I have the opportunity to get some hardware for my Keggle and I am looking at a weldless sight glass with a T shape that will allow me to screw on a thermo probe compression fitting. If I buy it I will be installing it at the same height as my welded fitting with the ball valve.

My question is Where is the best place to install a thermometer on a brew kettle and would there be any issues with installing it 2-3 inches above the bottom of the kettle?

I'm assuming that there will be a small differential in the temp closest to the bottom of the kettle as the middle when boiling wort.

4 Answers 4


Ideally you want your thermometer in the midline of your average batch. In a keggle you want it slightly below that first rib if you ever do 5gal batches.

Biggest thing is to make sure it doesn't get in the way of your immersion chiller if you use one.

They don't have much use on a boil kettle other than for cool down, hops rests, maybe estimating when boil will start etc. A turkey fryer style thermometer works just fine for me.


If you are too close to the bottom you'll pick up more heat from the heat source itself (burner or element if electric) than as a measurement of the wort. You want to be about 1/2 or a third of the way up from the bottom to somewhat get away from that effect. The longer the probe is helps with that issue too, however too long of a probe will interfere with hops sacks or an immersion chiller if you use those.

You definitely want to be just under that lowest rib on a keggle. Mine is above it and it never worked well for 5 gallon batches. I use that keggle now as a mash tun and I tend to use a higher water to grain ratio than most inorder to get it into the mash. If you can get a metal worker to professionally flatten a small square of that first rib, then weld a coupling in at that spot I think that would be pretty ideal.


Another issue with temperature probe height; if you are using your kettle to heat your mash water, placing the probe too high will prevent you from doing thick mashes (where the volume of water to grain ratio is low) as the probe will be above the water line.

For example, if you are brewing a mild, with a boil SG around 1.030 and you want a mash thickness of 1 qt / pound, you will only have 2.125 gallons of water for your mash. In my 8 gallon 13 1/2 inch diameter kettle, that's only about 3 1/2 inches, well below the probe.


Why do you need a thermometer in a brew kettle? Water boils at 212°F (100°C) at sea level everywhere on the planet.

  • 3
    This should be a comment under the OP question. The temp probe on a kettle lets you know when you are getting close to boiling so you can walk back and forth to do other things prior to a boil over. It also helps you monitor the progress of your chilling process if you are chilling in the kettle.
    – brewchez
    Commented Feb 23, 2016 at 12:28
  • I doubt that he'll have any trouble with a 5 gallon batch boiling over in a keggle. Temperature is a lot more important in the mash tun than in the boil kettle. Commented Feb 23, 2016 at 18:09

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