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Thermometer trust issues


Fat Guy
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Everyone says that the thermapen is very "fast". Does this mean it is fast in coming up to the temperature of the food because the tip is thin or does this mean the sampling rate is fast so you can see the numbers changing quickly?

Hi,

The Themapen is fast because it uses a thermal coupler to provide the temperature. It takes about 4 seconds to come up to temp.

In my experience, the Comark PDT 300 is also fast and at $30 a relative bargain. It gets within 3 degrees in about 4 seconds, and that is close enough for me.

Comark PDT300

One thing I've never seen mentioned about probe thermometers is that often the probe acts as an excellent conductor and will heat up the meat immediately adjacent to it and give spurious readings.

Shalmanese,

Do you heat up your thermometer before sticking it in the meat?

Tim

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. . .

You can also test the probe for accuracy by placing it boiling water, it should be 212 degrees. You can then mix crushed ice with water in a glass and take them temp, after it has sat for several minutes. The probe should read 32 degrees. Just make sure the probe isn't touching the ice.

But only at sea level! It is surprising if you look it up how a few hundred feet will throw off the boiling point. You don't have to live in Denver!

Denver isn't to bad ,200ºaprox.,its when you get up around 10,000 ft. Gotta bring the pressure cooker. Was at 10kft with a pal from France and we were doing some pasta. as I put it in the boiling water, he proudly looked at his watch and said "aha 11 minutes" I told him to look at it in a half hour to see if it was close yet.

Bud

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This was a recent thread about probe thermometers:

http://forums.egullet.org/index.php?showto...0entry1499788

There were some interesting suggestions, including one that sent me to scientific websites looking for other options. It might take some snooping around to find the best deal, but there are some products that compete well with the thermapen, which seems to be a repackaged scientific thermometer.

Here's just one option: http://www.bestlabdeals.com/CheckTemp_4_Fo.../haninmp019.htm

Notes from the underbelly

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Thing is, with a virtually instant readout, you can take measurements in lots of different places, so that you can, with practice, develop the skill of going straight for the critical coldest spot. As well as seeing the maximum...

If you want to poke the thing you're cooking five times while standing there with the oven door open, I suppose you can take a bunch of measurements for practice, but then again you can do this with a cheap instant-read thermometer too -- it will just take a little longer. I'd be interested to know how much longer. If it's, for example, 30 seconds v. 1 minute to take 5 readings then that doesn't seem like a big deal. I guess the Thermapen has a thinner probe. ...

Steven, you might be interested to see the timings reported in this review

http://www.cookingforengineers.com/article...en-Thermometers

At 3 seconds a time, you *could* do 5 tests literally in half the time of a more conventional thermometer.

Also, the comments on Thermapen calibration might interest those (like Lior) who have thermometers that, never mind trusting, they just don't believe.

"If you wish to make an apple pie from scratch ... you must first invent the universe." - Carl Sagan

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In my experience, the Comark PDT 300 is also fast and at $30 a relative bargain. It gets within 3 degrees in about 4 seconds, and that is close enough for me.

Comark PDT300

Okay, so I looked at the thread suggested by paulraphael and I checked out some pix of the above Comark. Now I am getting more confused. The PDT 300 is cute; it looks simple, like a pen-type. But then I looked at other more expensive Comark models that have interchangeable probes (what, different lengths for different meats?), a bigger readout contraption and timer with a cord connected to the probe. How do those work?

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I guess there's a point of no return...

In my smoker I use a Nu-Temp with three remotes; one for grate-level temp and two meat probes. While I don't know the absolute accuracy I presume it's within a couple of degrees; imho repeatability is perhaps more important than absolute accuracy.

And yes, the probe itself does conduct heat into the meat, leading to high readings. This leads to step two..

When the Nu-Temp indicates "done," the next step is to go move the probe to another spot _or_ poke the meat with the Thermapen. Or to put it differently, the probe-type therms will get you into the ballpark while the Thermapen will get you toward precision.

