I've been down that road too. In a pinch I used cardboard but it really got soggy as I tend to use a high-hydration dough. If you have a local restaurant supply store they should have a nice, inexpensive aluminum peel.
Slow Maverick probes – impact on control?
- Thread starter WayneM
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I've been down that road too. In a pinch I used cardboard but it really got soggy as I tend to use a high-hydration dough. If you have a local restaurant supply store they should have a nice, inexpensive aluminum peel.
Bryan Mayland
TVWBB Hall of Fame
Instead of using parchment, I use aluminum foil because it doesn't get brittle when cooked and transfers heat. It doesn't let the moisture out though so your crust doesn't crisp up enough. I have some sort of disability where when I go to shuffle something off the peel, it comes off but all the toppings and cheese go flying off too.
To test the temperature constant of the probe, can you just heat up the oven and put the probe in, then see how long it takes to reach X% of the final value? Ovens are pretty innacurate though because the temperature is all over the place but it maybe can give you an idea. Sunday night I'm making BBQ so once the pit gets up to temperature I'll toss a probe in the vent and post a graph of its curve and you can calculate it out.
To test the temperature constant of the probe, can you just heat up the oven and put the probe in, then see how long it takes to reach X% of the final value? Ovens are pretty innacurate though because the temperature is all over the place but it maybe can give you an idea. Sunday night I'm making BBQ so once the pit gets up to temperature I'll toss a probe in the vent and post a graph of its curve and you can calculate it out.
I turned my oven to 250 ºF, waited until it came up to temperature and put my thermocouple and Maverick probe in, taking a photo of the displays every second. After transcribing the temperatures from each frame, I plotted them. Here's what it looks like.
While there are too many variables to accurately measure the time constant of the Maverick probe, you can see that it takes almost three minutes for it come up to the final temperature, possible longer as the temperature as measured by the thermocouple is coming down already.
Note the stepwise function of the Maverick trace. It's not always three seconds but there is a pattern. It's not clear if this is a function of the Maverick monitor but that seems likely.
While there are too many variables to accurately measure the time constant of the Maverick probe, you can see that it takes almost three minutes for it come up to the final temperature, possible longer as the temperature as measured by the thermocouple is coming down already.
Note the stepwise function of the Maverick trace. It's not always three seconds but there is a pattern. It's not clear if this is a function of the Maverick monitor but that seems likely.
Ryan Evans
TVWBB Member
I have 2 observations about the TC/Maverick chart.
First is that the TC went high, then came back down. Did the oven heater element kick on from the door opening, and the TC picked this up?
Secondly, both sensors appear to be smoothing out at ~290degrees, 40degrees higher than the oven was set for. It appears as though 250degrees on your oven is not truly 250degrees.
Ryan
First is that the TC went high, then came back down. Did the oven heater element kick on from the door opening, and the TC picked this up?
Secondly, both sensors appear to be smoothing out at ~290degrees, 40degrees higher than the oven was set for. It appears as though 250degrees on your oven is not truly 250degrees.
Ryan
Bryan Mayland
TVWBB Hall of Fame
Yeah ovens are the worst at being a temperature, especially a somewhat low one. The thermocouple is most likely telling the whole story, that the oven overshoots and cools.
Based on the graph let's just ballpark some numbers. If the temperature range was 90-290F, then 63% of that is 126F, so the 63% mark is around 216F. The maverick reached that around the 70 second mark and the thermocouple around the 10 second mark. I don't think there's any denying that the thermocouple is has a much faster response and is better suited for control operations due to the shorter feedback loop.
Based on the graph let's just ballpark some numbers. If the temperature range was 90-290F, then 63% of that is 126F, so the 63% mark is around 216F. The maverick reached that around the 70 second mark and the thermocouple around the 10 second mark. I don't think there's any denying that the thermocouple is has a much faster response and is better suited for control operations due to the shorter feedback loop.
Agreed on oven temperature control. Add to that the fact that my oven is old and the temperature indicator ring on the dial control is well worn and barely legible and I'm surprised it even got as close as it did. I was going to mention that in my original post but forgot to.
On the question of control, I don't believe it's really a competition between technologies as much as thermal mass of the two sensors. The thermocouple is just the welded junction of two very small wires. For comparison see this photo of they type of thermocouple I'm using. The one on top is about 4.8 mm in diameter which should be close to the size of the Maverick pit probe.
With small temperature changes, I believe the Maverick probes are adequate but I would expect them to contribute significantly to an overshoot when getting the fire started, especially in a well insulated pit.
