RTD selection, installation

[Ramdough]

So I am trying to piece together an electric brewery but save money where I can. I like Kal's setup but cannot afford it. So I am taking every item and searching for the best bang for the buck.

I found numerous cheaper rtd pt100 sensors but most of the cheep ones ($5) are 5 mm in diameter at the sensor and have 8mm threads. The ones with NPT fittings cost 3x as much ($15). All of these are probably made in China. I am not sure how I would install the metric ones without buying a metric tap or doing something strange.


What is everyone using and how did you install them?

I am looking for the most bang for the buck. I plan to interface them to an Arduino if that makes any difference.

Thanks.



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[iijakii]

You'll wind up spending more making fittings for them than just springing for the $15 NPT ones on eBay.

 

[Brumateur]

Make it yourself. It can be cheap if ypu dont mind to have brass and copper at your kettle. Buy a sensor element ($1 for 5 pcs) take a compression fitting for 3/8 pipe ($3-4) and piece of copper pipe. Thats it.

 

[Ramdough]

Is that what you did? Do you need any heat transfer material in the tube?


I thought about buying a plug and drilling it out, maybe I could just drill until thin. And install into the opening.


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[Brumateur]

.I did use a thermo paste, but all sensor I've seen (around 20 different but all from China ) don't have it.

 

[augiedoggy]

I used a 1/2" threaded to 3/8 chrome compression fitting and a faucet washer...I stuck the probe through the washer and the put it were the compression bushine normally would go... if I didnt have the fittengs laying around I would have sprung for the $15 if I needed 1/2" fittings...they have never leaked a drop.

On my boil kettle I just drilled a smaller hole and inserted the M8 size or whatever it was straight through the kettle with a small silicone washer on the outside lip.... works great.

al in al $15 is still better than the $32.00 most are buying with the quick disconnects from auber..
I wish I had gone that route though for my BK for cleaning.

you can always just drill out the center of a 1/2" plug or cap and thread or jbweld the sensor into it.

 

[stevehaun]

I made my own thermowells from copper tubing and brass compression fittings. I bought about 20 feet of k type thermocouple wire off ebay. Hook up one end to the PID, cut wire to appropriate length, strip 1/4" insulation off both wires on the other end and twist the ends together - ouila! - a thermocouple! RTDs are a little more accurate but we are brewing beer not launching the space shuttle. YMMV

 

[Ramdough]

Right now I am leaning toward drilling a plug and using food safe silicone with a stainless metric probe.




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[Bobby_M]

If you're going that far, might as well just buy an M8 tap.

 

[augiedoggy]

If you're going that far, might as well just buy an M8 tap.

or just drill a 3/8 or whatever hole size fits the m8 probe and use silicone or silicone washer and a nut... thats what I did on my BK... no reason the hole has to be a larger hole.

 

[baulz]

My plan is to drill/tap a plug for the M8 threads. I already have a tap set, and the plugs are cheap. For a way to disconnect at the panel I bought some cheap 3 pin aviation connectors on ebay.

I did buy one of the $15 ebay RTD's with NPT threads, but all I could find is 50mm probes and I needed some longer ones thus the cheap ones and extra work involved threading the plug.

 

[Ramdough]

Ok, I ended up buying 10 waterproof rtd sensors for $6 shipped on eBay. They appear to have the sensor part in a stainless tube that is closed on one end. If they come in and are sealed in a stainless shell, then I will rtv them into plugs. If the metal part is not stainless, then I will have to cover them in stainless tubes and make my own thermowells. I will let everyone know once I get them.


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[cank]

I got these from Probes Unlimited on ebay then asked them to make some SS tubes with the ends sealed in the length I needed. About $30+ shipping for five compression fittings and SS tubes.
I need to polish the tubes up a little... and set up my raspberry pi system!

I am going to use DS18 sensors but these would work with others too.

 

[Ramdough]

I got these from Probes Unlimited on ebay then asked them to make some SS tubes with the ends sealed in the length I needed. About $30+ shipping for five compression fittings and SS tubes.

I need to polish the tubes up a little... and set up my raspberry pi system!



I am going to use DS18 sensors but these would work with others too.

Thanks Cank! I just ordered 10. I already had 10 rtd sensors off of eBay for $6 shipped, so I will probably go the rtd route.


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[rgauthier20420]

I've got an thermocouple with 6.7mm thread that doesn't even fit a 1/8" bushing. I figure I can stick in into the bushing and just fill the inside of the bushing with food grade silicone to seal it. Anyone have any suggestions/links for an inexpensive food grade silicone?

 

[baulz]

My plan is to drill/tap a plug for the M8 threads. I already have a tap set, and the plugs are cheap. For a way to disconnect at the panel I bought some cheap 3 pin aviation connectors on ebay.

I did buy one of the $15 ebay RTD's with NPT threads, but all I could find is 50mm probes and I needed some longer ones thus the cheap ones and extra work involved threading the plug.

An update to this, I finally got around to drilling and tapping the plug. Installed it in my HLT and found out that the probes aren't waterproof, water runs right through it and down the wires. Cheap is not always better obviously.

Now, what options do I have without wasting much more money. Is it ok to use silicone to seal where the water is getting through? Or I can go to Home Depot and look for a brass compression fitting. Is the chrome fitting that augiedoggy used ok for the HLT?

I searched ebay again and the only 100mm long probes I could find would be $25.50 with shipping. Bobby_M has those nice stainless compression fittings but shipping to Canada makes it more than I want to spend.