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Thermowell Build Options

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bignath

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Just working through some ideas in my head.

I have some copper tubing left over from a manifold build, and i also have some acrylic tube left over from a sightglass build....

I am building a new brewery and thought i'd mount a thermowell type device in the lid of the recirculating mashtun.

My STC probe fits down these tubes, and i was wondering could i use either of them to build a thermowell with some compression fittings?

If i could use either of them, which would be better...Can i use any of them at all?

I want to end up with a right angle comp fitting in the lid, with a rigid object guiding the probe down into the mash. As i will be recirculating the mash, i don't just want to throw the probe into the mash as i find when i've done this in the past, the probe tends to float and not stay put. I want to use the acrylic or copper tubing to guide the probe deep into the grain bed.

If this is possible, i've thought about crimping the copper tube shut at the end to keep the probe clean. I'm under the assumption that copper is excellent at transferring heat so in my head this should still work.

I want to be able to disconnect the probe at the comp fitting in the lid (which i've worked out how to do already).

I could also (i guess) use the acrylic tube, and then put a copper fitting over the end and crimp it closed too.

Are there any health issues with using the acrylic sitting in the mash? (I know stuff all about material composition and health issues).
The mash will be returned via another length of tube located right next to the thermowell idea, to go down into the grain bed to effectively keep it moving. (im thinking kind of like have a ghetto mash stirrer)...

Any thoughts?
 

RickyC

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Hi Big Nath

I'm an instrument tech by trade, currently working as an instrument engineer. We never use or offer 'plastic' type thermowells, PTFE thermowells are available on the market, but the transfer of temperature is poor and slow changes to measurement temperatures result.

Would definetely be using the copper tubing as the heat transfer will be much better. If you don't have a way of sealing one end of the copper tube (eg crimp and soldering) would go for a brass compression fitting with a cap. Take your tube down to Bunnings and have a look, should become more obvious.

Not saying the acrylic wouldn't work, just would not recommend it.

Cheers
Rick
 

benno1973

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I have not very much knowledge to impart here, but I would assume that the copper would be better for two reasons. Firstly, it's food grade as thousands of breweries/brew vessels can attest to. Secondly it's a better conductor of heat.

I assume that you'd need to fill the thermowell with some sort of fluid that would conduct heat to the probe, rather than having the probe sitting in open air?
 

bignath

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I assume that you'd need to fill the thermowell with some sort of fluid that would conduct heat to the probe, rather than having the probe sitting in open air?
hmm, i didn't know that. Makes sense....

I just assumed that the probe stayed dry inside a watertight tube. The more i think about it, it makes complete sense to fill the tube, then seal it up.

Quite obviously i've never used a thermowell before.
 

iralosavic

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hmm, i didn't know that. Makes sense....

I just assumed that the probe stayed dry inside a watertight tube. The more i think about it, it makes complete sense to fill the tube, then seal it up.

Quite obviously i've never used a thermowell before.

The ready made thermowells you see in brewery stores are designed for the probe to be a snug fit. I don't suppose you have smaller ID copper offcuts?
 

benno1973

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hmm, i didn't know that. Makes sense....

I just assumed that the probe stayed dry inside a watertight tube. The more i think about it, it makes complete sense to fill the tube, then seal it up.

Quite obviously i've never used a thermowell before.
Definitely don't take my word as gospel! I'm sure that you can get away with sitting it in an air filled tube, but the lag would be an issue, and you'd possibly fall short of your temps. You'd most likely want a close probe-metal contact (where the probe sits touching the copper and is insulated somewhat) or a liquid/gel heat conductor.
 

QldKev

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Will you be using a hear exchanger, cause then you should be measuring the outlet of the heat exchanger.

If you are recirc'ing the wort without a heat exchanger why are you not going to measure it from the outlet? Just wack a T piece prior to the tap and probe in from there.


If you want to stay with the thermo-well via the lid it does not need to be a sealed unit. Just mount the copper pipe into the lid facing into the grain bed. Drop the probe into it and back up from the bottom with a cable tie to hold it in place.

probe.GIF



QldKev
 

bignath

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Will you be using a hear exchanger, cause then you should be measuring the outlet of the heat exchanger.

If you are recirc'ing the wort without a heat exchanger why are you not going to measure it from the outlet? Just wack a T piece prior to the tap and probe in from there.


If you want to stay with the thermo-well via the lid it does not need to be a sealed unit. Just mount the copper pipe into the lid facing into the grain bed. Drop the probe into it and back up from the bottom with a cable tie to hold it in place.

View attachment 53532



QldKev
Thanks Kev. Nah, im not using a HX. I am a 3V brewer, but this build is for a BIAB rig (trying to simplify). Actually it's a recirculating BIAB. The wort return will come back in through the lid, down a tube to the bottom of the mash, from a pump mounted on a bottom draining ball valve. This bottom ball valve, will in turn have a t piece off of it, with one going to the lid (via pump) for wort return and the other end of the tee, will house a dial thermo. The dial thermo will monitor the temp of the wort coming out the bottom of the tun to give me an idea of what it's going back into the mash at, but the probe in the mash itself is what will actually control the elements.

I don't want the grain bed to compact down and stop the wort return being effective, which could create a situation where the wort return would then be heating up as the probe may think the mash isn't being heated.

I thought if i had one thermo measuring the wort return from the outlet, and the probe measuring that actual mash, and the probe would be connected to a stc1000, which would in turn engage the elements when (if) required.

This build should be finished by the weekend so i'll take some pics when it's done. Mounted the elements last night, but one of them leaks, so off to find some more cheap kettles now....taps are installed, only thing left is sightglass (easy as), and the actual mounting of the pump, and thermowells.

With a bit of luck, i might be able to brew on it next week.
 

sim

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I'm an instrument tech by trade, currently working as an instrument engineer. We never use or offer 'plastic' type thermowells, PTFE thermowells are available on the market, but the transfer of temperature is poor and slow changes to measurement temperatures result.

Would definetely be using the copper tubing as the heat transfer will be much better. If you don't have a way of sealing one end of the copper tube (eg crimp and soldering) would go for a brass compression fitting with a cap.
Sorry for the off topic.

Rick, through your trade do you happen to know whether your average off the shelf aussie brass compression fitting has lead in it?
 

pk.sax

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There is an AS number stamped on brass fittings. The one meant for potable water is meant to have less than 0.5% or something. Pick one up and google the standard.

Sort of unrelated, I read somewhere that brass fittings made in the USA contain no lead at all. Mitt be worth checking what their standards dictate.
 

alford_j

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Nath,

I use this heat transfer paste is my thermowell probes. The syringe is good to push the paste down a heatshrink tube to get it right to the end of the thermowell, then insert the sensor, I use the 18B20.
 

Feldon

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BigNath, I know you want to use your existing copper or acrylic tubing, but a low cost alternative might be someting like these oversize stainless knitting needles...

HiyaHiya.jpg

The end is spun closed and the tapered point would allow the temp probe to physically contact the internal sides for getting a good reading.

Those shown here are from a US web site ( http://www.shopatron.com/products/productd...972.41975.0.0.0 ).

But should be able to find something similar here in Australia.

(any knitters out there? c'mon fes up)
 

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