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Author Topic: Temperature sensors  (Read 742 times)

wdingus

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Temperature sensors
« on: November 02, 2016, 05:42:36 PM »

If you are measuring water temperature related to your OWB, with a digital sensor accessible via computer, how are you exposing it to the water? Analog gauges seem to commonly have a 1/4" NPT connection. Which I assume is typically screwed into a tee? The biggest differential I see in a brass tee @ supply house is 1" x 1" x 3/4". So a sleeve to connect the 1/4" gauge into the 3/4" side? Same principle for a digital sensor?

What kind of sensors are you using? There are automotive engine coolant sensors which seem like should work. https://www.amazon.com/Auto-Meter-2385-Autogage-Temperature/dp/B00062YVWU/ref=pd_sbs_263_3?ie=UTF8&psc=1&refRID=QS9TZHNF92VQMN6VVYFM They connect via NPT, are waterproof, and inexpensive, etc.. I'm not sure how to "read" one though. Are they just a packaged thermistor or similar? If there's some reason one of those can't work or would be too difficult/expensive, something like this perhaps? https://www.adafruit.com/products/642  Poke it into the tee and epoxy around it?

I've seen some sensors strapped to the outside of a pipe but have to think that wouldn't be quite as good, accurate, or quick to register change. Thoughts?

Thanks.

PS. 1" x 1" x 1/4" even though the picture appears incorrect. https://www.amazon.com/Everflow-Supplies-BRRT1000-NL-4-Inch-Reducing/dp/B00N2SDVTO/ref=sr_1_fkmr0_2?ie=UTF8&qid=1478129893&sr=8-2-fkmr0&keywords=1%22+x+1%22+x+1%2F4%22+tee+brass+npt
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RSI

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Re: Temperature sensors
« Reply #1 on: November 02, 2016, 08:42:02 PM »

Strapped to a pipe isn't that bad if you insulate it good. It will read a little low but that isn't a big deal normally.
You would now want to try epoxying a sensor in like that. It would most likely not hold up. I played around with putting a compression fitting on one and it looked like it might have worked but I decided I didn't want to take a chance with it. Also, putting the fittings in the pipe will cause more restriction and adds more possible leak points.
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NaturallyAspirated

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Re: Temperature sensors
« Reply #2 on: November 30, 2016, 05:01:07 AM »

"Reading" one is where the process becomes a bit complex. If you want the data to be displayed on a website where you can navigate to it from a browser, a good way may be Arduino (especially since you posed some adafruit gear).  If you are familiar with programming the arduino then you can code such that the Arduino + ethernet shield will allow it to function as a webserver, that will update with any information on the pins at a set refresh rate of your choosing.  The One Wire solution would work, as would an analog thermocouple amplifier ( https://www.amazon.com/gp/product/B01KTXNU0E/ref=oh_aui_detailpage_o06_s00?ie=UTF8&psc=1 ) and a K type thermocouple ( https://www.amazon.com/uxcell-Thread-Thermocouple-Temperature-Measurement/dp/B00899A53G/ref=sr_1_11?ie=UTF8&qid=1480506829&sr=8-11&keywords=k+type+thermocouple ).  For my deployment I have ordered the analog amplifier, as I wanted to keep all serial communications focused on the SPI buss for the ethernet shield.  If you want to take your project a step further (and add significant cost) you can deploy some HMI software that would allow you to create javascript style hooks to author a much higher functioning website than what the Arduino will be capable of.  For example I am wrapping all the pin data from my Arduino in Modbus TCP (via Mudbus library) and talking to HMI software ( https://www.openautomationsoftware.com/ ) which then allows all the tags (pin data) of the Arduino to be collected and published on a WAMP (http://www.wampserver.com/en/)

It's a complicated process but allows realtime monitoring and availbility of the furnace data to web based platforms.

Neal
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schoppy

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Re: Temperature sensors
« Reply #3 on: November 30, 2016, 10:11:13 PM »

Yup, way too complicated for me but I would go with RSI's suggestion. In 30 plus years of Hvac work we only used surface sensing temp testers. Started years ago with analog but last ones were digital and very accurate. Key on these sensors is positive contact with the piping surface, copper best but iron pipe ok, and as RSI said well insulated. Remember, only the very tip on almost all sensors is the sensing area and is the area needing good contact and insulation. The rest of your programming info is way over my head. Good luck. 
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marty

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Re: Temperature sensors
« Reply #4 on: December 15, 2016, 08:50:28 AM »

I'm definitely interested in an arduino/ raspberry pi custom solution sounds very cool to me.  I took the 'easy' way out and use an x300 temp logger, some details in the other post.  I just foil-taped my sensors to the copper (pex even in a couple cases) and wrapped with pipe insulation.  Agree with everything RSI mentions.   I think my temps are pretty spot on, maybe a tad low.  There is no issue with lag as you mention.  I see temps about 2 degrees cooler than my OWB display reads, but quite a bit of that (or all) is just heat loss from my pipe run.

I got my sensors on ebay, real cheap, they look like this:
« Last Edit: December 15, 2016, 08:56:35 AM by marty »
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NaturallyAspirated

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Re: Temperature sensors
« Reply #5 on: January 13, 2017, 07:50:56 PM »

I'm definitely interested in an arduino/ raspberry pi custom solution sounds very cool to me.  I took the 'easy' way out and use an x300 temp logger, some details in the other post.  I just foil-taped my sensors to the copper (pex even in a couple cases) and wrapped with pipe insulation.  Agree with everything RSI mentions.   I think my temps are pretty spot on, maybe a tad low.  There is no issue with lag as you mention.  I see temps about 2 degrees cooler than my OWB display reads, but quite a bit of that (or all) is just heat loss from my pipe run.

I got my sensors on ebay, real cheap, they look like this:
Those are just standard thermocouples.   :thumbup:  It wouldn't be much harder to get one with a threaded end, then you could install a T in your pex and install the thermocouple directly in the water.  That would make for a more accurate reading.

https://www.amazon.com/50x5mm-Thermocouple-Temperature-Sensor-Meters/dp/B00C97J5EE/ref=sr_1_6?ie=UTF8&qid=1484362158&sr=8-6&keywords=k+type+thermocouple

When I get some time I will post up some code and parts for a web based temp reading setup.  I would really like to incorporate flow rate with a few thermocouples to calculate BTU usage.

Neal
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mlappin

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Re: Temperature sensors
« Reply #6 on: January 13, 2017, 08:26:45 PM »

You can also buy threaded thermowells to screw into a T then the thermocouple can be slid into those with a little arctic silver on it.
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NaturallyAspirated

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Re: Temperature sensors
« Reply #7 on: January 14, 2017, 03:59:00 PM »

You can also buy threaded thermowells to screw into a T then the thermocouple can be slid into those with a little arctic silver on it.
A good idea if we all buy these super cheap chinese thermocouples.   ;D

Neal
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stryker

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Re: Temperature sensors
« Reply #8 on: March 22, 2017, 08:43:33 PM »

We do sell a decent amount of these wired units. They have a 75' wire on them and you just tee the sensor into your supply line. I mounted the readout next to my thermostat in the hallway. It works great.  http://www.ohiowoodfurnaces.com/catalog/product.php?productid=1982
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NaturallyAspirated

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Re: Temperature sensors
« Reply #9 on: March 30, 2017, 01:29:40 PM »



Doing some bench testing with thermocouples and Arduino.   :thumbup:

Neal
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Re: Temperature sensors
« Reply #10 on: March 30, 2017, 05:02:54 PM »

Got it rigged up so you can do as many thermocouples into your Arduino as you want.   :thumbup:



Neal
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