Quick question on thermometers

If it is also 8* high in the cold water then just take that into account and you should be alright.

 

I know you said it can't be calibrated, but what kind of thermometer is it? Most of the dial thermometers I have seen have a nut on the underside of the dial that allows you to turn the needle to calibrate to your known temp. (It looks structural and so a lot of people don't realize what it's for.)

If not, do what Eriktheipaman said.

 

If it's not, you could work up a speadsheet formula to approximate the amount to subtract at each temp, then print a table. It would be better to have at least one more data point for this to fit a curve, but a straight line may be good enough.

Or buy a good thermometer.

 

I agree with just buying a new one. My last glass one, which I had for over 2 years, dropped in the bath tub as I was cooling the wort :/ it broke. Needless to say it was a bummer picking up glass and lead. I just invested in a digital thermometer and hope it pays for itself in the long run.

 

I've been using a thermapen for a while and love it. Pretty fast and crazy accurate. Also comes in very handy for barbeque. I recently noticed that most/all of the competitors on Pitmasters seem to be using the same one.

 

I will point out that just because a thermometer is digital, it may not be more accurate.

Thermopens are however, accurate and precise. Really like the one we have, and it is also great for cooking and other temperature measurement jobs.

 

This is true. I have a drawer full of crappy ones. People should not buy hobby related Christmas gifts without checking first.

 

For the OP - there is a good instructional youtube video out there on how to properly make an ice bath. You want to fill the vessel with ice, then add the water. IF you just dump some ice into the water the "ice bath" may be considerably higher in temperature.

If you are really trying to calibrate at the high temperature, be sure to take the altitude and barometric pressure into account. Not sure where the OP is from but there are online calculators to find the boiling point at that altitude and pressure.

 

Very true about accuracy. But it won't brake like the glass on did so that is the main thing I'm excited about.

 

I also use a Thermapen and love it. It was a great investment for brewing, cooking, and grilling.

 

They have open box sales every now and then. This is what we have.

http://www.thermoworks.com/products/thermapen/

 

Yeah, I was hesitant to drop the coin, but I use my thermapen all the time for stuff beyond brewing.

 

I use glass thermometers. They can't be adjusted but you can use a simple two point calibration. Graph two points as a scatterplot (a, 32) and (b, 212), where a is the temp your thermometer reads in ice water and b is the temp it reads in boiling water. Use the line that connects the two points to evaluate your temperature based on the thermometer reading.

 

I've got a good half dozen thermometers and there isn't a single one that reads the same as any of the others. Most are good at the freezing / boiling points, but in between, at say mash temp, there's about a 5 degree separation between most of them, except one of my digitals, routinely reads about 20 degrees high.

 

Thanks for supporting my point that just because it is digital, it is not accurate. You can have a thermometer that reads fine at freezing and boiling, but can be way off at mash temp if it does not have a linear curve. You can connect the 2 points on the graph with curves, of compound curves. Have a multipoint calibration, or a calibration done in the mash range vs a good standard is more valuable for brewers.

 

This is the correct answer. This is pretty much the industry standard in professional kitchens and although it is pricey up front, it will outlast a bunch of $20-$30 thermometers so in the long run it is worth it and it will actually be cheaper. Plus, as others have said it is useful far beyond just brewing.

 

Good ole' rule of thumb is how they did it before thermometers....