Do you _really_ need this? No, of course not. But there's a huge difference between a pork butt at 190F and 200F; one isn't pullable while the one that's "done" is easily pullable. Of course you could determine "doneness" by pulling on the bone but that requires experience while cooking to temp works the first time.

So...imho these gizmos aren't all the incredibly expensive and can help lots toward consistency; we don't "need" them but otoh we don't "need" All-Clad etc, and better tools contribute toward a better product.

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I'm not sure I agree that All-Clad contributes to a better product. In some cases, more expensive equipment does contribute to a better product, in some cases it doesn't, and in other cases it does but only if you have a sufficient level of expertise to take advantage of it. So I like to determine whether a given product will actually help me improve my cooking. Of course there are other factors: convenience (a piece of equipment may make cooking easier, even if it doesn't make it better), elegance (some things just look nice), the gee-whiz factor (I like toys as much as the next person).

Anyway . . . this morning I boiled a pot of water and stuck all four of my thermometers (the four I could find, at least) in there. The results were surprising.

First the good news:

Polder. I don't think they still make the exact model I have, though I do see it in the occasional store -- probably old ones still knocking around the shelves. The most similar current model I could find on the manufacturer's website was model 602-90 -- pretty much the same thing. This digital thermometer with an oven probe proved surprisingly accurate. It measured boiling water bang-on at 100 C. When I switched to F, it mostly stayed on 212 but oscillated between 211 and 213. I suppose there are convection issues within a pot of boiling water that can account for such fluctuations. In any event, that's accurate enough for me. Because the intended use of this thermometer is to probe an item in the oven for a long time, I don't hold it against the Polder that it took about a minute to settle on the final temperature reading.

Now the bad news: all my other thermometers totally suck.

Comark Dial Thermometer T220A. I had long wondered why my instant-read thermometer was so damn slow. I got it as a giveaway at a trade show, it has some corporate logo on it, and the vendor was proudly saying that they were free instant-read thermometers. But I got a little more suspicious than usual when, under this morning's controlled circumstances, it took more than 40 seconds for this shirt-pocket thermometer to reach its cruising altitude. So I found the model number on the bottom of the dial and looked it up on the manufacturer's website. It's not an instant-read thermometer! It also was highly inaccurate, measuring boiling water at 200 F on the nose. Reading further on the manufacturer's website, however, I found out that this thermometer has a calibration nut. The manufacturer recommends calibrating in ice water, but I used boiling water. Now it's working. It's not a particularly useful thermometer, though.

Taylor. Again I couldn't find my exact thermometer in current production, however current model #5911N is very close. I have two of these. As far as I can tell they don't have a calibration option. And they are not accurate. They aren't even the same as one another, no less the same as the temperature of boiling water. One of them came sort of close at 208. The other was down at around 202. Both are going in the trash.

The other bad news is that, after years of having the crap kicked out of it, my Polder is in its final days. You have to bang and knock it to get it to register the switch between C and F, and once in awhile it spontaneously shuts off and won't go back on until you jiggle the battery (more of a problem if you're using the timer function).

So I am effectively down to no useful thermometers.

This presents an opportunity, though: I can start from scratch. Now I just have to decide whether I'm going to try to pull this off for less than $50, or if I'm going to spend triple that or more. I've got to say I am very reluctant to buy a Thermapen. Even were I convinced of all other aspects of its utility, I'd be turned off by its inability to display both F and C. It's ridiculous that this isn't part of the feature set. I use too many charts and references from all over the world to be bothered with a thermometer that can't switch back and forth.

Steven A. Shaw aka "Fat Guy"
Co-founder, Society for Culinary Arts & Letters, sshaw@egstaff.org
Proud signatory to the eG Ethics code
Director, New Media Studies, International Culinary Center (take my food-blogging course)

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...  I've got to say I am very reluctant to buy a Thermapen.
No kidding, really? :biggrin:
Even were I convinced of all other aspects of its utility, I'd be turned off by its inability to display both F and C. It's ridiculous that this isn't part of the feature set. I use too many charts and references from all over the world to be bothered with a thermometer that can't switch back and forth.

