Who can you trust?! (Thermometers)

[Javaslinger]

I've been consistently unable to reach an appropriate finishing gravity. Recently I noticed that my dial thermometer was reading ~207 at full boil. I compared it with my digital thermometer (CDN DTW-540L) and it was about the same. I tried a 'fluid' thermometer and it read the expected 212 at full boil.

Now some research led me to consider elevation. At ~2500ft where I live, it seems boiling is 207.5F. Now that matches my digital thermometer and dial thermometer... ok... Why not the fluid thermometer?

So do I need to be making a elevation adjustment during the mash?! If I was mashing at 154 should I really be going for??

 

[ancientmariner52]

I've been consistently unable to reach an appropriate finishing gravity. Recently I noticed that my dial thermometer was reading ~207 at full boil. I compared it with my digital thermometer (CDN DTW-540L) and it was about the same. I tried a 'fluid' thermometer and it read the expected 212 at full boil.

Now some research led me to consider elevation. At ~2500ft where I live, it seems boiling is 207.5F. Now that matches my digital thermometer and dial thermometer... ok... Why not the fluid thermometer?

So do I need to be making a elevation adjustment during the mash?! If I was mashing at 154 should I really be going for??

Boiling temperature is lower at higher altitudes on account of reduced atmospheric pressure, as the steam bubbles have less resistance to overcome. At any given time moment in time, you'd need to know the exact barometric pressure to determine the boiling point. Altitude will let you find an average number, though.

I wouldn't think that mashing would be affected by altitude at all, since it is a chemical (biochemical?) process. As far as your liquid thermometer goes, I don't know. Is it a laboratory grade item?

 

[AZCoolerBrewer]

I've been consistently unable to reach an appropriate finishing gravity. Recently I noticed that my dial thermometer was reading ~207 at full boil. I compared it with my digital thermometer (CDN DTW-540L) and it was about the same. I tried a 'fluid' thermometer and it read the expected 212 at full boil.

Now some research led me to consider elevation. At ~2500ft where I live, it seems boiling is 207.5F. Now that matches my digital thermometer and dial thermometer... ok... Why not the fluid thermometer?

So do I need to be making a elevation adjustment during the mash?! If I was mashing at 154 should I really be going for??

After using my fluid thermometer for a while it started reading higher for the boil - 218. It also read higher for my mash which had me mashing very low. After finding this I went to Thermoworks and bought a really long digital thermometer that has been working well. I live at about the same elevation as you and my wort boils at 208.

 

[bpgreen]

Boiling point shouldn't affect mashing, but it does affect hop utilization. I live at about 4500 feet and prior to Beersmith 3, I would just figure my IBUs were lower than predicted, so I'd aim for higher IBUs. There's a formula to adjust, but I'd just play it by ear.

BS3 lets you set your elevation and adjusts for that.

 

[AZCoolerBrewer]

Boiling point shouldn't affect mashing, but it does affect hop utilization. I live at about 4500 feet and prior to Beersmith 3, I would just figure my IBUs were lower than predicted, so I'd aim for higher IBUs. There's a formula to adjust, but I'd just play it by ear.

BS3 lets you set your elevation and adjusts for that.

It was off 10 degrees at boiling temps and off 5 degrees at mash temps, so when I mashed at 150 it was really at 145.

 

[S-Met]

Have you calibrated your thermometer? I suggest a simple 2 method calibration. Both using distilled water. Non-distilled water has minerals and salts that could affect the calibration readings.

Remember, a single-point test can only ensure that your thermometer is correctly calibrated for one temperature, it is best to conduct at least two different tests using the measuring points below for the most accurate calibration.

The first is the freezing point method. Fill a glass with crushed ice. Add a little distilled water until the glass is full and stir. Wait for about three minutes before inserting the sensor on the thermometer into the ice-filled water. Wait for about thirty seconds and check that the thermometer reads 32°F. If it does, then it is accurate, but if not, it requires calibration. This is by far the most accurate method, and it will also give you an idea of how far off your readings are when it comes time to reset it.

