I cooked a pork tenderloin on my SnS Kettle. This was my first cooking use of my new Fireboard Pulse probes and I wanted to see how the ambient temp measurements compared to a wired ambient probe plugged into the FB2. Here is a pic of the cooking session. While this is not a controlled 'experiment", from what I see, the ambient measurement of the Pulse was easily 30* lower than the wired probe. Now, the wired probe was right next to the pork, pretty close to the same distance the Pulse's external component stuck out from the pork. It will take a few more cooks with this kind of setup to get a good baseline, but I suspect if I wanted to rely solely on the Pulse for ambient control, I would adjust by knowing that the grate temp is definitely 25*-30* hotter than reported.
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That is interesting.
The Pulse likely reads lower, not just because of the 'bubble' of air around the butt, but also due to conductance of heat, being buried in the cold meat, while the freestanding ambient probe was unaffected by the conductance and only reported the ambient temp.
I've heard of this before, it's pretty well described in the hour and a half long video test Steve Gow did on his wireless thermometers testing video (Smoke Trails BBQ). It might also follow that using larger chunks of meat like brisket or pork butt would lead to more heat conductance and lower 'displayed' ambient temps than smaller pieces, due to their more efficient conductance and capacity as a heatsink. Something to consider if trying to use the ambient sensor as your sole temperature monitoring source and mentally building in an 'offset' into your calculations.
Interesting experiment and valuable data to know. Thanks for the report GolfGeezer!-
DFPS, Fireboard's port about all this is very enlightening. I won't summarize, but one highlight for me is this quote from it:
"We can see that the most significant difference in ambient temperature readings between the wired probes vs. the Pulses takes place in the first two hours of the cook."
I'll also post this in a separate thread as it is relevant to any wireless vs wired temperature monitoring.
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Thanks for the write-up. I’m still waiting for my Pulse probes to ship.☹️Comment
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I don't have a Pulse, but I do have the Combustion stuff. I ignore the ambient temp from the Combustion thermo. If I do need an ambient temp that's closer than the dome thermo, I'll place a wired probe in the kettle.
Actually I do occasionally look at the Combustion ambient temp, but that's just to check to see if the ambient temp is way off.Comment
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Some take away for those that don’t have a pulse is to build in a range for your ambient temperature. If you are cooking at 250* then allowing the temperature to fluctuate to 275* is going to speed up your cook at least at the beginning.Comment
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For those that can't read the chart due to the colors:
Time (-7 offset) Internal External Channel 1 10/26/2024 14:10 209.8 10/26/2024 14:11 288 10/26/2024 14:12 329.9 10/26/2024 14:13 352.2 10/26/2024 14:14 362.3 10/26/2024 14:15 364.3 10/26/2024 14:16 367.5 10/26/2024 14:17 367.5 10/26/2024 14:18 364.3 10/26/2024 14:19 44.6 68 363.2 10/26/2024 14:20 46.4 107.6 339.3 10/26/2024 14:21 46.4 159.8 350.7 10/26/2024 14:22 48.2 195.8 354 10/26/2024 14:23 50 224.6 353.1 10/26/2024 14:24 51.8 246.2 351.6 10/26/2024 14:25 55.4 262.4 349.8 10/26/2024 14:26 57.2 275 349.2 10/26/2024 14:27 60.8 285.8 350.3 10/26/2024 14:28 66.2 293 350.5 10/26/2024 14:29 69.8 300.2 350.2 10/26/2024 14:30 73.4 305.6 352.5 10/26/2024 14:31 73.4 305.6 353.2 10/26/2024 14:32 78.8 302 306.7 10/26/2024 14:33 82.4 294.8 331.4 10/26/2024 14:34 86 302 346.1 10/26/2024 14:35 89.6 309.2 356 10/26/2024 14:36 93.2 314.6 363 10/26/2024 14:37 96.8 316.4 365 10/26/2024 14:38 100.4 320 365.7 10/26/2024 14:39 104 320 364.6 10/26/2024 14:40 107.6 321.8 363.9 10/26/2024 14:41 107.6 321.8 362.1 10/26/2024 14:42 111.2 314.6 303.3 10/26/2024 14:43 114.8 300.2 329.3 10/26/2024 14:44 116.6 305.6 345.7 10/26/2024 14:45 120.2 311 358.4 10/26/2024 14:46 122 316.4 369.9 10/26/2024 14:47 125.6 323.6 379.4 10/26/2024 14:48 127.4 330.8 386 10/26/2024 14:49 129.2 338 390.3 10/26/2024 14:50 132.8 343.4 393.5 10/26/2024 14:51 134.6 334.4 260.2 10/26/2024 14:52 136.4 329 180.8 10/26/2024 14:53 136.4 329 154.7 10/26/2024 14:54 140 330.8 139.3
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This kind of fits with the reasoning Thermoworks gives for their decision to not even ATTEMPT to include an ambient probe in their new wireless thermometer, and instead simply include a wired ambient temp probe with their new wireless gateway device.
