Which probe to trust ?

[crater22]

Just for the heck of it, I ordered a new cat probe from Condor. The new one is reading about 200 deg below the old one. does not sound like a big deal, but when it gets up to about 1500 or so, it could become a problem. which one would you stick with?

Thanks in advance

 

[begreen]

The new one should be factory calibrated, but I can understand the concern.

 

[crater22]

Thank you sir. Just noticed the back of the old one was jacked up out of shape.

 

[Sawset]

Just for the heck of it, I ordered a new cat probe from Condor. The new one is reading about 200 deg below the old one. does not sound like a big deal, but when it gets up to about 1500 or so, it could become a problem. which one would you stick with?

Thanks in advance

Dip it in boiling water. Should read 212f

 

[jotul8e2]

Segal's law.

 

[Woody Stover]

noticed the back of the old one was jacked up out of shape.

The tip was corroded, or near the dial was jacked up?
New probe the same length as the old one?
Just off the top of my head, I would think the old one would read lower than the new one, but I don't know..

 

[Sawset]

Segal's law.

Captain James Cook, on his round the world tour, carried several Harrison watches used for navigating longitude. It made him go in circles.

 

[crater22]

yes they are the same length and mfg. It was the spring by the dial that was crooked in fact the pointer was rubbing against the dial. I thought it should have been lower as well. I will test them both out today in the boiling water trick as mentioned above. will insert them both at the same time and see what happens.

 

[jetsam]

Boiling water is bad for calibrating those because the steam warms the bimetal spring directly and makes it read funny.

Just leave the thing out at room temp, loosen the nut, and set the pointer to around 0.

If the spring is damaged, toss it.

 

[Sawset]

Boiling water is bad for calibrating those because the steam warms the bimetal spring directly and makes it read funny.

Just leave the thing out at room temp, loosen the nut, and set the pointer to around 0.

If the spring is damaged, toss it.

With most probe type thermometers its suggested to calibrate to some known value, like ice water or boiling water. And possibly compare to a known thermometer like a glass mercury filled. If you calibrate at room temp, isn't the needle off the scale on these? Maybe that's not an issue. If you did both room temp and water bath, how much would they be off?

 

[Sawset]

Hmm. Keep reading. Seems the condar probes of different types have been looked at before.
https://www.hearth.com/talk/threads/calibrating-testing-condar-probe-flue-thermometer.78251/

 

[jetsam]

With most probe type thermometers its suggested to calibrate to some known value, like ice water or boiling water. And possibly compare to a known thermometer like a glass mercury filled. If you calibrate at room temp, isn't the needle off the scale on these? Maybe that's not an issue. If you did both room temp and water bath, how much would they be off?

On those condor cat probes, the difference between 0°F and 100°F on the scale is about 1/8".

The number that you really want it to be accurate at is 500°F- less and your cat is going inactive, more and you're good. So single-point calibration would be great if done at 500°.

Most of us aren't willing to build a probe kiln to get our probes up to 500, and you can't use your cooking oven unless you drill a hole in it. (If you pop it in the oven, you are again directly heating the spring and will get a false reading.)

If you were really dedicated to the cause, you could buy a garage sale toaster oven, drill a probe hole in the side, use a known-good-at-500° oven thermometer to get the toaster oven up to 500, and then use it to set your condar.

Me, I figure 70 is about 2/3 of the way between 0 and 100, and stick the needle there. I expect my 500° mark ends up accurate +- 100°, which is close enough for my purposes.

 

[Sawset]

On those condor cat probes, the difference between 0°F and 100°F on the scale is about 1/8".

The number that you really want it to be accurate at is 500°F- less and your cat is going inactive, more and you're good. So single-point calibration would be great if done at 500°.

Most of us aren't willing to build a probe kiln to get our probes up to 500, and you can't use your cooking oven unless you drill a hole in it. (If you pop it in the oven, you are again directly heating the spring and will get a false reading.)

If you were really dedicated to the cause, you could buy a garage sale toaster oven, drill a probe hole in the side, use a known-good-at-500° oven thermometer to get the toaster oven up to 500, and then use it to set your condar.

Me, I figure 70 is about 2/3 of the way between 0 and 100, and stick the needle there. I expect my 500° mark ends up accurate +- 100°, which is close enough for my purposes.

Seems kind of odd that condar put their bimetal coils just under the dial. I have a handful of dial types of all sizes, and they all have the bimetal in a helix along the inside of the shaft. There must be a reason for both. It just threw me off that they would do that.

 

[crater22]

Well, I finally got around to testing. Large pan with boiling water, but heat off. Candy thermometer and IR read almost exactly the same. Old probe came in a about 200 deg higher. that is enough for me to determine that the old probe was off. Now I know why I could not always get the cat to engage. If my temps were reading 600 the actual temp would have been only about 400. Since I put the new probe in, my fires are behaving much better and cat is glowing away like it is supposed to do. Might have actually done something right for a change......thanks for all the help guys.