Has anyone set something up to measure the intake temp on a pool pump / heater?
There are easily accessible PCV pipes which can be drilled.
So far I found it looks like I could do Shelly Plus with the Add-on, and a DS18B20 sensor. I am sure someone has done this before. How do you secure the probe into the pipe leak free.
Or any other better devices to use besides Shelly?
My pool pipes are 2". I got a T with a 1/2" reduction:
I then bought a 1/2 Plug and drilled a hole, inserted the DS18B20 and epoxy.
I made multiple to insert before and after the heater and pump. I fed them all into a rPi, but for a single, the Shelly might be the right way. 
Last week, I bought a pressure sensor and it's 3/8" and I could not find the PVC T I used previously . 2" with a 3/4 reduction was plentiful and so I got one and a 3/4 to 3/8 stainless reduction.
I've had the whole system out in the weather for 3-4 years and you can see that they are unaffected in the slightest.
I should be able to use a Shelly dry contact as well, to turn the heater on an off, bonus.
I think this will work:
Shelly 1 Gen4 (has a dry contact and can take the add on module): Shelly 1 Gen4 — 16A Dry-Contact Smart Switch (Wi-Fi, Matter, Zigbee) – Shelly USA
Shelly Add on: Shelly Plus Add-On – Shelly USA
Now I just need to figure out a good way to get the probe on the pipe. Hopefully just going to drill it into the existing pipe without splicing in a Tee. You would think you could get some sort of a grommet that could be glued on, vs epoxying the entire probe in the hole.
Maybe something like this but local that will arrive faster, at least this would be easier to glue on: https://www.aliexpress.us/item/3256806533747112.html
@csteele I think you can connect up to 5 temp sensors to one Shelly add on..
Yea, I think that's true, 1-wire. They all just splice together.
I’ve used these for 1 inch irrigation pipe but unsure about larger sizes. Glue and snap on pipe and then drill the hole. Here is example:
If you have a Ewing Irrigation or Ferguson store locally they sell them.
I have done a similar DIY project using an ESP32 and 2 temp probes.
I am attaching some pictures so you can get the idea.
I am traveling currently thus can not add more details. If interested let me know and I can send you the full details and codes in a few days
I'm using a Fibaro Smart Implant for my water temp (with similar sensor probe in a 1/2" tee) and it has worked well. I will say the wiring harness from the Fibaro has very fine wires, but otherwise no complaints - easy to use.
https://www.fibaro.com/en/products/smart-implant/
I use the Fibaro Smart Implat as well and it has worked great.
I just had to order the extra long DS18B20 (3M) as thew standard ones seem to be about 1M.
The smart implant seems to be hard to get right now, that was my first thing I looked at. The Shelly was the backup plan but it looks like it has very similar functionality. Added bonus of getting the dry contact relay included on the main module which can be used for the heater on/off switch. Not sure if the Fibaro has a dry contact relay on it, did not get that far at looking at it,
Why not use some of the purpose built sensors like a Pentair 52027 or similar? They install with drilled hole and hose clamp. I believe they are 10k ohm. Maybe 20 bucks.
Because I didn't know what to look for, hence the reason for the post.
But what can I connect those to which can be read into Hubitat?
Now if there was a DS18B20 sensor in that style it would be perfect.
Not really knowing what you are into or hoping for the first easy path that comes to mind is a Shelly with the Shelly Plus Add-On. Combined with a Shelly Gen4 it can give you some options.
I use an ECOWITT ## WN34CL Waterproof thermometer which has been excellent and there's good Ecowitt integration for Hubitat. But be warned - the purchase of one, can lead to many.
Do you have it mounted in the pipe?
I've used DS18B20s with Arduino and ESP32 projects quite a bit. I like that they are digital so less impacted by electrical noise you contend with on analog sensors (thermistors). They are quite accurate.
You can get them with stainless steel jackets as shown below. I think using a PVC threaded cap and then drill a hole (around 1/4") for a snug fit of the stainless steel jacket would be easy enough. Then put it upside down (probe pointing to sky) and pour in some 5 minute epoxy to seal the inside of the cap to the probe tip. Once the epoxy sets you'll surely be leak free.
There can be some self heating artifacts if you continuously read the probe (more so in air than a liquid). Most of my applications have a separate power and data line and the power line is switched off between readings to reduce self heating. You can gang several of these together so it you wanted to go crazy put a couple probes in one cap and then add software to ensure they both are within an acceptable reading of each other.
Lastly be a little careful with controlling a heating device based on such a reading. You should have some sort of (independent) fail safe scheme such that if the controller gets locked up or the relay sticks closed there is a mechanism to stop the heater from running continuously.
I think the threaded cap is a good way to go, just need to find where to put it. Might need to get one of those snap-on tees for the cap to be added to.
Could possibly just jam a small cap into a hole in the pipe and seal it with glue/epoxy, but then if you need to replace the sensor at all it wont be easy.
The heater does have a failsafe max temp, and its own thermostat and flow sensor. It can flip from pool to spa mode but the switch on the heater is mechanical with no (good) way to switch it via automation. Can only shut it on or off. So it will always stay on spa mode with the max something like 104F. So possible issue is a failure while the valves are set for pool mode it could heat the entire pool to 104.
Probably will suggest adding some redundant sensors.
FYI I have this style (photo below) of sensor on my pool gear (Pentair). They just drill a hole into the pipe and install the probe and a clamp to hold it tight and compress the O-Ring. But these are thermistor sensors (10k ohm)....
I think I like the saddle tee idea. I found a few metal ones that might be easier to install than PVC. Rubber gasket to seal instead of glue fitting.
I know this is lame but I just hang my temp probe out of the intake basket and into the pool 50% down to the bottom.
I don't get the true temp of the pool if it's inline; the cover and sun passive heating don't reflect in the intake manifold.
Now I feel like a real bumpkin.
I think we would be fine with those but I dont know what device I can connect them to to read the temp? I think maybe they can connect to the Shelly Addon as well on one of the other inputs but its not super clear.
Only trying to use a DS18B20 because thats what the devices say they support.
I like those saddle Tee's, thanks for the tips. Now I know what to search for!
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