# Thermowell Questions....



## bignath (17/2/12)

Hi all,

have just purchased an STC-1000 off evilbay. I want to use it in my electric HLT to automate the strike and sparge water heating via a singular 2200W kettle element.

Thermowells. I've never used one before, never actually seen one in "the flesh" either.

Have been reading various threads most of the afternoon, but have some questions i need clarification on...

Am thinking about the ones beerbelly sell. Do they literally just install through the side of the HLT and then the probe "sits" inside the thermowell??

Assuming im correct, the probe doesn't actually come into contact with the water, but takes it's reading off of the metal on the inside of the thermowell??

Assuming that this is also correct, does the probe need to be a really snug fit inside the thermowell?

Do you need to allow for any temp variations considering the probe wouldn't be measuring the water itself or is the probe sitting inside the thermowell reading the thermowell wall accurate enough....

Sorry for what probably seem like really dumb questions, but i really don't know anything about thermowells and using them properly. 

I have tempmates on some fridges, so i'm comfortable with using one of those, and therefore will be comfortable wiring up the stc 1000, it's just that i don't fully understand the "installation and measuring" side of the equation.

All help appreciated.

Nath


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## MaltyHops (17/2/12)

Big Nath said:


> ...
> Assuming im correct, the probe doesn't actually come into contact with the water,
> but takes it's reading off of the metal on the inside of the thermowell??
> Assuming that this is also correct, does the probe need to be a really snug fit inside
> ...


I don't have a thermowell (or know for sure) but I'd say the first point above is
correct. Steel is not the best heat conductor but it's pretty good and there'd be
enough contact between probe and well surface to make remaining points
non-issues.

Recommend you think carefully how high up the pot you position the well as
that dictates the minimum fluid level you can have during operation.


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## QldKev (17/2/12)

Why don't you just hang the probe in the water? Lots cheaper and you get the actual water temp, I've used one this way for many batches (BIAB water temp, and today the first time in the HLT)


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## alford_j (17/2/12)

Big Nath,

you need to use a heat transfer compound such as "transfer compound". However good or bad stainless is as a heat transfer medium, air is much worse. The grease forms a thermal bridge from the sensor to the thermowell. I made a probe previously and used "jb weld" to seal the cable to the body of the thermowell.

Alfie


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## bignath (17/2/12)

MaltyHops said:


> Recommend you think carefully how high up the pot you position the well as
> that dictates the minimum fluid level you can have during operation.



Yeah, had thought about this. It's gonna be mounted very low in the keggle. 
My HLT drains out from the bottom of the keg (i have installed a ball valve tap to the flat circular area on the underneath panel of the keg) and into a little brown pump, which then sends it back up to the top of the keggle to recirculate, keeping the temp stable throughout. I currently have a mashmaster dial thermo mounted as low as i thought i could go without leaking, and i plan to install a sightguage soon too, so i was gonna replace the thermo with the "t piece" design and have the sightguage going vertical and install the thermowell in the front of the t piece.



QldKev said:


> Why don't you just hang the probe in the water? Lots cheaper and you get the actual water temp, I've used one this way for many batches (BIAB water temp, and today the first time in the HLT)



Cheers for this idea. I had also thought of that too, but i couldn't seem to find a definitive answer as to whether the probe was ok to submerge at sparge water temp. I know they are designed to go into an aquarium, but there were several posts i've read today that indicated submerging at hot water temps like brewers typically use may not be such a good idea.....
You've obviously had no worries kev? Do you use the standard supplied probe that comes with the stc1000?


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## bradsbrew (17/2/12)

Are you recirculating the water in your hlt? You will get pretty inaccurate temp measurements using a thermowell in the hlt and that is also dependant on where the element is situated in the vessel.
Best bet would be to recirc with a cheap pump and stick the probe in a T junction with compression fittings. I have an stc in my herms and the probe is set in the vertical part of the T so the fluid flows past the probe after the HX.
Another option would be the wiper motor to stir the water as it heats.

Cheers

Edit= I use the standard stc probe. I took kevs advice on that as well.


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## bignath (17/2/12)

bradsbrew said:


> Are you recirculating the water in your hlt? You will get pretty inaccurate temp measurements using a thermowell in the hlt and that is also dependant on where the element is situated in the vessel.
> Best bet would be to recirc with a cheap pump and stick the probe in a T junction with compression fittings. I have an stc in my herms and the probe is set in the vertical part of the T so the fluid flows past the probe after the HX.
> Another option would be the wiper motor to stir the water as it heats.
> 
> Cheers



I just got in before you mate, (as written in my post above yours)

Would love to use compression fittings....where would be the best bet to find one small enough to take a probe? I've found heaps of 12mm/ half inch ones but never seen any smaller like 3-6mm for example...

I have a couple of probes i'd like to try with the stc1000 (all are NTC but not sure if completely compatible) and the one i'd really like to use is about 3.5mm diameter. Can you get comp fitting that small??


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## DJR (17/2/12)

bradsbrew said:


> Are you recirculating the water in your hlt? You will get pretty inaccurate temp measurements using a thermowell in the hlt and that is also dependant on where the element is situated in the vessel.



This is where a PID controller comes into its own as it can control overshoot etc rather than an STC1000, but that's another matter 

In my HLT i have a custom made thermowell that Matho made up for me - it is basically just an SS bolt, nut, washer and silicon bakeware ring with a hole lathed out of it on the back. The DS1820 probe i have then sits inside it, with a dab of thermal grease, the white silicon based stuff that Jaycar sell.

