lying thermometer!

[Robar]

I just did a test at the end of my boil with two thermometers. The floater that came with my Brewers kit that I bought when I first started said boiling was 215 and the new 10.00 digital said 212. Maybe that is why I have problems with mashing and achieving what I want using mash temps as I've always used it as the one that was RIGHT. Should have done this test a long time ago...

Anybody else have this issue with the floating brewers kit thermometer?

 

[Wynne-R]

Wort boils at a different temperature than water. The stronger it is, the more the boiling point will be elevated. It also depends on elevation and a little bit on the weather.

I’m at 650 feet and ~1.060 wort seems to boil at about 214 F. Maybe one of your thermometers is a little high and the other a little low.

 

[jrgtr42]

I have a good half dozen thermometers and not one of them reads the same as any of the others at mash temp. Most of them are pretty close at freezing and boiling (within a degree or 2) but it's in the middle that there are issues. And of course, as brewers, that;s where the important numbers are for us. I have a couple that I think are closer to actual than some of the others, so those are the ones I more count on for mashing, and another one for pitching yeast.

 

[Robar]

Is there any way to find out if a thermometer is accurate in the mash temp range? I ask this fully believing the answer is NO, but I'll ask anyway just in case my girl friend is right and I truly don't know everything.

 

[Wynne-R]

Tough question. If you put a bunch of thermometers in the strike water and they agree, I’d take the consensus. Of course if they’re all off then you have to guess.

Having said that, the relative accuracy is more important than the absolute accuracy. If it’s consistently 2 degrees off, it’s useable. If it’s inconsistent, it’s useless.

I think everybody should have a glass lab type thermometer. They are often poorly calibrated but the linearity is good, and they don’t drift. If it’s 2 degrees off, it’s usually a constant, 2 degrees at both ends.

Electronics can be wacky, from drift or even battery voltage. The most common problem though is corrosion in the cable.

I think people get sucked in by cheap digital thermometers. If you see .1ºF resolution you want to believe the basic accuracy is in that neighborhood. It isn’t. The Thermapen, one of the best, is rated at ± .7°F. Mostly, they’re not even rated.

 

[BetterSense]

Buy a glass thermometer and make it your standard. You might prefer using digital units but you have to have something to check them against. Glass thermometers, regardless of accuracy, never drift. I use a Kodak mercury thermometer. I never actually use it for brewing, but I use it to check and calibrate my Taylor cooking thermometers, which to be honest are pretty good. The floating thermometers have a terrible lag time. It takes them like 10 minutes to stablize. I threw mine away.

http://www.sigmaaldrich.com/catalog/product/aldrich/z257761?lang=en&region=US

http://www.sigmaaldrich.com/catalog/product/aldrich/z423351?lang=en&region=US

 

[Robar]

Thanks for the links. I've been trying to put a little more science into my seat of the pants style of brewing. Accurate measurements and Temps seem like a great place to start.

Accuracy & Consistency = Known & Repeatable Results.

 

[fartinmartin]

I have proved that my mash varies in temp from the bottom to the top and outside to inside, very undesirable, my set up is quite crude. But even with a very good mash tun I bet the temp is all over the place in different parts of the tun ?

 

[Robar]

I have proved that my mash varies in temp from the bottom to the top and outside to inside, very undesirable, my set up is quite crude. But even with a very good mash tun I bet the temp is all over the place in different parts of the tun ?

TRUE

I do stir often to try and combat this. About every ten minutes I give a good stir trying to keep the mash we mixed to ensure the temps are as consistent as I can get them.