Contradiction between thermometer & Hydrometer.

[Sweber]

Alright, so what gives? I re-calibrate my thermometer every boil to the boiling temp of H2O. Theoretically, the sap should be syrup at 7 degrees above that temp. BUT when I check it with the hydrometer I'm not even close. The hydro has been "checked" by the State of NH and it's good. The temp of the sample in the cup can make a big difference but I'm reasonably sure I've got a good temp. This is driving me nuts. What am I missing??

[markct]

How are you sure you have a good temp in the cup? You can check it any temp just have to adjust for correct brix

[happy thoughts]

The hydrometer is the best guide. There are many reasons your thermometer reading could be off including how and where you're taking the temp, hot spots in your pan, etc. But 7*F is not high enough to indicate 66 brix syrup. Temp would need to be a bit above that. You might be better off switching to *C and cooking to 104*C. making sure you have at least a couple of inches of syrup depth in the pot, taking a couple of samples in various places to make sure you've reached that temp throughout the pot, and avoiding getting too close to the pan sides or the bottom. That said, If I remember correctly, the legal density of syrup in NH is 67 brix. In that case you'd need to be at least +7.5*F above boiling point of water. But again, if you have a hydrometer and know it's accurate, then use it.

[Russell Lampron]

Knowing the exact temperature of the syrup is important when testing with the hydrometer. The hot test is at 211*F and it doesn't take long for the syrup to cool more than that which will give you an incorrect reading. It is also important to keep the hydrometer clean. The weight of syrup on the upper part of the stem will effect the reading.

I use an Accu-cup and the conversion chart that goes with it when I do my final density adjustment before filtering.

[Ittiz]

What's your elevation? I always calibrate my thermometers to freezing since it's pretty steady while boiling changes quite a bit with altitude.

[Z/MAN]

[QUOTE=Ittiz;251364]What's your elevation? I always calibrate my thermometers to freezing since it's pretty steady while boiling changes quite a bit with altitude.[/QUOTE

I READ THAT YOU SHOULD ALWAYS CALIBRATE YOUR THERMOMETER CLOSE TO THE TEMPERATURE YOU USE IT AT. YOU ARE USING IT AT 215+ DEGREES SO I WOULD CALIBRATE AT BOILING. CALIBRATING AT 32 DEGREES IS A LONG WAY FROM 215+ AND LEAVES A LARGE AREA FOR IT TO VARY.

[bowtie]

I never use thermometer, always hydrometer. if you use a regular hydrometer cup and keep your hydrometer clean you should not have problem. I "dip" my hydrometer in evap or pan to clean any heavy sap residue off from it so I do not get false readings. syrup can cool down but that is why the hot level is at 211 f not 218 f or what ever the corrected temp for elevation and pressure is. I was told by a bigger producer that is hydrometer is not broken you can't go wrong with it. I always error on the side of "heavy" vs light but in small batches as soon as I see red"settled" , I turn off finish and filter, it will continue to "boil" off. it does not take long for small batches to get heavy in a hurry.

[sg5054]

I start with the thermometer and when it gets close,6 degrees or so, I switch to my hydrometer. I use a tall thermos for my test cup. Fill it once and wait a 5 minutes. Dump it and then fill and test.

[GeneralStark]

Thermometers are notoriously inaccurate and as with anything the cheaper they are, the less accurate they will be. This is why a good probe thermometer designed for draw off purposes can be easily adjusted and calibrated. As others have said, the hydrometer is the more accurate tool and should be the final measure of syrup density.

My technique is to begin checking with the hydrometer as the syrup gets close by the thermometer. When the hydrometer says it is on, I set the thermometer so the needle is on 7 (this is a thermo. with 0 for boiling point of water and 7 for boiling point of syrup). Then when the thermo. reads 7 I draw off, checking periodically with the hydrometer in case something changes due to the day's weather.

One other thing to consider when using a hydrometer in addition to all the other things mentioned is it is important to fill the test cup, then slowly lower in the hydrometer. Filling the test cup with the hydrometer in it can be inaccurate.

[PerryW]

ditto. trust the hydrometer, the thermometer only gets you close. Fill the cup right from the drawoff and test with the hydrometer promptly. Refill and check again if your starting with a cold hydrometer cup.