Thermocouple probe suggestions


 
Steve_M

Steve_M

TVWBB Guru
Looking for thermocouple probe suggestions.

eBay has a pretty wide variety ranging from $4 to $80

Primary use will be for low-n-slow in the kamado, so probably going to mount the probe on the grate, which is what I've always done with the thermistor style probes.

This one looks like it will do the trick:

http://www.ebay.ca/itm/121098643282
 
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Many have screw threads on them, although if you're going to drill a hole and mount it I'd just get a random probe off ebay or amazon and add the mini connector to it for half the price. Themocouples is thermocouples. There really aren't nicer or better made versions unless you really look for a poorly made thermocouple. It all just comes down to shape.

Wire insulation could also be a concern but not at the temperatures we work in, and especially not if only the thermowell is inside.
 
Yah, I bought an expensive TC from Thermoworks and a cheapo from Amazon, they both work fine. Though the Thermoworks TC has a super tough completely sealed sheath on the cable and the whole thing is completely water and steam proof. I have left it outside for more than 6 months now completely unprotected from weather and it is still going strong... I love this probe! Another thing I find nice about the (expensive) Thermoworks needle probe is you can poke it into a vent on the hood of a grill, or poke it in from the side at grill grate level and it has enough length to reach into the cooking area to get an accurate temp where your food is sitting for low or high heat cooks, cause it can read temps over 2000F!

So therein lie the differences, the cable quality, the waterproof-ness (for lack of better word), the temp range, and the shape and size. In addition to that thermocouples come in isolated and grounded designs. Pretty self explanatory here, it seems the grounded type TC's are more likely to give you problems if it touches the grill or something grounded, the isolated type can touch anything and will remain uneffected. I went out of my way to ask if the TC's I ordered were grounded or isolated and bought only isolated type. I'm glad I did, cause I have never had an issue, but I have read others posting about their grounded TC's flaking out a bit when they touch things...
 
That is kind of what I was thinking Ralph. Besides, I had just ordered the thermoworks about a minute before I got Bryans post. A few dollars is not going to kill me anyway. I am actually thinking of putting in a nut insert so I can just screw the thermocouple in when I need it. Thanks for the advice from both of you. Bob
 
The ThermoWorks needle TC does have a threaded end so you could make a rig to screw it in pretty easily, though I think you should be able to find a high temp grommet that would snug it firmly enough to hold it in place so you could just push it in/out rather than having to screw it in. If you put a stationary nut on the grill then you would have to rotate the probe to screw it in, and rotate the cord in the process (the cord is long), might be a PITA unless you want to catch just a few threads... I think pushed into a grommet it would be just fine...
 
Thanks Ralph. Forgot about those. When I the TC arrives I will measure and see if that will work. Thanks
 
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Looking to try this one out on the weekend.

For the probe, search ebay for "EGT K Type Thermocouple for Exhaust Gas Temperature Probe with M5 Threads". There's lot of them for sale. I chose the cheapest one ($5.00), placed the lowest bid and won the auction without any other bidders.

The clip is a $3 maverick replacement available here and they even ship free to Canada!

 
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Thanks, Steve, for the link for the probe clips, im always losing those. How hot can the tc go, looks pretty good.
 
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I bought this one from Amazon. It seems fine - except that my HM was reading 185 degF when it was in boiling water. It also was reading the same when connected to a T/C amp in my Rotodamper. I have not yet figured out if this is just normal, or if I have some bad connection, or bad wiring.

Over the years I have gotten into a habit of wrapping pit probes in foil - I guess to keep them from collecting smoke, etc. Does anyone else do that?
 
Dave Pasma said:
I bought this one from Amazon. It seems fine - except that my HM was reading 185 degF when it was in boiling water. It also was reading the same when connected to a T/C amp in my Rotodamper. I have not yet figured out if this is just normal, or if I have some bad connection, or bad wiring.
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I would say that's pretty unusual. I can see it being off by a couple of degrees, but that is way way off. That's 69 ADC ticks off, which is well beyond normal operating tolerances. I consider over 20 to be unusable. Based on the reviews I wonder if you didn't actually get a thermocouple?
 
I noticed the reviews also. They mention that the company shipped RTDs. I am curious now about what the difference is - both physically and electrically. More lunch-time research coming up
 
Dave Pasma said:
I noticed the reviews also. They mention that the company shipped RTDs. I am curious now about what the difference is - both physically and electrically. More lunch-time research coming up
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OK. I did some research right away. If this site is correct, I think I have a thermocouple - since it has only 2 wires.

From the Burns site:
Q: How do I identify what type of temperature probe I have? A: Begin by removing the sensor from the thermowell or process. Look for a 6 digit serial number on the probe sheath or wrench hex. It may be electro-etched or engraved by hand and may be difficult to read. Next note the number and color of the lead wires. If there are two wires it is most likely a thermocouple. The color codes will indicate the thermocouple type. Red is negative on all the standard types and the positive leads are: blue = type T, white = type J, yellow = type K, and purple = type E.If there are 3, 4, or 6 wires it is probably an RTD. Common lead wire colors are two reds and one white for one sensing element, and two greens and one black for the second element if present. Measure the overall length and diameter of the sensor and note if there is a process connection, exposed spring, or plain sheath. Knowing only a couple of these identifying characteristics we can help unravel your temperature sensor mystery

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Could it be possible that I wired the mini connector backwards? I don't suspect that, because I think the temperature reading would decrease as pit temperature increases.
 
From what you quoted and what you bought, it looks like a T tc, and not a k tc. T =Blue K=Yellow . Regardless if its t or k its still not giveing you the correct temperature. Auber instruments has some fairly good k TCs and are cheap, if you are going to try a new TC.
 
Most of my Type K TCs have blue/red wires on them.

I posted this is another thread, try measuring your TC with a multimeter and see what it reads.

Steve_M said:
If you have a multimeter that can read millivolts, you'll be able to simply take a voltage reading on the bare wires. If the voltage is reading negative, swap the probes to the opposite wires and it should read correctly. That will tell you what the positive and negative wires are.

At room temp, it should read around 0.8mv. At boiling water temps, it should read around 4.0mv
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