Thermometer Reading

[Cindee]

Today I tested my thermometer and it showed the water was full boiling at 209. I googled why this would happen and the site said it depends on where I live in regards to being about sea level. It went on to say for every recipe I do with this thermometer for example candy, fudge etc I am suppose to subtract 3 degrees. So am I to assume then when I do my sap finishing the sap will boil at 206 and then add my 7.5 degrees and I will have finished syrup at 213 degrees? My thermometer is digital and boughten exclusively at Maple Hollow. We live in Mountain WI which is in the northern part of the state.

[smokeyamber]

First I heard of the subtract 3 degrees... I just add the 7.5 to whatever I get for boiling water. My thermometers all give diff numbers for boiling water including the digital so I use one and stick with it. As long as it is consistent and doesn't jump around all is good. Also I did have my digital get wonky when it's batteries got low so now I know to keep spares. I don't think they figure you would run one for 6 hours straight :D

This year I splurged for an "old" style dial thermometer for the syrup pan after the digital tricked me last season and caused a last minute scramble to draw off syrup.






Today I tested my thermometer and it showed the water was full boiling at 209. I googled why this would happen and the site said it depends on where I live in regards to being about sea level. It went on to say for every recipe I do with this thermometer for example candy, fudge etc I am suppose to subtract 3 degrees. So am I to assume then when I do my sap finishing the sap will boil at 206 and then add my 7.5 degrees and I will have finished syrup at 213 degrees? My thermometer is digital and boughten exclusively at Maple Hollow. We live in Mountain WI which is in the northern part of the state.

[DonMcJr]

I noticed this too when boiling on my Half Pint the other day. Thermometer Read 206 when it started to boil. But that's sap not pur water right?

I believe what I need to do is Boil a pot of Plain water right by where my evaporator is. Take that reading and use that for boiling point and add 7.5 degreees for Syrup?

I'm either not getting enough heat due to wood not split small enough but I will have that taken care of before the next boil and/or I'm not letting the pan level get low enough for turning to syrup. Highest temp I got at the drawoff valve was 210 F when I boiled Friday...

[happy thoughts]

I believe what I need to do is Boil a pot of Plain water right by where my evaporator is. Take that reading and use that for boiling point and add 7.5 degreees for Syrup?



yes.

I did a great job confusing people the other day :cry: but I'm going to try again because a lot of people seem to be unaware that boiling point changes. Let me first say that your hydrometer is the best indicator of syrup density. Now that said, boiling point is affected by barometric pressure and your altitude. It can and will change with any change in air pressure, sometimes by a degree or so. If you want to use your thermometer as a guideline for testing then you need to do the boiling water test each time you boil. then add 7.5 F to whatever you get for a boiling point at that time to get the temp that is in the neighborhood of syrup. But again, if you have one, use a hydrometer to determine when your syrup is of the correct density and don't trust a thermometer to tell you when you have syrup.

If you want to test the accuracy of your thermometer then you'd do the calculations at the site below then do a boiling water test to see how your actual reading compares to the calculated estimate. Many thermometers are inaccurate to begin with so it is good to get a feel for how your thermometer reads to use as a baseline. Some thermometers can also be corrected.

http://www.virtualweberbullet.com/boilingpoint.html

For instance in Detroit today at an elevation of 600 feet and a pressure of 30.12 water will boil 210.7F. Assuming your thermometer is accurate that is what it should read if you were to test in boiling water at that elevation and pressure.

[PerryW]

where did the 206 degrees come from? Sap should boil at almost exactly the same temperature as water; maybe a tenth of a degree higher (certainly not 3 degrees lower).

[happy thoughts]

where did the 206 degrees come from? Sap should boil at almost exactly the same temperature as water; maybe a tenth of a degree higher (certainly not 3 degrees lower).

I think what that's showing is that the thermometer is inaccurate and off by 3 degrees F.... conditions say 209F but thermometer reads 206F.

[jake22si]

Just add 7 or so degrees to whatever you are getting a full boil of water going at. Or keep buying thermometers until you find one that reads the temp you want it to read.

[bowtie]

i do not use a thermometer, i use a hyrdometer it seemsto be much more accurate and reliable. i had a thermometer and tried it last year then i broke it and did not replace it!!

[Cindee]

Thank you so much, your information was spot on. I did as the site suggested, found my elevation and what the pressure is today, plugged it into the calculator provided and it said estimated water boiling is 209.4 and my thermometer was 209.2. I will be checking this site everyday during sap season and adding my 7.5 points accordingly, thank you very much. We will also be double checking with the hydrometer.

[Cindee]

Mapleaddict listed this site for you to check your thermometer.http://www.virtualweberbullet.com/boilingpoint.html
I did it and my thermometer reading of 209.2 was correct. You will need to know your elevation and pressure. You can get these from the weather channel site.

[DonMcJr]

Wow that Boiling Point Calculator is neat. If I were to boil today it says 210.4 F and that's what I was getting on my evaporator when it boiled Friday evening...Cool!

