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Old 06-05-2013, 04:39 PM   #1
Bensiff
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Looks like I made my mistake in ordering my kettle as I didn't switch out the thermowell where a dial thermometer with a 1/4" stem fits for a TC fitting. So now I need a plan for an RTD. I really like the Auber setups with deluxe cable as I want to be able to disconnect easily at the kettle. however they don't seem to make one with a 1/4" probe and 1/2" npt connector. Aubers customer service suggested I pack the thermowell with thermal grease but that seems like it would turn into an insulating compound used that way. I thought about turning the thermowell into an RTD probe but can't find 3 lead RTDs so don't know how I would accomplish that unless I'm missing something in how those are wired. My other thought is to get a prebuilt probe in the correct diameter casing and cut the wires to tie into an auber style quick release.

Any thoughts on how to proceed would be helpful.


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Old 06-05-2013, 05:19 PM   #2
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Could you explain your kettle setup a little more please? What kind of kettle, where you got it from (I'm in the market for a larger kettle) The thermowell currently attached is a weldless set up that fits 1/4" npt? I must not be picking up what your putting down.


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Old 06-05-2013, 06:32 PM   #3
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If you take apart one of the auber RTD sensors you will find that they use a 2 wire RTD with ~2" inch leads. They solder one white wire to one of the leads and two red wires to the other lead. This is how you make a 3 wire RTD out of an RTD with only 2 leads.

Also thermal grease is not an insulator. It is a thermal conductor and works very well for conducting heat. You will definitely want to use it inside the thermal well if you make your own sensor.
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Old 06-05-2013, 08:31 PM   #4
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Quote:
Originally Posted by rmaloney86
Could you explain your kettle setup a little more please? What kind of kettle, where you got it from (I'm in the market for a larger kettle) The thermowell currently attached is a weldless set up that fits 1/4" npt? I must not be picking up what your putting down.
It's from stout tanks. Thermowell has 1/2" female npt that has a 1/4" diameter probe going roughly 3" into the kettle. It is all integrated, not weldless.
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Old 06-05-2013, 08:40 PM   #5
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Quote:
Originally Posted by crane
If you take apart one of the auber RTD sensors you will find that they use a 2 wire RTD with ~2" inch leads. They solder one white wire to one of the leads and two red wires to the other lead. This is how you make a 3 wire RTD out of an RTD with only 2 leads.

Also thermal grease is not an insulator. It is a thermal conductor and works very well for conducting heat. You will definitely want to use it inside the thermal well if you make your own sensor.
I have only used thermal grease when building a computer which uses the thinnest of layers if it so I was worried that loading up a 1/4" tube with it would slow heat transfer. But I suppose an air gap would be pretty bad too so something has to be in there.

So would you recommend ripping apart an auber and housing the internals in the kettles integrated thermowell packed with thermal grease, building my own from the ground up, or just using the standard auber probes in a thermowell packed with thermal grease? In the latter option I would imagine the auber probe would have a few mm of grease between it and the kettles thermowell wall.
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Old 06-06-2013, 01:36 PM   #6
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Quote:
Originally Posted by Bensiff

I have only used thermal grease when building a computer which uses the thinnest of layers if it so I was worried that loading up a 1/4" tube with it would slow heat transfer. But I suppose an air gap would be pretty bad too so something has to be in there.

So would you recommend ripping apart an auber and housing the internals in the kettles integrated thermowell packed with thermal grease, building my own from the ground up, or just using the standard auber probes in a thermowell packed with thermal grease? In the latter option I would imagine the auber probe would have a few mm of grease between it and the kettles thermowell wall.
You don't need to load up the entire thermal well with grease. You really only need enough to make good contact between the RTD tip and the tip of the thermal well.

I wouldn't buy an auber RTD just to take it apart. It would be a lot cheaper to buy an RTD element with 1-2" leads on it and solder on three wires. I was just using that as an example of how 3 wire RTD sensors are constructed. If you are lucky you may be able to find out from auber the exact RTD they are using in their probes and buy some from Digikey or mouser.

I so wouldn't take the auber sensor and shove it into the thermal well. Stainless steal is t the best thermal conductor so adding an additional layer of it will slow down your sensors response to changes and possibly introduce an increasing offset as the water temp moves farther away from the ambient air temp.
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Old 06-06-2013, 05:55 PM   #7
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Quote:
Originally Posted by crane

You don't need to load up the entire thermal well with grease. You really only need enough to make good contact between the RTD tip and the tip of the thermal well.

I wouldn't buy an auber RTD just to take it apart. It would be a lot cheaper to buy an RTD element with 1-2" leads on it and solder on three wires. I was just using that as an example of how 3 wire RTD sensors are constructed. If you are lucky you may be able to find out from auber the exact RTD they are using in their probes and buy some from Digikey or mouser.

I so wouldn't take the auber sensor and shove it into the thermal well. Stainless steal is t the best thermal conductor so adding an additional layer of it will slow down your sensors response to changes and possibly introduce an increasing offset as the water temp moves farther away from the ambient air temp.
Wouldn't I need to fashion a Wheatstone bridge than? Does anyone have a design for this?
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Old 06-06-2013, 07:20 PM   #8
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So what's the problem with using this?
http://www.auberins.com/index.php?ma...roducts_id=261

This would be exactly the same as the stout setup only with an RTD instead of a dial thermometer. Fill the thermowell with mineral oil or thermal compound to improve response time (again just like stout).

I think the difference in delay would barely be noticable (if at all) between such a setup and just having the probe stick directly into the mash.
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Old 06-06-2013, 08:42 PM   #9
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Quote:
Originally Posted by orangehero
So what's the problem with using this?
http://www.auberins.com/index.php?ma...roducts_id=261

This would be exactly the same as the stout setup only with an RTD instead of a dial thermometer. Fill the thermowell with mineral oil or thermal compound to improve response time (again just like stout).

I think the difference in delay would barely be noticable (if at all) between such a setup and just having the probe stick directly into the mash.
That is pretty much exactly what I wanted but I was worried about the response time going through two metal casings and a thick thermal grease layer between the two.
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Old 06-07-2013, 03:14 PM   #10
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Quote:
Originally Posted by Bensiff

Wouldn't I need to fashion a Wheatstone bridge than? Does anyone have a design for this?
No. You would hook this up just like any other 3 wire RTD.


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