Thermometer Readings in Keggle Setup

I am doing all grain on a 3 tiered setup. My mash tun has a thermometer in it (in the wall of the keggle) reaching 4" or so into the mash tun. I am able to direct fire my mash tun and also have a pump to recirculate my mash.

On my last brew, I checked my temps and i was about a degree or two low, so I began to direct fire the mash tun. After a few minutes i was shocked i saw no difference in temp so i turned the heat up a bit. After about 10 minutes or longer i saw too much steam coming from the tun for this to be right. I threw another thermometer in there and read 165 and counting! After stirring it like mad to get the temps to come down and adding some cold water the thermometer in the tun read correctly again.

My thought is that the grain that was directly around the probe was insulating it and causing this reading to not change. I was not stirring the mash as i thought the recirc would be enough.

What are your thoughts? Is this common? What can I do to resolve this? I was so bummed out when i figured out what happened and am really concerned about the results.. only time will tell.

How deep was the thermometer in to the mash?
How is your recirc wort being distributed over the mash?
It sounds like this is the first time you experienced this. Did you do anything different?

Sounds like the batch will come out on the sweet side.

OneHoppyGuy said:

How deep was the thermometer in to the mash?

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It is about 2.5 gallons or so high but it is tricky (does that make sense?). I have a false bottom which is 2 gallons from the bottom of the tun. Then the thermometer is only about a half gallon above the bottom.

How is your recirc wort being distributed over the mash?

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it really is just being pumped on top of it. No stirring or anything like that being done.

It sounds like this is the first time you experienced this. Did you do anything different?

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This is the first time i have used this setup with my brew stand. I have not brewed on it previously so i am just getting used to it.

I am open to suggestions so feel free to throw them out there. I know that it takes time to get used to a brew rig.

If your not automated with a few temp. sensors/ Thermometers, you should stir while boosting temps.
My set up sounds similar (2gals. under bottom) and the original probe was a half gallon or so above the false bottom. I didn't like it bieng that low, so I put another probe a few inches higher. I keep a analog thermometer in lower and digital in upper.
I stir every 15- 20 mins, anyway.

do you direct fire throughout the mash or do you insulate? If you insulate, what do you use? If reflectix, how many layers?

Adding a thermometer temporarily to the line coming out of the keggle (a tee at your ball valve) for re-circulation might be helpful. It would notify you as to whether the heated wort is way out of range from the mash temperature.
Adding a thermometer or digital temperature sensor higher is a good idea.

I'm semi automated, I have a Ranco Temp probe at the pump which controls a selenoid gas valve.
For insulation I did a variation of THIS ,
I have a picture of the rig if you click my name.