Temp Control/Thermowell Questions

[mikesweeney]

So I've gone about trying to better regulate me fermentation temperature. So I bought a Ranco 2-Stage and a 6.5 gallon carboy hood with a thermowell. the thermowell seems to dip only about 3 or 4 inches under the wort, is this enough to get an accurate reading?

my stick on thermometer is showing a temperature of 72, but my thermowell is showing 68. I don't know which one to trust at this point.

any help?

[DannyW]

I don't trust those stick-on thermometers very far. The ones on my fermenters have stopped showing anything at all. Don't know why, they never got real hot or anything.

Only way to know for sure is to get a calibrated lab thermometer and see how far they are each off. Maybe someone in your club has one and will calibrate them for you?

Otherwise you can test them against a slurry of icewater. The stick-on may not go that low though.

The real ghetto answer is to compare each to whatever thermometers you have and trust. Might not be accurate, but you will be consistent anyway, at least until you buy a new thermometer!

[mikesweeney]

it's not that I don't trust my thermowell temp because of the calibration (though that could be an issue), but because it's not very deep in the wort. so I guess I'm curious to know if it being submerged in 3 or 4 inches is enough to get a proper reading.

[Bugeater]

Since heat rises, you may be reading a few degrees warmer than the average temp of the wort. On the other hand, you are reading the maximum temp. This will help you keep the wort from getting too warm.

Wayne
Bugeater Brewing Company

[mikesweeney]

Since heat rises, you may be reading a few degrees warmer than the average temp of the wort. On the other hand, you are reading the maximum temp. This will help you keep the wort from getting too warm.

Wayne
Bugeater Brewing Company

yeah, I was thinking the same thing, though I'm concerned about the other 10 inches not under the liquid being a part of the reading. which at that point all it's measuring is the ambient air.

[Henning1966]

Mike if it bothers you that much try looking at this post on the greenboard these are some nice thermowells http://www.brewboard.com/index.php?show ... hermowells

[Bugeater]

mmmmm....that is a problem. On probes you stick directly into the wort there is a little dimple that shows just where the sensor is located so you know just where you are taking the temp. In a thermowell with that much above the wort it is hard to tell. It would depend on how good a contact the sensor has with the inside walls of the thermowell. If it is a tight fit and all the way to the bottom, your temps should be accurate. If it is a loose fit, you will probably be off by a few degrees.

If you have a long stem probe thermometer, I would take a reading with that to check for the differential, if any. Beyond that, I don't know what to think.

Wayne
Bugeater Brewing Company

[mikesweeney]

ok, I'm going to seem like a real dummy, but the sensor goes all the way to the bottom of the thermowell? that probably makes a bit more sense.