The other method is called the boiling point method. You need to boil about six inches of water. When the water reaches its boiling point, place the sensor into the water and make sure that you keep it as close to the center as possible, away from the sides and bottom of the container. Wait for thirty seconds and check if the thermometer reads correctly at 212°F if you are at sea level or below 1,000 feet elevation. The boiling point of water will vary for different elevations: sea level at 212°F, 1000 feet at 210°F, 2000 feet at 208°F, 3000 feet at 206.4°F, 5000 feet at 202.75°F, and 8,000 feet at 197.5°F.

Also remember that calibrations are not permanent and instrument readings can drift. Re-cal if you are concerned, drop your instrument, or it sees heavy use.

For reference, I cal when I get a new device, if my results are not what I expect, or if I'm bored.

 

[Pkrd]

By "fluid" do you mean liquid in glass?

There are two types, total and partial immersion.

Partial immersion thermometers have a line that shows how far to put them in the liquid. It you put too much in you'll real a higher temperature.

 

[AZCoolerBrewer]

By "fluid" do you mean liquid in glass?

There are two types, total and partial immersion.

Partial immersion thermometers have a line that shows how far to put them in the liquid. It you put too much in you'll real a higher temperature.

Hmmm, maybe my thermometer is not broken after all. I had relegated it to being my fermentation chamber thermometer because it is correct at room temp.

 

[Hwk-I-St8]

Elevation affects the boiling point of water due to the reduced atmospheric pressure. Put water in a near vacuum and you can boil it at room temperature.

As far as the mash goes. elevation makes no difference. 152 degrees is 152 degrees. No elevation adjustment is necessary for the mash. Just make sure you have a thermometer you can trust. I have a Thermoworks MK4 and it rocks. Spot on temps and fast to settle on a reading. It was expensive (about $75 on sale) but worth every penny.

 

[GPP33]

Every thermometer, even one you paid $500 for needs to be verified for calibration before it can be trusted and needs to be regularly reverified for calibration in order to maintain that trust.

In god we trust, all others bring data.

 

[applescrap]

Boiling temperature is lower at higher altitudes on account of reduced atmospheric pressure, as the steam bubbles have less resistance to overcome. At any given time moment in time, you'd need to know the exact barometric pressure to determine the boiling point. Altitude will let you find an average number, though.

I wouldn't think that mashing would be affected by altitude at all, since it is a chemical (biochemical?) process. As far as your liquid thermometer goes, I don't know. Is it a laboratory grade item?

I could listen to your knowledge all day. Wish i lived by you. I would pester you to help me build stuff in your garage. Why do sailors seem to know everything?

Ot-the fluid thermometer needs calculated? Idk really but i would mostly just use my digital. If the dial works sharp then whats not to like. Fluid thermometer would be cool for coffee and food experiments.

 

[ancientmariner52]

I could listen to your knowledge all day. Wish i lived by you. I would pester you to help me build stuff in your garage. Why do sailors seem to know everything?

Ot-the fluid thermometer needs calculated? Idk really but i would mostly just use my digital. If the dial works sharp then whats not to like. Fluid thermometer would be cool for coffee and food experiments.

Thank you. You would be welcome, I love building things. As to knowing everything: work in a steam engine room, and you have to learn or die. Put me at a computer, and I'm like a chicken watching a card trick.

 

[WFox93]

I think I have a theory on the liquid thermometer.

Elevation impacts boiling point due to atmospheric pressure. The liquid thermometer is fully encased in glass or plastic essentially pressurizing it to what we consider normal. When dropped in boiling water or wort in this case, it shoots up to 212. Or maybe I'm missing something. But at any rate, all the knowledge provided by the folks who've already responded is good. Definitely need to calibrate new equipment and use in a "dry" run before fully trusting it with the real thing.