Temperature issue - thermometers

[GRosk]

So BN Army, I need some help. I'm bringing my water up to to temp for my mash and I'm getting different readings from my thermometers.

I have 152-154 on my Blichmann brewmometer and a simple dial thermometer. At the same time I have 173 on my KM14 and TruTemp digital thermometers. I have calibrated the KM14 in the ice bath and it's dead on 32 degrees per the instructions. I know for a fact my boil starts rolling when the guide on the Blichmann says "boil." I've used the Blichmann to measure my water temp in the past and usually by the time it gets into the igloo cooler and grain added, the TruTemp is showing about where I want to be based on the calculations. Today Beer Smith says 163.1 is what I need to go into the cooler.

What do I use? I need to hit 152 for my mash and I'm really lost as to what temp is correct. Any help or thoughts would be appreciated.

[BDawg]

20 degrees is too big of a difference to ignore.
If you have a 3rd (preferably analog) thermometer, use it as an arbitrator and go with whichever digital is closest.
if you don't have one, I don't know what else to tell you, other than stick your thumb in. If you can stand it for a second or so, it's probably 153. If you can't, its probably 173.

[edit- I just reread your OP and I see you mentioned you already said a 3rd thermometer agrees with Blichmann.
I'd go with that, and then "calibrate" your thumb by sticking it in to your mash at the known temp and see how long you can stand it just in case you ever need to estimate again in the future]

[GRosk]

Thanks BDawg, I appreciate the response. I just tried the boiling method and the KM14 is showing 266.7-267.1 depending on how long I can stand holding it in there. The other dial thermometer is just shy of 212 with a not so vigorous boil. I'm going to go with the dial and the Blichmann for today. I will also use my thumb, why not right.

Nothing like adding a few hours to the brew day!

[Ozwald]

FWIW, that KM14 isn't very accurate at all. I picked up 1 & threw it in the trash before it made it all the way through a brew day.

Whenever you're calibrating a thermometer you either want to calibrate it very close (preferably at the temp) to the critical temp you're measuring. The other method is to calibrate it at both freezing (32/0) AND boiling adjusted for altitude (212/100 at sea level). If you want to stick with a digital thermo, I would highly suggest 2 purchases:
A Workhorse Thermometer (search Amazon, there's a few different ones)
and
an alcohol filled lab thermometer

You can get the lab thermometer for fairly cheap, $10-15 at the most. You won't use it anywhere on your brew setup, but just to keep your other thermometers calibrated. The Workhorse, a.k.a. Traceable Workhorse is a moderately priced digital that works well, is reliable, has a replaceable K-type probe & you can calibrate it very easily. It's a little bit more, $50ish, but it should outlive you if you treat it well.

[GRosk]

I will be heading over to Amazon to pick that up for sure. I read some reviews which is why I bought that digital thermometer but now, I'm thinking the same thing, trash. It's not even scalable with the temps, just completely wrong. I'm not going to mess around and just replace it immediately.

One RR - Blind Pig later, I'm feeling better about the situation.

[GRosk]

Has anyone used one of these? They seem popular on a few searches I have done.

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

I know a few guys around Milwaukee were going to purchase this product.

[Ozwald]

I recall people talking about them a few years back perhaps. I don't know anything about them though. I've gone through a bunch of different thermometers, both for brewing & cooking. The only digi I'd ever recommend is the Traceable Workhorse, but whatever you have, a solid glass alcohol lab thermometer for calibration is a must.

[mabrungard]

Thermoworks has a lot better thermometers with better prices than the Thermopen. Don't blow your bucks needlessly.