I've got to agree that from the standpoint of the dilettante cook (ie those not working in a production or regulated environment, where one scale would be used exclusively) it does seem rather strange.

To put on a very old (electronics) hat of mine, I'd bet that there is an internal switch that is set at the factory to determine which way it swings. This is most likely going to be either a solder blob or a resistor that is placed in one of two alternate positions. And could go to a proper switch, without much design difficulty. (Modifying the case moulding would likely be the main expense.)

I do wonder somewhat as to whether it might be a design choice for improved reliability (after all, what component has worn out on the Polder!), but I lean towards thinking that their target market might well be seen (by the designers at least) as preferring something that could not possibly be set to the wrong scale, and thereby consequently create a business problem... the KISS principle.

I'm sure a special "keen cook's version" (with a switch) would sell well enough.

Would you use your gravitas to suggest it to them? I'd buy one tomorrow (rather than wait for next Christmas, as seems likely).

"If you wish to make an apple pie from scratch ... you must first invent the universe." - Carl Sagan

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WRT switching between degrees Celsius and Fahrenheit, I find that once you get used to one scale, switching doesn't really matter too much. Rare beef is rare beef, no matter what temperature scale is used. Since I've been using a Lauda circulating water bath heater for several years that measures in degrees Celsius, I have become accustomed to thinking in that scale. If I happen to have a cookbook that specifies some Fahrenheit temperature with which I am not familiar (I am quite familiar with meat cooking temperatures for various levels of "doneness" but not so familiar with, say the temperature at which egg yolks curdle) I simply visit the convert-me.com temperature conversion page, do a one-time conversion and write the temperature into the book in degrees Celsius.

--

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... I simply visit the convert-me.com temperature conversion page, do a one-time conversion and write the temperature into the book in degrees Celsius.

Just a BTW that Google will do it for you...

open Google (or use the thingy in the browser bar) and try

275F in C

:cool:

"If you wish to make an apple pie from scratch ... you must first invent the universe." - Carl Sagan

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This topic has emboldened me. Has anyone used the Comark DT15? I just bought one on eBay (impulse buy!) and I don't have any idea how exactly it works; the picture shows a cord from the probe to a stand-up monitor that clearly isn't long enough to go into the oven, so I assume it is an instant read-out type. It supposedly comes with interchangeable probes. On the Comark website it has a list price of $89. This one is new and the price was really great so I went for it. It will be my first meat thermometer ever. I think I've saved a lot of money not doing large rib roasts for so many years, but I seem to be having a mid-life meat crisis.

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I do wonder somewhat as to whether it might be a design choice for improved reliability (after all, what component has worn out on the Polder!), but I lean towards thinking that their target market might well be seen (by the designers at least) as preferring something that could not possibly be set to the wrong scale, and thereby consequently create a business problem... the KISS principle.

Well yeah, except the same manufacturer's I.R.F.S. "Next Generation Food Safety Meter" has a big, fat, juicy C/F selector right on its face. I'm wondering if it's actually a food-safety issue: having a switch anywhere on the surface might get the thing unapproved by health agencies?

Steven A. Shaw aka "Fat Guy"
Co-founder, Society for Culinary Arts & Letters, sshaw@egstaff.org
Proud signatory to the eG Ethics code
Director, New Media Studies, International Culinary Center (take my food-blogging course)

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WRT switching between degrees Celsius and Fahrenheit, I find that once you get used to one scale, switching doesn't really matter too much. 

I've been thinking for awhile that I should just switch to C for everything, and I may do that at some point, but I'm too stubborn to be prompted to do that by a design shortcoming in an expensive thermometer.

I have a question, maybe somebody knows the answer. The fast reading (response time) of the Thermapen (specifically models 3 and 7): is that a function of the thermocouple probe, or is it a function of the electronics inside the unit? In other words, using the same type K thermocouple probe, will every digital thermocouple thermometer have a similarly fast response time, or will some be faster than others?