Even with my controller I'll set the initial temp at 50 ºF below my ultimate cooking temp. Once it settles, I'll put the meat on. Knowing the lump will burn faster with the open lid, I usually wait a minute or two after buttoning things up. After the temp settles, I put in my final set point.
On the question of control, I don't believe it's really a competition between technologies as much as thermal mass of the two sensors. The thermocouple is just the welded junction of two very small wires. For comparison see this photo of they type of thermocouple I'm using. The one on top is about 4.8 mm in diameter which should be close to the size of the Maverick pit probe.
With small temperature changes, I believe the Maverick probes are adequate but I would expect them to contribute significantly to an overshoot when getting the fire started, especially in a well insulated pit.
Even with my controller I'll set the initial temp at 50 ºF below my ultimate cooking temp. Once it settles, I'll put the meat on. Knowing the lump will burn faster with the open lid, I usually wait a minute or two after buttoning things up. After the temp settles, I put in my final set point.
Bryan Mayland
TVWBB Hall of Fame
Prepare to be surprised. My big green egg comes up to temperature and has a degree or two of overshoot. I'm not sure how quickly your pit comes to temperature but as it gets close it is moving like a couple degrees per minute. That is TONS of time for the Maverick to stay in sync.
225F
400F (the dip = I opened the lid)
The controller is already ramping down as it approaches temperature and the temperature just settles in right on the nose. The pit itself helps prevent overshoot because even though the heat has reached 225F, the walls of the pit still haven't come quite up to full temperature. They'll absorb a little extra heat which is why the fan actually goes down a bit even after temperature is reached. Overshoot is for chumps.
That's as strong an argument for HM as I've seen. It's a testament to both your control loop programming and the tuning you've done to dial in the coefficients for your pit. Well done.
I'm smoking in a Weber kettle so thermal efficiency is just a bit lower than your BGE. . . It does come up to temp very quickly though.
I'm smoking in a Weber kettle so thermal efficiency is just a bit lower than your BGE. . . It does come up to temp very quickly though.
RJ Riememsnider
TVWBB Pro
The stair step would most likely be not using appropriate resistor values matched with your probe and leads to decreased resolution. Is this a 72/73 or 732 probe?
It's a 72/73 probe and I have no idea what resistor Maverick uses inside their ET-73 but it would be interesting if they have limited the resolution of their thermometer by using the wrong resistor values.
Bryan Mayland
TVWBB Hall of Fame
My Maverick is an ET-72 and it uses a 22kohm resistor. That gives them good resolution (0.3F max) across all the food temperature range (40F to 180F). My first HeaterMeter also used this value, but when it got to around 350F it was something like 1F per ADC tick so I switched to the lower resistor.
I think the stepping may be because it doesn't measure the temperature continuously, just every X seconds.
I think the stepping may be because it doesn't measure the temperature continuously, just every X seconds.
RalphTrimble
TVWBB Diamond Member
I am completely happy with the speed in which the Maverick probes read, however, I find them to be a bit delicate. They are sensitive to getting wet and don't handle high heat situations well. I've already melted my two high heat Maverick probes trying to cook pizza, the good news is I only burned myself on one of them... lol At this point I've given up on using my HM to control the kamado when I'm cooking pizza.
I would really like to get some kind of probe that is capable of monitoring a high heat situation like a pizza oven that would work with the HM, do you know of anything available? Thermocouples can be designed to work in these high temperature situation, that would be one good reason to use them. (if they were to interface with the HM). At this point I am pretty disappointed that I can only use my HM for low and slow cooks, I had hoped it would work for high temp cooks like pizza too...
I would really like to get some kind of probe that is capable of monitoring a high heat situation like a pizza oven that would work with the HM, do you know of anything available? Thermocouples can be designed to work in these high temperature situation, that would be one good reason to use them. (if they were to interface with the HM). At this point I am pretty disappointed that I can only use my HM for low and slow cooks, I had hoped it would work for high temp cooks like pizza too...
RJ Riememsnider
TVWBB Pro
It's not the value they use, it's the value you use for your ADC.
RJ Riememsnider
TVWBB Pro
So you're at 22k even with the 72 probes? I wonder if the the default should be changed from 10k to 22k since the 732 probes do so much better with the 22k.
Bryan Mayland
TVWBB Hall of Fame
No way, because ET-732 probes are balls. 22k with the ET-72/73 probes means that they get really imprecise (1.31 deg/ADC) by 400F.
I might add 47k 1% resistors to the parts list though so ET-732 owners won't have to make second order. Probably worth the 40 cents they cost.
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The only ADC in my workflow that could have caused that was in the Maverick ET-73. I took a time-lapse photo of the monitor every second and transcribed those values to a spreadsheet.
Bryan Mayland
TVWBB Hall of Fame