The metal shaft of the probe going into the cold meat acts as a heat-sink, throwing off the readings of the ambient end. That, combined with the fact the ambient end is in the "evaporative cooling zone" around the cooking meat just make the reading much lower than actual grate level temperatures, as your test shows.
I'll be curious if you find ways to get more accurate readings, but it sure sounds like you will need to keep a wired probe clipped to the grate if you want to truly know cooker temperature...Comment
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Good question and point jecucolo . If you look at GolfGeezer 's data, and his original post, you will read that he placed the wired probe at the same distance from the meat as the exposed ambient temp tip of the Pulse. And the Pulse still read 30 degrees cooler. To me that backs what Thermoworks says about the conductive cooling that happens with that wireless probe being stuck into a hunk of cold meat. The two probes will get closer as the core of the meat comes up, but never converge. -
I.e. to finish up that thought, his data was with the wired probe within the same "bubble" distance from the meat as the exposed end of the Pulse probe. If the wired probe had tracked closely with the Pulse, then you would be right - you WANT to temp at the surface of the meat to be 250 or whatever the set point is. However, that does not appear to be what he observed.
It is certainly worth more experiments to figure this all out, and sounds like that will be happening.
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jecucolo I see where you're coming from, we want the most accurate information we can get - and measuring the temp in the evaporative zone does tell us more about what is going on with the meat.
BUT...
Keep in mind - people been cooking low and slow for decades, hell over 100 years, and never knew a damned thing about all this specific science stuff. We have the same evaporative effects in an oven, but we set our temps at 300, 325, 350, whatever. Cooking techniques have evolved over centuries to attain the result of properly cooked, but not burned or dried out meat.
Essentially, I'd argue the evaporative zone - and the temps inside it - are pretty much irrelevant. Meaning that shifts so much as the meat cooks, warms and dries out, it isn't important. What's important is maintaining a controlled and relatively steady cook chamber temp and following the progress of the internal temp to determine if we need to make changes. Another reason I've taken to skipping use of my Thermopro TempSpikes for the most part - I don't care about their ambient readings, only the internal meat temps.
Actually, I read an article some years ago about why we use 350ºF as the 'usual' cooking temp in many recipes in the US, where in other parts of the world it is different. It's much more about just how we cook than it is that it is the most efficient or 'best' temp for so many foods. As we in the BBQ world realize, you can get some even better results with super low and super slow - like BBQ, or even LOWER and SLOWER with sous vide!
It's interesting. But overall, for me, I don't worry too much about the ambient temps in the 'meat bubble'. I try to keep my cooker temps steady and in the basic range, and I don't fret too much over swings - but I am a data guy, so I STILL love having a ton of probes and knowing what temps are at different places in the pit, and frequently use that info to cook different proteins in different places, or rotate meat around to achieve my desired results - sometimes low and slow with a fast, hot finish to crisp up skin on poultry or finish off that bark on some pork belly or whatever. For me, I'm all about as much data as I can collect and digest - but the 'meat bubble' temps aren't a huge concern that has ever really bothered me.
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Good points! I was successfully smoking ribs, butts, chicken and turkey for a couple of decades on an old offset with just the lid mounted thermometer for temp control, and an old dial type analog kitchen thermometer for checking the meat! I never knew that the grate was 25-50F cooler than the reading up top! Not too many people complained either... I do feel I got better with better thermometers, and knowledge gained here...
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You folks hit on the issue that bugs me about the current wireless offerings, specifically Fireboard, Thermoworks and Combustion Inc. As pointed out by realdocBBQ, we have "learned" to use ambient as our metric for what we want to get our cookers to hit to get desired results. So, a decent measure of ambient fits how the overwhelming majority of folks cook, or at least what we set to based on either experience or recipes or what gramma did.
My beef is that none of them have, so far, matched their food probes with an independent, wireless ambient probe. I did have several back-and-forth dialogs with Fireboard and CI about this, and they obviously think the mixed-n-one approach is sound enough.
Thermoworks at least does not buy into that, but still has not yet produced a purely ambient probe. So, the RFX, while it can reportedly handle dozens of wireless probes, the Gateway is still "tied" to one wired ambient probe. Thus, if you take the Gateway into the house or whatever, you lose the wired ambient monitoring. If you use multiple cookers at the same time, you can only monitor one ambient.
I admit that using one cooker at a time fits most of us, and a number of cookers have their own monitoring built-in, especially in the pellet pooper world. So, it is easy to use what is currently available quite successfully given whatever quirks and limitations they have.
