Making a thermal well...

[RogueAg]

I recently purchased a Ranco temp controller and am planning on using a thermal well as it turns out the probe on the controller isn't submersible.

A quick search yielded a pretty good debate on whether to even use a thermal well and submerse the probe (in the fermentation vessel) versus just using it to measure the air temp in the fermentation chiller.

I was thinking of just putting a small glass of water in the chiller and putting the probe in that. It's a much smaller volume of liquid and seems to be a good compromise.... but I"m no expert.

Anyway... my plan was to use a small piece of copper tubing... and seal one end.. drop the probe in.... and seal the other end with silicone. The probe fits in the tubing reasonably well.. but there's still some space around it.

So my question is this: Will a thermal well this simple yield me some reasonably accurate temps? Or is the space around the probe, inside the tubing going to interfere with the reading? Should I fill the copper tube with some heat tranferring material.. and if so.... what?

Any help is appreciated. Eyerolls and shrugs are understood.

 

[Henrythe9th]

to water proof my probe I slipped a piece of small surgical tubing over the probe and rolled it back on to its self or you could use small o-rings..
I use about 8" of tubing

hasn't failed yet yet

 

[passedpawn]

I think they are a great idea. Like you, the bulb on my temp sensor is too large for commercial thermowells. I just tape a rag onto the side of my carboy and slide the sensor in.

BTW, you do NOT want copper in the fermenter. Can't remember why, but John Palmer (who is a metalurgist as well as a preeminent brewer) states that copper is great in the boil and bad bad in the fermenter.

 

[RogueAg]

By no copper.... do you mean no copper in the fermentation chiller (fridge)... or just not in the actual fermenter (carboy) itself?? I was just planning on having it in the fridge with the carboy....

 

[passedpawn]

By no copper.... do you mean no copper in the fermentation chiller (fridge)... or just not in the actual fermenter (carboy) itself?? I was just planning on having it in the fridge with the carboy....

Woops. Sorry, I misunderstood apparently. I meant in the fermenter. When you said "drop it in" I assumed you meant in the fermenter.

Carry on, I'll just sit in the back with my mouth shut.

 

[GreenMonti]

If your not going to be in the liquid with the copper.....why do you need to water proof the probe? Humidity?

On your copper idea, you can place petroleum jelly in the copper tube before you seal in the probe. That should conduct the temp to the probe. At least that's what my Ashcroft temp gauges say to do when using a thermo-well.

 

[RogueAg]

It needs to be waterproof because I was going to put it in a glass of water sitting next to the fermenter in the fridge. My logic being I'd get an actual liquid temp but still not be putting anything into the fermenter. Plus I figure a small glass of water would be a good compromise between the big variations in fridge cycle times I might get with measuring air temp versus wort temp. Not sure if the logic is valid but it makes sense to me.

 

[RogueAg]

Btw.... Petroleum jelly. That's a good idea... Thanks!

 

[Scimmia]

It needs to be waterproof because I was going to put it in a glass of water sitting next to the fermenter in the fridge. My logic being I'd get an actual liquid temp but still not be putting anything into the fermenter.

That doesn't work. Don't forget, fermentation actually creates heat, so doing it this way, the fermenting wort will always be higher temp than what you want it to be.

 

[RogueAg]

That doesn't work. Don't forget, fermentation actually creates heat, so doing it this way, the fermenting wort will always be higher temp than what you want it to be.

hmmm... Good point. Uggh.... Now thoroughly confused on where the temp
probe should go.

 

[passedpawn]

Of course, it needs to go into your beer. Or, as I briefly said before, some blue painters tape to the side of the fermenter, then some insulation (rag) over that works fine too.

If you want to make something, get some spandex and cloth at a fabric store and make an elastic padded band to go around a carboy. Put a pocket in there for your probe that puts the probe against the carboy, with lots of padding on the outside. I've been putting this off for a while (daughter sews, and she's on summer break, so maybe soon)

 

[HopSong]

BTW, you do NOT want copper in the fermenter. Can't remember why, but John Palmer (who is a metalurgist as well as a preeminent brewer) states that copper is great in the boil and bad bad in the fermenter.

I'd guess that you'd be getting copper into your brew. As the brew ferments, it farts CO2 which is what makes Coke and other sodas acidic. Acid reacts pretty easily with, at least, copper oxide. Try putting some Tobasco on an oxidized penny. I'd guess soaking one in a glass of coke or vinegar would do the same thing