[johnallin]

Found this phone app that is pretty cool. Called My Altitude it's a navigation type of app giving you your coordinates, altitude, barometric pressure and Water Boiling Point based on the above info. Can't say that I use it much but it may help as a check to see if your thermo is reading correctly.
https://itunes.apple.com/us/app/my-altitude/id465262694?mt=8

[Schiefe4]

Thank you so much, your information was spot on. I did as the site suggested, found my elevation and what the pressure is today, plugged it into the calculator provided and it said estimated water boiling is 209.4 and my thermometer was 209.2. I will be checking this site everyday during sap season and adding my 7.5 points accordingly, thank you very much. We will also be double checking with the hydrometer.

At 7.5°F above the boiling point of pure (distilled) water, you will make syrup with a sugar solution of 67%. I believe standard density of maple syrup is 66% sugar solution and this is obtained by a temperature of 7.1°F above the boiling point of pure(distilled) water. But I agree, more sugar in solution makes thicker, tastier syrup lol.

[happy thoughts]

At 7.5°F above the boiling point of pure (distilled) water, you will make syrup with a sugar solution of 67%. I believe standard density of maple syrup is 66% sugar solution and this is obtained by a temperature of 7.1°F above the boiling point of pure(distilled) water. But I agree, more sugar in solution makes thicker, tastier syrup lol.

I believe 66 brix is the minimum density required by law in most places. As a minimum, that doesn't mean it can't be thicker. I believe VT has a slightly higher standard. I don't know off hand what the maximum density is by law though that too probably varies by state or province if it's addressed anywhere. At one time in PA max density was at or near 68 or 69 brix I *think*. Don't quote me because I don't see that in our current laws just the required minimum of 66 brix. If you are not using a hydrometer I'd go with the higher temp. I'd rather have crystals than spoilage.

[Lloyd Miller]

Can anyone explain this? When I finished two batches of syrup Sunday (1.25 gal each) the BP of H20 was 212 degrees. Boiled both batches to 219 degrees and one batch tested 64Brix and the second 68 Brix. I'm puzzled.

[johnallin]

Presuming you pre-wet your filters; it could be your filter had more water in it on the first batch...and less on the second. But if you mix the two together you'll have 2½ gallons at 66% - almost there and with some gentle reheating will get you spot on.

[crawflyer]

for Android users there is an app for this called Boiling Free.

Found this phone app that is pretty cool. Called My Altitude it's a navigation type of app giving you your coordinates, altitude, barometric pressure and Water Boiling Point based on the above info. Can't say that I use it much but it may help as a check to see if your thermo is reading correctly.
https://itunes.apple.com/us/app/my-altitude/id465262694?mt=8

[Cindee]

I have not read or was told about pre-wetting the filters. Is this something we should be doing?

[SWohio]

I use a thermometer and just add 7.5 degrees to whatever is the boiling temp. This changes with each batch, the weather. When I was a kid we had an old maple thermometer. (like 1920 or something old. maybe older) It was the same style that my father had seen his father using 30 years before, who for all I know learned from his father. In short it did not have any degree marking on it. It was a mercury filled tube mounted on a wide metal backing and a large wooden handle. On the side of the backing was a long screw that ran from just below the handle to near the base. There was a second piece of metal that was mounted around the backing and would slide up and down as you turned the screw. On the movable piece were markings and lines labeled "water boil" "syrups" "creme" "soft candy" "hard candy" etc. (truth I do not remember all exact terms but you get the idea.) You put the thermometer in the sap as it was boiling and then using the screw moved the sliding piece until the "water boil" line was even with the top of the mercury level. The thermometer was now set. Move it to the syrup end and when the mercury hit the "syrup" marking they drew off. They would adjust the thermometer (move back to sap end and use screw to move the sliding piece a bit) between each draw. They would adjust it a couple times a day. Sometimes it stayed the same other time they had big adjustments during the day. The old timers, as I have been told, even noted the need to change or not change during the day as part of their weather predicting (no accuweather back then). It kept the syrup consistent and was a barometer all in one. On a side note, Till the day he died my grandfather never trusted any thermometer that was not mercury. He would tell me to never trust red thermometers only silver ones. They made hundreds of gallons of syrup a year for a couple generations using buckets, horses, a sugarshack in the bush and that style of thermometer. My grandfather told me of how he and my great uncles, greatgrandfather would live for a week or more at a time out in the sugaring shack down in the sugarbush. At the end of runs they hauled the syrup up from the bush and returned to the farm.

[heus]

Found this phone app that is pretty cool. Called My Altitude it's a navigation type of app giving you your coordinates, altitude, barometric pressure and Water Boiling Point based on the above info. Can't say that I use it much but it may help as a check to see if your thermo is reading correctly.
https://itunes.apple.com/us/app/my-altitude/id465262694?mt=8
John thanks so much for this! Very convenient. Get ready for sap this weekend!