Steven A. Shaw aka "Fat Guy"
Co-founder, Society for Culinary Arts & Letters, sshaw@egstaff.org
Proud signatory to the eG Ethics code
Director, New Media Studies, International Culinary Center (take my food-blogging course)

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The response time for a thermocouple display depends on two things; the response time of the thermocouple and the sampling rate of the display.

In the case of the Thermapen the fast response is a result of a thin (low mass) thermocouple and a rapid sampling rate.

Examples:

If you plug Thermapen's low mass thermocouple into a display that samples once every minute the system response time will be one minute.

If you plug a large, high mass thermocouple into the Thermapen unit the system response time is limited to the thermocouple's response rate.

So to answer your question: It depends on the unit's sampling rate.

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This topic has emboldened me. Has anyone used the Comark DT15? I just bought one on eBay (impulse buy!) and I don't have any idea how exactly it works; the picture shows a cord from the probe to a stand-up monitor that clearly isn't long enough to go into the oven, so I assume it is an instant read-out type. It supposedly comes with interchangeable probes. On the Comark website it has a list price of $89. This one is new and the price was really great so I went for it. It  will be my first meat thermometer ever. I think I've saved a lot of money not doing large rib roasts for so many years, but I seem to be having a mid-life meat crisis.

For roasts (and lot of other stuff) you need an in-oven thermometer with a metal shielded cable and perhaps an alarm. I couldn't live without mine. I use it for roasts, fish, bread, duck breasts, confits etc...

I just ordered a Thermapen, but that is in the nice-to-have category.

Perhaps you can buy a shielded cable for your Comark? Otherwise there are plenty of options, eg:

http://www.amazon.com/Pyrex-Digital-Probe-...97817914&sr=8-4

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If you plug Thermapen's low mass thermocouple into a display that samples once every minute the system response time will be one minute.

Is there such a thing as a digital thermocouple thermometer that has a longer sampling time than a few seconds?

Steven A. Shaw aka "Fat Guy"
Co-founder, Society for Culinary Arts & Letters, sshaw@egstaff.org
Proud signatory to the eG Ethics code
Director, New Media Studies, International Culinary Center (take my food-blogging course)

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... I have a question, maybe somebody knows the answer. The fast reading (response time) of the Thermapen (specifically models 3 and 7): is that a function of the thermocouple probe, or is it a function of the electronics inside the unit? In other words, using the same type K thermocouple probe, will every digital thermocouple thermometer have a similarly fast response time, or will some be faster than others?

Specifically, the models 3 and 7 (detatchable probe) are not supplied with any probe included as standard.

A "fast response" probe is but one of the options...

http://www.thermoworks.com/products/therma...rmapen_3_7.html

Among the other models, some are sold as "fast response", some aren't.

Response time factors will include the thermal mass of the probe (and skinnier means faster, but all other things being equal, means more delicate (fragile) too).

There is the rate at which the electronics 'sample' the probe to take individual "instantaneous" measurements.

There may be a ("software") averaging function, for rf noise immunity and improved accuracy, combining several (many?) samples.

And then there is the rate that the display updates, which (whether or not related to any averaging going on) may be constrained by the display speed (it surely isn't designed for videogame speeds) and human perception, so that the display remains readable, even while changing - and stabilises so that the user doesn't complain of constant "flickering" between readings.

However, there is no advantage in "slugging" the total electronics' response to be slower than the response time of the (fastest) probe that it could be used with.

Just a BTW that the more sampling, the more processing, going on, then the harder the electronic designers have to work to get reasonable battery life out of the thing...

But with a well designed display (and maybe averaging) system, other than battery life, there's no advantage that I can imagine (in the enthusiast kitchen) in having deliberately slow electronics... or am I missing something obvious?

