I learned some cooking skills as a sous chef. I learned early on that grease is to be respected. I have kept my grill free of grease. I had it set up perfectly, so no grease dripping where it didn't belong. I'll post the after cook photo below, so you can see there was no grease fire. At least not apparent in the fire pot area. You have to trust what I say about the rest of the grill.


I think you are also correct when you state, "The controller isn’t going to overfeed the fire pot and yet still try to execute the cool-down process…not both at the same time"; however, this doesn't take into account the Minimum Feed Rate -- I believe the grill will continue to feed pellets at MFR regardless of current state.

I installed the new controller, and was able to duplicate the over temp conditions. Setting the MFR down from 3.5% to 1.5% actually fixed the issue. That was shown in the graph in my reply that you picked up on.

To keep it simple, that test run was done with no meat in the grill, simply turning the grill on and leaving the cover closed with a probe next to the base of the RTD. I waited until the grill was in the sun for the same conditions as the initial issue -- just without an eight hour run with meat. Ambient temperature was high 70's instead of low 80's.

I think you also said the lower MFR could cause higher perturbations in the temperature profile.

I did notice that with MFR set to 1.5%, so I raised it to 2.0% and ran it the next day under the same conditions.

With that setting, the temperature profile was beautiful. I'm including it here. You can see where I opened the lid just long enough to let the temperature drop. Perfect response. Just have to love these grills!

I'd bet you could recreate the over temp issue yourself by setting the MFR higher. Maybe 4% instead of 3.5% because you have a chimney? Maybe 5%? I mean, you have to agree that at some point the MFR will cause heating greater than heat dissipation. Try a set temp of "low" and a MFR of 5%. In my case, it was 3.5% and a set temp of 225 at first and lower in the tests after the new controller.

At higher set temp, there is no issue because the difference between set temp and ambient temp is larger. Heat dissipates faster with higher temperature difference. In that case, when the grill goes to MFR, cooling down to set temp is possible because heat dissipates faster than the MFR can add it back in.

The same is true when I was running the grill in lower ambient temperatures. It was able to maintain the set temp because it would lose heat faster than the MFR was heating it.

It doesn't have active cooling. It does have a MFR, so a certain amount of heating is always present. It's dependent on lower air temperature to dissipate heat.

I'm not trying to fault the grill or the PID technology. I think it's a beautiful, and like you say, a generational application of technology.

As I said, I don't think your analysis is incorrect in any way. That one probe just went bad. I tossed it for sure. They sent me new.

Does it seem incorrect that this is the cause when you have been doing cooks out in the sun and high ambient temperature? I bet it does. I can only suggest that your conditions overall were different than mine. For one, the RT-590 doesn't have a chimney. You already have suspicions about adverse effects from slotted vents. I don't know if your MFR was ever set high enough to offset the radiative cooling these grills rely on. That's why I suggest trying a low set temp on a hot day with the MFR cranked up. It will go as high as 6.5% At some setting you should see the same thing I have. Maybe not as low as 3.5%, but at some point you should see the effect.

I hope you can try that and let me know.


Meant to show no grease fire:

This is just the fire pot area. Only clean ash. No sign of a grease fire. The drip tray was the only place where there was grease. It was really dark like the bark. It couldn't have caught fire without flame, because the flash point of beef fat is 600F

 

[BChristo]

Off-the-wall thought here; assuming that the probes that showed odd spikes are wired RT OEMs, are the nuts securing the sockets to the panel tight? This has been a problem for some in the past, resulting in intermittent connections, Just a thought from the “Crazy Ol’ Basque “

I still have the old controller. I checked and those nuts are tight. I don't know why that probe went bad. I kinda wish I did, so I could prevent it from happening again. Yes, they were the RT OEMs. They so far seem close enough for my cooks.

Thanks for the thought

 

[Jim6820]

I don't know why that probe went bad. I kinda wish I did, so I could prevent it from happening again.

Sometimes, things just go bad for inexplicable reasons.

 

[TDK84]

I got a Backyard Beast about four months ago and I love it. I usually smoke around 225 and I get a wonderful smoke ring. Smoked two spatchcocked chickens last week and the wife said that's the way we are doing them from now on. Even at 600 degrees the temp never fluctuates more than two degrees. I bought it instead of the 1100 so I wouldn't have to mess with the smokestack when I covered it. Excellent smoke from 180-275. Could not be happier.