I hope my RFX order comes soon so I can play with it and compare the experience of how it performs and how it fits my brain's prejudice on how I cook.
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I agree GolfGeezer I'd love to see true wireless ambient probes as well. The problem is all of them to this point aren't able to handle truly high temps. I'm not sure if this is a limitation of the thought behind it, or a limitation of the capability in some way.
Personally, I'd love to see true wireless probes that will handle temps up to 500ºF.
I dunno, maybe peskelton can give us some insight into that? I mean the ambient sensor portion of the Fireboard Pulse can handle high temps, so why can't we do a true ambient-only probe? Since the FB2D will handle... I think 32 Pulse units, maybe we could have a Pulse Ambient and a Pulse Meat? If we simplified these, we could lower cost (at least somewhat, I'd think?) and I'd be willing to buy as many as I thought I needed of each one.
That's my thought process, anyways.Comment
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peskelton if that is so, how can the FireBoard Pulse, with its ambient sensor outside the meat, not get fried? I mean, eventually the temp next to the food would no longer keep the heat lower, and even then, when searing, the ambient component is exposed to much higher heat. -
@pskelton Got it. So, a design that simply uses a similar ceramic case, obviously thicker to protect the circuit board, could allow a standalone, separate ambient wireless - at least to my ignorant, not-an-engineer mind.
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I can answer why a truly wireless ambient sensor isn't currently viable (I engineer these for a living, so I'm pretty versed in the state of the technology). Ultimately, to make a wireless product you will need a microprocessor and Bluetooth radio to build a wireless product. The maximum temperature for these components is around 105C (at the very upper end, 85C is more common). This is a limits of the actual material science of silicone, above 150 °C the actual semiconductor nature of silicone breaks down and you now just have a fancy pile of minerals. At 105C, the junction temperature of the components is going to be _very_. close to this limit. There are exotic technologies like gallium nitride that might get to 300 °C someday, but no chip manufacture builds modern microprocessors and other such things from these materials.
Fine you think, I'll just put a bunch of insulation around it. That doesn't work because, eventually, even the best insulation (a combination of extreme vacuum and aerogel) will break down, plus the sensor itself provides a highly conductive pathway into the electronics, that bypasses the insulation. You might be able to design something that survives for tens of minutes if you're really clever, but that's about it. And it will cost a fortune and be pretty bulky—definitely not an easy to use consumer product.
You could something that's less complicated like insert all the electronics inside a wet sponge, and rely on water itself to evaporatively cool things below the boiling point. This is what wireless thermometers rely on to work at all, using meat as the sponge. And, of course, this brings you back to the original problem that your cool, wet material lowers the temperature around the ambient sensor.
I'll add one more comment about the trickiness of measuring the "true" ambient sensors. Wireless thermometers like the Meater, the Combustion Predictive Thermometer, the Pulse are all going to be cooled by the evaporating water around the food. And to some degree there will also be heat piping down the sensor tube and internal structures themselves. This causes them to under-read the air temperature right around the food. The exact amount depends on a lot of things.
At the same time, wired probes, measuring the same location will over read the "real" temperature. That's because the wired thermometer has, well, a metal wire (usually with copper inside). The wire will pick up heat all along its path and conduct this heat into the sensor, causing it to read higher than it would if you had a perfect sensor that was not divorced from everything around it. So what's the real temperature? It's somewhere between these two measurements.
You can do computer simulations to try to figure this out, and it's probably possible to build sophisticated math filters to compensate for this effect (this kind of thing is done in fields where it really matters). But generally, as the food surface dries out and heats up, the ambient sensors for most wireless thermometers will start to converge on a reasonably accurate measurement of the air temperature around them. Like the Firebird post says, the cooling effect is most pronounced when the food is very cold and wet.Comment
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realdocBBQ I see you're absolutely shameless when shilling for free stuff and exposure. I will admit that your writeups are quite comprehensive but I'm not sure your up to the level of chefchrisyoung and peskelton In other words don't quit the day job just yet -
chefchrisyoung Dang! I hate it when science conflicts with my gizmo lust. At least CI has a solution in the form of your upcoming Giant Grill Gauge that replaces a typical dome thermometer. I mean, it will have WiFi connectivity and no cables, just not quite grate level ambient monitoring. -
Haha Davek8282 you're absolutely right! lol I'm nowhere in their league, for sure, but... I do offer a unique perspective on some things. Never know when it may come in handy! lol Besides, I'm not asking them for free swag - not that I'd turn it down! I've been wanting to try both the Pulse and the Combustion, Inc. Gen 2 for a while, but they're both going to have to wait, unfortunately, until business gets better - IF it gets better. lol <sigh>
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