"If you wish to make an apple pie from scratch ... you must first invent the universe." - Carl Sagan

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So today I got the idea that maybe I could pick up a Thermapen cheap on eBay -- maybe someone wanted to get rid of a slightly used one or something. I didn't find a Thermapen but I did find this: the Comark P250. Seemed a lot like a Thermapen, right down to the same design problem of having to choose between C and F. The item was advertised as new, in a slightly damaged box, from a seller with a good reputation. I looked around online and found retail of $159 and street price of $99 -- that was the lowest I could find. So I figured if I could get it for half that I'd go for it. I won the item at $38.55. So, we'll see how it works. I'll report when it arrives.

Steven A. Shaw aka "Fat Guy"
Co-founder, Society for Culinary Arts & Letters, sshaw@egstaff.org
Proud signatory to the eG Ethics code
Director, New Media Studies, International Culinary Center (take my food-blogging course)

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Well yeah, except the same manufacturer's I.R.F.S. "Next Generation Food Safety Meter" has a big, fat, juicy C/F selector right on its face. I'm wondering if it's actually a food-safety issue: having a switch anywhere on the surface might get the thing unapproved by health agencies?

My first thought would be that perhaps the unit has to be totally sealed to meet some guideline. But, there are plenty of membrane type switches that could be used...it's a curious design decision to be sure--from an electronics standpoint.

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For an oven thermometer that might be able to accommodate expansion, I found this cheap thermocouple thermometer for $19.95 on eBay. The vendor has 36 more of the units available if anybody wants one. I should have it soon and will report whether it works. It seems to come with a simple wire probe, which is not going to be usable as an oven probe, so I also looked around for the cheapest available oven-safe needle probe I could find. That would appear to be this one from Comark. I was able to find it for $17.15 on this website. Plus shipping of course.

Steven A. Shaw aka "Fat Guy"
Co-founder, Society for Culinary Arts & Letters, sshaw@egstaff.org
Proud signatory to the eG Ethics code
Director, New Media Studies, International Culinary Center (take my food-blogging course)

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Why wouldn't the wire probe work as an oven probe? And have you considered using a dual-input smoker unit with high-temperature probes? (I did cook the probes of my first Redi-Check remote-sensing unit in my smoker; when I went looking for replacement probes, I purchased a new Redi-Check Maverick Remote-Sensing unit with high-temperature probes. So far they've survived.) With such a unit you could keep track of both the oven and the meat temperatures.

FWIW I checked the calibration and response time of my digital thermometers yesterday. The Redi-Check units ($40 or $50) and the cheapo instant-read pen thermometer that I picked up for under $20 were within 1 deg. F of each other and of the calibration point (both ice water in a well-chilled glass, and boiling water). I saw the same effects noted above: pen thermometer responded more quickly and had less thermal mass to influence its surroundings; of course, it isn't designed to stay in the oven, and the probes of the others are. Given the ease of use, accuracy and response time of the pen thermometer, I can't see a reason to spend so much on a Thermapen. When I get home tonight I'll check the manufacturer again, as well as whether it changes scale - I've forgotten both those details. I picked it up at a local hardware store so I'd have something for camping trips. It came up to temperature within 5 seconds, plenty quick enough for me.

Getting back to FG's original point, however, I'm still working on how to use the instrument so it gives me the correct information. This weekend I experimented with trying different probes in different parts of the meat, and using the same probe in different areas (with the oven door open, losing heat rapidly). I think it will come to developing different procedures for different cuts of meat.

Nancy Smith, aka "Smithy"
HosteG Forumsnsmith@egstaff.org

"Every day should be filled with something delicious, because life is too short not to spoil yourself. " -- Ling (with permission)

"There comes a time in every project when you have to shoot the engineer and start production." -- author unknown

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I use thermapen's for all my cooking. I need insta read when checking internal temps on nice steaks, I use it to check meat on the smoker and I now use it in the kitchen. I have actually bought probably 6-8 of them. I keep one by the smoke(covered area), dear wife uses one in the kitchen and I have backup.

I also use the armoured cable devices they have to watch the constant temp inside the pits, very accurate and they last a long time.

Given the high cost of meat it seems reasonable to pay $75 or so to insure getting a steak just right.

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