I've seen people use lengths of SS tube in a comp fitting clamped at one end, or even just with food grade epoxy up the end to seal the tube. If you went down that route you could use a longer length of 3/8" or 1/4" copper which is a far better heat conductor, crimped at one end. Only issue being copper isn't as simple as SS to keep clean etc. Shame Aluminium doesn't have the drawability of copper or SS to make pipe that's easy to work with as that'd be ideal, good heat conduction and easy to take care of

As for comp fittings try a Reece or other plumbing supplies shop - you'll annoy them slightly until you tell them it's for homebrew and you will ask countless stupid questions for the price of the free beer you hand them


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## bradsbrew (17/2/12)

I used the the 12mm one just pushed the probe through a bit of beer/gas line then put that into a bit of 12mm ext ID tube and put through the compression fitting. No leaks.

Cheers


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## bignath (17/2/12)

bradsbrew said:


> I used the the 12mm one just pushed the probe through a bit of beer/gas line then put that into a bit of 12mm ext ID tube and put through the compression fitting. No leaks.
> 
> Cheers



Man, that's an awesome idea! I never would have thought of that, thanks heaps!


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## voodoobrew (17/2/12)

I bought a cheap SS thermowell off Ebay, which from memory was about US$15. I snipped my probe and soldered it to an RCA fitting, mounted it in a brass plug from the plumbing supplier, then filled the plug with some 5min epoxy.







Then I put a matching connector on the thermostat end and now my HLT has a neat sensor connection which is convenient when I have to lift the HLT off the brew frame to empty the dregs, etc.






I thought I'd need to pump the thermowell full of thermal grease, but I used it a few times before the compound turned up in the mail and realised that it just didn't need it - it worked perfectly fine without.


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## bignath (17/2/12)

voodoo, great idea. 

I really like the idea of being able to disconnect it quickly to empty and clean out HLT just by removing the cable.

Do you find the temp that the controller gives is accurate inside the thermowell? Or do you adjust the setpoint to take into consideration any discrepancy??


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## voodoobrew (18/2/12)

I find it pretty accurate. I mean the great advantage I find from this setup is to be able to set and let it heat up unattended to ball-park while I mill grain, set up the rest of the brew gear, etc. Then it'll happily sit within a couple of degrees of your desired temp - so if you're finicky you can stir up the water, take final measurements with a glass thermometer, or whatever. Personally I don't bother and I'm happy with what the thermostat comes up with. I have a digital thermometer in my mash tun, so I've just learned what the temps indicated on the HLT tend to end up at in the mash and most times hit my targets reliably.

At the end of the day, brewing really is a bit of an exercise in getting to know the equipment you're brewing on. As long as your gear behaves consistently then it's all good.


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## Online Brewing Supplies (18/2/12)

voodoobrew said:


> I bought a cheap SS thermowell off Ebay, which from memory was about US$15. I snipped my probe and soldered it to an RCA fitting, mounted it in a brass plug from the plumbing supplier, then filled the plug with some 5min epoxy.
> 
> 
> 
> ...


You could have used the money you saved and replaced your old rope.I do laugh some times with the ingenuity of brewers then I see things held together with cable ties and rope. :icon_cheers: 
Nev


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## keifer33 (18/2/12)

Gryphon Brewing said:


> You could have used the money you saved and replaced your old rope.I do laugh some times with the ingenuity of brewers then I see things held together with cable ties and rope. :icon_cheers:
> Nev



I think they are shoe laces Nev


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## Edak (18/2/12)

keifer33 said:


> I think they are shoe laces Nev



And now he only wears thongs because he can't do up his shoes any more. 

These are good ideas guys keep them coming. 

I was under the impression that the stc1000 had pid control which took care of overshoot.


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## QldKev (18/2/12)

Big Nath said:


> Cheers for this idea. I had also thought of that too, but i couldn't seem to find a definitive answer as to whether the probe was ok to submerge at sparge water temp. I know they are designed to go into an aquarium, but there were several posts i've read today that indicated submerging at hot water temps like brewers typically use may not be such a good idea.....
> You've obviously had no worries kev? Do you use the standard supplied probe that comes with the stc1000?



No probs with the probe in the water. 

You can also get a compression fitting for smaller than 12mm hoses.




Edak said:


> I was under the impression that the stc1000 had pid control which took care of overshoot.





You can calibrate the temp using F4


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## beerdrinkingbob (18/2/12)

Craft brewer has a ss probe to suit. Cost about 30 from memory.


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## Burt de Ernie (4/5/14)

I just made these up last night which are designed to sit inline on the herms recirc pipe work. 2 x 20mm brass plugs and 200mm of 12mm copper.

EDIT: Sorry....I cant work out why these pics come out with the incorrect rotation


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## Salt (1/9/14)

voodoobrew said:


> I bought a cheap SS thermowell off Ebay, which from memory was about US$15. I snipped my probe and soldered it to an RCA fitting, mounted it in a brass plug from the plumbing supplier, then filled the plug with some 5min epoxy.
> 
> 
> 
> ...


Sorry to dig up an old thread, but why put the STC probe into a thermowell?

Could you not just have the probe itself in the water, given the correct fittings, you could screw your brass plug into a nipple/coupling connection and do away with the thermowell...??


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