Sensor question and using my boil kettle for BIAB.

[BitterSweetBrews]

I have been electric brewing with a 3 vessel system for 3 or 4 years.

Yesterday, I decided to use my boil kettle and mash bag to do a BIAB batch of Boulevard Tank 7 Saison (from their recipe in Zymergy). I have duplicate 15 gallon SS kettles for my MT and BK which both came with steamer racks that sit higher than the BK element. So, the mash bag I use for easy clean-up and recirculation filtering fits the boil kettle too and is up and away from the element. I worked great.

Using the boil kettle (which has a PT-100 sensor in it) allowed me to do a 2-step mash pretty easily. I replaced the whirlpool arm inside the kettle with a hose fitting and tubing to re-circulate during the mash and whirlpool later. It worked great! A normal 3 vessel brew day takes me 6 hours. I did the BIAB batch in 4. I will be doing more like this.

Anyway, while I was doing this I ran into something I had never realized in previous batches that made me wonder. It has to do with wort boiling temperature. Here goes:

I used half/half tap/RO water. I decided to pre-boil the tap water to get any precipitates out of it. I knew this would also end up getting me well on my way to the strike water temp once I added the RO water so it couldn't hurt.

When I had the water boiling, I went ahead and calibrated my boil kettle PT-100 sensor on my PID. At my altitude water boils at 212F degrees. I set the temp to that and continued my brew day. As I said, I did a two step mash. The first mash step was 45 minutes at 146F degrees, the second was 15 minutes at 155F degrees, then I mashed out at 168F degrees for 10 minutes and pulled the bag.

When I started to boil the wort, the temperature on my sensor went up to 224F at boiling. I had never noticed such a high temp before.

I have always thought that at atmospheric pressure you cannot get water hotter than it's boiling temp. To do this you must put it under pressure. So why did my sensor read 224F Degrees? Since there is sugar in the wort, would that raise the boiling temp temp of the liquid that much?

Since this happened yesterday I haven't checked the water boil temp again but I plan to.

 

[stevehaun]

Boiling point elevation effect of solute is not that dramatic. I would double check the calibration of your RTD sensor.

 

[BitterSweetBrews]

Boiling point elevation effect of solute is not that dramatic. I would double check the calibration of your RTD sensor.

I plan on doing just that when I get a few minutes. It is just weird that I did calibrate the PID and sensor at the beginning of the day. It makes no sense that it would change so dramatically in an hour and a half (unless it is a broken POS). I talked to a Master Brewer who is teaching a judging class we just finished up tonight and he said that the changes in gravity of the wort can definitely affect the boil temperature, but we didn't think it would be that much, maybe 8-10 degrees. I am not changing my elevation, so that would have no effect on the temp change. Water boils at 212 degrees where I live (1000Ft above Sea Level).

 

[BitterSweetBrews]

Last night I had the time to test the sensor on my boil kettle again. I boiled 5 gallons of water and set the offset temperature on my PID to show boiling temp at right around 211-212. The sensor calibration was the same as where I set it at the beginning of my brew day last week.

In addition to testing the installed BK sensor I put another one in the water, one I had previously pulled out of the BK, when I replaced it with the current one which has a removable cable. I also put in an electronic BBQ probe. They all validated that my sensor is fine.

So, apparently I had enough sugar in the wort that it raised the boiling temp by over 10 degrees.

Lesson learned.

 

[stevehaun]

Sorry, but there is no way that the sugar in your wort raised the boiling temp by 10 degrees. Look for another explanation.

https://lecturedemos.chem.umass.edu/solutions13_2.html

https://socratic.org/questions/what...solution-at-atmospheric-pressure-how-do-we-ca

 

[ancientmariner52]

Last night I had the time to test the sensor on my boil kettle again. I boiled 5 gallons of water and set the offset temperature on my PID to show boiling temp at right around 211-212. The sensor calibration was the same as where I set it at the beginning of my brew day last week.

In addition to testing the installed BK sensor I put another one in the water, one I had previously pulled out of the BK, when I replaced it with the current one which has a removable cable. I also put in an electronic BBQ probe. They all validated that my sensor is fine.

So, apparently I had enough sugar in the wort that it raised the boiling temp by over 10 degrees.

Lesson learned.

Boiling temp at 1000 feet above sea level is 210°F. It will vary a bit with atmospheric pressure change, which is the actual variable, rather than altitude. I think what is missing here is a reliable reference thermometer, such as a glass lab thermometer. "A man with one watch knows what time it is. A man with two watches is never quite sure."