Calibrating bimetal stem thermometer

[cncaboose]

I have questions about the calibration of the two bimetal 9" stem 0-50 degree syrup thermometers that came with my new evaporator last fall. I callibrated them with boiling water per the instructions but when installed in the syrup pan they read very low, by about 30 degrees, when the syrup is boiling, and then shoot up too high when the syrup starts to foam up a bit. Experimenting with them in boiling water again here at home it is apparent that small changes, even a quarter of an inch, in the depth the probe is in the water give large changes in the temperature reading. The depth I run my pan may vary and the varying depth of the boiling syrup make it so that it seems like the thermometer is nearly useless. Is there any way to make these thermometers more reliable as temperature indicators for my syrup or should I forget the thermometer and just use the hydrometer regularly when the syrup is getting near to finishing?

[Dave Y]

The 0-50 thermometer is very reliable, but you need to calibrate them every time you use them. The point of boiling water is always chainging. the best thing to do is set it to boiling water, then test with the hydrometer when you are close to syrup. When the hydometer say it is syrup adjust your thermometer to 7. then you will know when to draw off. I have found this to be the best method of use. Keeping in mind the thermometer must be covered completely. Hope this helps.

[Dave Puhl]

I got a same type of problem... cala. with the boiling water... but it just dont read well... you got to tap it to read ......I was tring to keep an inch or less in the syrup pan and I had to bend it down some to get the tip in the syrup..got a 3 dollar digital probe works alot better than the 48 bucker one....

[HanginAround]

They really are excellent thermometers, I think getting enough submerged in a shallow pan is the issue.

Dave, if you have to tap it for the needle to move, sounds like there could be some corrosion or something making the needle stick.

[sapman]

In my Leader evaporators, the 1/4" fittings have always been mounted about 1/4" off the bottom of the pans. This keeps the entire stem in liquid all the time. Do you have the thermometer going into the syrup from above the pan? If so, that would seem like a problematic angle to try and get accurate readings.

Good luck,
Tim

[cncaboose]

This could be the problem. The thermometer comes in at an angle from several inches above the syrup so as the syrup level goes up and down, so does the temperature reading. Having it low, horizontal, and fully submersed sounds like the cure. Now to figure out how to do that. I probably won't do it until after this season. Thanks Tim. After last week's rain I hope you can get into your woods now. Ian

[SapSuckers]

These dial thermometers read 3 1/2" from tip. There is a small grove on the stem shows were the reading is being taken. Best way is to have it level about 1/4" from bottom of pan

[SapSuckers]

Also, most have a 1/4" male NPT on them. You can have a metal fabricator add a 1/4" female fitting on both sides (if you draw on both sides) just before where you draw off. If you only have one thermometer just put a 1/4" plug in the off side.

[ibby458]

To get consistent results, I've always thought it important NOT to vary the syrup depth very much. Once I decide on the depth, I try to keep it there. When I draw off, I open the valve just a crack so the syrup just drizzles in, allowing time for the stuff in the other channels to start flowing to keep the level consistent. That might help to keep your temp readings stable. It works pretty good in my Waterloo.

[Russell Lampron]

It sounds like you need a thermometer with a longer stem so that it can reach down into the syrup. Like others have said 3" of the tip needs to be submersed to get an accurate reading.

Russ

[Dave Puhl]

Yep with my ...new.. Maple Pro comes in at the angle through the draw off area...it asays right on the dial to put it in boiling water 3.5 inches...I will stick with the digital probe for now...

[Lance]

Dave - Where'd you get the $3 digital probe?

[Dave Puhl]

Theres now way that I can get 3" on the stem I had to bend it down as is...or am I running to low in the syrup pan 1" or so?

[SapSuckers]

1" in your syrup pan is fine as long as you know your pan. I have heard of guys runnning it lower then that. The dial thermometers are ment to be paralel with the bottom of the pan, not come in from the top. If you need to come in form the top try a candy or old taylor thermometer which is ment to come in from the top, although harder to read

[Fred Henderson]

I got a same type of problem... cala. with the boiling water... but it just dont read well... you got to tap it to read ......I was tring to keep an inch or less in the syrup pan and I had to bend it down some to get the tip in the syrup..got a 3 dollar digital probe works alot better than the 48 bucker one....

Please tell me where I can get a $3 digital probe?