Thermometer Fluctuations

[2ShortHairs]

Temperature Gauge Fluctuations
I was brewing the other day and my dial thermometer was giving out some crazy readings. I have a Bayou Classic 8 gallon brew kettle that I use as a mash tun, it has the thermometer built in. During my mash at 153, the dial would rise to 180 and then a few minutes later, go back to the actual temp of 153. During this time no flame was under the mash tun to even raise the temp. I have been using a newer digital thermometer too when I brew, and I checked when the dial read 180 with the digital and it read at 153. Has anyone else experienced anything similar? Do I have a defaulty thermometer?

 

[acidrain]

Faulty thermometers are not that uncommon. It's good to use two or even three thermometers during an "active" mash.

 

[rbenn]

Sometimes you can hit a "hotspot" that will go away with mixing, but that seems pretty high.

 

[william_shakes_beer]

Also, heat rises and cold sinks. Over a 60 minute mash the temps will tend to stratify. Before I decide to fir ethe kettle, I always stir thoroughly to redistribute the hot and cold spots. Almost always eliminates the need to fire. Is the built in thermometer in the top, middle or bottom of the kettle height?

 

[2ShortHairs]

The thermometer is about 5" from the bottom. I don't think it could be hot spots because every ten minutes I would give it a good stir. I personally think the thermometer was malfunctioning, it did it twice, just shot up to the 180s sat there for a little then went back to 153. Next brew day I will try to get it on film. Thanks for the input!